Differentiate between an autotroph and a heterotroph.

What are the different modes of nutrition? Explain with one example of each mode of nutrition.

Second stage of urine formation is called selective re-absorption. Why?

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. A gas is released during photosynthesis. Name the gas and also state the way by which the gas is evolved.
2. What are stomata? What governs the opening and closing of stomata?

How does food prepared by leaves is utilized by roots? Explain.

Describe the structure and functioning of nephrons.

1. Draw a diagram depicting Human Alimentary Canal and label on it, Gall Bladder, Liver and Pancreas.
2. State the roles of Liver and Pancreas.
3. Name the organ which performs the following functions in humans:

1. Absorption of digested food.
2. Absorption of water.

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?

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