Problem: Flowering plant:

Double fertilization refers to a process in which two sperm cells fertilize cells in the ovary. This process begins when a pollen grain adheres to the stigma of the pistil (female reproductive structure), germinates, and grows a long pollen tube. While this pollen tube is growing, a haploid generative cell travels down the tube behind the tube nucleus. The generative cell divides by mitosis to produce two haploid (n) sperm cells. As the pollen tube grows, it makes its way from the stigma, down the style and into the ovary. Here the pollen tube reaches the micropyle of the ovule and digests its way into one of the synergids, releasing its contents (which include the sperm cells). The synergid that the cells were released into degenerates and one sperm makes its way to fertilize the egg cell, producing a diploid (2n) zygote. The second sperm cell fuses with both central cell nuclei, producing a triploid (3n) cell. As the zygote develops into an embryo, the triploid cell develops into the endosperm, which serves as the embryo's food supply. The ovary now will develop into fruit and the ovule will develop into seed.

What serves as the embryo's food supply?
---
A: endosperm


Problem: Adolescence:

A potential important influence on adolescence is change of the family dynamic, specifically divorce. With the divorce rate up to about 50%, divorce is common and adds to the already great amount of change in adolescence. Custody disputes soon after a divorce often reflect a playing out of control battles and ambivalence between parents. Divorce usually results in less contact between the adolescent and their noncustodial parent. In extreme cases of instability and abuse in homes, divorce can have a positive effect on families due to less conflict in the home. However, most research suggests a negative effect on adolescence as well as later development. A recent study found that, compared with peers who grow up in stable post-divorce families, children of divorce who experience additional family transitions during late adolescence, make less progress in their math and social studies performance over time. Another recent study put forth a new theory entitled the adolescent epistemological trauma theory, which posited that traumatic life events such as parental divorce during the formative period of late adolescence portend lifelong effects on adult conflict behavior that can be mitigated by effective behavioral assessment and training. A parental divorce during childhood or adolescence continues to have a negative effect when a person is in his or her twenties and early thirties. These negative effects include romantic relationships and conflict style, meaning as adults, they are more likely to use the styles of avoidance and competing in conflict management.

Does a parental divorce during childhood or adulthood have a positive or negative effect on a person during early adulthood?
---
A: negative


Problem: Crucifixion of Jesus:

An early non-Christian reference to the crucifixion of Jesus is likely to be Mara Bar-Serapion's letter to his son, written sometime after AD 73 but before the 3rd century AD. The letter includes no Christian themes and the author is presumed to be a pagan. The letter refers to the retributions that followed the unjust treatment of three wise men: Socrates, Pythagoras, and "the wise king" of the Jews. Some scholars see little doubt that the reference to the execution of the "king of the Jews" is about the crucifixion of Jesus, while others place less value in the letter, given the possible ambiguity in the reference.

How much value did Pythagoras place in the crucifixion?
---
A: unanswerable


Problem: Alps:

Major European rivers flow from Switzerland, such as the Rhine, the Rhone, the Inn, the Ticino and the Po, all of which have headwaters in the Alps and flow into neighbouring countries, finally emptying into the North Sea, the Mediterranean Sea, the Adriatic Sea and the Black Sea. Other rivers such as the Danube have major tributaries flowing into them that originate in the Alps. The Rhone is second to the Nile as a freshwater source to the Mediterranean Sea; the river begins as glacial meltwater, flows into Lake Geneva, and from there to France where one of its uses is to cool nuclear power plants. The Rhine originates in a 30 square kilometre area in Switzerland and represents almost 60 percent of water exported from the country. Tributary valleys, some of which are complicated, channel water to the main valleys which can experience flooding during the snow melt season when rapid runoff causes debris torrents and swollen rivers.

Where do the major tributaries that flow through the Danube originate from?
---
A:
the Alps