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.
(i) Water gathers in B and C in light of the fact that in both the circumstances there is contrast in the centralization of water in the box and water in some Potato. Therefore, osmosis happens as the potato cells go about as a semipermeable membrane.
(ii) Potato A is necessary for this experiment for comparison, it acts as a control.
(iii) Water doesn't gather in the emptied out parts of A and D. As some A doesn't have change in the concentration for water to stream. For osmosis to happen one of the concentrations ought to be higher than the other.
In cup D, the cells are dead and thus the semi-permeable membrane doesn't exist for the progression of water and no osmosis happens.
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.
Prokaryotic Cell | Eukaryotic Cell |
1. Size : generally small (1-10 μm) 1 μm = 10-6 m |
1. Size generally large (5-100 μm) |
2. Nuclear region: ________________ and known as _________________ |
2. Nuclear region: well defined andsurrounded by a nuclear membrane |
3. Chromosome: single |
3. More than one chromosome |
4. Membrane-bound cell organelles absent | 4. _______________________ _______________________ |
Why are lysosomes known as suicide bags?
Where do the lipids and proteins constituting the cell membrane get synthesised?
How is a prokaryotic cell different from a eukaryotic cell?
Make a comparison and write down ways in which plant cells are different from animal cells.
Who discovered cells, and how?
How do substances like CO2 and water move in and out of the cell? Discuss.
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?
Give reason for the following observations.
(a) Naphthalene balls disappear with time without leaving any solid.
(b) We can get the smell of perfume sitting several metres away.
A large truck and a car, both moving with a velocity of magnitude v, have a head-on collision and both of them come to a halt after that. If the collision lasts for 1 s:
(a) Which vehicle experiences the greater force of impact?
(b) Which vehicle experiences the greater change in momentum?
(c) Which vehicle experiences the greater acceleration?
(d) Why is the car likely to suffer more damage than the truck?
Calculate the molar mass of the following substances.
(a) Ethyne, C2H2
(b) Sulphur molecule, S8
(c) Phosphorus molecule, P4 (Atomic mass of phosphorus = 31)
(d) Hydrochloric acid, HCl
(e) Nitric acid, HNO3
A person has a hearing range from 20 Hz to 20 kHz. What are the typical wavelengths of sound waves in air corresponding to these two frequencies? Take the speed of sound in air as 344 m s-1.
Why do organisms need water?
A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
When 3.0 g of carbon is burnt in 8.00 g oxygen, 11.00 g of carbon dioxide is produced. What mass of carbon dioxide will be formed when 3.00 g of carbon is burnt in 50.00 g of oxygen? Which law of chemical combination will govern your answer?
Describe with the help of a diagram, how compressions and rarefactions are produced in air near a source of sound.
What is loudness of sound? What factors does it depend on?
Compare the use of manure and fertilizers in maintaining soil fertility.