Describe the flow of blood through the heart of human beings.

There are five animals P, Q, R, S and T. The animal P always lives in water and has gills for breathing. The animal Q can stay in water as well as on land and can breathe both, through moist skin and lungs. The animal R lives in soil and breathes only through its skin. The animal S lives on land and breathes through spiracles and tracheae. And animal T lives in water and breathes through its cell membrane.

1. Which of the animals could be Amoeba?
2. Which of the animals could be frog?
3. Which animal could be fish?
4. Which animal could be grasshopper?
5. Which animal could be earthworm?

Explain how deoxygenated blood travel from body to lung for purification. Draw well-labeled diagram in support of your answer.

Draw a schematic representation of transport and exchange of oxygen and carbon dioxide during transportation of blood in human beings and label on it, Lung capillaries, Pulmonary artery to lungs Aorta to body, Pulmonary veins from lungs.

A unicellular animal P having no fixed shape ingests a food particle by forming temporary finger-like projections Q. The food particle is engulfed with a little surrounding water to form a temporary stomach R inside it. The chemicals S from surrounding cytoplasm enter into R and break down food into small and soluble molecules by chemical reactions. The digested food is absorbed directly into cytoplasm by the process T. The undigested food is thrown out of the body by the rupture of a cell organelle U in a process called V.

1. Name the unicellular animal P.
2. What are (i) Q, and (ii) R?
3. Name (i) chemical S, and (ii) process T.
4. Name (i) organelle U, and (ii) process V.

A liquid X of colour Y circulates in the human body only in one direction: from body tissues to the heart. Among other things, liquid X contains germs from cells and dead cells. The liquid X is cleaned of germs and dead cells by a special type of white blood cells called Z. This cleaned liquid is then put into blood circulatory system in subclavian veins.

1. What is (i) liquid X and (ii) colour Y?
2. What are Z.
3. The liquid X is somewhat similar to a component of blood. Name this component.
4. Why is liquid X not red?

Excretion is different in multi-cellular organisms as compared to unicellular organisms. How?

Name the conducting structures present in plants.

What is the difference between excretion and defecation? Explain the process of excretion in humans.

Describe the parts of our tooth with the help of a labelled diagram.