Model Paper 1 — BIOLOGY STD 12 Science — Question

Generally, it is observed that human males suffer from hemophilia more than human females, who rarely suffer from it. Explain giving reasons.

In a sea shore, the benthic animals live in sandy, muddy and rocky substrata and accordingly developed the following adaptations.

1. Burrowing.
2. Building cubes.
3. Holdfasts/ peduncle.

Find the suitable substratum against each adaptation.

Prior to a sports event blood & urine samples of sportspersons are collected for drug tests.

1. Why is there a need to conduct such tests?
2. Name the drugs the authorities usually look for.
3. Write the generic names of two plants from which these drugs are obtained.

Explain how surrogacy is helpful in case of an infertile woman.

How do genes and chromosomes share similarity from the point of view of genetical studies?

Distinguish between :
Grazing food chain and detritus food chain

Name the stage ofthe Plasmodium thall is trrnsmitted to human body by the vector. Describe the life cycle of the plrasite in humans.

OR

Trace the life cycle of Plasmodium in humans from the stage of entry, until it is picked up by the female Anopheles.

What is LAB? What is its role in human stomach?

In certain seasons we sweat profusely while in some other season we shiver. Explain.

A and B are two different cloning vectors in two different bacterial colonies cultured in chromogenic substrate. Bacterial colonies with cloning vector A were colourless, whereas those with B were blue coloured. Explain by giving reasons the cause of difference in colour that appeared.