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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
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.
"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.
In a human, how many chromosmes are present in a sperm in the testes?
Which combination of genes in the zygote will produce children with brown eyes?
Name two animals which have nineteen pairs of chromosomes.
Name any two genetic in humans.
Does the sex of the child depend on the father or it is just a matter of chance? Discuss.
Choose the correct answer from the four options given below :
In a human male, a sperm will contain :
Define the following:
Sex-linked characters
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 ______________
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.
Complete the following sentence with appropriate word:
______are the alternative forms of a gene producing different effects.
How drones are produced in honey bees?
Brief about female heterogamety.
A man with blood group A marries a woman having blood group O. What will be the blood group of the child?
Which of the following decides the sex of the child?
Which of the following is an example of genetic variation?
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 ______
Which of the following statements is not true with respect to variation?
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
A woman has only daughters. Analyse the situation genetically and provide a suitable explanation.
The chromosomal constitution of a human female can be written as ______
What is the probability of a girl or a boy being born into a family? Justify your answer.
How is the sex of a newborn individual determined in different species of animals? Give three examples to support your answer.
