Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.

Principles of Inheritance and Variation

Short Answer Type

121.

What is a test cross? How can it decipher the heterozygosity of a plant?

2413 Views

Long Answer Type

122.

(a) What is polygenic inheritance ? Explain with the help of a suitable example.

(b) How are pleiotropy and Mendelian pattern of inheritance different from polygenic pattern of inheritance ?

3035 Views

Short Answer Type

123.

State a difference between gene and an allele.

1457 Views

124.

Give an example of an autosomal recessive trait in humans. Explain its pattern of inheritance with the help of a cross.

1339 Views

Long Answer Type

125.

Describe the mechanism of pattern of inheritance of ABO blood groups in humans.

803 Views

126.
A. Why is haemophilia generally observed in human males? Explain the conditions under which a human female can be haemophilic.

B. A pregnant human female was advised to undergo M.T.P. It was diagnosed by her doctor that the foetus she is carrying has developed from a zygote formed by an XX egg fertilized by Y-carrying sperm. Why was she advised to undergo M.T.P.?

A. Haemophilia is sex-linked recessive disease; it is transmitted from unaffected female carrier to male child with haemophilia. It is an X-linked recessive gene.

The females have XX condition and thus may be heterozygous carrying one normal X chromosome and diseased/affected X. Since the disease is a recessive one, therefore, it does not express until it is present in the homozygous condition.

The males have XY condition. The presence of the diseased allele of X will result in the person to develop the disease. The Y has no allele for this disease. Thus the probability of the males getting affected is much more than the females.

B. MTP stands for medical termination of pregnancy (MTP) or it may be called as abortion in common language.
The egg usually has one of the two X-chromosomes, but in this case, the pregnant female has egg having XX condition. The doctor advises for M.T.P. because her foetus may be carrying an abnormal number of chromosomes as the fertilisation of the XX egg by the Y sperm will create a trisomy condition.

It will result in a zygote having XXY condition, It will lead to nondisjunction abnormality such as Klinefelter syndrome where males may have an extra X chromosome. The child may suffer from abnormalities and thus the female was advised to have termination of pregnancy.

1251 Views

Short Answer Type

127.

During a medical investigation, an infant was found to possess an extra chromosome 21. Decribe the symptoms the child is likely to develop later in the life.

323 Views