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Page No 149:

Question 1:

Capillaries exchange the following between blood and tissues:
(a) oxygen, carbon dioxide, nitrogen, plasma
(b) oxygen, carbon dioxide, food, wastes
(c) water, plasma, WBC, RBC
(d) oxygen, carbon dioxide, WBC, RBC

Answer:

(b) oxygen, carbon dioxide, food, wastes

The walls of capillaries are very thin. Gases, digested food, hormones and waste products of the body easily pass through the capillaries and get exchanged in the blood.

Page No 149:

Question 2:

Salts and urea are filtered out of the blood mainly by the _________________
(a) bladder
(b) ureter
(c) kidney
(d) urethra

Answer:

(c) kidney

Kidney filters out salt and urea from the body. 

Page No 149:

Question 3:

The substance not circulated by the circulatory system is
(a) food.
(b) hormones.
(c) oxygen.
(d) nitrogen.

Answer:

(d) nitrogen

Nitrogen is not circulated by the circulatory system. We get nitrogen from the protein-rich food we eat.

Page No 149:

Question 4:

An animal that lacks blood is the
(a) earthworm.
(b) human.
(c) cockroach.
(d) sponge.

Answer:

(d) sponge

Sponges do not have blood. They absorb oxygen and nutrients and eliminate their waste directly into the surroundings, i.e., water. 



Page No 150:

Question 5:

In which of the following is the order of organs correct?
(a) kidney, urethra, urinary bladder, ureter
(b) kidney, ureter, urinary bladder, urethra
(c) ureter, kidney, urethra, urinary bladder
(d) urethra, urinary bladder, ureter, kidney

Answer:

(b) kidney, ureter, urinary bladder, urethra

Kidneys are the main excretory organs in the human body. Ureters carry urine from the kidneys to the urinary bladder, where  it is stored. Urine is then excreted from the urethra.

Page No 150:

Question 6:

An artificial kidney machine works on the principle of
(a) circulation.
(b) excretion.
(c) analysis.
(d) dialysis.

Answer:

(d) dialysis

Dialysis is the process of separating small molecules from large molecules using a membrane. An artificial kidney is required when both the kidneys of a person fail to function.

Page No 150:

Question 7:

The disease not spread through blood transfusion is
(a) AIDS.
(b) asthma.
(c) hepatitis.
(d) malaria.

Answer:

(b) asthma

Asthma is a respiratory disease; it does not spread through blood transfusion. AIDS, hepatitis and malaria spread through blood transfusion.

Page No 150:

Question 8:

Urea is excreted through
(a) kidneys only.
(b) skin and kidneys.
(c) lungs and kidneys.
(d) skin only.

Answer:

(b) skin and kidneys

Urea is formed by the breakdown of proteins. It is removed from the body in the form of urine through the kidneys and in the form of sweat from the skin.

Page No 150:

Question 9:

Which of the following organisms is not multicellular?
(a) Hydra
(b) cockroach
(c) Amoeba
(d) sponge.

Answer:

(c) Amoeba

Multicellular organisms are made up of more than one cell. Amoeba is made up of a single cell; hence, it is a unicellular organism.

Page No 150:

Question 10:

Arteries
A. have values.
B. are deep-seated under the skin.
C. have thick muscular walls.
D. carry blood to the heart.

(a). A and B are correct.
(b) B and D are correct.
(c) Only C is correct.
(d) B and C are correct.

Answer:


(d) B and C are correct.

Valves are not present in arteries. They are deep-seated under the skin. They have thick muscular walls. Arteries carry blood from the heart to other parts of the body.

Page No 150:

Question 11:

The Amoeba carries out transport of materials through
(a) its circulatory system.
(b) its general surface.
(c) the streaming movement of its cytoplasm.
(d) vacuoles which travel throughout the cytoplasm

Answer:

(c) the streaming movement of its cytoplasm

Amoeba is a unicellular organism. It does not have special organs to carry out processes such as circulation and excretion. The absorption and movement of food are carried out by the streaming movement of the cytoplasm within the cell.

Page No 150:

Question 12:

In which group is there a word which does not belong?
(a) liver, lungs, skin, kidneys
(b) urine, sweat, oxygen, carbon dioxide
(c) butterfly, cockroach, beetle, ant
(d) heart, arteries, veins, capillaries

Answer:

(b) urine, sweat, oxygen, carbon dioxide

Urine, sweat and carbon dioxide are waste products; they are eliminated from the body. Oxygen, on the other hand, is not a waste product.

Page No 150:

Question 13:

Two functions of kidney are
(a) filtering wastes and maintaining water balance.
(b) maintaining salt balance and filtering waste
(c) transporting wastes and maintaining salt balance.
(d) filtering wastes and maintaining temperature.

Answer:

(b) maintaining salt balance and filtering waste

Wastes are filtered out in kidneys. Kidneys also maintain salt balance by removing excess sodium, potassium and calcium ions from the body.



Page No 151:

Question 14:

Which of these flow charts correctly shows the circulation of blood in the human body?
graph

Answer:

Figure c is correct.

Page No 151:

Question 15:

Name the following:
(a) largest artery
(b) urine-collecting sac
(c) pigment present in RBCs
(d) lower chambers of the heart
(e) one artery that does not carry oxygenated blood
(f) prevents backward flow of blood in veins
(g) deep-seated blood vessels with thick muscular walls
(h) blood cells that fight germs
(i) process by which exchange of materials take place through thin capillary walls
(j) blood cells which help in the clotting of blood

Answer:

(a) The aorta
(b) The urinary bladder
(c) Haemoglobin
(d) Ventricles
(e) The pulmonary artery
(f) Valves
(g) Arteries
(h) White blood cells
(i) Diffusion
(j) Platelets

Page No 151:

Question 16:

Mark the following statements as true or false. Correct the false statements.
(a) The function of kidney is to store urine.
(b) The blood is sent to all parts of the body from the right side of the heart through the aorta.
(c) Blood gets its red colour due to haemoglobin which is present in plasma.
(d) White blood cells fight disease causing germs.
(e) The excretory system helps in removing undigested food.
(f) It is necessary to match blood types before transferring blood to a patient.
(g) The pulmonary vein carries blood from the heart to the lungs.
(h) The exchange of gases and food materials take place through the walls of the capillaries.
(i) Your pulse rate increases when you are cycling.
(j) Arteries are thick walled and have valves.

Answer:

(a) False
The function of the kidney is to excrete urine.

(b) False
Blood is sent to all parts of the body from the left side of the heart through the aorta.

(c) False
Blood gets its red colour because of haemoglobin, which is present in RBCs.

(d) True

(e) False
The excretory system helps in removing nitrogenous wastes.

(f) True

(g) False
The pulmonary vein carries blood from the lungs to the heart.

(h) False
The exchange of gases and nutrients takes place through the walls of capillaries.

(i) True

(j) False
Arteries are thick walled and do not have valves. 

Page No 151:

Question 17:

Define excretion.

Answer:

Excretion is the process of removal of waste products from the body. Kidney is the chief excretory organ of the body. The skin and lungs are other important excretory organs of the body.

Page No 151:

Question 18:

(a) List the functions of blood.
(b) List the differences between arteries and veins.

Answer:

(a) Following are the functions of blood:

  • It carries oxygen and food to all cells of the body.
  • It transports hormones.
  • It transports waste materials to the excretory organs.
  • It maintains fluid balance and body temperature.
  • It protects against diseases.
(b)
Arteries Veins
They carry blood from the heart to other parts of the body. They carry blood from other parts of the body to the heart.
They have thick walls. They have thin walls.
They are placed deeply under the skin, and blood can move under high pressure. They are placed superficially, and blood cannot move under high pressure.
They do not have valves. They have valves to prevent the backflow of impure blood to the organs.

Page No 151:

Question 19:

Name the different excretory organs of the human body. What does each excrete?

Answer:

The different excretory organs of the human body are the kidneys, lungs and skin. The kidneys remove waste products, such as urea, from the body. The lungs remove carbon dioxide and water. The skin removes small amounts of salt and urea in the form of sweat.

Page No 151:

Question 20:

What are the functions of the followings:
kidney, heart, vein, artery, valves

Answer:

Kidney is the chief excretory organ of the body. It removes urea in the form of urine. 

Heart is the pumping organ of the body. It pumps blood to each cell of the body.

Vein, except the pulmonary vein, is a blood vessel that carries deoxygenated blood from all parts of the body to the heart.

Artery, except the pulmonary artery, is a blood vessel that carries oxygenated blood from the heart to all parts of the body.

Valves are present in veins. These prevent blood from flowing back.



Page No 152:

Question 21:

What happens when kidneys stop functioning?

Answer:

When kidneys stop functioning, waste products start accumulating in the body. These waste products are toxic and may even cause the death of the person. People whose kidneys stop working usually need an artificial kidney that removes the waste products from the body.

Page No 152:

Question 22:

Distinguish between urea and urine.

Answer:

Urea Urine
Urea is a solid formed by the breakdown of proteins. Urine consists of urea and water. Urine also contains salts of sodium, potassium and calcium, which are produced as wastes.

 

Page No 152:

Question 23:

How are substances transported in Amoeba?

Answer:

Amoeba is a unicellular organism. It does not have special organs to carry out processes such as circulation and excretion. The absorption and movement of food are carried out by the streaming movement of the cytoplasm within the cell.

Page No 152:

Question 24:

Name the different types of cells found in blood. Give one function of each.

Answer:

The different types of cells found in blood are:
(a) Red blood cells: These cells contain haemoglobin; they carry oxygenated blood to different parts of the body.
(b) White blood cells: These cells help our body to fight germs and diseases.
(c) Platelets: These help in the clotting of blood.

Page No 152:

Question 25:

What happens when the blood containing absorbed food flows through the liver?

Answer:

The liver converts the nitrogen-containing wastes in blood into urea. The urea is then taken to the kidneys for removal as urine.

Page No 152:

Question 26:

How do animals with no blood system transport their food?

Answer:

In unicellular organisms, such as Amoeba, the absorption and transport of food are carried out by the streaming movement of the cytoplasm within the cell. Simple multicellular organisms, such as Hydra and sponges, absorb oxygen and nutrients and eliminate the wastes directly into the surroundings. 

Page No 152:

Question 27:

Draw a simple labelled diagram of the excretory system showing the kidneys, ureters, bladder and urethra.

Answer:



The Excretory System

Page No 152:

Question 28:

The crossword given here contains words from Chapters 2, 9 and 10.
Graphic

Answer:



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