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Describe:
(i) Process of inhalation in mammals
(ii) Mechanisms of opening and closing of stomata.

Answer Text:
i)- External intercostal muscles contracts, as internal intercostal muscles relax. This make the thoracic cavity/ribcage to move upwards and outwards. The muscles of the diaphragm contracts causing the diaphragm to flatten from dome shape. The movements increases the volume of the thoracic cavity reducing the pressure inside thoracic cavity compared to atmospheric pressure
this forces air to rush into the lungs through the nostril, lung inflate.
ii)- Guard cells have chloroplasts unlike other epidermal cells. During daylight, they carry out
photosynthesis producing glucose. The glucose increase the osmotic pressure of the cell sap. This causes water to move into guard cells from the neighbouring epidermal cells by osmosis. The results is an expansion and increase in turgidity
of the guard cells causing the stomata to open. In darkness, photosynthesis stop. The glucose in the guard cells is converted to starch. Starch is osmotically inactive. This lowers the osmotic pressure of the guard cells causing them to lose
water to neighbouring epidermal cells by osmosis. The guard cells become flaccid and the stomata close.