Chloroplasts' main role is to conduct photosynthesis, where the photosynthetic pigment chlorophyll captures the energy from sunlight and converts it and stores it in the energy-storage molecules ATP and NADPH while freeing oxygen from water. They then use the ATP and NADPH to make organic molecules from carbon dioxide in a process known as the Calvin cycle. Chloroplasts carry out a number of other functions, including fatty acid synthesis, much amino acid synthesis, and the immune response in plants. The number of chloroplasts per cell varies from 1 in algae up to 100 in plants like Arabidopsis and wheat.
What is the primary purpose of chloroplasts?
Ground Truth Answers: to conduct photosynthesisconduct photosynthesisconduct photosynthesis
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What does ATP store?
Ground Truth Answers: energyenergyenergy
Prediction:
What does NADPH store?
Ground Truth Answers: energyenergyenergy
Prediction:
What is the process of turning CO2 into organic molecules called?
Ground Truth Answers: the Calvin cycleCalvin cycleCalvin cycle
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How many chloroplasts per cell does algae have?
Ground Truth Answers: 111
Prediction:
Chloroplasts are highly dynamic—they circulate and are moved around within plant cells, and occasionally pinch in two to reproduce. Their behavior is strongly influenced by environmental factors like light color and intensity. Chloroplasts, like mitochondria, contain their own DNA, which is thought to be inherited from their ancestor—a photosynthetic cyanobacterium that was engulfed by an early eukaryotic cell. Chloroplasts cannot be made by the plant cell and must be inherited by each daughter cell during cell division.
How do chloroplasts reproduce?
Ground Truth Answers: pinch in twopinch in twopinch in two
Prediction:
What influences chloroplasts' behavior?
Ground Truth Answers: environmental factors like light color and intensityenvironmental factorsenvironmental factors like light color and intensity
Prediction:
How are chloroplasts similar to mitochondria?
Ground Truth Answers: contain their own DNAcontain their own DNAcontain their own DNA,
Prediction:
What was the ancestor of chloroplasts?
Ground Truth Answers: a photosynthetic cyanobacterium that was engulfed by an early eukaryotic cella photosynthetic cyanobacteriumphotosynthetic cyanobacterium that was engulfed by an early eukaryotic cell
Prediction:
How do plants get chloroplasts?
Ground Truth Answers: must be inherited by each daughter cell during cell divisioninheritedinherited by each daughter cell during cell division
Prediction:
Chloroplasts are one of many types of organelles in the plant cell. They are considered to have originated from cyanobacteria through endosymbiosis—when a eukaryotic cell engulfed a photosynthesizing cyanobacterium that became a permanent resident in the cell. Mitochondria are thought to have come from a similar event, where an aerobic prokaryote was engulfed. This origin of chloroplasts was first suggested by the Russian biologist Konstantin Mereschkowski in 1905 after Andreas Schimper observed in 1883 that chloroplasts closely resemble cyanobacteria. Chloroplasts are only found in plants and algae.
Which organisms have chloroplasts?
Ground Truth Answers: plants and algaeplants and algaeplants and algae.
Prediction:
What nationality was Konstantin Mereschkowski?
Ground Truth Answers: RussianRussianRussian
Prediction:
What was Konstantin Mereschkowski's career?
Ground Truth Answers: biologistbiologistbiologist
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When did Konstantin Mereschkowski suggest the origin of chloroplasts?
Ground Truth Answers: 190519051905
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Who said chloroplasts are similar to cyanobacteria?
Ground Truth Answers: Andreas SchimperAndreas SchimperAndreas Schimper
Prediction:
Cyanobacteria are considered the ancestors of chloroplasts. They are sometimes called blue-green algae even though they are prokaryotes. They are a diverse phylum of bacteria capable of carrying out photosynthesis, and are gram-negative, meaning that they have two cell membranes. Cyanobacteria also contain a peptidoglycan cell wall, which is thicker than in other gram-negative bacteria, and which is located between their two cell membranes. Like chloroplasts, they have thylakoids within. On the thylakoid membranes are photosynthetic pigments, including chlorophyll a. Phycobilins are also common cyanobacterial pigments, usually organized into hemispherical phycobilisomes attached to the outside of the thylakoid membranes (phycobilins are not shared with all chloroplasts though).
What are chloroplasts descended from?
Ground Truth Answers: CyanobacteriaCyanobacteriaCyanobacteria
Prediction:
What type of organism are cyanobacteria?
Ground Truth Answers: prokaryotesbacteriaprokaryotes
Prediction:
What does 'gram-negative' mean?
Ground Truth Answers: they have two cell membranestwo cell membranesthey have two cell membranes.
Prediction:
What kind of cell wall do cyanobacteria have?
Ground Truth Answers: peptidoglycanpeptidoglycanpeptidoglycan
Prediction:
How are cyanobacteria sometimes wrongly described?
Ground Truth Answers: blue-green algaeblue-green algaesometimes called blue-green algae
Prediction:
Somewhere around a billion years ago, a free-living cyanobacterium entered an early eukaryotic cell, either as food or as an internal parasite, but managed to escape the phagocytic vacuole it was contained in. The two innermost lipid-bilayer membranes that surround all chloroplasts correspond to the outer and inner membranes of the ancestral cyanobacterium's gram negative cell wall, and not the phagosomal membrane from the host, which was probably lost. The new cellular resident quickly became an advantage, providing food for the eukaryotic host, which allowed it to live within it. Over time, the cyanobacterium was assimilated, and many of its genes were lost or transferred to the nucleus of the host. Some of its proteins were then synthesized in the cytoplasm of the host cell, and imported back into the chloroplast (formerly the cyanobacterium).
What kind of cell did cynaobacteria enter long ago?
Ground Truth Answers: eukaryotican early eukaryotic celleukaryotic
Prediction:
How long ago did cyanobacteria enter a cell?
Ground Truth Answers: around a billion years agoa billion years agoaround a billion years ago
Prediction:
What surrounds chloroplasts?
Ground Truth Answers: two innermost lipid-bilayer membranesphagocytic vacuolelipid-bilayer membranes
Prediction:
What kind of membrane came from the host?
Ground Truth Answers: phagosomalphagosomalphagosomal
Prediction:
What happened when cyanobacteria was assimilated?
Ground Truth Answers: many of its genes were lost or transferred to the nucleus of the hostmany of its genes were lost or transferredmany of its genes were lost or transferred to the nucleus of the host
Prediction:
These chloroplasts, which can be traced back directly to a cyanobacterial ancestor, are known as primary plastids ("plastid" in this context means almost the same thing as chloroplast). All primary chloroplasts belong to one of three chloroplast lineages—the glaucophyte chloroplast lineage, the rhodophyte, or red algal chloroplast lineage, or the chloroplastidan, or green chloroplast lineage. The second two are the largest, and the green chloroplast lineage is the one that contains the land plants.What does 'plastid' mean?
Ground Truth Answers: almost the same thing as chloroplastchloroplastchloroplast
Prediction:
How many chloroplast lineages are there?
Ground Truth Answers: threethreethree
Prediction:
What does rhodophyte mean?
Ground Truth Answers: red algal chloroplastred algal chloroplast lineagered algal chloroplast lineage
Prediction:
What does chloroplastidan mean?
Ground Truth Answers: green chloroplastgreen chloroplast lineagegreen chloroplast lineage
Prediction:
Which lineage includes land plants?
Ground Truth Answers: the green chloroplast lineagethe green chloroplast lineagegreen chloroplast lineage
Prediction:
The alga Cyanophora, a glaucophyte, is thought to be one of the first organisms to contain a chloroplast. The glaucophyte chloroplast group is the smallest of the three primary chloroplast lineages, being found in only 13 species, and is thought to be the one that branched off the earliest. Glaucophytes have chloroplasts that retain a peptidoglycan wall between their double membranes, like their cyanobacterial parent. For this reason, glaucophyte chloroplasts are also known as muroplasts. Glaucophyte chloroplasts also contain concentric unstacked thylakoids, which surround a carboxysome - an icosahedral structure that glaucophyte chloroplasts and cyanobacteria keep their carbon fixation enzyme rubisco in. The starch that they synthesize collects outside the chloroplast. Like cyanobacteria, glaucophyte chloroplast thylakoids are studded with light collecting structures called phycobilisomes. For these reasons, glaucophyte chloroplasts are considered a primitive intermediate between cyanobacteria and the more evolved chloroplasts in red algae and plants.
What chloroplast lineage is Cyanophora in?
Ground Truth Answers: glaucophyteglaucophyteglaucophyte chloroplast group
Prediction:
What kind of organism is Cyanophora?
Ground Truth Answers: algaalgaglaucophyte
Prediction:
What are muroplasts?
Ground Truth Answers: glaucophyte chloroplastsglaucophyte chloroplastsglaucophyte chloroplasts
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What do concentric unstacked thylakoids surround?
Ground Truth Answers: a carboxysomecarboxysomecarboxysome
Prediction:
What kind of structure is a carboxysome?
Ground Truth Answers: icosahedralicosahedralicosahedral
Prediction:
Rhodoplasts have a double membrane with an intermembrane space and phycobilin pigments organized into phycobilisomes on the thylakoid membranes, preventing their thylakoids from stacking. Some contain pyrenoids. Rhodoplasts have chlorophyll a and phycobilins for photosynthetic pigments; the phycobilin phycoerytherin is responsible for giving many red algae their distinctive red color. However, since they also contain the blue-green chlorophyll a and other pigments, many are reddish to purple from the combination. The red phycoerytherin pigment is an adaptation to help red algae catch more sunlight in deep water—as such, some red algae that live in shallow water have less phycoerytherin in their rhodoplasts, and can appear more greenish. Rhodoplasts synthesize a form of starch called floridean, which collects into granules outside the rhodoplast, in the cytoplasm of the red alga.
What kinds of pigments do rhodoplasts have?
Ground Truth Answers: chlorophyll a and phycobilinsphycobilinphycobilin
Prediction:
What are rhodoplasts' phycobilin pigments combined into?
Ground Truth Answers: phycobilisomesphycobilisomesphycobilisomes
Prediction:
What makes red algae red?
Ground Truth Answers: the phycobilin phycoerytherinphycobilin phycoerytherinphycobilin phycoerytherin
Prediction:
What is the benefit of red algae being red?
Ground Truth Answers: catch more sunlight in deep watercatch more sunlight in deep watercatch more sunlight in deep water
Prediction:
What is floridean?
Ground Truth Answers: a form of starcha form of starcha form of starch
Prediction:
The chloroplastidan chloroplasts, or green chloroplasts, are another large, highly diverse primary chloroplast lineage. Their host organisms are commonly known as the green algae and land plants. They differ from glaucophyte and red algal chloroplasts in that they have lost their phycobilisomes, and contain chlorophyll b instead. Most green chloroplasts are (obviously) green, though some aren't, like some forms of Hæmatococcus pluvialis, due to accessory pigments that override the chlorophylls' green colors. Chloroplastidan chloroplasts have lost the peptidoglycan wall between their double membrane, and have replaced it with an intermembrane space. Some plants seem to have kept the genes for the synthesis of the peptidoglycan layer, though they've been repurposed for use in chloroplast division instead.
What do red algal chloroplasts have that green chloroplasts don't?
Ground Truth Answers: phycobilisomesphycobilisomesphycobilisomes
Prediction:
Why aren't some forms of Hæmatococcus pluvialis green?
Ground Truth Answers: accessory pigments that override the chlorophylls' green colorsaccessory pigmentsaccessory pigments that override the chlorophylls' green colors
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What don't chloroplastidan chloroplasts have?
Ground Truth Answers: the peptidoglycan wallthe peptidoglycan wallpeptidoglycan wall between their double membrane
Prediction:
What have some plants repurposed the peptidoglycan layer genes for?
Ground Truth Answers: chloroplast divisionchloroplast divisionchloroplast division
Prediction:
What do green chloroplasts have instead of phycobilisomes?
Ground Truth Answers: chlorophyll bchlorophyll bchlorophyll b
Prediction:
While primary chloroplasts have a double membrane from their cyanobacterial ancestor, secondary chloroplasts have additional membranes outside of the original two, as a result of the secondary endosymbiotic event, when a nonphotosynthetic eukaryote engulfed a chloroplast-containing alga but failed to digest it—much like the cyanobacterium at the beginning of this story. The engulfed alga was broken down, leaving only its chloroplast, and sometimes its cell membrane and nucleus, forming a chloroplast with three or four membranes—the two cyanobacterial membranes, sometimes the eaten alga's cell membrane, and the phagosomal vacuole from the host's cell membrane.
What kind of membrane do primary chloroplasts have?
Ground Truth Answers: doubledouble membranedouble membrane
Prediction:
What differs about secondary chloroplasts' membranes?
Ground Truth Answers: additional membranes outside of the original twoadditional membraneshave additional membranes outside of the original two
Prediction:
What was the secondary endosymbiotic event?
Ground Truth Answers: a nonphotosynthetic eukaryote engulfed a chloroplast-containing alga but failed to digest ita nonphotosynthetic eukaryote engulfed a chloroplast-containing alga but failed to digest itnonphotosynthetic eukaryote engulfed a chloroplast-containing alga but failed to digest it
Prediction:
What additional membranes do secondary chloroplasts have?
Ground Truth Answers: sometimes the eaten alga's cell membrane, and the phagosomal vacuole from the host's cell membranesometimes the eaten alga's cell membranethe two cyanobacterial membranes, sometimes the eaten alga's cell membrane, and the phagosomal vacuole from the host's cell membrane
Prediction:
What was left when engulfed algae was broken down?
Ground Truth Answers: its chloroplast, and sometimes its cell membrane and nucleusits chloroplastchloroplast
Prediction:
Euglenophytes are a group of common flagellated protists that contain chloroplasts derived from a green alga. Euglenophyte chloroplasts have three membranes—it is thought that the membrane of the primary endosymbiont was lost, leaving the cyanobacterial membranes, and the secondary host's phagosomal membrane. Euglenophyte chloroplasts have a pyrenoid and thylakoids stacked in groups of three. Starch is stored in the form of paramylon, which is contained in membrane-bound granules in the cytoplasm of the euglenophyte.
What kind of chloroplasts do Euglenophytes have?
Ground Truth Answers: chloroplasts derived from a green algagreen algagreen alga
Prediction:
What kind of protists are Euglenophytes?
Ground Truth Answers: common flagellatedcommon flagellatedcommon flagellated
Prediction:
How are the pyrenoid and thylakoids arranged?
Ground Truth Answers: stacked in groups of threegroups of threestacked in groups of three
Prediction:
What does paramylon store?
Ground Truth Answers: StarchStarchStarch
Prediction:
Which membrane was lost in euglenophyte chloroplasts?
Ground Truth Answers: the membrane of the primary endosymbiontthe primary endosymbiontprimary endosymbiont
Prediction:
Cryptophytes, or cryptomonads are a group of algae that contain a red-algal derived chloroplast. Cryptophyte chloroplasts contain a nucleomorph that superficially resembles that of the chlorarachniophytes. Cryptophyte chloroplasts have four membranes, the outermost of which is continuous with the rough endoplasmic reticulum. They synthesize ordinary starch, which is stored in granules found in the periplastid space—outside the original double membrane, in the place that corresponds to the red alga's cytoplasm. Inside cryptophyte chloroplasts is a pyrenoid and thylakoids in stacks of two.
What is another word for cryptophytes?
Ground Truth Answers: cryptomonadscryptomonadscryptomonads
Prediction:
What kind of chloroplasts do cryptophytes have?
Ground Truth Answers: red-algal derived chloroplastred-algalred-algal derived
Prediction:
What part of cryptophyte chloroplasts is similar to chlorarachniophytes?
Ground Truth Answers: nucleomorphnucleomorphnucleomorph
Prediction:
Where do cryptophyte chloroplasts store starch?
Ground Truth Answers: in granules found in the periplastid spacegranulesin granules found in the periplastid space
Prediction:
How do cryptophyte chloroplasts arrange their pyrenoid and thylakoids?
Ground Truth Answers: stacks of twostacks of twoin stacks of two
Prediction:
Apicomplexans are another group of chromalveolates. Like the helicosproidia, they're parasitic, and have a nonphotosynthetic chloroplast. They were once thought to be related to the helicosproidia, but it is now known that the helicosproida are green algae rather than chromalveolates. The apicomplexans include Plasmodium, the malaria parasite. Many apicomplexans keep a vestigial red algal derived chloroplast called an apicoplast, which they inherited from their ancestors. Other apicomplexans like Cryptosporidium have lost the chloroplast completely. Apicomplexans store their energy in amylopectin starch granules that are located in their cytoplasm, even though they are nonphotosynthetic.
What are Apicomplexans similar to?
Ground Truth Answers: helicosproidiahelicosproidiahelicosproidia
Prediction:
What are Apicomplexans a type of?
Ground Truth Answers: chromalveolateschromalveolateschromalveolates
Prediction:
What is Plasmodium?
Ground Truth Answers: the malaria parasiteapicomplexansmalaria parasite
Prediction:
What is an apicoplast?
Ground Truth Answers: a vestigial red algal derived chloroplasta vestigial red algal derived chloroplastred algal derived chloroplast
Prediction:
Where do Apicomplexans store energy?
Ground Truth Answers: in amylopectin starch granules that are located in their cytoplasmamylopectin starch granulesamylopectin starch granules
Prediction:
Apicoplasts have lost all photosynthetic function, and contain no photosynthetic pigments or true thylakoids. They are bounded by four membranes, but the membranes are not connected to the endoplasmic reticulum. The fact that apicomplexans still keep their nonphotosynthetic chloroplast around demonstrates how the chloroplast carries out important functions other than photosynthesis. Plant chloroplasts provide plant cells with many important things besides sugar, and apicoplasts are no different—they synthesize fatty acids, isopentenyl pyrophosphate, iron-sulfur clusters, and carry out part of the heme pathway. This makes the apicoplast an attractive target for drugs to cure apicomplexan-related diseases. The most important apicoplast function is isopentenyl pyrophosphate synthesis—in fact, apicomplexans die when something interferes with this apicoplast function, and when apicomplexans are grown in an isopentenyl pyrophosphate-rich medium, they dump the organelle.
What do apicoplasts synthesize?
Ground Truth Answers: fatty acids, isopentenyl pyrophosphate, iron-sulfur clustersfatty acids, isopentenyl pyrophosphate, iron-sulfur clustersfatty acids, isopentenyl pyrophosphate, iron-sulfur clusters
Prediction:
What kind of diseases do drugs target apicoplasts for?
Ground Truth Answers: apicomplexan-related diseasesapicomplexan-related diseasesapicomplexan-related
Prediction:
What is the most important thing apicoplasts do?
Ground Truth Answers: isopentenyl pyrophosphate synthesisisopentenyl pyrophosphate synthesisisopentenyl pyrophosphate synthesis
Prediction:
What are apicoplasts missing?
Ground Truth Answers: photosynthetic pigments or true thylakoidsphotosynthetic functionall photosynthetic function
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How many membranes do apicoplasts have?
Ground Truth Answers: fourfourfour
Prediction:
The most common dinophyte chloroplast is the peridinin-type chloroplast, characterized by the carotenoid pigment peridinin in their chloroplasts, along with chlorophyll a and chlorophyll c2. Peridinin is not found in any other group of chloroplasts. The peridinin chloroplast is bounded by three membranes (occasionally two), having lost the red algal endosymbiont's original cell membrane. The outermost membrane is not connected to the endoplasmic reticulum. They contain a pyrenoid, and have triplet-stacked thylakoids. Starch is found outside the chloroplast An important feature of these chloroplasts is that their chloroplast DNA is highly reduced and fragmented into many small circles. Most of the genome has migrated to the nucleus, and only critical photosynthesis-related genes remain in the chloroplast.
What is only found in peridinin-type chloroplasts?
Ground Truth Answers: Peridininperidininperidinin
Prediction:
Where is Peridinin found?
Ground Truth Answers: peridinin-type chloroplastchloroplastschloroplasts
Prediction:
How are peridinin-type chloroplasts' thylakoids arranged?
Ground Truth Answers: triplet-stackedtriplet-stackedtriplet-stacked
Prediction:
What have peridinin-type chloroplasts lost?
Ground Truth Answers: the red algal endosymbiont's original cell membranethe red algal endosymbiont's original cell membranered algal endosymbiont's original cell membrane
Prediction:
The fucoxanthin dinophyte lineages (including Karlodinium and Karenia) lost their original red algal derived chloroplast, and replaced it with a new chloroplast derived from a haptophyte endosymbiont. Karlodinium and Karenia probably took up different heterokontophytes. Because the haptophyte chloroplast has four membranes, tertiary endosymbiosis would be expected to create a six membraned chloroplast, adding the haptophyte's cell membrane and the dinophyte's phagosomal vacuole. However, the haptophyte was heavily reduced, stripped of a few membranes and its nucleus, leaving only its chloroplast (with its original double membrane), and possibly one or two additional membranes around it.
What lineage is Karlodinium in?
Ground Truth Answers: fucoxanthin dinophytefucoxanthin dinophytefucoxanthin dinophyte
Prediction:
What lineage is Karenia in?
Ground Truth Answers: fucoxanthin dinophytefucoxanthin dinophytefucoxanthin dinophyte
Prediction:
How many membranes does the haptophyte chloroplast have?
Ground Truth Answers: fourfourfour
Prediction:
What is tertiary endosymbiosis of haptophyte chloroplasts expected to create?
Ground Truth Answers: a six membraned chloroplasta six membraned chloroplastsix membraned chloroplast
Prediction:
Members of the genus Dinophysis have a phycobilin-containing chloroplast taken from a cryptophyte. However, the cryptophyte is not an endosymbiont—only the chloroplast seems to have been taken, and the chloroplast has been stripped of its nucleomorph and outermost two membranes, leaving just a two-membraned chloroplast. Cryptophyte chloroplasts require their nucleomorph to maintain themselves, and Dinophysis species grown in cell culture alone cannot survive, so it is possible (but not confirmed) that the Dinophysis chloroplast is a kleptoplast—if so, Dinophysis chloroplasts wear out and Dinophysis species must continually engulf cryptophytes to obtain new chloroplasts to replace the old ones.
Where did Dinophysis get its chloroplasts from?
Ground Truth Answers: a cryptophytecryptophytecryptophyte
Prediction:
What have the Dinophysis chloroplasts lost?
Ground Truth Answers: its nucleomorph and outermost two membranesits nucleomorph and outermost two membranesnucleomorph and outermost two membranes
Prediction:
What is the chloroplast of Dinophysis?
Ground Truth Answers: a phycobilin-containing chloroplastphycobilin-containing chloroplastphycobilin-containing
Prediction:
What is left of the Dinophysis chloroplasts?
Ground Truth Answers: a two-membraned chloroplasta two-membraned chloroplasta two-membraned chloroplast
Prediction:
Some dinophytes, like Kryptoperidinium and Durinskia have a diatom (heterokontophyte) derived chloroplast. These chloroplasts are bounded by up to five membranes, (depending on whether you count the entire diatom endosymbiont as the chloroplast, or just the red algal derived chloroplast inside it). The diatom endosymbiont has been reduced relatively little—it still retains its original mitochondria, and has endoplasmic reticulum, ribosomes, a nucleus, and of course, red algal derived chloroplasts—practically a complete cell, all inside the host's endoplasmic reticulum lumen. However the diatom endosymbiont can't store its own food—its starch is found in granules in the dinophyte host's cytoplasm instead. The diatom endosymbiont's nucleus is present, but it probably can't be called a nucleomorph because it shows no sign of genome reduction, and might have even been expanded. Diatoms have been engulfed by dinoflagellates at least three times.
What is another word for diatom?
Ground Truth Answers: heterokontophyteheterokontophyteheterokontophyte
Prediction:
What is Durinskia's chloroplast?
Ground Truth Answers: a diatom (heterokontophyte) derived chloroplastdiatom (heterokontophyte) deriveddiatom (heterokontophyte) derived
Prediction:
How many membranes does Durinskia's chloroplast have?
Ground Truth Answers: up to fiveup to fivefive
Prediction:
What is sometimes but not always counted regarding Durinskia's chloroplast membranes?
Ground Truth Answers: the entire diatom endosymbiont as the chloroplastthe entire diatom endosymbiontdiatom endosymbiont
Prediction:
Where does the diatom endosymbiont store starch?
Ground Truth Answers: granules in the dinophyte host's cytoplasmin the dinophyte hostgranules in the dinophyte host's cytoplasm
Prediction:
Lepidodinium viride and its close relatives are dinophytes that lost their original peridinin chloroplast and replaced it with a green algal derived chloroplast (more specifically, a prasinophyte). Lepidodinium is the only dinophyte that has a chloroplast that's not from the rhodoplast lineage. The chloroplast is surrounded by two membranes and has no nucleomorph—all the nucleomorph genes have been transferred to the dinophyte nucleus. The endosymbiotic event that led to this chloroplast was serial secondary endosymbiosis rather than tertiary endosymbiosis—the endosymbiont was a green alga containing a primary chloroplast (making a secondary chloroplast).
Where do nucleomorph genes transfer to?
Ground Truth Answers: the dinophyte nucleusthe dinophyte nucleusdinophyte nucleus
Prediction:
What is the only dinophyte that has a non-rhodoplast chloroplast?
Ground Truth Answers: LepidodiniumLepidodiniumLepidodinium
Prediction:
What did Lepidodinium viride lose?
Ground Truth Answers: their original peridinin chloroplastnucleomorphtheir original peridinin chloroplast
Prediction:
What did Lepidodinium viride replace their original chloroplast with?
Ground Truth Answers: a green algal derived chloroplastprasinophytegreen algal derived chloroplast (more specifically, a prasinophyte)
Prediction:
What is a prasinophyte?
Ground Truth Answers: a green algal derived chloroplasta green algal derived chloroplastgreen algal derived chloroplast
Prediction:
While most chloroplasts originate from that first set of endosymbiotic events, Paulinella chromatophora is an exception that acquired a photosynthetic cyanobacterial endosymbiont more recently. It is not clear whether that symbiont is closely related to the ancestral chloroplast of other eukaryotes. Being in the early stages of endosymbiosis, Paulinella chromatophora can offer some insights into how chloroplasts evolved. Paulinella cells contain one or two sausage shaped blue-green photosynthesizing structures called chromatophores, descended from the cyanobacterium Synechococcus. Chromatophores cannot survive outside their host. Chromatophore DNA is about a million base pairs long, containing around 850 protein encoding genes—far less than the three million base pair Synechococcus genome, but much larger than the approximately 150,000 base pair genome of the more assimilated chloroplast. Chromatophores have transferred much less of their DNA to the nucleus of their host. About 0.3–0.8% of the nuclear DNA in Paulinella is from the chromatophore, compared with 11–14% from the chloroplast in plants.
Where did most chloroplasts come from?
Ground Truth Answers: first set of endosymbiotic eventsfirst set of endosymbiotic eventsfirst set of endosymbiotic events
Prediction:
What is different about Paulinella chromatophora?
Ground Truth Answers: acquired a photosynthetic cyanobacterial endosymbiont more recentlyacquired a photosynthetic cyanobacterial endosymbiont more recentlyacquired a photosynthetic cyanobacterial endosymbiont more recently
Prediction:
How many base pairs are there in Chromatophore DNA?
Ground Truth Answers: about a millionabout a millionabout a million
Prediction:
How many protein-encoding genes are there in Chromatophore DNA?
Ground Truth Answers: around 850850850
Prediction:
How many base pairs are there in Synechococcus DNA?
Ground Truth Answers: three million150,000three million
Prediction:
Chloroplasts have their own DNA, often abbreviated as ctDNA, or cpDNA. It is also known as the plastome. Its existence was first proved in 1962, and first sequenced in 1986—when two Japanese research teams sequenced the chloroplast DNA of liverwort and tobacco. Since then, hundreds of chloroplast DNAs from various species have been sequenced, but they're mostly those of land plants and green algae—glaucophytes, red algae, and other algal groups are extremely underrepresented, potentially introducing some bias in views of "typical" chloroplast DNA structure and content.
What is chloroplast DNA abbreviated as?
Ground Truth Answers: ctDNA, or cpDNActDNActDNA, or cpDNA
Prediction:
What is a synonym for chloroplast DNA?
Ground Truth Answers: the plastomecpDNAplastome
Prediction:
When was the plastome discovered?
Ground Truth Answers: 196219621962
Prediction:
When was the first plastome sequenced?
Ground Truth Answers: 198619861986
Prediction:
Who sequenced the first plastome?
Ground Truth Answers: two Japanese research teamstwo Japanese research teamstwo Japanese research teams
Prediction:
The inverted repeat regions are highly conserved among land plants, and accumulate few mutations. Similar inverted repeats exist in the genomes of cyanobacteria and the other two chloroplast lineages (glaucophyta and rhodophyceæ), suggesting that they predate the chloroplast, though some chloroplast DNAs have since lost or flipped the inverted repeats (making them direct repeats). It is possible that the inverted repeats help stabilize the rest of the chloroplast genome, as chloroplast DNAs which have lost some of the inverted repeat segments tend to get rearranged more.
What seldom mutates?
Ground Truth Answers: The inverted repeat regionsinverted repeat regionsinverted repeat regions
Prediction:
What have some inverted repeats become?
Ground Truth Answers: direct repeatsdirect repeatsdirect repeats
Prediction:
What could inverted repeats help do?
Ground Truth Answers: stabilize the rest of the chloroplast genomestabilize the rest of the chloroplasthelp stabilize the rest of the chloroplast genome
Prediction:
The mechanism for chloroplast DNA (cpDNA) replication has not been conclusively determined, but two main models have been proposed. Scientists have attempted to observe chloroplast replication via electron microscopy since the 1970s. The results of the microscopy experiments led to the idea that chloroplast DNA replicates using a double displacement loop (D-loop). As the D-loop moves through the circular DNA, it adopts a theta intermediary form, also known as a Cairns replication intermediate, and completes replication with a rolling circle mechanism. Transcription starts at specific points of origin. Multiple replication forks open up, allowing replication machinery to transcribe the DNA. As replication continues, the forks grow and eventually converge. The new cpDNA structures separate, creating daughter cpDNA chromosomes.
How is chloroplast replication observed?
Ground Truth Answers: electron microscopyvia electron microscopyelectron microscopy
Prediction:
How many major chloroplast replication models have been suggested?
Ground Truth Answers: twotwotwo
Prediction:
What is a Cairns replication intermediate?
Ground Truth Answers: a theta intermediary formtheta intermediary forma theta intermediary form
Prediction:
What is a D-loop?
Ground Truth Answers: a Cairns replication intermediatedouble displacement loopdouble displacement loop
Prediction:
How does the D-loop finish replicating?
Ground Truth Answers: with a rolling circle mechanisma rolling circle mechanismwith a rolling circle mechanism
Prediction:
In cpDNA, there are several A → G deamination gradients. DNA becomes susceptible to deamination events when it is single stranded. When replication forks form, the strand not being copied is single stranded, and thus at risk for A → G deamination. Therefore, gradients in deamination indicate that replication forks were most likely present and the direction that they initially opened (the highest gradient is most likely nearest the start site because it was single stranded for the longest amount of time). This mechanism is still the leading theory today; however, a second theory suggests that most cpDNA is actually linear and replicates through homologous recombination. It further contends that only a minority of the genetic material is kept in circular chromosomes while the rest is in branched, linear, or other complex structures.
What kind of gradients does cpDNA have?
Ground Truth Answers: A → G deaminationA → G deamination gradientsA → G deamination
Prediction:
What makes DNA vulnerable to deamination?
Ground Truth Answers: when it is single strandedwhen it is single strandedreplication forks form
Prediction:
How does the secondary theory say most cpDNA is structured?
Ground Truth Answers: linearlinearlinear
Prediction:
How does the secondary theory say most cpDNA replicates?
Ground Truth Answers: homologous recombinationhomologous recombinationthrough homologous recombination
Prediction:
Where does the secondary theory say most genes are kept?
Ground Truth Answers: in branched, linear, or other complex structuresbranched, linear, or other complex structuresin branched, linear, or other complex structures
Prediction:
One of competing model for cpDNA replication asserts that most cpDNA is linear and participates in homologous recombination and replication structures similar to bacteriophage T4. It has been established that some plants have linear cpDNA, such as maize, and that more species still contain complex structures that scientists do not yet understand. When the original experiments on cpDNA were performed, scientists did notice linear structures; however, they attributed these linear forms to broken circles. If the branched and complex structures seen in cpDNA experiments are real and not artifacts of concatenated circular DNA or broken circles, then a D-loop mechanism of replication is insufficient to explain how those structures would replicate. At the same time, homologous recombination does not expand the multiple A --> G gradients seen in plastomes. Because of the failure to explain the deamination gradient as well as the numerous plant species that have been shown to have circular cpDNA, the predominant theory continues to hold that most cpDNA is circular and most likely replicates via a D loop mechanism.
What is cpDNA's replication similar to?
Ground Truth Answers: bacteriophage T4bacteriophage T4.bacteriophage T4
Prediction:
What kind of cpDNA does maize have?
Ground Truth Answers: linearlinearlinear
Prediction:
How is most plants' cpDNA arranged?
Ground Truth Answers: circularcircularcircular
Prediction:
How does most plants' cpDNA replicate?
Ground Truth Answers: via a D loop mechanismvia a D loop mechanismvia a D loop mechanism
Prediction:
Endosymbiotic gene transfer is how we know about the lost chloroplasts in many chromalveolate lineages. Even if a chloroplast is eventually lost, the genes it donated to the former host's nucleus persist, providing evidence for the lost chloroplast's existence. For example, while diatoms (a heterokontophyte) now have a red algal derived chloroplast, the presence of many green algal genes in the diatom nucleus provide evidence that the diatom ancestor (probably the ancestor of all chromalveolates too) had a green algal derived chloroplast at some point, which was subsequently replaced by the red chloroplast.
What shows us lost chloroplasts?
Ground Truth Answers: Endosymbiotic gene transferEndosymbiotic gene transferEndosymbiotic gene transfer
Prediction:
What do donated genes give evidence of?
Ground Truth Answers: the lost chloroplast's existencefor the lost chloroplast's existencethe lost chloroplast's existence
Prediction:
What kind of chloroplasts do diatoms have?
Ground Truth Answers: a red algal derived chloroplastred algalred algal derived
Prediction:
What kind of chloroplasts did diatoms have but lost?
Ground Truth Answers: green algal derived chloroplastgreen algalgreen algal derived
Prediction:
Curiously, around half of the protein products of transferred genes aren't even targeted back to the chloroplast. Many became exaptations, taking on new functions like participating in cell division, protein routing, and even disease resistance. A few chloroplast genes found new homes in the mitochondrial genome—most became nonfunctional pseudogenes, though a few tRNA genes still work in the mitochondrion. Some transferred chloroplast DNA protein products get directed to the secretory pathway (though it should be noted that many secondary plastids are bounded by an outermost membrane derived from the host's cell membrane, and therefore topologically outside of the cell, because to reach the chloroplast from the cytosol, you have to cross the cell membrane, just like if you were headed for the extracellular space. In those cases, chloroplast-targeted proteins do initially travel along the secretory pathway).
What is the status of most chloroplast genes in the mitochondrion?
Ground Truth Answers: nonfunctional pseudogenesnonfunctionalmost became nonfunctional pseudogenes
Prediction:
How much of the protein products of transferred genes don't go back to chloroplasts?
Ground Truth Answers: around halfhalfhalf
Prediction:
What new tasks do the protein products of transferred genes take on?
Ground Truth Answers: participating in cell division, protein routing, and even disease resistancecell division, protein routing, and even disease resistancecell division, protein routing, and even disease resistance
Prediction:
What do you have to cross to reach the chloroplast in many secondary plastids?
Ground Truth Answers: the cell membranethe cell membranethe cell membrane
Prediction:
After a chloroplast polypeptide is synthesized on a ribosome in the cytosol, an enzyme specific to chloroplast proteins phosphorylates, or adds a phosphate group to many (but not all) of them in their transit sequences. Phosphorylation helps many proteins bind the polypeptide, keeping it from folding prematurely. This is important because it prevents chloroplast proteins from assuming their active form and carrying out their chloroplast functions in the wrong place—the cytosol. At the same time, they have to keep just enough shape so that they can be recognized by the chloroplast. These proteins also help the polypeptide get imported into the chloroplast.
What is the chloroplast polypeptide synthesized on?
Ground Truth Answers: a ribosomea ribosomeribosome
Prediction:
Where is the chloroplast polypeptide synthesized?
Ground Truth Answers: in the cytosolin the cytosolcytosol
Prediction:
What does Phosphorylation do?
Ground Truth Answers: helps many proteins bind the polypeptidehelps many proteins bind the polypeptidehelps many proteins bind the polypeptide
Prediction:
What is the benefit of polypeptide binding?
Ground Truth Answers: keeping it from folding prematurelykeeping it from folding prematurelyprevents chloroplast proteins from assuming their active form and carrying out their chloroplast functions in the wrong place
Prediction:
In land plants, chloroplasts are generally lens-shaped, 5–8 μm in diameter and 1–3 μm thick. Greater diversity in chloroplast shapes exists among the algae, which often contain a single chloroplast that can be shaped like a net (e.g., Oedogonium), a cup (e.g., Chlamydomonas), a ribbon-like spiral around the edges of the cell (e.g., Spirogyra), or slightly twisted bands at the cell edges (e.g., Sirogonium). Some algae have two chloroplasts in each cell; they are star-shaped in Zygnema, or may follow the shape of half the cell in order Desmidiales. In some algae, the chloroplast takes up most of the cell, with pockets for the nucleus and other organelles (for example some species of Chlorella have a cup-shaped chloroplast that occupies much of the cell).
How are chloroplasts in land plants usually shaped?
Ground Truth Answers: lens-shapedlens-shapedlens-shaped
Prediction:
How large across are chloroplasts in land plants?
Ground Truth Answers: 5–8 μm in diameter5–8 μm5–8 μm in diameter
Prediction:
How thick are chloroplasts in land plants?
Ground Truth Answers: 1–3 μm1–3 μm1–3 μm
Prediction:
What shape is Oedogonium's chloroplasts?
Ground Truth Answers: a neta netnet
Prediction:
What shape is Chlamydomonas's chloroplasts?
Ground Truth Answers: a cupa cupcup
Prediction:
There are some common misconceptions about the outer and inner chloroplast membranes. The fact that chloroplasts are surrounded by a double membrane is often cited as evidence that they are the descendants of endosymbiotic cyanobacteria. This is often interpreted as meaning the outer chloroplast membrane is the product of the host's cell membrane infolding to form a vesicle to surround the ancestral cyanobacterium—which is not true—both chloroplast membranes are homologous to the cyanobacterium's original double membranes.
What is evidence chloroplasts descended from endosymbiotic cyanobacteria?
Ground Truth Answers: a double membranesurrounded by a double membranesurrounded by a double membrane
Prediction:
What is incorrectly thought about the outer chloroplast membrane?
Ground Truth Answers: the product of the host's cell membrane infolding to form a vesicle to surround the ancestral cyanobacteriumis the product of the host's cell membraneis the product of the host's cell membrane infolding to form a vesicle to surround the ancestral cyanobacterium
Prediction:
How do both chloroplast membranes compare to cyanobacterium's original double membranes?
Ground Truth Answers: homologoushomologoushomologous
Prediction:
The chloroplast double membrane is also often compared to the mitochondrial double membrane. This is not a valid comparison—the inner mitochondria membrane is used to run proton pumps and carry out oxidative phosphorylation across to generate ATP energy. The only chloroplast structure that can considered analogous to it is the internal thylakoid system. Even so, in terms of "in-out", the direction of chloroplast H+ ion flow is in the opposite direction compared to oxidative phosphorylation in mitochondria. In addition, in terms of function, the inner chloroplast membrane, which regulates metabolite passage and synthesizes some materials, has no counterpart in the mitochondrion.
What is the chloroplast double membrane sometimes compared to?
Ground Truth Answers: the mitochondrial double membranethe mitochondrial double membranemitochondrial double membrane
Prediction:
What does the inner mitochondria membrane do?
Ground Truth Answers: run proton pumps and carry out oxidative phosphorylationto run proton pumpsrun proton pumps and carry out oxidative phosphorylation across to generate ATP energy
Prediction:
What does oxidative phosphorylation do?
Ground Truth Answers: generate ATP energygenerate ATP energygenerate ATP energy
Prediction:
What chloroplast structure is similar to the inner mitochondria membrane?
Ground Truth Answers: the internal thylakoid systemthe internal thylakoid systeminternal thylakoid system
Prediction:
What part of chloroplasts isn't similar to mitochondria?
Ground Truth Answers: the inner chloroplast membranethe inner chloroplast membraneinner chloroplast membrane
Prediction:
The chloroplast membranes sometimes protrude out into the cytoplasm, forming a stromule, or stroma-containing tubule. Stromules are very rare in chloroplasts, and are much more common in other plastids like chromoplasts and amyloplasts in petals and roots, respectively. They may exist to increase the chloroplast's surface area for cross-membrane transport, because they are often branched and tangled with the endoplasmic reticulum. When they were first observed in 1962, some plant biologists dismissed the structures as artifactual, claiming that stromules were just oddly shaped chloroplasts with constricted regions or dividing chloroplasts. However, there is a growing body of evidence that stromules are functional, integral features of plant cell plastids, not merely artifacts.
What are more common in other plastids than chloroplasts?
Ground Truth Answers: StromulesStromulesStromules
Prediction:
What is a stromule?
Ground Truth Answers: stroma-containing tubulestroma-containing tubulestroma-containing tubule
Prediction:
Why do stromules exist?
Ground Truth Answers: to increase the chloroplast's surface area for cross-membrane transportto increase the chloroplast's surface areato increase the chloroplast's surface area for cross-membrane transport
Prediction:
When were stromules discovered?
Ground Truth Answers: 196219621962
Prediction:
Some chloroplasts contain a structure called the chloroplast peripheral reticulum. It is often found in the chloroplasts of C4 plants, though it has also been found in some C3 angiosperms, and even some gymnosperms. The chloroplast peripheral reticulum consists of a maze of membranous tubes and vesicles continuous with the inner chloroplast membrane that extends into the internal stromal fluid of the chloroplast. Its purpose is thought to be to increase the chloroplast's surface area for cross-membrane transport between its stroma and the cell cytoplasm. The small vesicles sometimes observed may serve as transport vesicles to shuttle stuff between the thylakoids and intermembrane space.
Where is the chloroplast peripheral reticulum usually found?
Ground Truth Answers: in the chloroplasts of C4 plantsin the chloroplasts of C4 plants,chloroplasts of C4 plants
Prediction:
Where is the chloroplast peripheral reticulum less commonly found?
Ground Truth Answers: in some C3 angiosperms, and even some gymnospermsC3 angiospermsC3 angiosperms, and even some gymnosperms
Prediction:
What is a maze of membranous tubes?
Ground Truth Answers: The chloroplast peripheral reticulumThe chloroplast peripheral reticulum
Prediction:
What does the chloroplast peripheral reticulum do?
Ground Truth Answers: increase the chloroplast's surface area for cross-membrane transportto increase the chloroplast's surface areaincrease the chloroplast's surface area for cross-membrane transport between its stroma and the cell cytoplasm
Prediction:
Where do transport vesicles move between?
Ground Truth Answers: the thylakoids and intermembrane spacethylakoids and intermembrane spacethylakoids and intermembrane space
Prediction:
Chloroplasts have their own ribosomes, which they use to synthesize a small fraction of their proteins. Chloroplast ribosomes are about two-thirds the size of cytoplasmic ribosomes (around 17 nm vs 25 nm). They take mRNAs transcribed from the chloroplast DNA and translate them into protein. While similar to bacterial ribosomes, chloroplast translation is more complex than in bacteria, so chloroplast ribosomes include some chloroplast-unique features. Small subunit ribosomal RNAs in several Chlorophyta and euglenid chloroplasts lack motifs for shine-dalgarno sequence recognition, which is considered essential for translation initiation in most chloroplasts and prokaryotes. Such loss is also rarely observed in other plastids and prokaryotes.
What do chloroplasts use their ribosomes for?
Ground Truth Answers: synthesize a small fraction of their proteinsto synthesize a small fraction of their proteinssynthesize a small fraction of their proteins
Prediction:
How large are Chloroplast ribosomes?
Ground Truth Answers: 17 nmaround 17 nm17 nm
Prediction:
How large are Cytoplasmic ribosomes?
Ground Truth Answers: 25 nm25 nm25 nm
Prediction:
What are some Chlorophyta and euglenid chloroplasts missing?
Ground Truth Answers: motifs for shine-dalgarno sequence recognitionmotifs for shine-dalgarno sequence recognitionmotifs for shine-dalgarno sequence recognition
Prediction:
Why is shine-dalgarno sequence recognition important?
Ground Truth Answers: is considered essential for translation initiation in most chloroplasts and prokaryotestranslation initiationessential for translation initiation in most chloroplasts and prokaryotes
Prediction:
Plastoglobuli (singular plastoglobulus, sometimes spelled plastoglobule(s)), are spherical bubbles of lipids and proteins about 45–60 nanometers across. They are surrounded by a lipid monolayer. Plastoglobuli are found in all chloroplasts, but become more common when the chloroplast is under oxidative stress, or when it ages and transitions into a gerontoplast. Plastoglobuli also exhibit a greater size variation under these conditions. They are also common in etioplasts, but decrease in number as the etioplasts mature into chloroplasts.
What is a single Plastoglobuli called?
Ground Truth Answers: plastoglobulus, sometimes spelled plastoglobule(s)plastoglobulusplastoglobulus
Prediction:
What shape are Plastoglobuli?
Ground Truth Answers: spherical bubblessphericalspherical
Prediction:
What are Plastoglobuli made of?
Ground Truth Answers: lipids and proteinslipids and proteinslipids and proteins
Prediction:
How large are Plastoglobuli?
Ground Truth Answers: 45–60 nanometers across45–60 nanometers across45–60 nanometers across
Prediction:
What surrounds Plastoglobuli?
Ground Truth Answers: a lipid monolayerlipid monolayera lipid monolayer
Prediction:
Plastoglobuli were once thought to be free-floating in the stroma, but it is now thought that they are permanently attached either to a thylakoid or to another plastoglobulus attached to a thylakoid, a configuration that allows a plastoglobulus to exchange its contents with the thylakoid network. In normal green chloroplasts, the vast majority of plastoglobuli occur singularly, attached directly to their parent thylakoid. In old or stressed chloroplasts, plastoglobuli tend to occur in linked groups or chains, still always anchored to a thylakoid.
What are Plastoglobuli attached to?
Ground Truth Answers: either to a thylakoid or to another plastoglobulus attached to a thylakoida thylakoidthylakoid or to another plastoglobulus attached to a thylakoid
Prediction:
What do Plastoglobuli exchange contents with?
Ground Truth Answers: the thylakoid networkthe thylakoid networkthylakoid network
Prediction:
How are green chloroplasts' Plastoglobuli arranged?
Ground Truth Answers: singularly, attached directly to their parent thylakoidsingularlysingularly, attached directly to their parent thylakoid
Prediction:
When do Plastoglobuli occur in linked groups?
Ground Truth Answers: In old or stressed chloroplastsIn old or stressed chloroplastsIn old or stressed chloroplasts
Prediction:
The chloroplasts of some hornworts and algae contain structures called pyrenoids. They are not found in higher plants. Pyrenoids are roughly spherical and highly refractive bodies which are a site of starch accumulation in plants that contain them. They consist of a matrix opaque to electrons, surrounded by two hemispherical starch plates. The starch is accumulated as the pyrenoids mature. In algae with carbon concentrating mechanisms, the enzyme rubisco is found in the pyrenoids. Starch can also accumulate around the pyrenoids when CO2 is scarce. Pyrenoids can divide to form new pyrenoids, or be produced "de novo".
Where are pyrenoids found?
Ground Truth Answers: The chloroplasts of some hornworts and algaesome hornworts and algaechloroplasts of some hornworts and algae
Prediction:
What shape are pyrenoids?
Ground Truth Answers: roughly sphericalroughly sphericalspherical
Prediction:
What do pyrenoids look like?
Ground Truth Answers: highly refractivehighly refractiveroughly spherical and highly refractive
Prediction:
What do pyrenoids store?
Ground Truth Answers: starchstarchstarch
Prediction:
How can pyrenoids replicate?
Ground Truth Answers: divide to form new pyrenoids, or be produced "de novo"dividedivide to form new pyrenoids, or be produced "de novo"
Prediction:
In the helical thylakoid model, grana consist of a stack of flattened circular granal thylakoids that resemble pancakes. Each granum can contain anywhere from two to a hundred thylakoids, though grana with 10–20 thylakoids are most common. Wrapped around the grana are helicoid stromal thylakoids, also known as frets or lamellar thylakoids. The helices ascend at an angle of 20–25°, connecting to each granal thylakoid at a bridge-like slit junction. The helicoids may extend as large sheets that link multiple grana, or narrow to tube-like bridges between grana. While different parts of the thylakoid system contain different membrane proteins, the thylakoid membranes are continuous and the thylakoid space they enclose form a single continuous labyrinth.
In what model do grana look like pancakes?
Ground Truth Answers: the helical thylakoid modelthe helical thylakoid modelhelical thylakoid
Prediction:
What shape are granal thylakoids?
Ground Truth Answers: flattened circularflattened circularflattened circular
Prediction:
How many granal thylakoids can be in each granum?
Ground Truth Answers: anywhere from two to a hundredtwo to a hundredtwo to a hundred
Prediction:
How many granal thylakoids are usually in each granum?
Ground Truth Answers: 10–2010–2010–20
Prediction:
What are frets?
Ground Truth Answers: helicoid stromal thylakoidshelicoid stromal thylakoidshelicoid stromal thylakoids
Prediction:
Embedded in the thylakoid membranes are important protein complexes which carry out the light reactions of photosynthesis. Photosystem II and photosystem I contain light-harvesting complexes with chlorophyll and carotenoids that absorb light energy and use it to energize electrons. Molecules in the thylakoid membrane use the energized electrons to pump hydrogen ions into the thylakoid space, decreasing the pH and turning it acidic. ATP synthase is a large protein complex that harnesses the concentration gradient of the hydrogen ions in the thylakoid space to generate ATP energy as the hydrogen ions flow back out into the stroma—much like a dam turbine.
What does chlorophyll absorb?
Ground Truth Answers: light energylight energylight energy
Prediction:
What do carotenoids absorb?
Ground Truth Answers: light energylight energylight energy
Prediction:
What does chlorophyll use light energy to do?
Ground Truth Answers: energize electronsto energize electronsenergize electrons
Prediction:
What does the thylakoid membrane use the energized electrons for?
Ground Truth Answers: pump hydrogen ions into the thylakoid spacepump hydrogen ionspump hydrogen ions into the thylakoid space
Prediction:
What is ATP synthase similar to?
Ground Truth Answers: a dam turbinea dam turbinea dam turbine
Prediction:
There are two types of thylakoids—granal thylakoids, which are arranged in grana, and stromal thylakoids, which are in contact with the stroma. Granal thylakoids are pancake-shaped circular disks about 300–600 nanometers in diameter. Stromal thylakoids are helicoid sheets that spiral around grana. The flat tops and bottoms of granal thylakoids contain only the relatively flat photosystem II protein complex. This allows them to stack tightly, forming grana with many layers of tightly appressed membrane, called granal membrane, increasing stability and surface area for light capture.
How many types of thylakoids are there?
Ground Truth Answers: twotwotwo
Prediction:
What distinguishes granal thylakoids?
Ground Truth Answers: are arranged in granaarranged in granaarranged in grana
Prediction:
What distinguishes stromal thylakoids?
Ground Truth Answers: are in contact with the stromain contact with the stromahelicoid sheets
Prediction:
What shape are granal thylakoids?
Ground Truth Answers: pancake-shaped circular diskspancakepancake-shaped
Prediction:
How large are granal thylakoids?
Ground Truth Answers: about 300–600 nanometers in diameter300–600 nanometers300–600 nanometers in diameter
Prediction:
In addition to chlorophylls, another group of yellow–orange pigments called carotenoids are also found in the photosystems. There are about thirty photosynthetic carotenoids. They help transfer and dissipate excess energy, and their bright colors sometimes override the chlorophyll green, like during the fall, when the leaves of some land plants change color. β-carotene is a bright red-orange carotenoid found in nearly all chloroplasts, like chlorophyll a. Xanthophylls, especially the orange-red zeaxanthin, are also common. Many other forms of carotenoids exist that are only found in certain groups of chloroplasts.
How many photosynthetic carotenoids are there?
Ground Truth Answers: about thirtyabout thirtythirty
Prediction:
What do photosynthetic carotenoids do?
Ground Truth Answers: help transfer and dissipate excess energytransfer and dissipate excess energyhelp transfer and dissipate excess energy
Prediction:
Why do carotenoids make leaves change color in the fall?
Ground Truth Answers: their bright colors sometimes override the chlorophyll greenoverride the chlorophyll greenoverride the chlorophyll green
Prediction:
What is beta carotene?
Ground Truth Answers: a bright red-orange carotenoida bright red-orange carotenoidbright red-orange carotenoid found in nearly all chloroplasts
Prediction:
What is the most common Xanthophyll?
Ground Truth Answers: orange-red zeaxanthinzeaxanthinorange-red zeaxanthin
Prediction:
Phycobilins are a third group of pigments found in cyanobacteria, and glaucophyte, red algal, and cryptophyte chloroplasts. Phycobilins come in all colors, though phycoerytherin is one of the pigments that makes many red algae red. Phycobilins often organize into relatively large protein complexes about 40 nanometers across called phycobilisomes. Like photosystem I and ATP synthase, phycobilisomes jut into the stroma, preventing thylakoid stacking in red algal chloroplasts. Cryptophyte chloroplasts and some cyanobacteria don't have their phycobilin pigments organized into phycobilisomes, and keep them in their thylakoid space instead.
What are Phycobilins?
Ground Truth Answers: e a third group of pigments found in cyanobacteriaa third group of pigmentsa third group of pigments found in cyanobacteria, and glaucophyte, red algal, and cryptophyte chloroplasts
Prediction:
What color is phycoerytherin?
Ground Truth Answers: redredred
Prediction:
What does phycoerytherin appear in?
Ground Truth Answers: red algaered algaealgae
Prediction:
What are phycobilisomes?
Ground Truth Answers: relatively large protein complexeslarge protein complexeslarge protein complexes
Prediction:
How big are phycobilisomes?
Ground Truth Answers: about 40 nanometers acrossabout 40 nanometers across40 nanometers across
Prediction:
To fix carbon dioxide into sugar molecules in the process of photosynthesis, chloroplasts use an enzyme called rubisco. Rubisco has a problem—it has trouble distinguishing between carbon dioxide and oxygen, so at high oxygen concentrations, rubisco starts accidentally adding oxygen to sugar precursors. This has the end result of ATP energy being wasted and CO2 being released, all with no sugar being produced. This is a big problem, since O2 is produced by the initial light reactions of photosynthesis, causing issues down the line in the Calvin cycle which uses rubisco.
What do chloroplasts use to fix carbon dioxide into sugar?
Ground Truth Answers: an enzyme called rubiscoan enzyme called rubiscoenzyme called rubisco
Prediction:
What is rubisco's flaw?
Ground Truth Answers: it has trouble distinguishing between carbon dioxide and oxygentrouble distinguishing between carbon dioxide and oxygenhas trouble distinguishing between carbon dioxide and oxygen
Prediction:
What effect does rubisco's flaw have?
Ground Truth Answers: at high oxygen concentrations, rubisco starts accidentally adding oxygen to sugar precursorsat high oxygen concentrations, rubisco starts accidentally adding oxygen to sugar precursorsat high oxygen concentrations, rubisco starts accidentally adding oxygen to sugar precursors
Prediction:
What process down the line does rubisco's flaw interfere with?
Ground Truth Answers: the Calvin cycleCalvin cycleCalvin cycle
Prediction:
What is wasted by rubisco's flaw?
Ground Truth Answers: ATP energyATP energyATP energy
Prediction:
As a result, chloroplasts in C4 mesophyll cells and bundle sheath cells are specialized for each stage of photosynthesis. In mesophyll cells, chloroplasts are specialized for the light reactions, so they lack rubisco, and have normal grana and thylakoids, which they use to make ATP and NADPH, as well as oxygen. They store CO2 in a four-carbon compound, which is why the process is called C4 photosynthesis. The four-carbon compound is then transported to the bundle sheath chloroplasts, where it drops off CO2 and returns to the mesophyll. Bundle sheath chloroplasts do not carry out the light reactions, preventing oxygen from building up in them and disrupting rubisco activity. Because of this, they lack thylakoids organized into grana stacks—though bundle sheath chloroplasts still have free-floating thylakoids in the stroma where they still carry out cyclic electron flow, a light-driven method of synthesizing ATP to power the Calvin cycle without generating oxygen. They lack photosystem II, and only have photosystem I—the only protein complex needed for cyclic electron flow. Because the job of bundle sheath chloroplasts is to carry out the Calvin cycle and make sugar, they often contain large starch grains.
What are chloroplasts in mesophyll cells specialized for?
Ground Truth Answers: light reactionseach stage of photosynthesislight reactions
Prediction:
What do chloroplasts in mesophyll cells lack?
Ground Truth Answers: rubiscorubiscorubisco
Prediction:
What do chloroplasts in mesophyll cells specialized use to make ATP?
Ground Truth Answers: normal grana and thylakoidsnormal grana and thylakoidsgrana and thylakoids
Prediction:
What do chloroplasts in mesophyll cells store carbon dioxide in?
Ground Truth Answers: a four-carbon compounda four-carbon compounda four-carbon compound
Prediction:
What do bundle sheath chloroplasts specialize in?
Ground Truth Answers: to carry out the Calvin cycle and make sugarthe Calvin cyclecyclic electron flow
Prediction:
Not all cells in a multicellular plant contain chloroplasts. All green parts of a plant contain chloroplasts—the chloroplasts, or more specifically, the chlorophyll in them are what make the photosynthetic parts of a plant green. The plant cells which contain chloroplasts are usually parenchyma cells, though chloroplasts can also be found in collenchyma tissue. A plant cell which contains chloroplasts is known as a chlorenchyma cell. A typical chlorenchyma cell of a land plant contains about 10 to 100 chloroplasts.
What parts of plants have chloroplasts?
Ground Truth Answers: All green partsgreen partsAll green parts
Prediction:
What makes plants green?
Ground Truth Answers: the chlorophyll in themchlorophyllchlorophyll
Prediction:
What plant cells have chloroplasts in them?
Ground Truth Answers: parenchyma cellsphotosyntheticparenchyma cells
Prediction:
Where can chloroplasts sometimes be found?
Ground Truth Answers: collenchyma tissuein collenchyma tissuecollenchyma tissue
Prediction:
What is a chlorenchyma cell?
Ground Truth Answers: A plant cell which contains chloroplastscell which contains chloroplastsplant cell which contains chloroplasts
Prediction:
In some plants such as cacti, chloroplasts are found in the stems, though in most plants, chloroplasts are concentrated in the leaves. One square millimeter of leaf tissue can contain half a million chloroplasts. Within a leaf, chloroplasts are mainly found in the mesophyll layers of a leaf, and the guard cells of stomata. Palisade mesophyll cells can contain 30–70 chloroplasts per cell, while stomatal guard cells contain only around 8–15 per cell, as well as much less chlorophyll. Chloroplasts can also be found in the bundle sheath cells of a leaf, especially in C4 plants, which carry out the Calvin cycle in their bundle sheath cells. They are often absent from the epidermis of a leaf.
Where do cacti have chloroplasts?
Ground Truth Answers: in the stemsstemsstems
Prediction:
Where do most plants have chloroplasts?
Ground Truth Answers: concentrated in the leavesthe leavesleaves
Prediction:
How many chloroplasts are in stomatal guard cells?
Ground Truth Answers: 8–15 per cellaround 8–158–15
Prediction:
How many chloroplasts are in a square mm of a leaf?
Ground Truth Answers: half a millionhalf a millionhalf a million
Prediction:
What layers of a leaf have chloroplasts?
Ground Truth Answers: the mesophyll layersmesophyllmesophyll
Prediction:
The chloroplasts of plant and algal cells can orient themselves to best suit the available light. In low-light conditions, they will spread out in a sheet—maximizing the surface area to absorb light. Under intense light, they will seek shelter by aligning in vertical columns along the plant cell's cell wall or turning sideways so that light strikes them edge-on. This reduces exposure and protects them from photooxidative damage. This ability to distribute chloroplasts so that they can take shelter behind each other or spread out may be the reason why land plants evolved to have many small chloroplasts instead of a few big ones. Chloroplast movement is considered one of the most closely regulated stimulus-response systems that can be found in plants. Mitochondria have also been observed to follow chloroplasts as they move.
When do chloroplasts spread out flat?
Ground Truth Answers: low-light conditionslow-light conditionsIn low-light conditions
Prediction:
When do chloroplasts arrange in vertical columns or turn sideways?
Ground Truth Answers: Under intense lightintense lightUnder intense light
Prediction:
What does turning sideways protect chloroplasts from?
Ground Truth Answers: photooxidative damagephotooxidative damagephotooxidative damage
Prediction:
Why do land plants have more and smaller chloroplasts?
Ground Truth Answers: to distribute chloroplasts so that they can take shelter behind each other or spread outthey can take shelter behind each otherso that they can take shelter behind each other or spread out
Prediction:
What sometimes follows moving chloroplasts?
Ground Truth Answers: MitochondriaMitochondriaMitochondria
Prediction:
Plants have two main immune responses—the hypersensitive response, in which infected cells seal themselves off and undergo programmed cell death, and systemic acquired resistance, where infected cells release signals warning the rest of the plant of a pathogen's presence. Chloroplasts stimulate both responses by purposely damaging their photosynthetic system, producing reactive oxygen species. High levels of reactive oxygen species will cause the hypersensitive response. The reactive oxygen species also directly kill any pathogens within the cell. Lower levels of reactive oxygen species initiate systemic acquired resistance, triggering defense-molecule production in the rest of the plant.
How many major immune responses do plants have?
Ground Truth Answers: twotwotwo
Prediction:
What is the hypersensitive response of a plant immune system?
Ground Truth Answers: infected cells seal themselves off and undergo programmed cell deathprogrammed cell deathinfected cells seal themselves off and undergo programmed cell death
Prediction:
What is the systemic acquired resistance response of a plant immune system?
Ground Truth Answers: infected cells release signals warning the rest of the plant of a pathogen's presencecells release signalsinfected cells release signals warning the rest of the plant of a pathogen's presence
Prediction:
How do chloroplasts trigger the plant's immune system?
Ground Truth Answers: by purposely damaging their photosynthetic systempurposely damaging their photosynthetic systempurposely damaging their photosynthetic system
Prediction:
What does damaging photosynthesis systems create?
Ground Truth Answers: reactive oxygen speciesreactive oxygen speciesreactive oxygen species
Prediction:
Chloroplasts can serve as cellular sensors. After detecting stress in a cell, which might be due to a pathogen, chloroplasts begin producing molecules like salicylic acid, jasmonic acid, nitric oxide and reactive oxygen species which can serve as defense-signals. As cellular signals, reactive oxygen species are unstable molecules, so they probably don't leave the chloroplast, but instead pass on their signal to an unknown second messenger molecule. All these molecules initiate retrograde signaling—signals from the chloroplast that regulate gene expression in the nucleus.
What molecules act as defense signals?
Ground Truth Answers: salicylic acid, jasmonic acid, nitric oxide and reactive oxygen speciessalicylic acid, jasmonic acid, nitric oxide and reactive oxygen speciesreactive oxygen species
Prediction:
When do chloroplasts produce defense signals?
Ground Truth Answers: After detecting stress in a cellAfter detecting stress in a cellAfter detecting stress in a cell
Prediction:
What happens to reactive oxygen species signals since they don't leave the chloroplast?
Ground Truth Answers: pass on their signal to an unknown second messenger moleculepass on their signalpass on their signal to an unknown second messenger molecule
Prediction:
What is retrograde signaling?
Ground Truth Answers: signals from the chloroplast that regulate gene expression in the nucleussignals from the chloroplast that regulate gene expressionsignals from the chloroplast that regulate gene expression in the nucleus
Prediction:
One of the main functions of the chloroplast is its role in photosynthesis, the process by which light is transformed into chemical energy, to subsequently produce food in the form of sugars. Water (H2O) and carbon dioxide (CO2) are used in photosynthesis, and sugar and oxygen (O2) is made, using light energy. Photosynthesis is divided into two stages—the light reactions, where water is split to produce oxygen, and the dark reactions, or Calvin cycle, which builds sugar molecules from carbon dioxide. The two phases are linked by the energy carriers adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADP+).
What is the most important role of chloroplasts?
Ground Truth Answers: photosynthesisphotosynthesisits role in photosynthesis
Prediction:
What is the process of changing light into chemical energy?
Ground Truth Answers: photosynthesisphotosynthesisphotosynthesis
Prediction:
What is chemical energy used to produce in plants?
Ground Truth Answers: food in the form of sugarslightfood in the form of sugars
Prediction:
What are the molecular inputs for photosynthesis?
Ground Truth Answers: Water (H2O) and carbon dioxide (CO2)Water (H2O) and carbon dioxide (CO2)Water (H2O) and carbon dioxide (CO2)
Prediction:
What are the molecular outputs for photosynthesis?
Ground Truth Answers: sugar and oxygen (O2)sugar and oxygen (O2)sugar and oxygen (O2)
Prediction:
Like mitochondria, chloroplasts use the potential energy stored in an H+, or hydrogen ion gradient to generate ATP energy. The two photosystems capture light energy to energize electrons taken from water, and release them down an electron transport chain. The molecules between the photosystems harness the electrons' energy to pump hydrogen ions into the thylakoid space, creating a concentration gradient, with more hydrogen ions (up to a thousand times as many) inside the thylakoid system than in the stroma. The hydrogen ions in the thylakoid space then diffuse back down their concentration gradient, flowing back out into the stroma through ATP synthase. ATP synthase uses the energy from the flowing hydrogen ions to phosphorylate adenosine diphosphate into adenosine triphosphate, or ATP. Because chloroplast ATP synthase projects out into the stroma, the ATP is synthesized there, in position to be used in the dark reactions.
What do chloroplasts do like mitochondria?
Ground Truth Answers: generate ATP energyuse the potential energy stored in an H+use the potential energy stored in an H+, or hydrogen ion gradient to generate ATP energy
Prediction:
Where do chloroplasts pump hydrogen?
Ground Truth Answers: into the thylakoid spacethylakoid spaceinto the thylakoid space
Prediction:
How concentrated do the hydrogen ions get in the thylakoid space?
Ground Truth Answers: up to a thousand timesup to a thousand times as many(up to a thousand times as many) inside the thylakoid system than in the stroma
Prediction:
What does ATP synthase change into ATP?
Ground Truth Answers: phosphorylate adenosine diphosphatephosphorylate adenosine diphosphateenergy from the flowing hydrogen ions
Prediction:
What does ATP mean?
Ground Truth Answers: adenosine triphosphateadenosine triphosphateadenosine triphosphate
Prediction:
While photosystem II photolyzes water to obtain and energize new electrons, photosystem I simply reenergizes depleted electrons at the end of an electron transport chain. Normally, the reenergized electrons are taken by NADP+, though sometimes they can flow back down more H+-pumping electron transport chains to transport more hydrogen ions into the thylakoid space to generate more ATP. This is termed cyclic photophosphorylation because the electrons are recycled. Cyclic photophosphorylation is common in C4 plants, which need more ATP than NADPH.
What usually takes reenergized electrons?
Ground Truth Answers: NADP+photosystem INADP+
Prediction:
In what process are electrons recycled?
Ground Truth Answers: cyclic photophosphorylationcyclic photophosphorylationcyclic photophosphorylation
Prediction:
Where is cyclic photophosphorylation common?
Ground Truth Answers: in C4 plantsin C4 plantsin C4 plants
Prediction:
What do C4 plants need?
Ground Truth Answers: more ATP than NADPHmore ATP than NADPHmore ATP than NADPH
Prediction:
The Calvin cycle starts by using the enzyme Rubisco to fix CO2 into five-carbon Ribulose bisphosphate (RuBP) molecules. The result is unstable six-carbon molecules that immediately break down into three-carbon molecules called 3-phosphoglyceric acid, or 3-PGA. The ATP and NADPH made in the light reactions is used to convert the 3-PGA into glyceraldehyde-3-phosphate, or G3P sugar molecules. Most of the G3P molecules are recycled back into RuBP using energy from more ATP, but one out of every six produced leaves the cycle—the end product of the dark reactions.
What cycle starts with rubisco?
Ground Truth Answers: The Calvin cycleThe Calvin cycleCalvin cycle
Prediction:
What is the result of the Calvin cycle?
Ground Truth Answers: unstable six-carbon molecules that immediately break downunstable six-carbon moleculesunstable six-carbon molecules
Prediction:
What do unstable 6-carbon molecules become?
Ground Truth Answers: three-carbon molecules called 3-phosphoglyceric acidthree-carbon moleculesthree-carbon molecules called 3-phosphoglyceric acid, or 3-PGA
Prediction:
How many G3P molecules leave the cycle?
Ground Truth Answers: one out of every sixout of every sixone out of every six
Prediction:
Alternatively, glucose monomers in the chloroplast can be linked together to make starch, which accumulates into the starch grains found in the chloroplast. Under conditions such as high atmospheric CO2 concentrations, these starch grains may grow very large, distorting the grana and thylakoids. The starch granules displace the thylakoids, but leave them intact. Waterlogged roots can also cause starch buildup in the chloroplasts, possibly due to less sucrose being exported out of the chloroplast (or more accurately, the plant cell). This depletes a plant's free phosphate supply, which indirectly stimulates chloroplast starch synthesis. While linked to low photosynthesis rates, the starch grains themselves may not necessarily interfere significantly with the efficiency of photosynthesis, and might simply be a side effect of another photosynthesis-depressing factor.
What is an alternate way to make starch?
Ground Truth Answers: glucose monomers in the chloroplast can be linked togetherglucose monomersglucose monomers in the chloroplast
Prediction:
When might starch grains become overly large?
Ground Truth Answers: Under conditions such as high atmospheric CO2 concentrationshigh atmospheric CO2 concentrationsUnder conditions such as high atmospheric CO2 concentrations,
Prediction:
What happens when starch grains become overly large?
Ground Truth Answers: distorting the grana and thylakoidsdistorting the grana and thylakoidsdisplace the thylakoids, but leave them intact.
Prediction:
What root problem can cause starch buildup?
Ground Truth Answers: Waterlogged rootsWaterloggedWaterlogged roots
Prediction:
What might starch grains be a side effect of?
Ground Truth Answers: another photosynthesis-depressing factoranother photosynthesis-depressing factoranother photosynthesis-depressing factor
Prediction:
Photorespiration can occur when the oxygen concentration is too high. Rubisco cannot distinguish between oxygen and carbon dioxide very well, so it can accidentally add O2 instead of CO2 to RuBP. This process reduces the efficiency of photosynthesis—it consumes ATP and oxygen, releases CO2, and produces no sugar. It can waste up to half the carbon fixed by the Calvin cycle. Several mechanisms have evolved in different lineages that raise the carbon dioxide concentration relative to oxygen within the chloroplast, increasing the efficiency of photosynthesis. These mechanisms are called carbon dioxide concentrating mechanisms, or CCMs. These include Crassulacean acid metabolism, C4 carbon fixation, and pyrenoids. Chloroplasts in C4 plants are notable as they exhibit a distinct chloroplast dimorphism.
What can rubisco do by mistake?
Ground Truth Answers: add O2 instead of CO2 to RuBPadd O2 instead of CO2add O2 instead of CO2 to RuBP
Prediction:
When does photorespiration happen?
Ground Truth Answers: when the oxygen concentration is too highwhen the oxygen concentration is too highwhen the oxygen concentration is too high
Prediction:
Why is using O2 instead of CO2 less efficient?
Ground Truth Answers: it consumes ATP and oxygen, releases CO2, and produces no sugarit consumes ATP and oxygen, releases CO2, and produces no sugarconsumes ATP and oxygen, releases CO2, and produces no sugar
Prediction:
How much carbon gets wasted by using O2 instead of CO2?
Ground Truth Answers: up to half the carbon fixed by the Calvin cycleup to halfhalf
Prediction:
What is unusual about C4 plants' chloroplasts?
Ground Truth Answers: they exhibit a distinct chloroplast dimorphismexhibit a distinct chloroplast dimorphismexhibit a distinct chloroplast dimorphism
Prediction:
Chloroplasts alone make almost all of a plant cell's amino acids in their stroma except the sulfur-containing ones like cysteine and methionine. Cysteine is made in the chloroplast (the proplastid too) but it is also synthesized in the cytosol and mitochondria, probably because it has trouble crossing membranes to get to where it is needed. The chloroplast is known to make the precursors to methionine but it is unclear whether the organelle carries out the last leg of the pathway or if it happens in the cytosol.
Where do chloroplasts make amino acids?
Ground Truth Answers: in their stromastromain their stroma
Prediction:
Which amino acids contain sulfur?
Ground Truth Answers: cysteine and methioninecysteine and methioninecysteine and methionine
Prediction:
What is the problem with cysteine?
Ground Truth Answers: it has trouble crossing membranes to get to where it is neededit has trouble crossing membraneshas trouble crossing membranes to get to where it is needed
Prediction:
What are we unsure of about how chloroplasts make methionine precursors?
Ground Truth Answers: whether the organelle carries out the last leg of the pathway or if it happens in the cytosolwhether the organelle carries out the last leg of the pathwaywhether the organelle carries out the last leg of the pathway or if it happens in the cytosol
Prediction:
Chloroplasts are a special type of a plant cell organelle called a plastid, though the two terms are sometimes used interchangeably. There are many other types of plastids, which carry out various functions. All chloroplasts in a plant are descended from undifferentiated proplastids found in the zygote, or fertilized egg. Proplastids are commonly found in an adult plant's apical meristems. Chloroplasts do not normally develop from proplastids in root tip meristems—instead, the formation of starch-storing amyloplasts is more common.
What is sometimes used interchangeably with 'plastids'?
Ground Truth Answers: ChloroplastsChloroplastsChloroplasts
Prediction:
What do a plant's chloroplasts descend from?
Ground Truth Answers: undifferentiated proplastids found in the zygote, or fertilized eggundifferentiated proplastidsundifferentiated proplastids found in the zygote
Prediction:
Where are Proplastids usually found?
Ground Truth Answers: in an adult plant's apical meristemszygoteadult plant's apical meristems
Prediction:
What is more often seen in root tip maristems?
Ground Truth Answers: the formation of starch-storing amyloplastsamyloplastsstarch-storing amyloplasts
Prediction:
If angiosperm shoots are not exposed to the required light for chloroplast formation, proplastids may develop into an etioplast stage before becoming chloroplasts. An etioplast is a plastid that lacks chlorophyll, and has inner membrane invaginations that form a lattice of tubes in their stroma, called a prolamellar body. While etioplasts lack chlorophyll, they have a yellow chlorophyll precursor stocked. Within a few minutes of light exposure, the prolamellar body begins to reorganize into stacks of thylakoids, and chlorophyll starts to be produced. This process, where the etioplast becomes a chloroplast, takes several hours. Gymnosperms do not require light to form chloroplasts.
What happens if angiosperm shoots don't get enough light?
Ground Truth Answers: proplastids may develop into an etioplast stage before becoming chloroplastsproplastids may develop into an etioplast stage before becoming chloroplastsproplastids may develop into an etioplast stage before becoming chloroplasts
Prediction:
What is an etioplast?
Ground Truth Answers: a plastid that lacks chlorophyllplastid that lacks chlorophyllplastid that lacks chlorophyll
Prediction:
What do etioplasts' internal membranes have?
Ground Truth Answers: invaginations that form a lattice of tubes in their stromainvaginationslattice of tubes in their stroma, called a prolamellar body
Prediction:
What do etioplasts have instead of chlorophyll?
Ground Truth Answers: a yellow chlorophyll precursoryellow chlorophyll precursoryellow chlorophyll precursor
Prediction:
What plants don't need light to make chloroplasts?
Ground Truth Answers: GymnospermsGymnospermsGymnosperms
Prediction:
Plastid differentiation is not permanent, in fact many interconversions are possible. Chloroplasts may be converted to chromoplasts, which are pigment-filled plastids responsible for the bright colors seen in flowers and ripe fruit. Starch storing amyloplasts can also be converted to chromoplasts, and it is possible for proplastids to develop straight into chromoplasts. Chromoplasts and amyloplasts can also become chloroplasts, like what happens when a carrot or a potato is illuminated. If a plant is injured, or something else causes a plant cell to revert to a meristematic state, chloroplasts and other plastids can turn back into proplastids. Chloroplast, amyloplast, chromoplast, proplast, etc., are not absolute states—intermediate forms are common.
What can chloroplasts change into?
Ground Truth Answers: chromoplastschromoplastschromoplasts
Prediction:
What are chromoplasts?
Ground Truth Answers: pigment-filled plastids responsible for the bright colors seen in flowers and ripe fruitpigment-filled plastidspigment-filled plastids responsible for the bright colors seen in flowers and ripe fruit
Prediction:
What can amyloplasts become?
Ground Truth Answers: chromoplastschromoplastschromoplasts
Prediction:
What can proplastids become?
Ground Truth Answers: chromoplastschromoplastschromoplasts
Prediction:
When a plant is injured, what can become proplastids?
Ground Truth Answers: chloroplasts and other plastidschloroplasts and other plastids can turn back into proplastidschloroplasts and other plastids
Prediction:
The division process starts when the proteins FtsZ1 and FtsZ2 assemble into filaments, and with the help of a protein ARC6, form a structure called a Z-ring within the chloroplast's stroma. The Min system manages the placement of the Z-ring, ensuring that the chloroplast is cleaved more or less evenly. The protein MinD prevents FtsZ from linking up and forming filaments. Another protein ARC3 may also be involved, but it is not very well understood. These proteins are active at the poles of the chloroplast, preventing Z-ring formation there, but near the center of the chloroplast, MinE inhibits them, allowing the Z-ring to form.
What do FtsZ1 and FtsZ2 combine into?
Ground Truth Answers: filamentsfilamentsfilaments
Prediction:
What are FtsZ1 and FtsZ2?
Ground Truth Answers: proteinsproteinsproteins
Prediction:
What do FtsZ1 and FtsZ2 plus ARC6 form?
Ground Truth Answers: a structure called a Z-ringa Z-ringZ-ring
Prediction:
Where is the Z-ring?
Ground Truth Answers: within the chloroplast's stromawithin the chloroplast's stromawithin the chloroplast's stroma
Prediction:
What gets the Z-ring in the right place?
Ground Truth Answers: The Min systemThe Min systemMin system
Prediction:
Next, the two plastid-dividing rings, or PD rings form. The inner plastid-dividing ring is located in the inner side of the chloroplast's inner membrane, and is formed first. The outer plastid-dividing ring is found wrapped around the outer chloroplast membrane. It consists of filaments about 5 nanometers across, arranged in rows 6.4 nanometers apart, and shrinks to squeeze the chloroplast. This is when chloroplast constriction begins. In a few species like Cyanidioschyzon merolæ, chloroplasts have a third plastid-dividing ring located in the chloroplast's intermembrane space.
What are PD rings?
Ground Truth Answers: plastid-dividing ringsplastid-dividing ringsplastid-dividing rings
Prediction:
How many PD rings are there?
Ground Truth Answers: twotwotwo
Prediction:
How large are the outer PD ring's filaments?
Ground Truth Answers: about 5 nanometers acrossabout 5 nanometers across5 nanometers across
Prediction:
How far apart are the outer PD ring's filaments?
Ground Truth Answers: 6.4 nanometers6.4 nanometers6.4 nanometers
Prediction:
What is different about Cyanidioschyzon merolæ?
Ground Truth Answers: chloroplasts have a third plastid-dividing ringchloroplasts have a third plastid-dividing ringchloroplasts have a third plastid-dividing ring located in the chloroplast's intermembrane space
Prediction:
Light has been shown to be a requirement for chloroplast division. Chloroplasts can grow and progress through some of the constriction stages under poor quality green light, but are slow to complete division—they require exposure to bright white light to complete division. Spinach leaves grown under green light have been observed to contain many large dumbbell-shaped chloroplasts. Exposure to white light can stimulate these chloroplasts to divide and reduce the population of dumbbell-shaped chloroplasts.
What is necessary for chloroplasts to replicate?
Ground Truth Answers: LightLightLight
Prediction:
What kind of light is important for chloroplasts to divide?
Ground Truth Answers: bright white lightwhite lightbright white light
Prediction:
What do chloroplasts look like in spinach grown in green light?
Ground Truth Answers: large dumbbell-shapeddumbbell-shapeddumbbell-shaped
Prediction:
What kind of light is inadequate for chloroplasts to divide?
Ground Truth Answers: poor quality green lightgreen lightpoor quality green light
Prediction:
Recently, chloroplasts have caught attention by developers of genetically modified crops. Since, in most flowering plants, chloroplasts are not inherited from the male parent, transgenes in these plastids cannot be disseminated by pollen. This makes plastid transformation a valuable tool for the creation and cultivation of genetically modified plants that are biologically contained, thus posing significantly lower environmental risks. This biological containment strategy is therefore suitable for establishing the coexistence of conventional and organic agriculture. While the reliability of this mechanism has not yet been studied for all relevant crop species, recent results in tobacco plants are promising, showing a failed containment rate of transplastomic plants at 3 in 1,000,000.
Why are chloroplasts of interest in GMO crops?
Ground Truth Answers: transgenes in these plastids cannot be disseminated by pollenchloroplasts are not inherited from the male parenttransgenes in these plastids cannot be disseminated by pollen
Prediction:
What is reduced by using plastid transformation for gene modification?
Ground Truth Answers: environmental risksenvironmental risksenvironmental risks
Prediction:
What was the containment failure rate in a tobacco plant study using plastid transformation?
Ground Truth Answers: 3 in 1,000,0003 in 1,000,0003 in 1,000,000
Prediction:
What are plants with plastid gene transformations called?
Ground Truth Answers: transplastomicgenetically modified cropsgenetically modified plants
Prediction: