Advertisements
Advertisements
Question
Explain the mechanism of sex determination in humans with a suitable chart.
Advertisements
Solution
Sex Determination in human being:
- The chromosomal mechanism of sex determination in human beings is of the XX – XY type. The human diploid cell has 23 pairs of chromosomes.
- Out of these, 22 pairs of chromosomes are called autosomes, and one pair of chromosomes is called sex chromosomes that are responsible for the determination of sex.
- The human female has a pair of XX, homomorphic sex chromosomes while the male has XY, heteromorphic sex chromosomes.
- A human male has 44 autosomes + XY sex chromosomes, whereas a female has 44 autosomes + XX sex chromosomes.
- During gamete formation in males, the diploid germ cells in testis undergo spermatogenesis to produce two types of haploid sperms, 50% of sperms contain 22 autosomes and X chromosome while 50% of sperms contain 22 autosomes and the Y chromosome.
- In females, the diploid germ cells in ovaries undergo oogenesis to produce only one type of egg. All eggs contain 22 autosomes and an X chromosome.
- Thus human male is heterogametic and the female is homogametic.
- If sperm containing the X chromosome fertilizes the egg (ovum), the diploid zygote formed after fertilization grows into a female child.
- If sperm containing the Y chromosome fertilizes the egg, then the diploid zygote formed after fertilization grows into a male child.
- The sex of a child depends on the type of sperm fertilizing the egg and hence the father is responsible for the determination of the sex of the child and not the mother.
RELATED QUESTIONS
If X chromosome is inherited from mother and Y from father, the offspring will be male.
Which of the following combinations of sex chromosomes produce a male child : XX or XY?
Fill in the following blank with suitable word :
Genes always work in ................ .
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
A zygote which has inherited an X chromosome from the father will develop into :
(a) baby boy
(b) baby girl
(c) adult
(d) either boy or girl
- E is the gene for brown eye colour and e is the gene for blue eye colour. Which gene is (i) recessive, and (ii) dominant?
- Both father and mother have the genes Ee in their cells. What colour are their eyes?
- Which combination of genes in the zygote will produce children with blue eyes?
- Which combinations of genes in the zygote will produce children with brown eyes?
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 ?
Answer the following question:
How is sex determined in human beings? Explain with the help of a diagram.
Write the functional activity of the following structure:
Heterosomes
Short Answer Question.
“Father is responsible for determination of sex of child and not the mother”. Justify.
XO type of sex determination and XY type of sex determination are examples of ____________.
What is haplodiploidy?
Distinguish between heterogametic and homogametic sex determination systems.
The maleness of a child is determined by
Does a male child inherit X chromosome from his father? Justify.
An organism that possesses both male and female reproductive organs in the same individual is classified as which type?
Which term describes organisms where male and female reproductive organs are present in separate individuals?
