Ques 1: Choose the correct option:
(i) Cheek cells do not have
(A) Cell membrane
(B) Golgi apparatus
Ques 2: Choose the correct option:
(ii) Which of the following secondary sexual character is not present in male?
(A) Growth of facial hair
(B) Hair grows under the arms
(C) Hair grows in the region above thighs
(D) Development of breasts.
Ques 3: Choose the correct option:
(iii) 1 hertz is equal to
(A) 1 vibration per minute
(B) 10 vibrations per minute
(C) 60 vibrations per minute
(D) 600 vibrations per minute
Ques 4: Choose the correct option:
(iv) The earth's plate responsible for causing earthquakes is:
(A) The crust of the earth
(B) The mantle of the earth
(C) The inner core of the earth
(D) The outer core of the earth.
Ques 5: Choose the correct option:
(v) The outer planet is
Ques 6: Choose the correct option:
(vi) The substance that does not burn with flame is
(C) Dry gas
Ques 7: Choose the correct option:
(vii) Pitch of sound is determined by its
Ques 8: Choose the correct option:
(viii) The number of nuclei present in zygote is:
Ques 9: Choose the correct option:
(ix) Green colour of leaves is due to presence of the pigment.
Ques 10: Choose the correct option:
(x) Coal tar contains about _____ substances.
Ques 11: Name the hormone which controls metamorphosis in frog.
Ans: Thyroxine hormone which is produced by thyroid controls the metamorphosis in frogs.
Ques 12: While sieving grains, small pieces fall down which force pulls them down.
Ans: It is the force of gravity which is responsible for the grains to fall down.
Ques 13: Fishes move easily in water. How?
Ans: Fishes are having streamlined shape, so they can move easily in the water.
Ques 14: Define 1 Hertz.
Ans: 1 Hz is one oscillation per second.
Ques 15: Plastic straws A and B are rubbed with dry cotton cloth. What will happen, if they are brought near each other?
Ans: The straws will acquire the similar charge and hence they will repel each other.
Ques 16: Why does banana appear yellow?
Ans: The banana appears yellow because it reflects red and green light but absorbs blue light.
Ques 17: A bucket made up of plastic does not rust like a bucket made up of iron. Why?
Ans: Plastic is non-reactive material. When left exposed to moisture and air, it does not react with air and water which are essential for corrosion, therefore does not rust.
Ques 18: In what form is magnesium found in plants?
Ans: Magnesium is found in plants in the form of ionic salts in chlorophyll. Due to its deficiency, plants are unable to produce enough chlorophyll and as a result, leaves develop yellowish colour.
Ques 19: Look at the following figure where petroleum and natural gas deposits are shown. Why do we find oil layer above water layer?
Ans: Oil is lighter than water, hence it will float over water.
Ques 20: The calorific values of petrol and CNG are 45000 kj/kg, and 50000 kj/kg respectively. If you have vehicle which can run on petrol as well as CNG, which fuel will you prefer and why?
Ans: We will prefer CNG (Compressed Natural Gas) because the calorific value of CNG is higher than that of petrol. Therefore, CNG will be more economical. CNG will produce larger amount of heat energy than petrol. At the same time, it produces the least air pollutants.
Ques 21: Write any two consequences of deforestation.
Ans: Consequences of deforestation:
(i) Deforestation increases the temperature and pollution level on the earth. It increases the level of carbon dioxide in the atmosphere.
(ii) It also disturbs the balance in nature and increases chances of natural calamities such as floods and droughts.
Ques 22: Draw a labelled diagram of human ovum.
Ques 23: Name the hormone which would be released during the following situations:
(i) a frightened person.
(ii) growth of a child to adult.
(iii) development of caterpillar to moth.
(iv) development of tadpole to frog.
(i) Adrenaline is secreted from adrenal gland during the stress conditions.
(ii) Growth hormone is secreted from pituitary gland to regulate the normal growth of a person.
(iii) Insect hormones control the development of caterpillar to moth.
(iv) Thyroxine is produced by thyroid gland to control the development of tadpole to frog.
Ques 24: In the circuit shown in Fig. when the key is closed, the compass needle placed in the match box deflects.
Name the force which causes this deflection.
Ans: On closing the switch, the current starts flowing in the wire and due to this current, a magnetic field gets established around the wire which exerts magnetic force on the needle and it gets deflected.
Ques 25: Name two methods of reducing friction with examples.
(i) Rolling: The rolling wheels attached to luggage bags make it comfortable for passengers to carry them because rolling reduces friction and is smaller than sliding friction.
(ii) Sliding: By polishing surfaces or by applying a lubricant.
Ques 26: Write difference between regular and irregular reflection.
Ans: Difference between Regular and Irregular reflection:
|S. No.||Regular reflection||Irregular reflection|
|(i)||It takes place on a smooth and shining surface.||It takes place on rough surface.|
|(ii)||All rays are parallel after reflection.||Reflected rays are in different directions.|
Ques 27: What is natural gas? What are the advantages of using CNG?
Ans: Natural gas is a very important fossil fuel. It is stored under high pressure as compressed natural gas (CNG).
Advantages of CNG:
(i) It is easy to transport.
(ii) It does not produce any pollution.
(iii) No residue is left after burning of CNG.
(iv) It burns completely in the air.
Ques 28: Give two examples each for a solid, liquid and gaseous fuel along with some important uses.
Ans: Solid Fuels: Examples are wood and coal. These are used to cook food in homes. Coal is also used in industries
Liquid Fuels: Examples are kerosene and petrol. Kerosene is used in stoves and in lamps to cook food and petrol is used as a fuel in automobiles.
Gaseous Fuels: Examples are natural gas and petroleum gas. These are used in industries. CNG is used to run automobiles.
Ques 29: Why are endemic organisms in greater danger of becoming extinct?
Ans: Endemic organisms are confined to a limited geographical area. They cannot adapt or live outside their natural habitat; any disturbance to their habitat will adversely affect them. Thus, they are in greater danger of becoming extinct.
Ques 30: Label the parts A to E in the given diagram.
Ques 31: Draw a labelled diagram of female reproductive organs.
Ques 32: Write four ways through which AIDS is transmitted.
Ans: Four ways through which AIDS is transmitted are:
(i) Sharing the syringes for injecting drugs.
(ii) Unprotected sex with an infected person.
(iii) Transfusion of blood into a healthy person from an infected person.
(iv) Through milk from an infected mother to Infant.
Ques 33: Two friends are trying to push a heavy load as shown in fig. Suggest a way which will make this task easier for them.
Ans: The friends can put rollers below the heavy load. Since the rolling friction is smaller than the sliding friction, therefore, putting rollers below the heavy load will make this task easier for them.
Ques 34: Write down the names of parts of the eye in the blank spaces shown in fig. below.
Ques 35: Write a short note about planets of the solar system.
Ans: There are eight planets in our solar system:
(i) Mercury (Budh): It is nearest to the Sun. It is the smallest planet of our solar system. It is very difficult to visualize because it is near to the Sun. It has no satellite.
(ii) Venus (Shukra): It is nearest to the Earth. It is the brightest planet. It is also called as morning and evening star due to its appearance. It also has no moon or satellite. It rotates from East to West.
(iii) Earth (Prithvi): The earth is the only planet where life exists. It has special environmental conditions, right distance from the Sun, so has right temperature, presence of water and blanket of ozone that makes life possible here.
(iv) Mars (Mangal): It is the first planet outside the orbit of the Earth. It appears reddish, so is called red planet. It has two small natural satellites.
(v) Jupiter (Brihaspati): It is the largest planet. It rotates very rapidly on its axis. It has large number of satellites. It also has faint rings and large moons.
(vi) Saturn (Shani): Saturn is yellowish in colour. It has beautiful rings. It has large number of satellites. It is least dense, density is less than water.
(vii) Uranus and Neptune: They are outermost planets of our solar system. Uranus rotates East to West, and has high rotation speed.
Ques 36: It is said, "CO2 Contributes to global warming". Explain.
Ans: Plants utilise CO2 from the atmosphere for photosynthesis, thereby decreasing the amount of CO2 in the air. Deforestation leads to an increase in the amount of CO2 in the air because the number of trees which consume CO2 is reduced. Human activities thus contribute to the accumulation of CO2 in the atmosphere. CO2 traps heat and it does' not allow it to escape into space. As a result, the average temperature of the atmosphere is gradually increasing. This is called global warming. Thus, increased CO2 contributes to global warming.
Ques 37: Explain the use of Bacteria, Fungi and Algae.
Ans: Uses of Bacteria:
(i) They are used to increase soil fertility by fixing nitrogen.
(ii) Some bacteria are used to produce antibiotics.
(iii) Lactobacillus bacterium converts milk into curd.
(iv) Some bacteria help in many functions of our body.
Uses of Fungi:
(i) Yeasts are used to prepare alcohol and vinegar by fermentation.
(ii) Mushrooms are eaten as food.
(iii) Penicillin is an antibiotic formed by a fungus called Penicillium.
Uses of Algae:
(i) Algae are used to make jellies.
(ii) Chlorella is used to obtain proteins.
(iii) Silica from diatoms are used in toothpastes.