Control and Coordination — Science STD 10 — Question

What are the environmental consequences of the increasing demand for energy?

Write a short note on the pollution caused by burning fossil fuels.

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 suggested that the genetic make up (or genotype) of the tall parent can be depicted as:

1. TTWW
2. TTww
3. TtWW
4. TtWw

Give reason for your choice.

A current of 1 ampere flows in a series circuit containing an electric lamp and a conductor of 5Ω when connected to a 10V battery. Calculate the resistance of the electric lamp.
Now if a resistance of 10Ω is connected in parallel with this series combination, what change (if any) in current flowing through 5Ω conductor and potential difference across the lamp will take place? Give reason.

An object 2cm tall is placed on the axis of a convex lens of focal length 5cm at a distance of 10m from the optical centre of the lens. Find the nature, position and size of the image formed. Which case of image formation by convex lenses is illustrated by this example?

A concave lens of 20cm focal length forms an image 15cm from the lens. Compute the object distance.

A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y and Z.

In the nuclear reactor of a power plant:

1. How do control rods control the rate of fission?
2. How is heat removed from the reactor core, and what use is made of this heat?