1. Draw a diagram of human alimentary canal and label on it: Oesophagus, Gallbladder, Liver and Pancreas.
2. Explain the statement, ‘Bile does not contain any enzyme but it is essential for digestion.’

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

Suggest a suitable reason for the heart having four separate chambers.

What is the main difference between aerobic respiration and anaerobic respiration? Give one example of each.

Describe the process of urine formation in kidneys.

Explain the principle of dialysis with the help of a labelled diagram.

1. Define excretion.
2. Name the basic filtration unit present in the kidney.
3. Draw excretory system in human beings and label the following organs of excretory system which perform following functions:

1. Form urine.
2. Is a long tube which collects urine from kidney.
3. Store urine until it is passed out.

Given below is the experimental set-up to establish that one of the atmospheric gases is essential for photosynthesis in plants.

1. Name the atmospheric gas which is essential for photosynthesis.
2. What is kept in watch-glass in figure 'a' and why?
3. Write the balanced chemical equation for the process of photosynthesis.
4. When do the desert plants takeup carbon dioxide and perform photosynthesis?

Describe the exchange of gases which takes place in the leaves of a plant:

1. During daytime.
2. At night.

In the artificial kidneys, the tubes are all with semi-permeable lining. Why?