Biodiversity and Conservation — BIOLOGY STD 12 Science — Question

Explain the phenomena of dominance, multiple allelism and co–dominance taking ABO blood group as an example.

Describe the development of endosperm after double fertilization in an angiosperm. Why does endosperm development precedes that of zygote?

Alien species invasion has been a threat to biodiversity. Justify with the help of a suitable example. List any other three causes responsible for such a loss.

Describe the mammary gland by drawing well labelled diagram of sectional view and explain the mechanism of lactation.

A cross is made between different homozygous pea plants for contrasting flower positions.

1. Find out the position of flowers in F₁ generation on the basis of genotypes.
2. Work out the cross upto F₂ generation.
3. Compute the relative fraction of various genotypes in the F₂ generation?

Study the diagram given below:

Name the linkages X, Y, Z and the respective molecules formed by them.

Seeing a crowd of students in one corner of the school, the principal rushed to see the matter and found some children beating and chasing a small lizard. On seeing the principal, all the children fled to their classes except Alok who requested the principal to arrange for some medical assistance for the injured animal. The principal rewarded Alok for his attitude to save guard our biodiversity.

1. Mention the factors resulting in loss of biodiversity
2. Was Alok an indisciplined boy, who did not run to the class on seeing the principal? What values does the act promote?

This is the pedigree of a family tracing the movement of the gene for haemophilia. Explain the pattern of inheritance of the disease in the family.

Enumerate the complications that untreated STDs can lead to.