This biology question covers important biological concepts and processes. The step-by-step explanation below helps you understand the underlying mechanisms and reasoning.
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You're on a roll — 2.1.1 The type of inheritance is polygenic inheritance. 2.1.2 Two reasons for the answer in QUESTION 2.1.1: • Milk production is controlled by three pairs of genes (multiple genes). • Each dominant gene has an additive effect, increasing the milk yield by a specific amount (30 litres). 2.1.3 Step 1: Determine the number of dominant alleles in the genotype PPQqRr. The genotype is PPQqRr. • P contributes 2 dominant alleles (PP). • Q contributes 1 dominant allele (Q). • R contributes 1 dominant allele (R). Total number of dominant alleles = 2 + 1 + 1 = 4. Step 2: Calculate the additional milk yield from the dominant alleles. Each dominant gene adds 30 litres of milk. Additional milk yield = 4 dominant alleles × 30 litres/allele = 120 litres. Step 3: Calculate the total milk yield. The base milk yield for genotype ppqqrr (0 dominant alleles) is 200 litres. Total milk yield = Base milk yield + Additional milk yield Total milk yield = 200 litres + 120 litres = 320 litres. The milk yield of a Jersey cow with the PPQqRr genotype is 320 litres. 2.2.1 The genetic phenomenon is codominance. 2.2.2 Both alleles for coat color (black and white) are expressed equally and simultaneously in the heterozygous individual, resulting in a roan phenotype where both black and white hairs are distinctly visible. 2.3.1 Prepotency is the ability of an individual to transmit its characteristics to its offspring with a high degree of certainty. It is important in genetics for selective breeding, as it allows breeders to consistently pass on desirable traits to future generations, improving livestock or crop varieties. 2.3.2 Atavism is the reappearance of a trait or characteristic in an organism after several generations of absence. It is important in genetics as it indicates the presence of dormant genes that can be expressed under certain conditions, providing insights into evolutionary history and the genetic potential within a species. Got more? Send 'em!