(a) What provides nutrition to human sperms? State the genetic constitution of a sperm.
(b) Mention the chromosome pair present in zygote which determines the sex of (i) a female child, and (ii) a male child.
(a) What provides nutrition to human sperms? State the genetic constitution of a sperm.
(b) Mention the chromosome pair present in zygote which determines the sex of (i) a female child, and (ii) a male child.
(a)
- Nutrition to human sperms: The secretions of the seminal vesicles and the prostate gland provide nutrition to the sperms. These secretions form a fluid medium that nourishes the sperms and facilitates their transport.
- Genetic constitution of a sperm: A human sperm is a haploid male gamete containing 23 chromosomes. Its genetic constitution is either or (carrying either an X or a Y sex chromosome along with 22 autosomes).
(b)
- (i) Female child: The chromosome pair present in the zygote is XX.
- (ii) Male child: The chromosome pair present in the zygote is XY.
Marking Scheme
- 11 mark
- 21 mark
- 31 mark
Hint
Think about the glands associated with the male reproductive tract that secrete fluids, and recall how sex chromosomes (X and Y) combine during fertilization to determine the sex of the offspring.
Quick Oral Answer
Sperms receive nutrition from the secretions of the seminal vesicles and prostate gland. A sperm has a haploid genetic constitution, carrying either an X or a Y sex chromosome ( or ). A female child has an XX chromosome pair in her zygote, while a male child has an XY pair.
Analysis & Explanation
In human beings, the male reproductive system includes glands like the prostate gland and seminal vesicles that add their secretions to the vas deferens. This fluid serves a dual purpose: it makes sperm transport easier and provides essential nutrition to the sperms.
Sex determination in humans is genetically controlled. Human somatic cells have 23 pairs of chromosomes (22 pairs of autosomes and 1 pair of sex chromosomes). Gametes are haploid, formed by meiosis. Sperms contain 22 autosomes and either an X or a Y chromosome. When a sperm carrying an X chromosome fertilizes an egg (which always carries an X chromosome), the resulting zygote has the XX pair, developing into a female child. If a sperm carrying a Y chromosome fertilizes the egg, the zygote has the XY pair, developing into a male child.
Common Mistakes
- 1Confusing the role of the testes (which produce sperms and testosterone) with the glands that provide nutrition (seminal vesicles and prostate gland).
- 2Writing that sperms contain both X and Y chromosomes simultaneously, rather than either X or Y.
Interesting Facts
The sex of a human child is determined entirely by the father's sperm, as the mother's egg can only contribute an X chromosome.
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Frequently Asked Questions
How many marks does this question carry in CBSE Class 10 Science 2020?
This question carries 3 marks in the CBSE Class 10 Science 2020 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 in Humans and Sex Determination" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2020 paper?
This is a Short Answer question from Section B in the CBSE Class 10 Science 2020 paper.