Question

1. What will happen if excess bleeding takes place and what natural device preventing it?2. Correct the false statements:(a) The walls of the atrium are thicker than the ventricles(b) The oxygen carrying blood goes into the left ventricle(c) Valves open on both the sides(d) Xylem transports food material(e) The blood circulation in man is of open type3. Differentiate between excretion and osmoregulation? Describe how excretion takes place on Amoeba.4. What is dialysis? How is it useful?5. What is excretion? How is solid and gaseous waste excreted in humans?

Answer 1

1. Excess bleeding will result in the loss of blood(obviously) and the platelets along with RBC's form a clog which stops the blood loss.

2. (a) The walls of the ventricles are thicker than the walls of the atrium.
    (b)The oxygen carrying blood goes in the left atrium, then the left                      ventricle
    (c)Valves are are unidirectional, i.e, they only open upwards or forwards            to prevent backflow of blood
    (d)Xylem transports water
    (e)The blood circulation in man is of closed type

3. Excretion is the process of elimination of biological waste from the body like utilised cells, chyme(food whose nutrients have been absorbed, or faeces), etc. While osmoregulation is the maintenance of the salt-water concentration in the body

An amoeba excretes waste material by moving waste through the cytoplasm to the cell membrane, and expels it from the body through the contractile vacuole.

4. Dialysis is the process of artificial filtration of nitrogenous waste and excess water and formation of urine as the kidneys have malfunctioned or ceased to function due to various medical reasons. it is useful for people whose kidneys have failed(duh!) as without expelling the waste material from the body, it might become toxic and the person may die.

5.Excretion is the process of expelling waste materials from the body having absorbed all the nutrients present. Solid food is passed through the digestive system (it moves around due to the presence of muscles in various parts like the intestines) and bit by bit, most utilisable nutrients are absorbed from it until it finally becomes chyme, or as we call it, faeces. It is expelled through the anal opening.

Liquid water and other body fluids are passed through the kidneys where the nephrons of the medullary pyramids absorb all the nutrients it has to offer and even water enough for excretion is used. the rest is recycled. then the combination of useless fluids, called urine is formed and it travels through the entire urinary tract and is expelled through the urethra(whose length differs in males and females because of the presence of the penis in males).