Why are angiosperm anthers called dithecous? Describe the structure of its microsporangium

If implementation of better techniques and new strategies are required to provide more efficient care and assistance to people, then why is there a statutory ban on amniocentesis? Write the use of this technique and give reason to justify.

Why is pedigree analysis done in the study of human genetics? State the conclusions that can be drawn from it.

Identify ‘a’, ‘b’, ‘c’, ‘d’, ‘e’ and ‘f’ in the table given below :

Community Service department of your school plan a visit to a slum area near the school with an objective to educate the slum dwellers with respect to health and hygiene.

(a)Why is there a need to organize such visits?

The following graph shows the species – area relationship. Answer the following questions as directed

(a) Name the naturalist who studied the kind of relationship shown in the graph. Write the observations made by him.

(b) Write the situations as discovered by the ecologists when the value of ‘Z’ (slope of the line) lies between (i) 0.1 and 0.2 (ii) 0.6 and 1.2 What does ‘Z’ stand for ?

(c) When would the slope of the line ‘b’ become steeper ?

Name and describe the technique that helps in separating the DNA fragments formed by the use of restriction endonuclease.

28.

State the function of a reservoir in a nutrient cycle. Explain the simplified model of carbon cycle in nature.

Since the origin of life on the earth, there were five episodes of mass extinction of species.

(i)How is the 'Sixth Extinction', presently in progress, different from the previous episodes?

(ii)Who is mainly responsible for the 'Sixth Extinction''?

(iii)List any four points that can help to overcome this disaster.

(a) Where does fertilization occur in human ? Explain the events that occur during this process.