A zygote is formed by the fusion of a male gamete and a female gamete. The number of chromosomes in the zygote of a human is :
A zygote is formed by the fusion of a male gamete and a female gamete. The number of chromosomes in the zygote of a human is :
Options
The correct option is C.
Marking Scheme
- 11 mark
Hint
Recall that gametes have half the chromosome number () of normal body cells. Fertilization combines two gametes to restore the diploid number ().
Quick Oral Answer
A human zygote has 46 chromosomes, which is restored when a sperm with 23 chromosomes fertilizes an egg with 23 chromosomes.
Analysis & Explanation
In human beings, the non-reproductive body cells (somatic cells) are diploid and contain chromosomes ( pairs).
During gametogenesis, specialized germ-cells undergo a reduction division called meiosis to produce haploid gametes (sperm and egg), each containing half the number of chromosomes, which is .
When the male gamete ( chromosomes) fuses with the female gamete ( chromosomes) during fertilization, a diploid zygote is formed. This fusion re-establishes the original chromosome number:
- Option C is correct because the zygote contains chromosomes.
- Option A is incorrect because is the haploid number of chromosomes found in gametes, not the zygote.
- Option B is incorrect because is the number of autosomes in a human somatic cell, excluding the sex chromosomes.
- Option D is incorrect because would be double the diploid number, which is prevented by meiosis during gamete formation.
Common Mistakes
- 1Students often confuse the haploid number of chromosomes in gametes (23) with the diploid number in the zygote (46).
Interesting Facts
If meiosis did not halve the chromosome number in gametes, the chromosome number would double with every generation, leading to cellular chaos!
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Frequently Asked Questions
How many marks does this question carry in CBSE Class 10 Science 2024?
This question carries 1 mark in the CBSE Class 10 Science 2024 examination.
Which chapter does this question come from in Science?
This question is from the chapter "How do Organisms Reproduce?" in the CBSE Class 10 Science syllabus.
What topic does this question cover in Science?
This question covers the topic "Sexual Reproduction and Chromosome Number" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2024 paper?
This is a MCQ question from Section A in the CBSE Class 10 Science 2024 paper.