List of practice Questions

Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?
Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to electric mains supply. What current is drawn from the line if the supply voltage is 220 V?
Compare the power used in the 2 Ω resistor in each of the following circuits:
  1. a 6 V battery in series with 1 Ω and 2 Ω resistors,
  2. a 4 V battery in parallel with 12 Ω and 2 Ω resistors.
Why does the sky appear dark instead of blue to an astronaut?
Explain why the planets do not twinkle?
Why do stars twinkle?
What happens to the image distance in the eye when we increase the distance of an object from the eye?
Why is a normal eye not able to see clearly the objects placed closer than 25 cm?
Make a diagram to show how hypermetropia is corrected. The near point of a hypermetropic eye is 1 m. What is the power of the lens required to correct this defect? Assume that the near point of the normal eye is 25 cm.
How is the equal genetic contribution of male and female parents ensured in the progeny?
Outline a project which aims to find the dominant coat colour in dogs.
A study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?
The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct the problem?
A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as
What could be the reasons for adopting contraceptive methods?

Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.

How does reproduction help in providing stability to populations of species?
A person needs a lens of power −5.5 diopters for correcting his distant vision. For correcting his near vision, he needs a lens of power +1.5 diopter. What is the focal length of the lens required for correcting?
(i) distant vision, and
(ii) near vision?
How are the modes for reproduction different in unicellular and multicellular organisms?
What are the different methods of contraception?
Draw a labelled diagram of the longitudinal section of a flower.
What are the differences between the transport of materials in xylem and phloem?
Why does menstruation occur?

Describe double circulation of blood in human beings.Why is it necessary?

The change in focal length of an eye lens is caused by the action of the