ST’ XAVIER’S SCHOOL
CLASS: IX
SCIENCE
CHAPETR 5 : FUNDAMENTAL UNIT OF LIFE
INTEXT QUESTIONS
Question 1. Fill in the gaps in the following table illustrating differences between
prokaryotic and eukaryotic cells.
Answer:
Question 2. Can you name the two organelles we have studied that contain their own
genetic material?
Answer: The two organelles which have their own genetic material are:
1. Mitochondria 2. Plastids
Both these organelles have their own DNA and ribosomes.
Question 3. If the organisation of a cell is destroyed due to some physical or chemical
influence, what will happen?
Answer: The cell will not be able to revive and lysosomes will digest it.
Question 4. Why are lysosomes known as suicide bags?
Answer: When the cell gets damaged, lysosomes may burst, and the enzymes digest their own
cell. Therefore lysosomes are known as suicide bags.
Question 5. Where are proteins synthesised inside the cell?
Answer: The proteins are synthesised in the ribosomes that are also known as protein factories.
1
ST’ XAVIER’S SCHOOL
CLASS: IX
SCIENCE
CHAPETR 5 : FUNDAMENTAL UNIT OF LIFE
TEXTUAL QUESTIONS
Question 1. Make a comparison and write down ways in which plant cells are also different
from animal cells.
Answer:
Question 2. How is prokaryotic cell different from a eukaryotic cell?
Answer: Prokaryotic cell is generally smaller in size (1-10 pm), nuclear region is poorly defined,
the cell organelles are not membrane-bound and has a single chromosome.
Eukaryotic cell is generally larger in size (5-100 pm), nuclear region is well defined with nuclear
membrane. Membrane-bound cell organelles are present and has more than one chromosome.
Question 3. What would happen if the plasma membrane ruptures or breaks down?
Answer: If plasma membrane ruptures or breaks down then molecules of some substances will
freely move in and out.
Question 4. What would happen to the life of a cell if there was no Golgi apparatus?
Answer: Golgi apparatus has the function of storage, modification and packaging of the products
in vesicles. If there were no Golgi bodies, packaging and dispatching of materials synthesised by
the cell will be stocked.
Question 5. Which organelle is known as the powerhouse of the cell? Why?
Answer: Mitochondria is known as powerhouse of the cell because it releases the energy
required for different activities of life in the form of ATP(Adenosine triphosphate) molecule.
Question 6. Where do the lipids and proteins constituting the cell membrane get
synthesised?
Answer: Lipids and proteins are synthesised in ER [Endoplasmic Reticulum].
SER(smooth endoplasmic reticulum) helps in manufacturing of lipids.
RER(Rough endoplasmic reticulum) has particles attached to its surface, called ribosomes.These
ribosomes are the sites for protein synthesis.
Question 7. How does Amoeba obtain it’s food?
Answer: Amoeba take it’s food by the cell membrane which forms the food vacuole.
2
ST’ XAVIER’S SCHOOL
CLASS: IX
SCIENCE
CHAPETR 5 : FUNDAMENTAL UNIT OF LIFE
Question 8. What is osmosis?
Answer: Osmosis is the process of movement of water molecule from a region of higher water
concentration through a semi-permeable membrane to a region of lower water concentration.
Question 9. Carry out the following osmosis experiment:
Take four peeled potato halves and scoop 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.
Now,
(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) Water gathers in B and C because in both the situations there is difference in the
concentration of water in the trough and water in the cup of Potato. Hence, osmosis takes place
as the potato cells act as a semi-permeable membrane.
(ii) Potato A is necessary for this experiment for comparison, it acts as a control.
(iii) Water does not gather in the hollowed out portions of A and D. As cup of A does not have
change in the concentration for water to flow. For osmosis to occur one of the concentration
should be higher than the other.
In cup D, the cells are dead and hence the semi-permeable membrane does not exists for the flow
of water and no osmosis takes place.
