During respiration,the exchange of gases takes place in:

What prevents backflow of blood inside the heart during contraction?

Assume that you are a veterinary surgeon and you have removed a significant length of the small intestine of a bear suffering from an intestinal tumour. After its recovery,would you suggest a plant-based or a meat-based diet for the bear? Provide a reason for your answer.

$(a)$ State two functions of bile juice.
$(b)$ Differentiate between the functions of enzymes pepsin and trypsin.

Name the reserved food of plant cell.

What are the factors needed for maintaining the direction of diffusion in plants?