Human Reproduction — BIOLOGY STD 12 Science — Question

What is meant by addictive disorder?

Mrs. Peter and Mrs. James had babies at the same hospital. Mrs. Peter took home a girl, Nancy and Mrs. James received a boy, Richard. However, Mrs. James was certain she gave birth to a girl and brought suit against the hospital. Blood tests showed that Mr. James was type O, Mrs. James was type AB and Mr. and Mrs. Peter were both type B. Nancy was type A and Richard was type O. List the possible genotypes of each individual and then indicate the correct parents for each child.
Genotypes :

1. Mrs. Peter ____________.
2. Mr. Peter ______________.
3. Nancy _____________.
4. Mrs. James _________________.
5. Mr. James ________________.
6. Richard _______________.
7. Whose baby is Nancy?
8. Whose baby is Richard?

Explain Hershey - Chase experiment. What was proved through this experiments?

A red–eyed heterozygous female fruit fly is crossed with a red–eyed male. Work out all possible genotypes and phenotypes of the progeny. Comment on the pattern of inheritance of eye colour in fruit flies.

Name and explain the type of interaction between big trees and certain species of wasps?

"Pollen grains in wheat are shed at 3-celled stage while in peas they are shed at 2-celled stage." Explain. Where are germ pores present in a pollen grain?

While creation and presence of variation are directionless, natural selection is directional as it is in the context of adaptation. Comment.

Study a part of the life cycle of malarial parasite given below. Answer the questions that follow:

1. Mention the roles of 'A' in the life cycle of the malarial parasite.
2. Name the event 'C' and the organ where this event occurs.
3. Identify the organ 'B' and name the cells being released from it.

F₁ progeny of pea plant bearing violet flowers and snapdragon plant bearing red flowers were selfed to produce their respective F₂ progeny. Compare the phenotypes, the genotypes and the pattern of inheritance of their respective F₂ progeny.

Name the particular technique whose steps are shown in the following figure. Use the figure to summarise the technique in three steps: