Question

1. gregor mendel used pea plants to study heredity. the diagram shows the cross between pea plants with inflated pods and pea plants with constricted pods over three generations. how does this cross explain a basic principle of heredity? a traits are determined by two alleles of a gene. b genes control how many offspring appear in each generation. c scientists study inheritance by examining only one allele per trait. d each generation has more individuals than the previous generation.

Explanation:

• Option A: In genetics, a key principle is that traits are determined by two alleles of a gene. In the cross shown, the pod - shape trait (inflated or constricted) is determined by alleles \(G\) (dominant) and \(g\) (recessive). For example, \(GG\) and \(Gg\) result in inflated pods (dominant trait), and \(gg\) results in constricted pods (recessive trait).
• Option B: Genes do not control the number of offspring. The number of offspring is more related to factors like reproductive capacity, environmental conditions, etc., not the genetic cross itself.
• Option C: Scientists study inheritance by looking at the combination of alleles (not just one per trait). Each organism has two alleles for a given trait (diploid organisms), and Mendel's work was based on analyzing these allele combinations.
• Option D: The diagram does not show any information about the number of individuals in each generation being more than the previous one. It focuses on the genetic makeup (\(GG\), \(Gg\), \(gg\)) and the resulting trait (pod - shape).

Answer:

A. Traits are determined by two alleles of a gene.