Solution to Activity 8.3 of NCERT Class 7 Science Chapter 8 Reproduction in Plants

3. Complete Activity 8.3 (Page 84). Take a piece of yeast cake or yeast powder from a bakery or a chemist shop. Take a pinch of yeast and place it in a container with some water. Add a spoonful of sugar and shake to dissolve it. Keep it in the warm part of a room. After an hour, put a drop of this liquid on a glass slide and observe under a microscope. What do you observe?

Answer:

The Activity 8.3 should be carried out in the following way:

Aim: To examine how yeast reproduces.

Materials Required: Yeast powder, water, sugar, container, glass slide, microscope.

Procedure:

(i) Procure some yeast powder from a bakery or a chemist shop.

(ii) Take a pinch of yeast and place it in a container of water.

(iii) Now add a spoonful of sugar to the container of water and dissolve by stirring.

(iv) Store the container in a warm place.

(v) Wait for an hour, put a drop of this liquid on glass slide and observe under a microscope.

Observations: You will see that many new yeast cells are quickly formed and in many cases there are small bulb-like projections coming out of many yeast cells.

Yeast reproducing under microscope. — **Yeast Reproducing Under Microscope:** You can clearly see the formation of new yeast cells by budding. Observe the chain of buds that are forming.

Conclusions:

The small bulb-like projections coming out of the yeast cell are called buds. These buds gradually grow and get detached from the parent cell to form new yeast cells. This mode of asexual reproduction is called budding.
Sometimes another bud arises from a bud and so on, to form a chain of buds and a large number of yeast cells are produced in a short time.

“Take a piece of yeast cake or yeast powder from a bakery or a chemist shop. Take a pinch of yeast and place it in a container with some water. Add a spoonful of sugar and shake to dissolve it. Keep it in the warm part of a room. After an hour, put a drop of this liquid on a glass slide and observe under a microscope. What do you observe?” – Solved.