CLASS 8 REVISION

CLASS 8 REVISION 

1. The stage of an embryo when all the body parts can be identified is called____________

2. Time taken by an object to complete one oscillation is called______________________.

3. The process of depositing a layer of any desired metal on another material by means of electricity is called ______________________.

4. In which female reproductive organ does the embryo get embedded? 

5. Name the male hormone responsible for secondary sexual characters.

6. What is the audible range of frequencies for a normal human ear?

7. Fertilisation is necessary even in asexual reproduction.(T/F)

8. The passage of an electric current through a conducting liquid causes chemical reactions.(T/F)

9. Which of the following is essential for the production of thyroxine that changes a tadpole to a frog?

 (a) Sodium (b) Iodine (c) Nitrogen (d) Oxygen

10. In which of the following materials speed of sound is maximum? ( ) 

(a) Iron (b) Sea water (c) Fresh water (d) Air

11.Adrenalin is the hormone secreted by an endocrine gland. Name the gland and write about the function of adrenalin.

12. Define fertilisation. Differentiate between internal and external fertilisation.

13. A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.

 14. i) Draw and label a simple circuit showing electroplating.

ii) List any two objects around you that are electroplated.

15. i List any two sources of noise pollution in your surroundings.

 ii) Explain in what way noise pollution is harmful to human.

 iii) Write any two measures to limit noise pollution.

16.Define the following terms:

(i) Reproduction (ii) Fertilization (iii) Metamorphosis (iv) Foetus

(v) Binary Fission

                                               

17. (a) Write the differences between sexual and asexual reproduction. 

(b) Describe the asexual method of reproduction in amoeba with suitable diagram.

18.Which of these is an example of unicellular animals?

 (a) paramecium (b) hydra (c) Ant (d) All of these

19. The mode of reproduction in Hydra is

 (a) sexual reproduction (b) asexual reproduction

 (c) both (a) & (b) (d) None of these

20. Budding takes place in

(a) Amoeba (b) Hydra (c) Fist (d) Frog

21. Sperms collect and mature in the –

a) epididymis b) vas deferens c) scrotal sac d) testes

22.The electrode, connected to the negative terminal of a battery is - 

a) anode b) cathode c) electrolyte d) can’t say