Question

9. A family is analyzing why two siblings look so different. One child inherited alleles linked to darker hair and higher cholesterol, while the other inherited different alleles from the same parents. In class, students flip coins to model how chromosomes line up during meiosis. One student argues that gametes are always identical, while another points out that differences can also come from which sperm cell fertilizes which egg.

Which statements explain why the siblings inherited different combinations of alleles?
(Select all that apply).

Responses

A. Each gamete from a parent always carries the exact same set of alleles.
A. Each gamete from a parent always carries the exact same set of alleles.

B. Independent assortment produces gametes with different allele combinations.
B. Independent assortment produces gametes with different allele combinations.

C. Fertilization adds variation because any sperm can combine with any egg.
C. Fertilization adds variation because any sperm can combine with any egg.

D. Environment controls which alleles are packaged into gametes.
D. Environment controls which alleles are packaged into gametes.

E. Random sorting of alleles during meiosis is one reason siblings are genetically unique.

Answer 1

Correct answers: B, C, and E.

- B. Independent assortment produces gametes with different allele combinations — during meiosis homologous chromosomes segregate independently, producing different combinations.
- C. Fertilization adds variation because any sperm can combine with any egg — random fusion of gametes creates many possible zygote genotypes.
- E. Random sorting of alleles during meiosis is one reason siblings are genetically unique — stochastic segregation and crossing over produce variation.

A is false: gametes from the same parent are not all identical.
D is false: the environment does not determine which alleles are packaged into gametes.