Explain the three pathways of breakdown in living organisms.

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.

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

1. During daytime.
2. At night.

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?

Explain the digestion of chapati in human beings. Draw a diagram depicting human alimentary canal.

Where does anaerobic respiration occur in human body?

Describe the structure and functioning of nephrons.

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.

Describe the alimentary canal of man.

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.