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प्रश्न
In humans, males are heterogametic and females are homogametic. Explain. Are there any examples where males are homogametic and females heterogametic?
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उत्तर
The term homogametic and heterogametic refer to the organism depending upon whether all the gametes contain one type of sex chromosome (Homo = same) or two different types of sex chromosomes (Hetero = different) Humans show XX/XY type of sex determination i.e. Females contain 2 copies of X chromosome and males contain 1 X and 1 Y chromosome. Therefore, ova produced by females contain the same sex chromosome i.e. X. On the other hand, the sperms contain 2 different types of chromosomes i.e. 50% sperms have X and 50% have Y chromosome open from half the autosomes (Meiosis) Therefore, the sperms are different with respect to the composition of sex chromosome. In case of humans, females are considered to be homogametic while males are heterogametic. Yes, there are examples where males are homogametic and females are heterogametic. In some birds, the mode of sex determination is denoted by ZZ (males) and ZW (females).
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संबंधित प्रश्न
Answer the following questions related to sex determination in human beings:
i. What is sex chromosome?
ii. How many pairs of chromosomes are present in human beings?
iii. How is the sex of the human offspring determined?
iv. Draw a diagram depicting sex determination in man.
Write notes on sex determination in the unborn baby.
Explain the mechanism of 'sex determination' in birds. How does it differ from that of human beings?
In a human, how many chromosmes are present in an egg which has just been produced by the ovary?
In a human, how many chromosmes are present in a skin cell?
The number of pair(s) of sex chromosomes in the zygote of humans is :
(a) one
(b) two
(c) three
(d) four
The sex of a child is determined by which of the following?
(a) the length of the mother's pregnancy
(b) the length of time between ovulation and copulation
(c) the presence of and X chromosome in an ovum
(d) the presence of a Y chromosome in a sperm
E is the gene for brown eye colour and an is the gene for blue eye colour. which gene is (1) recessive, and (2) dominant?
Which combination of genes in the zygote will produce children with brown eyes?
The person A has only B chromosomes in all its gametes. On the other hand, another person C has chromosome D in half of gametes and chromosome E in the other half of gametes. When chromosomes B and D combine during fertilisation, a female zygote results. On the other hand, combination of B and E chromosomes produces a male zygote.
(a) What are chromosomes (i) B (ii) D, and (iii) E?
(b) Out of B, D and E, which two chromosomes are of the same type?
(c) Which chromosome is smaller in size?
(d) What is the general name of chromosomes such as B and E?
(e) Out of the two persons A and C, which one is (i) male, and (ii) female?
Complete the following sentence with appropriate word:
______are the alternative forms of a gene producing different effects.
Explain the haplo-diploid method of sex determination in the honey bee.
How drones are produced in honey bees?
What is Lyonisation?
Identify the female heterogamety from the chromosomal complements given below.
Sex is determined in human beings ______.
The ‘X’ body of Henking was observed in ______.
Which of the following combination of chromosome numbers represents the correct sex determination pattern in honey bees?
The number of pairs of sex chromosomes in the zygote of a human being is ______
A man with blood group A marries a woman having blood group O. What will be the blood group of the child?
The maleness of a child is determined by
Select the incorrect statement
How many types of gametes are produced by a human female?
Which of the following group shows ZW-ZZ type of sex determination?
Which pair of sex chromosome will determine a male?
