(a) Name the two types of gametes produced by men.
(b) Does a male child inherit X chromosome from his father? Justify.
(c) How many types of gametes are produced by a human female?
(a) Name the two types of gametes produced by men.
(b) Does a male child inherit X chromosome from his father? Justify.
(c) How many types of gametes are produced by a human female?
Official answer
(a) Men produce two types of gametes (sperms): half of them carry the chromosome, and the other half carry the chromosome.
(b) No, a male child does not inherit an chromosome from his father. A male child has the sex chromosome combination . He inherits the chromosome from his father and the chromosome from his mother. If he inherited an chromosome from his father, he would have an combination and would be a female child.
(c) Human females produce only one type of gamete (egg/ovum), which always carries an chromosome.
Marking scheme
- 1.Name the two types of gametes produced by men (sperm with X and sperm with Y chromosome). (1 mark)
- 2.Justify why a male child does not inherit an X chromosome from his father (inherits Y from father to be XY). (1 mark)
- 3.State the number of types of gametes produced by a human female (only one type, carrying X). (1 mark)
Hint
Recall that males have mismatched sex chromosomes () while females have a perfect pair (). The father determines the sex of the child.
Quick oral answer
Q: Why is the father responsible for the sex of the child in humans? A: Because human females only produce eggs with X chromosomes, whereas males produce two types of sperm: 50% with an X chromosome and 50% with a Y chromosome. The type of sperm that fertilizes the egg determines the sex.
Common mistakes
- 1.Students often mistakenly believe that both parents contribute to the sex of the male child, or that the mother's egg can carry a Y chromosome.
- 2.Confusing autosomes with sex chromosomes.
Analysis and explanation
In human beings, sex is genetically determined. Out of the 23 pairs of chromosomes, 22 pairs are perfect autosomes. The 23rd pair consists of sex chromosomes. Females have a perfect pair of sex chromosomes (), meaning all eggs produced contain an chromosome. Males have a mismatched pair (), where one is a normal-sized and the other is a short chromosome. Consequently, spermatogenesis produces two distinct populations of sperm: 50% carrying the chromosome and 50% carrying the chromosome. The sex of the child is determined entirely by which paternal gamete fertilizes the maternal egg.
Interesting facts
In some reptiles, sex is determined by environmental temperature during egg incubation, whereas in snails, individuals can actually change their sex!
Question details
Q10 of 22 questions
- Board
- CBSE
- Class
- Class 10
- Subject
- Science
- Year
- 2022
- Section
- Section Section B
- Marks
- 3
- Type
- Short Answer
- Chapter
- Heredity
- Topic
- Sex Determination
- Bloom's level
- Understanding
- Syllabus topic
- Sex determination: Brief introduction
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Frequently asked questions
How many marks does this question carry in CBSE Class 10 Science 2022?
This question carries 3 marks in the CBSE Class 10 Science 2022 examination.
Which chapter does this question come from in Science?
This question is from the chapter "Heredity" in the CBSE Class 10 Science syllabus.
What topic does this question cover in Science?
This question covers the topic "Sex Determination" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2022 paper?
This is a Short Answer question from Section Section B in the CBSE Class 10 Science 2022 paper.