Genetics And Plant Breeding - Study Mode

[#186] Single Seed Descent (SSD) is a modification of which one of the following methods of selection
Correct Answer

(C) Bulk

Explanation

Solution: Single Seed Descent (SSD) is a modification of the Bulk method of selection. SSD is the modification of the bulk method. It is first proposed by Goulden (1939) and later modified by Brim (1966). Instead of bulking a whole seed lot of selected plants, a single seed is selected randomly from each selected plant to make bulk. The SSD method consists of advancing hybrid populations by taking a single seed from each plant and compositing the seeds to perpetuate the next generation.

[#187] Global Gene Bank of Barley is located at
Correct Answer

(A) ICARDA

Explanation

Solution: Global Gene Bank of Barley is located at ICARDA. The ICARDA genebank network and research stations in North Africa and West and South Asia test the new barley varieties for tolerance to diseases, drought, heat, and cold, as well as for precise end-use product classification. Since 1977, ICARDA has released more than 250 barley varieties in 46 countries under CGIAR's Global Barley Breeding Program.

[#188] The best method to carry forward the maximum number of genotype/genes to the advanced generations against the force of natural selection
Correct Answer

(D) Single seed descent method

Explanation

Solution: The best method to carry forward the maximum number of genotypes/genes to the advanced generations against the force of natural selection is the Single seed descent method. The single-seed descent (SSD) method of inbreeding minimizes the amount of genetic sampling. Single-seed-descent (SSD) is a modification of conventional plant breeding used by breeders to rapidly fix genes in breeding lines. As its name implies, SSD is the advancement of one randomly selected seed per plant through the early segregating stages.

[#189] A neuploidy occurs due to
Correct Answer

(B) Change in a subset of chromosome

Explanation

Solution: Aneuploidy occurs due to a change in a subset of the chromosome. A change in chromosome number that is not the exact multiple of the haploid karyotype is known as aneuploidy. It does not include a difference of one or more complete sets of chromosomes. A cell with any number of complete chromosome sets is called a euploid cell. This condition interferes with the growth and development of an organism.

[#190] Ultimate source of variation is
Correct Answer

(C) Mutation

Explanation

Solution: The ultimate source of variation is Mutation. Genetic variation is the difference in DNA among individuals or the differences between populations. Mutations are the ultimate sources of genetic variation, but other mechanisms, such as genetic drift, contribute to it, as well. A mutation is a change in the DNA sequence of an organism. Mutations can result from errors in DNA replication during cell division, exposure to mutagens, or a viral infection. It is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA.