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.

Explain the process of digestion of food in mouth, stomach and small intestine in human body.

An organism A which cannot move from one place to another, makes a simple food B from the substances C and D available in the environment. This food is made in the presence of a green coloured substance E present in organs F in the presence of light energy in a process called G. Some of the simple food B also gets converted into a complex food H for storage purposes. The food H gives a blue-black colour with dilute iodine solution.

1. What is (i) organism A, (ii) food B and (iii) food H?
2. What are C and D?
3. Name (i) green coloured substance E, and (ii) organ F.
4. What is the process G?

There is a pair of bean-shaped organs P in the human body towards the back, just above the waist. A waste product Q formed by the decomposition of unused proteins in the liver is brought into organ P through blood by an artery R. The numerous tiny filters S present in organ P clean the dirty blood by removing the waste product Q. The clean blood goes into circulation through a vein T. The waste substance Q, other waste salts, and excess water form a yellowish liquid U which goes from organ P into a bag-like structure V through two tubes W. This liquid is then thrown out of the body through a tube X.

1. What is (i) organ P and (ii) waste substance Q?
2. Name (i) artery R, and (ii) vein T.
3. What are tiny filters S known as?
4. Name (i) liquid U, (ii) structure V, (iii) tubes W and (iv) tube X.

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?

The liquid connective tissue A circulates in our body continuously without stopping. This tissue contains a pigment B which imparts it a colour C. The tissue A consists of four components D, E, F and G. The component D fights infection and protects us from diseases. The component E helps in the clotting of tissue A if a person gets a cut. The component F is a liquid which consists mainly of water with many substances dissolved in it and component G carries oxygen from the lungs to all the parts of the body.

1. What is (i) tissue A, (ii) pigment B and (iii) colour C?
2. Name (i) D, (ii) E, (iii) F and (iv) G.
3. Name one substance (other than oxygen) which is transported by tissue A in the human body.
4. Which two components of tissue A are the cells without nucleus?
5. Name any two organisms (animals) which do not have liquid like A in their body.

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?

The human body has an organ A which acts as a double pump. The oxygenated blood coming from the lungs through a blood vessel B enters the upper left chamber C of the double pump. When chamber C contracts, then blood goes into lower left chamber D. The contraction of chamber D forces the blood to go into a blood vessel E which supplies oxygenated blood to all the organs of the body (except the lungs). The deoxygenated blood coming out of the body organs is taken by a blood vessel F to the right upper chamber G of pumping organ. Contraction of chamber G forces the deoxygenated blood into right lower chamber H. And finally the contraction of chamber H sends the deoxygenated blood into lungs through a blood vessel I.

1. What is organ A?
2. Name the blood vessel (i) B (ii) E (iii) F, and (iv) I.
3. What are chambers (i) C, and (ii) D?
4. What are chambers (i) G and (ii) H?