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प्रश्न
Differentiate between ‘ZZ’ and ‘XY’ type of sex-determination mechanisms.
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उत्तर
| ZZ Sex-Determination Mechanism | XY Sex-Determination Mechanism |
| In this type of chromosomal sex determination mechanism, the females are heterogametic, that is, they produce two types of gametes, while the males are homogametic. | In this type of chromosomal sex determination mechanism, the males are heterogametic, that is, they produce two types of gametes, while the females are homogametic. |
| Here, the females produce two types of eggs (A + Z) and (A + W), while the males produce only one type of sperm (A + Z). | Here, the males have an X chromosome and its counterpart Y chromosome, which is distinctly smaller. Hence, the males are XY. However, females have a pair of X chromosomes; therefore, they are XX. |
| Organisms that have the ZZ type of sex-determination mechanism are birds, fishes, some reptiles, etc. | Organisms that have the XY type of sex-determination mechanism are humans and Drosophila. |
संबंधित प्रश्न
Write the types of sex-determination mechanisms the following crosses show. Give an example of each type.
(i) Female XX with Male XO
(ii) Female ZW with Male ZZ
Write notes on sex determination in the unborn baby.
There are ................ pairs of chromosomes in the human being.
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?
Give Reason:
Why X-linked recessive diseases are more common among males than females.
What is parthenogenesis?
How drones are produced in honey bees?
Which of the following is incorrect regarding ZW-ZZ type of sex determination?
Explain the mode of sex determination in honeybees.
A man with blood group A marries a woman having blood group O. What will be the blood group of the child?
If a normal cell of the human body contains 46 pairs of chromosomes then the numbers of chromosomes in a sex cell of a human being is most likely to be ______
A zygote which has an X-chromosome inherited from the father will develop into a
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 belief that the mother is completely responsible for the sex of the child is wrong because the child
The chromosomal constitution of a human female can be written as ______
Sex of an individual is determined by different factors in various species. Some animals rely entirely on the environmental ones, while in some other animals the individuals can change their sex during their life time indicating that sex of some species is not genetically determined. However in human beings, the sex of an individual is largely determined genetically.
- In what way are the sex chromosomes 'X' and 'Y' different in size? Name the mismatched pair of sex chromosome in humans.
- Write the number of pair/pairs of sex chromosomes present in human beings. In which one of the parent (male/female) perfect pair/pairs of sex chromosome are present?
- Citing two examples, justify the statement "Sex of an individual is not always determined genetically".
OR
Draw a flow chart to show that sex is determined genetically in human beings.
What is the probability of a girl or a boy being born into a family? Justify your answer.
