Question

Assertion (A) : Oxygen is essential for all aerobic forms of life. Reason (R) : Free oxygen atoms combine with molecular oxygen to form ozone.

Write the main difference between aerobic and anaerobic respiration. State the pathway which is common for both. Write the overall chemical equation of aerobic respiration and mention the site where this process occurs inside the cells.

Give reasons for the following : (i) Alveoli in lungs are richly supplied with blood capillaries. (ii) Respiratory pigment in the blood takes up oxygen and not carbon dioxide. (iii) During anaerobic respiration, a 3-carbon molecule is formed as an end product instead of CO₂ in human beings.

Name the movements that occur all along the gut in human digestive system. How do they help in digestion ?