Question: While the use of iron started to become more widespread around 1200 BC, mainly because of interruptions in the trade routes for tin, the metal is much softer than bronze. However, very small amounts of steel, (an alloy of iron and around 1% carbon), was always a byproduct of the bloomery process. The ability to modify the hardness of steel by heat treatment had been known since 1100 BC, and the rare material was valued for the manufacture of tools and weapons. Because the ancients could not produce temperatures high enough to melt iron fully, the production of steel in decent quantities did not occur until the introduction of blister steel during the Middle Ages. This method introduced carbon by heating wrought iron in charcoal for long periods of time, but the penetration of carbon was not very deep, so the alloy was not homogeneous. In 1740, Benjamin Huntsman began melting blister steel in a crucible to even out the carbon content, creating the first process for the mass production of tool steel. Huntsman's process was used for manufacturing tool steel until the early 1900s.
Try to answer this question if possible: When did Benjamin Huntsman begin to melt blister steel in a crucible
Answer: 1740
Question: After the Civil War, population expansion, railroad construction, and the disappearance of the buffalo herds heightened military tensions on the Great Plains. Several tribes, especially the Sioux and Comanche, fiercely resisted confinement to reservations. The main role of the Army was to keep indigenous peoples on reservations and to end their wars against settlers and each other, William Tecumseh Sherman and Philip Sheridan were in charge. A famous victory for the Plains Nations was the Battle of the Little Big Horn in 1876, when Col. George Armstrong Custer and two hundred plus members of the 7th Cavalry were killed by a force consisting of Native Americans from the Lakota, Northern Cheyenne, and Arapaho nations. The last significant conflict came in 1891.
Try to answer this question if possible: What caused a spike in difficulties between settlers and indigenous peoples on the western plains after the Civil War?
Answer: population expansion, railroad construction, and the disappearance of the buffalo herds
Question: The vast majority of living organisms encode their genes in long strands of DNA (deoxyribonucleic acid). DNA consists of a chain made from four types of nucleotide subunits, each composed of: a five-carbon sugar (2'-deoxyribose), a phosphate group, and one of the four bases adenine, cytosine, guanine, and thymine.:2.1
Try to answer this question if possible: What type of sugar composes part of the DNA molecule?
Answer: a five-carbon sugar (2'-deoxyribose)
Question: Modern evolutionary theory continues to develop. Darwin's theory of evolution by natural selection, with its tree-like model of branching common descent, has become the unifying theory of the life sciences. The theory explains the diversity of living organisms and their adaptation to the environment. It makes sense of the geologic record, biogeography, parallels in embryonic development, biological homologies, vestigiality, cladistics, phylogenetics and other fields, with unrivalled explanatory power; it has also become essential to applied sciences such as medicine and agriculture. Despite the scientific consensus, a religion-based political controversy has developed over how evolution is taught in schools, especially in the United States.
Try to answer this question if possible: What does the theory of evolution explain about living organisms?
Answer:
The theory explains the diversity of living organisms and their adaptation to the environment.