Class 5 Science Lesson 3

 Exercise-1 Heat and Light

1. Select the most appropriate option among the given options:

(a) Which of the following is the main source of heat?

👉 iv. sun

(b) Which of the following is the main reason for plants not growing properly in winter?

👉 ii. lack of heat required by plants

(c) Which of the following is the main function of the tunnel made for vegetable cultivation?

👉 i. increasing the temperature inside the tunnel

(d) Which of the following elements are required for plants to make food along with the substances absorbed from the roots?

👉 iii. light, chlorophyll and carbon dioxide

2. If the statement given below is correct, put a tick mark (✓) and if it is wrong, put a cross mark (✗):

👉

(a) Chicken need light to hatch their chicks from eggs.✓

(b) Plants grow faster in areas exposed to sunlight for longer periods.✓

(c) The leaves of plants found in the Himalayas are needle-shaped. ✓

(d) Heat, light, soil, and air are inorganic elements of the environment. ✓

(e) Tunnel protects the plants inside it by not letting the sunlight enter through the plastic. ✗

3. Fill in the blanks in the sentences below with the appropriate word:

(a) Energy is obtained from the  environment

(b)  Favourable weather is necessary for farming.

(c) In adverse weather, animals move to  suitable places from their habitat.

(d) Plants turn  yellow in the absence of sunlight.

(e) Chlorophyll is present only in green plants.

4. Write the answers to the following questions:

(a) List any three sources of heat and light.

👉 Sun, firewood, electricity

(b) Write the reasons why plants do not grow well in places without sunlight.

👉 Plants cannot make food without sunlight. Without food, they don’t get energy to grow properly.

(c) Why are plastic tunnels used for vegetable cultivation during winter?

👉 Tunnels trap heat inside and protect plants from the cold, helping them grow better.

(d) For what functions do living things require heat?

👉 Living things need heat for keeping warm, reproduction, drying food, and hatching eggs.

Exercise-2 Sources of energy in environmenet

1.Select the most appropriate answer from the given options:

(A) Which of the following is a renewable source of energy?

👉 iii. water

(B) Which of the following sources of energy causes the air more polluted?

👉 i. diesel

(C) Which of the following source of energy does not pollute the air?

👉 ii. hydropower

(D) Which of the following methods is suitable for preventing the unnecessary use of energy?

👉 iii. use of a pressure cooker in an improved stove

2. If the statement given below is correct, put a tick mark (✓) and if it is wrong, put a cross mark (✗):

👉

(a) Use of electric vehicles causes pollution. ✗

(b) Excessive and unnecessary use of energy affects the environment. ✓

(c) Coal is abundant in nature. ✗

(d) Keeping lights on when there is no one in the room is an example of unnecessary use of energy. ✓

3. Fill in the blanks in the sentences given below with suitable words:

(a)  Coal is a source of energy that will finish when we go on using it.

(b)  Excessive use of energy causes natural sources of energy to become depleted.

(c)  Use of solar energy does not cause pollution in the environment.

(d)  Sun is the main source of energy.

4. Write the answers to the following questions:

(a) Prepare a list of items used as sources of energy in daily life.

👉 Firewood, electricity, sunlight, biogas, gas, diesel, petrol

(b) Write any two measures you have applied or seen in your home or community to save energy.

👉 Using LED bulbs instead of high-wattage bulbs, turning off lights and fans when not needed

(c) “Use of biogas is better than the use of firewood as a source of heat.” Write any two justifications for this statement.

👉 Biogas produces less smoke and does not harm the environment. It is made from waste and is renewable.

(d) Which one is better to use, a diesel vehicle or an electric vehicle? Give reason.

👉 Electric vehicle is better because it does not produce smoke and keeps the environment clean.

(e) Correct selection of the source of energy helps to keep the environment clean. Clarify this with a suitable example.

👉 Using solar power instead of diesel generator reduces smoke and keeps air pollution low.

(f) Write the ways to conserve energy.

👉 Use energy only when needed, use energy-efficient devices, prefer renewable energy sources like solar and hydro power.