Heredity and Evolution — Science STD 10 — Question

What would be the ratio of chromosome number between an egg and its zygote? How is the sperm genetically different from the egg?

Name the various tools of tracing evolutionary relationships which have been used for studying human evolution.

The eyes of a person are focused

1. On a nearby object, and
2. On a distant object, turn by turn. In which case:

1. The focal length of ye-lens will be the maximum?
2. The converging power of eye-lens will be the maximum?

Why did Mendeleev leave some gaps in his periodic table?

When a person breathes in air, the air enters into his body through an organ Ahaving two holes B in it. The air then passes through pharynx and larynx and enters into a tube C. The tube C divides into two smaller tubes D at its lower end. The two smaller tubes are attached to two respiratory organs E. Each smaller tube divides inside the organs E to form a large number of still smaller tubes called F. The smallest tubes F have air-sacs G at their ends in which gaseous exchange takes place in the body of the person. What are A, B, C, D, E, F and G?

List two reasons to show that the existence of decomposers is essential in an ecosystem.

State the uses of plane mirrors.

Name four appliances wherein an electric motor, a rotating device that converts electrical energy to mechanical energy, is used as an important component. In what respect motors are different from generators?

What would be the consequences of a deficiency of haemoglobin in our bodies?

What is the commercial unit of electrical energy? Represent it in terms of joules.