The Fundamental Unit of Life — Science STD 9 — Question

What are the advantages of composite fish culture?

Akhtar, Kiran and Rahul were riding in a motorcar that was moving with a high velocity on an expressway when an insect hit the windshield and got stuck on the windscreen. Akhtar and Kiran started pondering over the situation. Kiran suggested that the insect suffered a greater change in momentum as compared to the change in momentum of the motorcar (because the change in the velocity of the insect was much more than that of the motorcar). Akhtar said that since the motorcar was moving with a larger velocity, it exerted a larger force on the insect. And as a result the insect died. Rahul while putting an entirely new explanation said that both the motorcar and the insect experienced the same force and a change in their momentum. Comment on these suggestions.

Name the cell organelle in which following structures are present:

1. Cristae.
2. Stroma
3. Centriole.
4. Chromosome.

State an important characteristic of uniform circular motion. Name the force which brings about uniform circular motion.

How much water should be mixed with 12ml of alcohol so as to obtain 12% alcohol solution?

Classify the following into elements, compounds and mixtures:
Marble, Air, Gold, Brass, Sand, Diamond, Graphite, Petroleum, Common salt, Sea-water, chalk.

Classify the following into elements, compounds and mixtures.

1. Sodium.
2. Soil.
3. Sugar solution.
4. Silver.
5. Calcium carbonate.
6. Tin.
7. Silicon.
8. Coal.
9. Air.
10. Soap.
11. Methane.
12. Carbon dioxide.
13. Blood.

What is the main function of each of the following organelles?

1. Golgi bodies.
2. Vacuole.