Question

somatic cells in llamas contain 74 chromosomes. if a cell from a llama undergoes nondisjunction of chromosome 25 at meiosis i, how many chromosomes may be found in a resultant gamete? check all that apply 36 37 38 74

Explanation:

Step1: Recall normal gamete chromosome number

Normal somatic cells have 74 chromosomes. Gametes are formed by meiosis. In normal meiosis, a diploid (2n) somatic cell with 74 chromosomes will produce haploid (n) gametes with 37 chromosomes.

Step2: Consider nondisjunction at meiosis I

Nondisjunction at meiosis I means that homologous chromosomes fail to separate properly. For chromosome 25, instead of one chromosome 25 going to each daughter - cell in meiosis I, both homologous chromosomes of chromosome 25 go to one daughter - cell and none go to the other. So, one resulting gamete will have an extra chromosome 25 (37 + 1=38 chromosomes) and the other will be missing chromosome 25 (37 - 1 = 36 chromosomes).

Answer:

A. 36
C. 38