Evolution — BIOLOGY STD 12 Science — Question

“Forests provide us unlimited benefits.”Explain how this happens with the help of three different areas.

It is commonly observed that parents feel embarrassed to discuss freely with their adolescent children about sexuality and reproduction. The result of this parental inhibition is that the children go astray sometimes.

1. Explain the reasons that you feel are behind such embarrassment amongst some parents to freely discuss such issues with their growing children.
2. By taking one example of a local plant and animal, how would you help these parents to overcome such inhibitions about reproduction and sexuality?

How does an electrostatic precipitator work?

What are the characteristics of DNA?

Mention their source and the function they perform:
hCG, LH, FSH, Relaxin.

Study the given aquatic food chain and answer the questions that follow:

1. Give reasons why there is a continuous increase in the DDT content in different trophic levels of the chain.
2. Name the phenomenon responsible for the increase in DDT content.

When and where are primary oocytes formed in a human female? Trace the development of these oocytes till ovulation (in menstrual cycle). How do gonadotropins influence this developmental process?

Answer the following questions:
How is ‘oogenesis’ markedly different from ‘spermatogenesis’ with respect to the growth till puberty in the humans?

The following is the illustration of the sequence of ovarian events (a – i) in a human female.
What is the difference between “d” and “e” ?

Describe in detail the origin and evolution of human?