When a person puts food in his mouth, then teeth cut it into small pieces, chew and grind it. The glands A in the mouth secrete a substance B which is mixed with the food by tongue. The substance B contains an enzyme C which starts the digestion of food in the mouth. The slightly digested food from the mouth goes down a tube D. The special type of movements E in the walls of tube D push the food into stomach for further digestion. The stomach wall secretes gastric juice containing three substance F, G and H. One of the functions of F is to kill bacteria which may enter the stomach with food. The substance G protects the inside layer of stomach from the damaging effect of substance F whereas substance H is and enzyme for digestion. The partially digested food then enters into small intestine for further digestion.

1. What is Gland A, Substance B and Enzyme C?
2. Name the tube D.
3. What is the movement E known as?
4. What are F, G and H?

1. Draw the structure of a nephron and label the following on it: Glomerulus, Bowman’s capsule, Renal artery, Collecting duct.
2. What happens to glucose that enters the nephron along with filtrate?

1. Draw a diagram of human alimentary canal and label - gall bladder, pancreas, liver and small intestine on it.
2. Give two reasons to explain why absorption of digested food occurs mainly in the small intestine.

Plants absorb water from the soil. How does this water reach to the top of the tree? Explain in detail.

Name the main organs of the human digestive system in the order they participate in the process of digestion. Describe how digestion of carbohydrates and proteins take place in our body.

1. Draw a diagram of excretory system in human beings and label on it: Aorta, Vena cava, Urinary bladder, Urethra.
2. List two vital functions of the kidney.

1. Mention any two components of blood.
2. Trace the movement of oxygenated blood in the body.
3. Write the function of valves present in between atria and ventricles.
4. Write one structural difference between the composition of artery and veins.

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?

Valves are present in between the auricles and ventricles of the heart. Give one reason.

‘Aerobic respiration produces more ATP than anaerobic respiration’. Justify this statement.