NCERT solutions for class 9 science

Chapter 05-Fundamental Unit of Life-Exercise Solutions

NCERT Text Book Exercise Page Number 66-67
Q.1. Make a comparison and write down ways in which plant cells are different from animal cells.


Q.2. How is prokaryotic are different from a eukaryotic cell?


Q.3. What would happen if the plasma membrane ruptures or breaks down?
Answer. If the plasma membrane ruptures or breaks down, the constant internal composition of the cell will be lost and it will not be able to perform basic functions.
Q.4. What would happen to the life of a cell if there was no Golgi apparatus?
Answer. The material synthesised in ER will not be packed, stored and transported to various targets and lysosome formation will also not take place.
Q.5. Which organelle is known as the power house of the cell? Why?
Answer. Mitochondria is known as the power house of the cell because it releases the energy required
for different activities needed for life.
Q.6. Where do the lipids and proteins constituting the cell membrane get synthesised?
Answer. Proteins in RER and lipids in SER.
Q.7. How does an Amoeba obtain its food?
Answer. Amoeba acquires its food through the process of endocytosis. This process takes place due to the flexible nature of cell membrane which forms the stucture pseudopodia of Amoeba. The flexible pseudopodia enables the Amoeba to engulf food and other material from its external environment.
Q.8. What is osmosis?
Answer. Osmosis is the movement of water from a region of higher concentration to a region of lower concentration through a cell membrane or outer semi permeable membrane until an equilibrium is reached.
Q.9. Carryout the following osmosis experiment : Take four peeled potato halves and scoos each one out to make potato cups one of these potato cups should be made from a boiled potato.
Put each potato cup in a trough containing water.
(a) Keep cup A empty
(b) Put one teaspoon sugar in cup B
(c) Put one teaspoon salt in cup C
(d) Put one teaspoon sugar in the boiled potato cup D.
Keep these for two hours. Then observe the four potato cups and answer the following :
(i) Explain why water gathers in the hollowed portion of B and C
(ii) Why is potato A necessary for this experiment ?
(iii) Explain why water does not gather in the hollowed out portions of A and D.
Answer. (i) When unboiled potato cups B and C were put into a trough containing water, the cells of potatoes gained water by endosmosis.
When a tea spoon of sugar and salt were added later in the hollowed portions B and C cups respectively, water movement occurred through the plasma membrane of the cells from within the cells of potato into the hollowed portion of both B and C cups because of exosmosis
(ii) Potato A is necessary for this experiment for comparison, it acts as a reference.
(iii) Water does not gather in the hollowed portion of potato cup A because it does not possess higher osmotic concentration on than the cells of potato.
Potato cup D is boiled potato cup on boiling, potato cells die and the membrane of the potato cells lose their permeability. The result is, when tea spoon of sugar is added into the hollowed portion of boiled potato cup D, water does not come out from within the potato cells into the hollowed portion