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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
If X chromosome is inherited from mother and Y from father, the offspring will be male.
Differentiate between male and female heterogamety.
Write notes on sex determination in the unborn baby.
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 (i) sperm cell, and (ii) zygote?
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.
Does the sex of the child depend on the father or it is just a matter of chance? Discuss.
Explain the following terms:
Identical twins
With the help of a chart, explain the method of sex determination in honeybees.
Drone of the honeybees shows haploid number of chromosomes. Illustrate.
Complete the following sentence with appropriate word:
___________ chromosomes do not take part in sex determination.
Explain the haplo-diploid method of sex determination in the honey bee.
Distinguish between heterogametic and homogametic sex determination systems.
How is sex determined in human beings?
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.
From the following which option correctly represents the normal genetic constitution of a ovum?
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 |
Chromosomal constitution of normal human females can be written as ______.
The number of pairs of sex chromosomes in the zygote of a human being is ______
Which of the following is an example of genetic variation?
The maleness of a child is determined by
A trait in an organism is influenced by
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
Fill the blank circles in figure and identify the sex of child A and B.
The chromosomal constitution of a human female can be written as ______
Also describe as to, who determines the sex of an unborn child? Mention whether temperature has a role in sex determination.
Which of the following group shows ZW-ZZ type of sex determination?
The sex chromosome in a human ovum is ______.
