The question asks to identify the scientists credited with proposing the double-helical structure of DNA. This is a fundamental concept in biology and genetics, often tested in competitive exams. We need to recall the key figures involved in this discovery.
Correct Option: A) James Watson and Francis Crick are credited with proposing the double-helical structure of DNA in 1953. Their model, based on X-ray diffraction data primarily from Rosalind Franklin and Maurice Wilkins, and chemical data from Erwin Chargaff, revolutionized biology and laid the foundation for modern molecular genetics. They received 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.
The question asks about the term 'Denisovan' and its reference in media, specifically in the context of general knowledge for competitive exams. This requires knowledge of recent discoveries in anthropology and human evolution.
B) an early human species
Denisovans are an extinct species or subspecies of archaic humans that ranged across Asia during the Lower and Middle Paleolithic periods. They are known primarily from DNA evidence found in a finger bone and teeth discovered in the Denisova Cave in Siberia. Their genetic material indicates interbreeding with modern humans and Neanderthals. The discovery of Denisovans has significantly contributed to our understanding of human evolutionary history, making them a frequent topic in scientific media.
The question asks for the definition of 'inheritance' in genetics. We need to identify the option that accurately describes this fundamental biological process.
Correct Option: B) Passing of traits from parents to offspring
The question asks for the definition of a 'true-breeding' line. This concept is fundamental in genetics, particularly in Mendelian inheritance. A true-breeding line refers to organisms that produce offspring with the same traits as the parents when self-pollinated or crossed with genetically identical individuals.
D) A line showing stable trait inheritance over generations — This accurately defines a true-breeding line. Such a line is homozygous for the traits under consideration, meaning it will consistently produce offspring with the same traits as the parents through self-pollination or breeding with similar true-breeding individuals.
The question asks to identify the organism Gregor Mendel used for his pioneering hybridization experiments that laid the foundation for modern genetics. This is a direct recall question from basic biology.
Correct Option: B) Garden pea
The question asks to evaluate two statements regarding hereditary diseases, specifically mitochondrial diseases and their inheritance/prevention. We need to determine the correctness of each statement based on biological facts.
C) Both 1 and 2 are correct. Statement 1 accurately describes the purpose and timing of mitochondrial replacement therapy, which aims to prevent the inheritance of mitochondrial diseases. Statement 2 correctly states the maternal inheritance pattern of mitochondrial diseases, a fundamental concept in genetics.