Class 9 Science - Chapter The Fundamental Unit of Life NCERT Solutions | Why are lysosomes known as suicide bags?

Carry out 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. 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.

How does an Amoeba obtain its food?

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

Fill in the gaps in the following table illustrating differences between prokaryotic and eukaryotic cells.

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

How is a prokaryotic cell different from a eukaryotic cell?

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

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

Who discovered cells, and how?

Where are proteins synthesised inside the cell?

Which of the following has more inertia: (a) a rubber ball and a stone of the same size? (b) a bicycle and a train? (c) a five-rupees coin and a one-rupee coin?

State the universal law of gravitation.

Which of the following are matter?

Chair, air, love, smell, hate, almonds, thought, cold, cold-drink, smell of perfume.

A force of 7 N acts on an object. The displacement is, say 8 m, in the direction of the force (Fig. 11.3). Let us take it that the force acts on the object through the displacement. What is the work done in this case?

What is meant by a pure substance?

How does the sound produced by a vibrating object in a medium reach your ear?

In a reaction, 5.3 g of sodium carbonate reacted with 6 g of ethanoic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium observations are in agreement with the law of conservation of mass.

sodium carbonate + ethanoic acid → sodium ethanoate + carbon dioxide + water

What are canal rays?

State any two conditions essential for good health.

How is our atmosphere different from the atmospheres on Venus and Mars?

A person is listening to a tone of 500 Hz sitting at a distance of 450 m from the source of the sound. What is the time interval between successive compressions from the source?

You have a bag of cotton and an iron bar, each indicating a mass of 100 kg when measured on a weighing machine. In reality, one is heavier than other. Can you say which one is heavier and why?

Two children are at opposite ends of an aluminium rod. One strikes the end of the rod with a stone. Find the ratio of times taken by the sound wave in air and in aluminium to reach the second child.

A certain household has consumed 250 units of energy during a month. How much energy is this in joules?

How do plants get nutrients?

In which of the three media, air, water or iron, does sound travel the fastest at a particular temperature?

What is the audible range of the average human ear?

What are the benefits of cattle farming?

List any three human activities which would lead to an increase in the carbon dioxide content of air.

How much momentum will a dumb-bell of mass 10 kg transfer to the floor if it falls from a height of 80 cm? Take its downward acceleration to be 10 m s^-2.