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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.
संबंधित प्रश्न
If X chromosome is inherited from mother and Y from father, the offspring will be male.
Differentiate between ‘ZZ’ and ‘XY’ type of sex-determination mechanisms.
How is the sex of the child determined in human beings?
Explain the mechanism of 'sex determination' in birds. How does it differ from that of human beings?
What are the chromosomes XY and XX known as?
If a normal human cell has 46 chromosomes, how many chromosomes will be there in a human sperm cell?
In a human, how many chromosmes are present in a sperm in the testes?
In a human, how many chromosmes are present in a skin cell?
In a human, how many chromosmes are present in a fertilised egg?
Does genetic combination of mother play a significant role in determining the sex of a new born baby?
The exchange of genetic material takes place in :
(a) vegetative reproduction
(b) asexual reproduction
(c) sexual reproduction
(d) budding
The two versions of a trait (character) which are brought in by the male and female gametes are situated on :
(a) copies of the same chromosome
(b) sex chromosomes
(c) two different chromosomes
(d) any chromosomes
Define the following:
Autosomes
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.
Short Answer Question.
“Father is responsible for determination of sex of child and not the mother”. Justify.
Explain the mechanism of sex determination in birds.
ZW-ZZ system of sex determination occurs in
What is male heterogamety?
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 |
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
Which of the following determines the sex of a child?
A zygote which has an X-chromosome inherited from the father will develop into a
Select the incorrect statement
Which of the following statements is not true with respect to variation?
A woman has only daughters. Analyse the situation genetically and provide a suitable explanation.
Fill the blank circles in figure and identify the sex of child A and B.
What is sex determination? Explain the mechanism of sex determination in the case of birds.
How is the sex of a newborn individual determined in different species of animals? Give three examples to support your answer.
