Explain budding in Hydra with the help of diagrams only.

List any two modes of asexual reproduction in animals. Under which mode of reproduction is vegetative propagation placed and why? List two advantages of vegetative propagation.

(i) Describe the methods of reproduction found in unicellular organism.
(ii) Explain budding in Hydra.

What is regeneration? Give one example of an organism that shows this process and one organism that does not. Why does regeneration not occur in the latter?

What are the advantages of sexual reproduction over asexual reproduction?

Why is variation beneficial to the species but not necessarily for the individual?

Draw diagrams to explain the regeneration that takes place in each of the body parts of planaria when its body is cut into three pieces. Name any other organism in which  a similar process can be observed.

Describe the layering method for the artificial propagation of plants. Illustrate your answer with the help of a labelled diagram. Name any five plants which are propagated by the layering method.

What are the functions of testis in the human male reproductive system? Why are these located outside the abdominal cavity? Who is responsible for bringing about changes in appearance seen in boys at the time of puberty?

What does HIV stand for? Is AIDS an infectious disease? List any four modes of spreading AlDS.