Evolution — BIOLOGY STD 12 Science — Question

Study the 3 representative figures of age pyramid relating to human population given below and answer the following question:

1. Mention the names given to the 3 kinds of age profiles (i), (ii), and (iii).
2. Which one of them is ideal for a population and why?
3. How do such age-profile studies help policy makers get concerned about our growing population and prepare for future planning? (say for example: for the year 2022.)

[Hint. The age profile you would name as stable was prepared on the data available on January 2007].

Describe briefly about embryonic stages in human being.

The graph shows species-area relationship:

1. If b denotes the relationship on log scale-

1. Describe a and b.
2. How is slope represented? Give the normal range of slope.
3. What kind of slope will be observed for frugivorous birds and mammals in a tropical forest?

2. Species diversity of plants (22%) is much less than that of animals (72%). Analyze the reasons for greater diversity of animals as compared to plants.

 

Define linkage and linkage group. Discuss the effect of linkage and its importance.###What is linkage? Who coined the term? Write the name of the insect used for this study.

Give the technical terms for the following:

1. Molecular Scissors.
2. Molecular Sieve.
3. Molecular Glue.
4. Autonomous replicating circular DNA.
5. First isolated restriction endonuclease.
6. Extraction of DNA fragments from gel.

Why do some adolescents start taking drugs? How can the situation be avoided?

What do you mean by biofertilizer? How do biofertilizers increase soil fertility?

Study the illustration given and answer the questions that follow:

Explain the role of hormones in the formation and release of ‘a’.

Do you think microbes can also be used as source of energy? If yes, how?