The question asks to identify the pair of scientists who were awarded the Nobel Prize in 1962 for their discovery of the DNA structure. This is a direct factual recall question related to significant scientific discoveries and their recognition.
In 1953, James Watson and Francis Crick published their groundbreaking paper describing the double helix structure of DNA. This discovery was pivotal in understanding genetics and molecular biology. For this monumental work, they, along with Maurice Wilkins, were awarded the Nobel Prize in Physiology or Medicine in 1962.
C) Watson and Crick were awarded the Nobel Prize in Physiology or Medicine in 1962, along with Maurice Wilkins, for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material. This directly matches the question's criteria.
The question asks for the year in which the double-helical structure of DNA was proposed. This is a factual recall question related to a significant discovery in molecular biology.
James Watson and Francis Crick, building upon the work of Rosalind Franklin and Maurice Wilkins (X-ray diffraction data) and Erwin Chargaff (base pairing rules), published their model of the DNA double helix in the journal Nature. This seminal publication occurred in 1953.
B) 1953 — James Watson and Francis Crick published their paper describing the double-helical structure of DNA in 1953. This discovery was a landmark event in biology, leading to a deeper understanding of genetics and heredity.
The question asks for the specific title of Francis Crick's Ph.D. thesis. This requires knowledge of the historical context of his early scientific work, particularly before his groundbreaking work on the structure of DNA.
C) X-ray Diffraction: Polypeptides and Proteins. This was indeed the title of Francis Crick's Ph.D. thesis, completed in 1954 at Gonville and Caius College, Cambridge. His work focused on using X-ray diffraction techniques to study the structure of proteins.
The question asks for the definition of 'variation' in genetics. Variation refers to the differences observed within a species, particularly between parents and their offspring, or among individuals in a population. Understanding this fundamental concept is key to answering the question.
Correct Option: B) Differences among progeny and their parents. This option accurately describes genetic variation, which is the raw material for evolution and explains why offspring are not identical to their parents or to each other.
Mendel's groundbreaking work on inheritance involved careful experimentation and observation. To establish universal principles (laws), he needed to ensure his findings were consistent and not merely random occurrences. The question asks what allowed him to generalize his laws.
C) Confirmation over successive generations. Mendel's ability to observe consistent patterns and ratios of traits appearing and reappearing in predictable ways over multiple generations (F1, F2, F3, etc.) was essential for him to generalize his findings into universal laws of inheritance. This demonstrated the reliability and reproducibility of his observations.
The question asks about the number of contrasting traits in pea plants that Gregor Mendel studied during his groundbreaking genetics experiments. This is a factual recall question from the history of genetics.
Correct Option: C) Mendel studied 7 contrasting traits in pea plants.