Genetics And Plant Breeding - Study Mode
[#261] Before reaching the adulthood some individuals die because of the presence of gene in the appropriate genotype is
Correct Answer
(C) Lethal gene
Explanation
Solution: Before reaching adulthood some individuals die because of the presence of the gene in the appropriate genotype Lethal gene. This gene causes death if both recessive alleles are possessed by the same individual. They are usually a result of mutations in genes that are essential for growth or development. Lethal alleles may be recessive, dominant, or conditional depending on the gene or genes involved. Recessive lethal alleles do not cause death in the heterozygous form because a certain threshold of protein output is maintained. In the homozygous form, the protein output does not meet the threshold, causing death.
[#262] Self-incompatibility is helpful for the development of
Correct Answer
(C) Pure line variety
Explanation
Solution: Self-incompatibility is helpful for the development of Pure line variety. Self-incompatibility (SI) is a general name for several genetic mechanisms that prevent self-fertilization in sexually reproducing organisms and thus encourage outcrossing and allogamy. SI is one of the most important means of preventing inbreeding and promoting the generation of new genotypes in plants. A pure line is the progeny of a single self-fertilized homozygous plant. Therefore self-incompatibility is helpful in the development of pure line varieties.
[#263] Which of the following is responsible for guttation?
Correct Answer
(A) Root pressure
Explanation
Solution: Root pressure is responsible for guttation. Guttation is the exudation of drops of xylem sap on the tips or edges of leaves of some vascular plants, such as grasses, and several fungi, which are not plants but were previously categorized as such and studied as part of botany. The root pressure forces some water to exude through special leaf tip or edge structures, hydathodes, or water glands, forming drops. Root pressure provides the impetus for this flow, rather than transpirational pull.
[#264] The crossing between two different species of the same genus is called
Correct Answer
(B) Interspecific hybridization
Explanation
Solution: The crossing between two different species of the same genus is called Interspecific hybridization. Interspecific hybridization is the crossing of two species from the same genus. This allows the exploitation of useful genes from wild, unimproved species for the benefit of the cultivated species. The Pisum species are diploid self-pollinators sharing a similar karyotype.
[#265] Choose the correct match.
Correct Answer
(D) All of the above
Explanation
Solution: A. Operon concept-Jacob and Monod is correct match. Operon Theory is the concept of gene regulation proposed by François Jacob and Jacques Monod (1961). An operon is a group of structural genes whose expression is coordinated by an operator. B. Transposons-McClintock is correct match. The existence of transposons was postulated in the late 1940s by Barbara McClintock, who was studying the inheritance of maize, but the actual molecular basis for transposition was described by later groups. C. Khorana-Genetic code is also a correct match. Har Gobind Khorana was the chemist who cracked DNA's code and made the first artificial gene. genetic code is the once-secret language of our DNA.