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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
Explain sex determination in human beings.
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
Differentiate between male and female heterogamety.
Which of the two, sperm or ovum, decides the sex of the child?
Explain how, sex is determined in human babies.
Name two animals which have nineteen pairs of chromosomes.
Choose the correct answer :
Human sex chromosomes are __________
Write a short note on sex determination in man.
Give Technical Term:
The cell which determines the sex of a baby.
What is parthenogenesis?
What is Lyonisation?
How is sex determined in human beings?
Diploid larvae which get royal jelly as food develops into ____________ and other develops into workers (sterile females).
Haplodiploidy is found in ______.
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
Some dinosaurs had feathers although they could not fly but birds have feathers that help them to fly. In the context of evolution this means that
A woman has only daughters. Analyse the situation genetically and provide a suitable explanation.
Does a male child inherit X chromosome from his father? Justify.
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 ______.
