Give reasons for the following:
(iv) A matured mammalian erythrocyte lacks nucleus and mitochondria.
A lack of nucleus increases the surface area volume ratio. More erythrocytes can be
accommodated in the same space. At the same time, the oxygen-carrying capacity of
erythrocytes also increases.
Lack of mitochondria ensures that all the oxygen carried by RBCs is transported and delivered to the tissues. Therefore, a mature mammalian erythrocyte lacks a nucleus and mitochondria.
Give reasons for the following:
(v) Photosynthesis is considered as a process supporting all life on Earth.
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?
With reference to the functioning of the eye, answer the following questions:
(i) What is power of accommodation of the eye?
(b) Give reasons for the following:
(iii) Potato cubes when placed in water become firm and increase in size.
With reference to the human ear, answer the following questions:
(i) Give the technical term for the structure found in the inner ear.
Give reasons for the following:
People living in hilly regions usually suffer from simple goitre.
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
