Ecosystems — BIOLOGY STD 12 Science — Question

Prior a sports event blood and 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.

Study the figure (a) and (b) given below and answer the questions given after the graphs.

1. Under the influence of which type of Natural Selection would graph (a) become like graph.
2. What could be the likely reasons of new variations arising in the population?
3. Who suggested Natural Selection as a mechanism of evolution?

1. Expand BOD.
2. At a particular segment of a river near a sugar factory, the BOD is much higher than the normal level. What is it indicative of? What will happen to the living organisms in this part of the river?
3. Under what conditions will the BOD be lowered in the river? How will it affect the aquatic life?

A team of students are preparing to participate in the interschool sports meet. During a practice session, you find some vials with labels of certain cannabinoids.

1. Will you report to the authorities? Why?
2. Name a plant from which such chemicals are obtained.
3. Write the effect of these chemicals on human body.

Briefly explain IVF and ET What are the conditions in which these methods are advised?

1. Mark the positive and negative terminals.
2. What is the charge carried by DNA molecule and how does it help in its separation?
3. How the separated DNA fragments are finally isolated?

Draw a diagram of a male gametophyte of an angiosperm. Label any four parts. Why is sporopollenin considered the most resistant organic material?

Suggest and explain any three Assisted Reproductive Technologies (ART) to an infertile couple.

Describe the types of fruits.

Mention the location and the function of Leydig cells in humans.