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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
Explain the mechanism of sex determination in birds.
Fill in the following blank with suitable word :
Genes always work in ................ .
Explain how, sex is determined in human babies.
If a normal human cell has 46 chromosomes, how many chromosomes will be there in a human (i) sperm cell, and (ii) zygote?
In a human, how many chromosmes are present in an egg which has just been produced by the ovary?
A zygote which has inherited an X chromosome from the father will develop into :
(a) baby boy
(b) baby girl
(c) adult
(d) either boy or girl
A couple with a newborn baby is troubled that the child does not resemble either of them. Suspecting that a mixup occurred at the hospital, they check the blood type of the infant. It is type O. Because the father is type A and the mother type B, they conclude that a mixup has definitely occurred. Are they correct? Give reason for your answer.
Explain the following terms:
Identical twins
Answer the following question:
How is sex determined in human beings? Explain with the help of a diagram.
Write a short note on sex determination in man.
Give Technical Term:
The cell which determines the sex of a baby.
Complete the following sentence with appropriate word:
___________ chromosomes do not take part in sex determination.
ZW-ZZ system of sex determination occurs in
Brief about female heterogamety.
Number of autosomes present in liver cells of a human female is ______.
A zygote which has an X-chromosome inherited from the father will develop into a
The two versions of a trait (character) which are brought in by the male and female gametes are situated on
Select the statements that describe characteristics of genes
- genes are specific sequence of bases in a DNA molecule
- a gene does not code for proteins
- in individuals of a given species, a specific gene is located on a particular chromosome
- each chromosome has only one gene
The belief that the mother is completely responsible for the sex of the child is wrong because the child
Structures present in a cell which is responsible for determination of the sex of a baby is ______.
How many types of gametes are produced by a human female?
All human chromosomes ate not paired. Most human chromosomes have a maternal and a paternal copy, and we have 22 such pairs. But one pair called the sex chromosomes, is odd in not always being a perfect pair. Women have a perfect pair of sex chromosomes. But men have a mismatched pair in which one is normal sized while the other is a short one.
(a) In humans, how many chromosomes are present in a Zygote and in each gamete?
(b) A few reptiles rely entirely on environmental cues for sex determination. Comment.
(c) "The sex of a child is a matter of chance and none of the parents are considered to be responsible for it." Justify it through flow chart only.
OR
(c) Why do all the gametes formed in human females have an X chromosome?
The sex chromosome in a human ovum is ______.
How is the sex of a newborn individual determined in different species of animals? Give three examples to support your answer.
A zygote which has Y chromosome inherited from the father will develop into a ______.
