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Question
Differentiate between male and female heterogamety.
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Solution
Male heterogamety: Male heterogamety includes human males having XY sex chromosomes and males of some insects, such as grasshopper and bugs, having XO sex chromosomes.
Female heterogamety: Female heterogamety includes females of some species of birds, fishes and insects. Females of butterfly and moth consist ZO sex chromosomes, while females of fish, reptiles and birds consist ZW sex chromosomes.
RELATED QUESTIONS
Answer the following questions related to sex determination in human beings:
i. What is sex chromosome?
ii. How many pairs of chromosomes are present in human beings?
iii. How is the sex of the human offspring determined?
iv. Draw a diagram depicting sex determination in man.
Which of the following is an example of ZW – ZZ type of mechanism of sex determination?
Which combination of genes in the zygote will produce children with brown eyes?
The person A has only B chromosomes in all its gametes. On the other hand, another person C has chromosome D in half of gametes and chromosome E in the other half of gametes. When chromosomes B and D combine during fertilisation, a female zygote results. On the other hand, combination of B and E chromosomes produces a male zygote.
(a) What are chromosomes (i) B (ii) D, and (iii) E?
(b) Out of B, D and E, which two chromosomes are of the same type?
(c) Which chromosome is smaller in size?
(d) What is the general name of chromosomes such as B and E?
(e) Out of the two persons A and C, which one is (i) male, and (ii) female?
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?
Choose the correct answer from the four options given below :
In a human male, a sperm will contain :
Define the following:
Sex chromosomes
Choose the correct answer:
A single recessive trait, able to express must be on _________
Answer the following question:
How is sex determined in human beings? Explain with the help of a diagram.
Give Reason:
Why X-linked recessive diseases are more common among males than females.
What is haplodiploidy?
Diploid larvae which get royal jelly as food develops into ____________ and other develops into workers (sterile females).
Haplodiploidy is found in ______.
The maleness of a child is determined by ______
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.
Also describe as to, who determines the sex of an unborn child? Mention whether temperature has a role in sex determination.
Does a male child inherit X chromosome from his father? Justify.
Sex of an individual is determined by different factors in various species. Some animals rely entirely on the environmental ones, while in some other animals the individuals can change their sex during their life time indicating that sex of some species is not genetically determined. However in human beings, the sex of an individual is largely determined genetically.
- In what way are the sex chromosomes 'X' and 'Y' different in size? Name the mismatched pair of sex chromosome in humans.
- Write the number of pair/pairs of sex chromosomes present in human beings. In which one of the parent (male/female) perfect pair/pairs of sex chromosome are present?
- Citing two examples, justify the statement "Sex of an individual is not always determined genetically".
OR
Draw a flow chart to show that sex is determined genetically in human beings.
