Which of the following is not true about sexual reproduction?

Options

A. Gametes are diploid in humans
B. Sperm and ova fuse to form zygote
C. It introduces new gene combinations is a population
D. Diploid zygote divides by mitosis

Answer

To determine which statement is not true about sexual reproduction, we will analyze the provided options step by step.

### Step-by-Step Solution:

1. **Understanding Sexual Reproduction**:
- Sexual reproduction involves the fusion of male and female gametes (sperm and ovum) to form a zygote, which develops into a new individual.

2. **Evaluating the Options**:
- **Option A**: "Gametes are diploid in humans."
- This statement is **not true**. In humans, gametes (sperm and ovum) are haploid, meaning they contain only one set of chromosomes (23 chromosomes).

- **Option B**: "Sperm and ovum are used to form a zygote."
- This statement is **true**. The sperm (male gamete) and ovum (female gamete) fuse to form a zygote during fertilization.

- **Option C**: "It introduces new gene combinations in a population."
- This statement is **true**. Sexual reproduction results in genetic variation due to the combination of genes from two parents, leading to new gene combinations in the offspring.

- **Option D**: "Diploid zygote divides by mitosis."
- This statement is **true**. After fertilization, the diploid zygote undergoes mitosis to develop into an embryo.

3. **Conclusion**:
- The only statement that is not true about sexual reproduction is **Option A**: "Gametes are diploid in humans." This is incorrect because gametes are haploid.

### Final Answer:
The correct answer is **Option A**: "Gametes are diploid in humans."

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