GENETICS AND EVOLUTION
GENETIC BASIS OF INHERITANCE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Half heterozygous, half homozygous dominant
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Half round, half wrinkled
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All heterozygous
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All round
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Detailed explanation-1: -The homozygous dominant variety will make all gametes with “R” allele only. Random fertilization of gametes of two parent plants will obtain RR (homozygous dominant) and Rr (heterozygous dominant) genotypes in 1:1 ratio.
Detailed explanation-2: -The P cross produces F1 offspring that are all heterozygous for both characteristics. The resulting 9:3:3:1 F2 phenotypic ratio is obtained using a Punnett square. In pea plants, purple flowers (P) are dominant to white (p), and yellow peas (Y) are dominant to green (y).
Detailed explanation-3: -You’ll note that 100% of all offspring are Rr, which is the genotype. Since the genotype for all offspring are the same, and the Rr genotype encodes a pink color, then 100% of the phenotypes will be pink (NOT red-remember that this is incomplete dominance).
Detailed explanation-4: -A true-breeding plant with round seeds would have a genotype of (RR) for that trait and a true-breeding plant with wrinkled seeds would have a genotype of (rr).
Detailed explanation-5: -When two individuals that are homozygous for the same alleles are crossed, all of their offspring will all also be homozygous. The continuation of such crosses constitutes a true breeding line or strain.