Science [2 Mark Questions]

Diffusion is insufficient to meet the oxygen requirements of large multicellular organisms like humans because the volume of human body is so big that the oxygen cannot diffuse into all the cells of the human body quickly and oxygen will have to travel large distances to reach each and every cell of the body.

The opening and closing of stomatal pores is controlled by the guard cells, when water flows into the guard cells, they swell, become curved and cause the pore to open whereas when the guard cells lose water, they shrink, become straight and close the stomatal pore.

The function of respiratory system is to breathe in oxygen for respiration (producing energy from food), and to breathe out carbon-dioxide produced by respiration.

Carnivores eat a smaller amount of food compared to herbivores, and it is in theform of high energy molecules which are relatively easy to digest, compared to theplant material that herbivores eat, which contains cellulose. Therefore, carnivores have a smaller intestine.