Give reasons for the following:
People living in hilly regions usually suffer from simple goitre.
Give reasons for the following:
(ii) Urine is slightly thicker in summer than in winter.
(b) Give reasons for the following:
(iii) Potato cubes when placed in water become firm and increase in size.
Give reasons for the following:
(iv) A matured mammalian erythrocyte lacks nucleus and mitochondria.
Give reasons for the following:
(v) Photosynthesis is considered as a process supporting all life on Earth.
With reference to the functioning of the eye, answer the following questions:
(i) What is power of accommodation of the eye?
The process of focusing the eye at different distances is called power of accommodation of the eye. The process by which the ciliary muscles change the focal length of an eye lens to focus distant or near objects clearly on the retina is called the accommodation of the eye.
With reference to the functioning of the eye, answer the following questions:
(iv) Name the cells of the retina and their respective pigments which get activated (1)
in dark and (2) in light
With reference to the human ear, answer the following questions:
(i) Give the technical term for the structure found in the inner ear.
With reference to the human ear, answer the following questions:
(ii) Name the three small bones present in the middle ear. What is the biological term
for them collectively?