A worm X found in freshwater and slow-moving streams has been accidently cut into three pieces. It was observed that in due course of time, each cut piece of the worm develops to become a complete worm by growing all the missing parts.

(a) Name the worm X which can exhibit this phenomenon of making complete worm from its cut body parts.

(b) Name another organism Y which possesses the same characteristic of growing fully from its cut body parts.

(c) What is the name of this process in which a complete organism is formed from its cut body part.

(d) State whether X and Y are unicellular and/or multicellular organisms.

(e) Can a dog be produced completely from its cut body part (say, a cut tail) just like organisms X and Y ? Why?

A small part of the shoot of a plant is removed with a sharp knife. When the lower end of this small part of the shoot is buried in moist soil, it gradually develops roots and shoots and grows to become a new plant.

(a) What is the name of this method of propagating plants?

(b) What care should be taken while removing a small part of the shoot from the parent plant with a knife?

(c) Name any two plants which provide us with food directly or indirectly and are grown by this method.

(d) Give one advantage of this method of producing new plants.

(e) State whether it is a sexual method of reproduction or an asexual method. Why?

(f) What special name can be given to the genetically identical new plants produced by this technique?

When the branches of a plant growing in the field are pulled towards the ground and a part of them is covered with moist soil (leaving the tips of the branches exposed above the ground), then after some time new roots develop from the parts of branches buried in the soil. On cutting these branches from the parent plant, new plants are produced from the cut parts of branches which had developed roots.

(a) What is this method of propagation of plants known as ?

(b) What type of branches should a plant have to be able to be propagated by this method ?

(c) Name any two plants which are grown for their flowers and propagated by this method.

(d) Name any two plants which are grown for their fruits and propagated by this method

(e) Name one plant which gets propagated by this method naturally by forming runners (soft horizontal stems running above the ground).

A thickened underground stem X of a plant which is swollen with stored food has a number of points Y on its surface. When the old stem X is planted in the soil of a field in the next growing season, then each point Y present on its surface grows into a new plant.

(a) What is the general name of the underground stems like X?

(b) Give one example of X.

(c) What are points Y present on X known as?

(d) Is it necessary to plant the whole of stem X in the ground to obtain its new plants? Explain your answer.

(e) What is the name of this method of reproduction of plants?

(f) What is the advantage of growing new plants from the underground stems like X ?

A filamentous alga X is found in ponds, lakes and slow-moving streams. The filament of this alga simply breaks into two (or more) pieces on maturing and each piece then grows. to become a complete new alga.

(a) Name an alga which X is likely to be.

(b) What is the colour of X?

(c) What is the method of forming new algae by the breaking of parent alga known as ?

(d) An Amoeba also breaks up to form two. daughter Amoebae. What is the difference in the splitting Amoeba and splitting of this alga as a method of reproduction ?

(e) Name one marine animal which reproduces in the same way as alga X.