Question

Which one of the following combinations showing the chromosome numbers for human cells is CORRECT?

• A. Oogonium = 23, Fibroblast at G2/M = 92, Egg before fertilization = 23, Sperm = 23
• B. Oogonium = 46, Fibroblast at G2/M = 92, Egg before fertilization = 46, Sperm = 23
• C. Oogonium = 46, Fibroblast at G2/M = 46, Egg before fertilization = 46, Sperm = 23
• D. Oogonium = 46, Fibroblast at G2/M = 92, Egg before fertilization = 23, Sperm = 23

Hint:

Remember that oogonium and egg cells have 46 chromosomes (diploid), while sperm cells are haploid with 23 chromosomes.

Answer 1

The Correct Option is B

Step 1: Understanding chromosome numbers.
- The oogonium (female germ cell) starts with 46 chromosomes, which are reduced to 23 chromosomes during meiosis in the egg cell.
- Fibroblast cells at G2/M phase have 92 chromosomes (since they are diploid and the chromosomes are doubled during cell division).
- The sperm cell has 23 chromosomes, as it is a haploid gamete.

Step 2: Analyzing the options.
- (A) Oogonium = 23, Fibroblast at G2/M = 92, Egg before fertilization = 23, Sperm = 23: Incorrect. The oogonium should have 46 chromosomes, not 23.
- (B) Oogonium = 46, Fibroblast at G2/M = 92, Egg before fertilization = 46, Sperm = 23: Correct. The numbers of chromosomes match the typical human cell and gamete counts.
- (C) Oogonium = 46, Fibroblast at G2/M = 46, Egg before fertilization = 46, Sperm = 23: Incorrect. Fibroblast at G2/M phase should have 92 chromosomes, not 46.
- (D) Oogonium = 46, Fibroblast at G2/M = 92, Egg before fertilization = 23, Sperm = 23: Incorrect. The egg before fertilization should have 46 chromosomes.

Step 3: Conclusion.
The correct answer is (B) as it shows the correct number of chromosomes for each cell type.