Syngamy results in formation of
- A.haploid zygote
- B.diploid zygote
- C.non-motile male gametes
- D.motile male gametes
Correct answer
Explanation
The correct answer is B, diploid zygote. Syngamy is the fusion of a male and a female gamete, and since each gamete is haploid, their union gives a diploid zygote.
Gametes are produced by meiosis, which halves the chromosome number, so each carries one set (n). When they fuse in syngamy, the two sets come together and the zygote has two sets (2n). In humans each gamete has 23 chromosomes and the zygote has 46. The zygote then divides by mitosis to form the embryo. In flowering plants, syngamy is one of the two fusions of double fertilisation; the other, triple fusion, forms the triploid endosperm.
A is wrong: the fusion of two haploid gametes cannot give a haploid cell; the number of sets doubles.
C is wrong: male gametes are formed before syngamy, by meiosis, not as a result of it.
D is wrong: motile male gametes, such as sperm, also exist before fertilisation and take part in syngamy.
Exam tip: syngamy = gamete fusion → diploid zygote (2n); triple fusion in angiosperms → triploid endosperm (3n).
Practice Questions
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- B.Two
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- D.CₙH₂ₙ₋₁
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- B.N/m
- C.N-m²
- D.N/m²
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