Why do ventricles have thicker walls than atria?

How does aerobic respiration differ from anaerobic respiration?

Name the following:
$(a)$ The process in plants that links light energy with chemical energy
$(b)$ Organisms that can prepare their own food
$(c)$ The cell organelle where photosynthesis occurs
$(d)$ Cells that surround a stomatal pore
$(e)$ Organisms that cannot prepare their own food
$(f)$ An enzyme secreted from gastric glands in the stomach that acts on proteins

$A$ few drops of iodine solution were added to rice water. The solution turned blue-black in colour. This indicates that rice water contains:

How many chambers are present in the heart of fishes? How many times does blood flow through the heart during each cycle?

How do carbohydrates,proteins,and fats get digested in human beings?