NCERT Solutions For Class 9 Science

Who discovered cells, and how?

Why is the cell called the structural and functional unit of life? 

How do substances like CO₂ and water move in and out of the cell? Discuss.

Why is the plasma membrane called a selectively permeable membrane?

Can you name the two organelles we have studied that contain their own genetic material?

If the organisation of a cell is destroyed due to some physical or chemical influence, what will happen?

Why are lysosomes known as suicide bags?

Where are proteins synthesised inside the cell?

Make a comparison and write down ways in which plant cells are different from animal cells.

How is a prokaryotic cell different from a eukaryotic cell?

What would happen if the plasma membrane ruptures or breaks down?

What would happen to the life of a cell if there was no Golgi apparatus?

Which organelle is known as the powerhouse of the cell? Why?

Where do the lipids and proteins constituting the cell membrane get synthesised?

How does an Amoeba obtain its food?

What is osmosis?

Carry out the following osmosis experiment:

Take four peeled potato halves and scoops 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.

Which type of cell division is required for growth and repair of body and which type is involved in formation of gametes?