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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
There are two sets of chromosomes in the zygote.
Which of the following combinations of sex chromosomes produce a male child : XX or XY?
A normal cell of human body contains 23 pairs of chromosomes. The number of chromosomes in a sex cell (sperm or ovum) of a human being is most likely to be :
(a) 46
(b) 23
(c) 21
(d) 42
Name two animals which have nineteen pairs of chromosomes.
Does the sex of the child depend on the father or it is just a matter of chance? Discuss.
Choose the correct answer :
Human sex chromosomes are __________
Choose the correct answer:
A single recessive trait, able to express must be on _________
Give Reason:
Why X-linked recessive diseases are more common among males than females.
Which of the following is incorrect regarding ZW-ZZ type of sex determination?
What is male heterogamety?
There are five daughters and no son in a family. It is because
Match the items of Column I with Column II:
| Column I | Column II | ||
| i. | XX-XO method of Sex Determination | a. | Turner syndrome |
| ii. | XX-XY method of Sex Determination | b. | Female heterog ametic |
| iii. | karyotype-45 | c. | Grasshopper |
| iv. | ZW-ZZ method of Sex Determination | d. | Female homogametic |
Grasshopper is an example of XO type of sex determination in which the males have ______.
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?
A trait in an organism is influenced by
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 number of pair (s) of sex chromosomes in the zygote of humans is
A woman has only daughters. Analyse the situation genetically and provide a suitable explanation.
The belief that the mother is completely responsible for the sex of the child is wrong because the child
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?
A zygote which has Y chromosome inherited from the father will develop into a ______.
Given below are two statements:
Statement - I: The male Drosophila has a pair of homomorphic sex chromosomes.
Statement - II: The male human being has a pair of heteromorphic sex chromosomes.
In the light of above statements, Choose the most appropriate answer from the options given below:
An organism that possesses both male and female reproductive organs in the same individual is classified as which type?
Which term describes organisms where male and female reproductive organs are present in separate individuals?
In 1891, H. Henking studied spermatogenesis in squash bugs and observed that a specific nuclear structure was present in what percentage of the resulting sperms?
What did H. Henking originally call the nuclear structure he discovered during his 1891 study of squash bug spermatogenesis?
In the haplodiploidy system observed in honeybees, fertilized eggs develop into which type of individual?
In a bird population using the ZW–ZZ sex determination system, if a ZZ male mates with a ZW female, what proportion of offspring would be expected to be female?
