Question

select the correct answer. an elephant has 56 chromosomes. which statement about a zygote of an elephant is true?
a. the zygote has 28 chromosomes, mostly inherited from the father.
b. the zygote has 56 chromosomes, all inherited from the mother.
c. the zygote has 28 chromosomes, all inherited from the mother.
d. the zygote has 56 chromosomes, 28 inherited from the mother and 28 from the father.
e. the zygote has 28 chromosomes, 14 inherited from the mother and 14 from the father.

Explanation:

1. Recall that a zygote is formed by the fusion of a sperm (from father) and an egg (from mother).
2. In elephants, body cells (like the ones that produce gametes) have 56 chromosomes. Gametes (sperm and egg) are haploid, meaning they have half the number of chromosomes of body cells. So each gamete (sperm and egg) has \( \frac{56}{2}=28 \) chromosomes.
3. When the sperm (28 chromosomes from father) and egg (28 chromosomes from mother) fuse to form a zygote, the zygote has \( 28 + 28=56 \) chromosomes, with 28 from each parent.
4. Now analyze the options:

• Option A: Zygote has 28 chromosomes? No, zygote is diploid, should have 56. Also, "mostly inherited from father" is wrong as it's 28 from each. Eliminate A.
• Option B: All from mother? No, zygote gets chromosomes from both parents. Eliminate B.
• Option C: 28 chromosomes all from mother? No, zygote has 56 and gets from both. Eliminate C.
• Option D: 56 chromosomes, 28 from mother and 28 from father. This matches our reasoning.
• Option E: 28 chromosomes with 14 from each? No, gametes have 28 each, so zygote should have 56 (28 + 28). Eliminate E.

Answer:

D. The zygote has 56 chromosomes, 28 inherited from the mother and 28 from the father.