15. 1. The pregnancy of the women can be prevented by the method of Vasectomy.   16. 2. Cones are the receptors cells in the retina of the eye sensitive to dim light.   17. 3. The unit of light absorbed by the chlorophyll during photosynthesis is the proton.   18. 4. D.D.T is a disinfectant.   19. 5. Lungs of man are protected by the pericardium.   20. 6. The part of the ear associated with balance is the cochlea.   21. (ii) Rewrite the wrong statements from 1 to 6 above in the correct form by changing only the first or last word.