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प्रश्न
How is sex determined in human beings?
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उत्तर
The XX-XY chromosomal pattern determines sex in humans. Humans possess 22 pairs of autosomes and one pair of sex chromosomes. The female has two homomorphic sex chromosomes called XX. The males have two heteromorphic sex chromosomes, XY. Female oocytes have equivalent chromosomal types (22 + X). As a result, girls are homogametic. Human males produce two types of male gametes or sperm: gynosperms (22 + X) and androsperms (22 + Y). Human males are hence heterogametic. The gender of the offspring is determined at fertilisation. Fertilisation of the egg (22 + X) with a gynosperm (22 + X) results in a female child (44 + XX), whereas fertilisation with an androsperm (22 + Y) results in a male child (44 + XY). Because the two types of sperm are produced in equal quantities, there is an equal possibility of having a male or female child in a given pairing. The Y-chromosome, which defines an individual’s male sex, is also known as the androsome.
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संबंधित प्रश्न
"The sex of a newborn child is a matter of chance and none of the parents may be considered responsible for it". Draw a flow chart showing determination of sex of a newborn to justify this statement.
Name the species used in sericulture. Name the stages in the life cycle of a silk moth in cyclic form.
Which of the following combinations of sex chromosomes produce a male child : XX or XY?
Explain how, sex is determined in human babies.
In a human, how many chromosmes are present in a brain cell?
The human animal which has an XY pair of chromosomes is called :
(a) male
(b) hybrid
(c) female
(d) doomed
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.
A family consists of two parents and their five children and the pedigree chart below shows the inheritance of the trait colour blindness in them.
Who is colour blind in the parents – the Father or the Mother?
Why did T. H. Morgan select Drosophila melanogaster to study sex linked genes for his lab experiments ?
________ shows haplo-diploid type of sex-determination.
Explain the following terms:
Identical twins
Choose the correct answer:
Chromosomes identical in male and female are called __________
Choose the correct answer:
A man can transfer his sex-linked gene to his ______________
With the help of a chart, explain the method of sex determination in honeybees.
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.
Complete the following sentence with appropriate word:
______are the alternative forms of a gene producing different effects.
Explain the mechanism of sex determination in birds.
Brief about female heterogamety.
Explain the mode of sex determination in honeybees.
Read the following statements and select the correct option.
i. If sperm containing Y chromosome fertilizes the ovum, then diploid zygote is formed that grows into a male child.
ii. If sperm containing X chromosome fertilizes ovum, then diploid zygote is formed, that grows into a female child.
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 |
Which of the following organisms has haploid number of chromosomes?
In human males all the chromosomes are paired perfectly except one. This/these unpaired chromosomes is/are ______.
- large chromosome
- small chromosome
- Y-chromosome
- X-chromosome
Select the incorrect statement
Sex in honey bee is determined by ______.
