Describe double circulation in human beings. Why is it necessary?

Draw a neat labelled diagram of the human excretory system.

The partially digested food coming from the stomach of a person enters a long and narrow organ A in his body. The organ A receives the secretion of two glands: liver and pancreas. Liver secretes a greenish - yellow liquid B which is normally stored in the organ C. Pancreas secretes pancreatic juice which contains three digestive enzymes D, E and F. The intestinal juice completes the process of digestion of food. The inner wall of organ A has millions of tiny finger - like projections G which help in the rapid absorption of digested food into blood stream. The undigested part of food then passes into wider tube H which absorbs most of the water from undigested food. The last part of tube H called I stores this undigested food (or waste) for some time. The undigested food is then passed out though opening J as faeces in the process known as K.

1. Name the organ A.
2. Name liquid B and organ C.
3. What are the digestive enzymes D, E and F?
4. Name the projections G present on the inner wall of organ A.
5. Name Tube H, Part I, Opening J and Process K.

The organs A of a person have been damaged completely due to which too much of a poisonous waste material B has started accumulating in his blood, making it dirty. In order to save this person's life, the blood from an artery in the person's arm is made to flow into long tubes made of substance E which are kept in coiled form in a tank containing solution F. This solution contains three materials G, H and I in similar proportions to those in normal blood. As the person's blood passes through long tubes of substance E, most of the wastes present in it go into solution. The clean blood is then put back into a vein in the arm of the person for circulation.

1. What are organs A?
2. Name the waste substance B.
3. What are (i) E and (ii) F? Name G, H and I.
4. What is the process described above known as?

Explain the process of nutrition in Amoeba.

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?

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

State one difference between artificial kidney and natural 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.

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