Principles of Inheritance and Variation — BIOLOGY STD 12 Science — Question

Put these statements in the proper order, by rearranging the letters, to describe Darwin's theory of natural selection-

1. The end result of organic evolution is many different species, each adapted to specific environments.
2. Many more individuals are produced each generation that can survive and reproduce.
3. Gradually, over long periods of time, a population can become well adapted to a particular environment.
4. There are inheritable variation among the members of a population.
5. Individuals with adaptive characteristics are more likely to be selected to reproduce by the environment.

Draw a schematic diagram of L.S. of a typical flower.

Explain the status, function and percentage of RNA polymerase enzyme found in eukaryotic cells.

Discuss one example, based on your day-to-day observations, showing how loss of one species may lead to the extinction of another.

The barriers in the innate immunity are given in the following table. Identify a, b, c and d.

S.No.	Type of Barrier	S.No.	Barrier
a.	Physical	i.	Skin, a
b.	Physiological	ii.	b, in the eye
c.	c	iii.	Interferon
d.	Cellular	iv.	WBC, d

 

Apomixis resembles asexual reproduction, as well as mimics sexual reproduction in plants. Explain with the help of a suitable example.

A pedigree chart given below, present a particular generation which shows a trait irrespective of sexes (i.e., present in both male and female). Neither of the parents of the particular generation shows the trait. Draw your conclusion on the basis of the pedigree.

List the three parameters used for constructing ecological pyramids. Describe any one instance where the pyramid may look inverted.

A childless couple has agreed for a test tube baby programme. List only the basic steps the procedure would involve to conceive the baby.