What is the number of chromosomes present in gametes (egg and sperm) of human beings?
A. Three sets of chromosomes
B. 22 pairs of chromosomes
C. One set of chromosomes
D. No chromosomes
Correct Answer: C. One set of chromosomes
Explanation
In human beings, gametes (the egg in females and sperm in males) contain 23 chromosomes each.
Explanation
- Gametes are haploid cells (n).
- This means they carry half the number of chromosomes compared to normal body (somatic) cells.
- Human somatic cells are diploid (2n) and contain 46 chromosomes (23 pairs).
- During fertilization, the egg (23) and sperm (23) combine to form a zygote with 46 chromosomes (2n).
Final Answer
👉 23 chromosomes in each gamete (egg and sperm).
Other Option Details
Here is the explanation of each option:
A. Three sets of chromosomes
- This means the cell contains three complete sets of chromosomes.
- It is called triploid (3n).
- Triploidy is abnormal in humans and usually occurs due to errors during fertilization (e.g., two sperm fertilizing one egg).
- Organisms like some plants can naturally be triploid.
B. 22 pairs of chromosomes
- This refers to autosomes only.
- Humans have 22 pairs of autosomes + 1 pair of sex chromosomes.
- So total = 23 pairs = 46 chromosomes in a normal human somatic (body) cell.
- This option means only the autosomes are included, not including the sex chromosomes.
C. One set of chromosomes
- This means the cell contains one complete set of chromosomes.
- It is called haploid (n).
- Human gametes (egg and sperm) contain 23 chromosomes, which is one set.
- The haploid number is important for sexual reproduction so that after fertilization the zygote becomes diploid (2n).
D. No chromosomes
- A cell with no chromosomes cannot perform normal life processes.
- Human cells cannot survive without chromosomes, as chromosomes carry genetic information (DNA).
- This situation is not biologically normal.
Summary Table
Option Meaning Example A Three sets (3n) Triploid cells (abnormal in humans) B 22 pairs of autosomes Somatic cells excluding sex chromosomes C One set (n) Sperm and ovum D No chromosomes Not compatible with life
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Writer: Vandita Singh, Lucknow (GS India Nursing Group