Genetics And Plant Breeding - Study Mode
[#406] Crossing over occurs between
Correct Answer
(B) Non-sister chromatids
Explanation
Solution: Crossing over occurs between Non-sister chromatids. Crossing over is a cellular process that happens during meiosis when chromosomes of the same type are lined up. When two chromosomes, one from the mother and one from the father line up, parts of the chromosome can be switched.
[#407] When we want to transfer a single gene from undesirable variety into a well adopted agronomically desirable variety the most suitable breeding method is
Correct Answer
(C) Back cross
Explanation
Solution: When we want to transfer a single gene from an undesirable variety into a well-adopted agronomically desirable variety the most suitable breeding method is Back cross. It is the mating of a hybrid organism (offspring of genetically unlike parents) with one of its parents or with an organism genetically similar to the parent. The backcross is useful in genetics studies for isolating (separating) certain characteristics in a related group of animals or plants.
[#408] In which crop, the first transgenic was developed
Correct Answer
(B) Tobacco
Explanation
Solution: In which crop, the first transgenic was developed Tobacco. The first genetically modified crop plant was produced in 1982, an antibiotic-resistant tobacco plant. The first field trials of genetically engineered plants occurred in France and the US in 1986, tobacco plants were engineered to be resistant to herbicides. Tobacco is the most commonly used plant for the expression of transgenes from a variety of organisms. Among the many genes from different organisms expressed in tobacco plants, genes of bacterial origin are the most common.
[#409] In nitrogen fixation
Correct Answer
(A) Plants convert atmospheric nitrogen to nitrates
Explanation
Solution: In nitrogen fixation plants convert atmospheric nitrogen to nitrates. Nitrogen fixation is any natural or industrial process that causes free nitrogen (N 2 ), which is a relatively inert gas plentiful in air, to combine chemically with other elements to form more-reactive nitrogen compounds such as ammonia, nitrates, or nitrites. Nitrogen-fixing plants are those whose roots are colonized by certain bacteria that extract nitrogen from the air and convert or “fix” it into a form required for their growth.
[#410] Giant chromosome is found in
Correct Answer
(A) Salivary gland chromosome of drosophilla
Explanation
Solution: The giant chromosome is found in Salivary gland chromosome of drosophila. The giant chromosomes are very large compared to normal chromosomes. They are also called mega chromosomes. They increase the cell volume and DNA content so it has multiple copies of genes that allow a high level of gene expression. Polytene giant chromosomes are found in the cells of salivary glands of Drosophila. It helps produce a large amount of adhesive mucoprotein, a type of glue before pupation.