Human Reproduction — BIOLOGY STD 12 Science — Question

Explain the different organs of flower by drawing longitudinal section (L.S.) of a typical flower.

Explain the following two components of Darwin's theory of natural selection.

1. Variations.
2. Formation of new species.

Explain - Nucleoside & Nucleotide

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.

What is recombinant DNA? For creating recombinant vector molecule, can two different restriction enzymes be used for cutting vector and source DNA?

1. What are the three kinds into which all the wastes we generate can be categorised. How can they be disposed of?
2. Why are the colourful polysterene and plastic packaging used for protecting the food, considered an environmental menace?

1. Match the microbes listed under Column-A with the products mentioned under Column-B.

	Column-A		Column-B
(a)	Penicillium notatum	(i)	Statin
(b)	Trichoderma polysporum	(ii)	Ethanol
(c)	Monascus purpurea	(iii)	Antibiotic
(d)	Saccharomyces cerevisiae	(iv)	Cyclosporin-A

2. Why does ‘Swiss Cheese’ develop large holes?

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.

Why should we conserve biodiversity? How can we do it?OR
Why should we conserve biodiversity? Why is it a moral as well as social duty to contribute towards its protection?

Describe the inter-relationship between productivity, gross primary productivity and net productivity.