Life Process - Lakhmir Singh Manjit Kaur Solutions Pg No. 48 Class 10 Biology

Solutions of Life Process Lakhmir Singh Manjit Kaur MCQ, SAQ, and VSAQ Pg No. 48 Class 10 Biology

Solutions of Life Process Lakhmir Singh Manjit Kaur MCQ, SAQ, and VSAQ Pg No. 48 Class 10 Biology

Multiple Choice Questions (MCQs)-Pg-48

52. Which of the following is not produced during anaerobic respiration in unicellular fungus?
A. C2H50H
B. H2O
C. C02
D. ATP

Answer

→ During anaerobic respiration, the unicellular fungus (yeast) breaks down the glucose into ethanol (C2H50H) and carbon dioxide (C02), and release energy in the form of ATP.

53. One of the following organisms can live without oxygen of air. This organism is:
A. Amoeba
B. Yak
C. Yeast
D. Leech

Answer

→ The respiration which takes place without oxygen is called anaerobic respiration. Some micro-organisms like yeast and bacteria obtain energy by anaerobic respiration.

54. During respiration, the exchange of gases takes place in :
A. bronchi
B. alveoli
C. bronchioles
D. trachea

Answer

→ The tiny air-sacs at the end of the smallest bronchioles are known as Alveoli. Alveoli is the place where gaseous exchange take place.

55. In one of the following organisms, the gaseous exchange during respiration does not take place through cell membrane/skin. This organism is:
A. Electric eel
B. Leech
C. Earthworm
D. Amoeba

Answer

→ Aquatic animals like electric eel have gills as respiratory organs which extract oxygen dissolved in the water and carbon dioxide from the body.

56. Which of the following is correct for the process of anaerobic respiration?
Carbon dioxide A lot of energy always produced released
A. No Yes
B. No No
C. Yes No
D. Yes Yes

Answer

→ The end product of anaerobic respiration may be ethanol and carbon dioxide (in yeast) or lactic acid (in animal muscles). Anaerobic respiration produces much less energy which gets stored in the ATP molecules.

57. Which of the following increases in muscle cells when they are lacking in oxygen?
A. carbon dioxide
B. lactose
C. lactic acid
D. uric acid

Answer

→ Due to the lack of oxygen, muscles do anaerobic respiration and produce lactic acid.

58. Internal respiration may be defined as:
A. breathing in and releasing of oxygen in the tissue
B. the oxidation of food substances to release energy
C. the building up (synthesis) of complex substances
D. getting rid of carbon dioxide that would accumulate in the tissues.

Answer

→ Internal respiration is the exchange of gases between body cells and blood to oxidize food substances to release energy.

59. When air is blown from mouth into a test-tube containing lime water, the lime water turns milky due to the presence of :
A. oxygen
B. carbon dioxide
C. nitrogen
D. water vapour

Answer

→ When air is blown from mouth into a test-tube containing lime water, the lime water turns milky due to the presence of carbon dioxide.

60. Which of the following is the correct sequence of air passage during inhalation?
A. nostrils larynx pharynx trachea lungs
B. nasal passage trachea pharynx larynx alveoli
C. larynx nostrils pharynx lungs
D. nostrils pharynx larynx trachea alveoli

Answer

→ The correct sequence of air passage during inhalation is :
nostrils→  pharynx→  larynx→  trachea→  alveoli.

61. Lack of oxygen in muscles often leads to cramps in the legs of sprinters. This is due to conversion of pyruvate to:
A. ethanol
B. carbon dioxide
C. acetic acid
D. lactic acid

Answer

→ Due to the lack of oxygen, anaerobic respiration takes place in the human muscles

62. During the deficiency of oxygen in tissues of human beings, pyruvic acid is converted into lactic acid in :
A. cytoplasm
B. chloroplast
C. mitochondria
D. golgi body

Answer

→ In the absence of oxygen, pyruvic acid is converted into lactic acid in the cytoplasm of the cell.

63. Which of the following statements are correct ?
(i) pyruvate can be converted into ethanol and carbon dioxide by yeast
(ii) fermentation takes place in the case of aerobic bacteria
(iii) fermentation takes place in mitochondria
(iv) fermentation is a form of anaerobic respiration
A. (i) and (iii)
B. (ii) and (iv)
C. (i) and (iv)
D. (ii) and (iii)

Answer

→ Fermentation is a form of anaerobic respiration. Pyruvate can be converted into ethanol and carbon dioxide by yeast during fermentation.

64. Which of the following statements are true about respiration?
(i) during inhalation, ribs move inward and diaphragm is raised.
(ii) the. gaseous exchange takes place in the alveoli.
(iii) haemoglobin has greater affinity for carbon dioxide than oxygen.
(iv) alveoli increase surface area for the exchange of gases
A. (i) and (iv)
B. (ii) and (iii)
C. (i) and (iii)
D. (ii) and (iv)

Answer

→ The tiny air-sacs at the end of the smallest bronchioles are known as Alveoli. Alveoli provides a large surface area for the exchange of gases.

65. Which of the following is known as the energy currency of cells in biology ?
A. DTP
B. PDP
C. ATP
D. DDT

Answer

→ The energy currency in the living organisms is called as “ATP”. During anaerobic respiration, it is produced in cytoplasm while in higher organisms, which respire aerobically, it is produced in mitochondria.

66. The two organisms which breathe only through their moist skin are :
A. fish and frog
B. frog and earthworm
C. leech and earthworm
D. fish and earthworm

Answer

→ The animals like earthworm which live in soil use their skin to absorb oxygen from the air and remove carbon dioxide in the atmosphere.

67. One of the following animals does not use tracheae as the respiratory organs. This animal is:
A. grasshopper
B. prawn
C. mosquito
D. cockroach

Answer

→ In insects like grasshopper, mosquito and cockroach has the tiny holes called spiracles on the sides of their body and the air tube called tracheae as respiratory organs.

68. The photosynthesis in a plant is not taking place during the day time if the plant is releasing:
A. water vapour
B. oxygen
C. carbon dioxide
D. all the above

Answer

→ Photosynthesis is the process by which green plants make their own food by using simple substances like CO2 and water in the presence of sunlight. During the day time, if plant is releasing CO2, it means photosynthesis is not taking place in a plant and only respiration is happening.

69. The breathing and respiration in woody stem of a plant takes place through :
A. root hair
B. lenticels
C. closed stomata
D. open stomata

Answer

→ In woody stem, breathing and respiration takes place through lenticels.

70. One of the following organism does not depend on simple diffusion of gases for breathing and respiration. This organism is :
A. Amoeba
B. Prawn
C. Planaria
D. Bryophyllum

Answer

→ Prawn is a multicellular organism. So it is not dependent on simple diffusion of gases for breathing and respiration.

71. During marathon, we sometimes get painful contractions of leg muscles due to the accumulation of one of the following in leg muscles. This is :
A. carbon dioxide
B. alcohol
C. lactose
D. lactic acid

Answer

→ During vigorous physical exercise, anaerobic respiration takes place in human muscles because oxygen is used faster in the muscles compared to its supply by the blood. Thus, sudden buildup of lactic acid poison our muscles and cause muscular cramps.

72. In cockroaches, air enters the body through:
A. lungs
B. gills
C. spiracles
D. skin

Answer

→ A cockroach has small openings on the sides of the body called spiracles. Air enters the body though these external openings.

73. Which of the following is most likely to have a much higher breathing rate?
A. man
B. fish
C. dog
D. sparrow

Answer

→ The oxygen content of water is much less than the oxygen content of air and hence rate of breathing is aquatic organisms like fish is faster than in terrestrial organisms like dog, man and sparrow.

Questions Based on High Order Thinking Skills (HOTS)-Pg-50

74. During the respiration of an organism A, 1 molecule of glucose produces 2 ATP molecules whereas in the respiration of another organism B, 1 molecule of glucose produces 38 ATP molecules.
(a) Which organism is undergoing aerobic respiration?
(b) Which organism is undergoing anaerobic respiration?
(c) Which type of organism, A or B, can convert glucose into alcohol?
(d) Name one organism which behaves like A
(e) Name two organisms which behave like B

Answer

→ (a) Organism B
(b) Organism A
(c) Organism A can convert glucose into alcohol by anaerobic respiration.
(d) Yeast behaves like organism A

(e) Man, fish behave like organism B

75. A, Band Care three living organisms. The organism A is a unicellullar fungus which can live without air. It is used in the commercial production of an organic compound P from molasses. The organism B is a unicellular animal which lives in water and feeds and moves by using pseudopodia. It breathes through an organelle Q. The organism C is a tiny animal which acts as a carrier of malarial parasite. It breathes and respires through a kind of tiny holes Rand air-tubes Sin its body.
(a) What are organisms (i) A (ii) B, and (iii) C?
(b) Name (i) P (ii) Q (iii) R, and (iv) S.
(c) Which organism/ organisms undergo aerobic respiration?
(d) Which organism/ organisms undergo anaerobic respiration?

Answer

→ (a) Organisms (i) Yeast (ii) Amoeba (iii) Mosquito
(b) (i) Ethanol (C2H5OH) (ii) Cell membrane (iii) Spiracles and (iv) Tracheae
(c) Organism B (Amoeba) and organism C (mosquito) undergo aerobic respiration.
(d) Organism A (yeast) undergoes anaerobic respiration and produce ethanol and carbon dioxide.

76. 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.
(a) Which of the animals could be Amoeba?
(b) Which of the animals could be frog?
(c) Which animal could be fish?
(d) Which animal could be grasshopper?
(e) Which animal could be earthworm?

Answer

→ (a) Animal T could be Amoeba because it lives in water and breathes through its cell membrane.
(b) Animal Q could be frog because it can stay in water as well as on land and can breathe both, through moist skin and lungs.
(c) Animal P could be fish because it lives in water and has gills for breathing.
(d) Animal S could be grasshopper because lives on land and breathes through spiracles and tracheae.
(e) Animal R could be earthworm because it lives in soil and breathes only through its skin.

77. Some sugar solution is taken in a test-tube and a little of substance X in powder form is added to it. The mouth of test-tube is closed with a cork and allowed to stand for some time. On opening the cork, a characteristic smell of substance Y is obtained and a gas Z is also observed to be formed. The gas Z extinguishes a burning matchstick.
(a) What could be (i) X, (ii) Y, and (iii) Z ?
(b) What is the process of converting sugar into substance Y by the action of X known as? (c) What type of respiration is exhibited by X in the above process ?

Answer

(a) (i) Yeast (ii) Ethanol (iii) Carbon dioxide
(b) Fermentation is the process by which sugar converts into ethanol by the action of Yeast.
(c) Fermentation is an example of anaerobic respiration which is done by yeast (X) in the above experiment.

78. Consider the following chemical reactions which take place in different organisms/tissues under various conditions:
(i) Glucose Ethanol + Carbon dioxide + Energy
(ii) Glucose Carbon dioxide + Water + Energy
(iii) Glucose Lactic acid + Energy
(a) Name one organism which respires according to equation (i) above.
(b) Name one organism which respires according to equation (ii) above.
(c) When and where does respiration represented by equation (iii) above take place?
(d) Which equation/equations represent aerobic respiration ?
(e) Which equation/equations represent anaerobic respiration ?
(f) Which of the above reactions produces the maximum amount of energy ?

Answer

(a) Yeast.
(b) Human beings
(c) Such kind of respiration occurs in animal’s muscles, when the animal needs more energy for doing heavy physical exercises.
(d) Chemical reaction (ii) represents the aerobic respiration.
(e) Chemical reactions (i) and (iii) represent the anaerobic respiration.
(f) Chemical reaction (ii) represents the aerobic respiration. In aerobic respiration, maximum amount of energy is produced.

79. When a person breathes in air, the air enters into his body through an organ A having two holes B in it. The air then passes through pharynx and larynx and enters into a tube C. The tube C divides into two smaller tubes D at its lower end. The two smaller tubes are attached to two respiratory organs E. Each smaller tube divides inside the organs E to form a large number of still smaller tubes called F. The smallest tubes F have air-sacs G at their ends in which gaseous exchange takes place in the body of the person. What are A, B, C, D, E, F and G?

Answer

→ A = Nose; B =Nostrils; C =Trachea (Windpipe); D =Bronchi; E =Lungs; F =Bronchioles; G =Alveoli

80. An organism X having breathing organs A lives on land. When organism X goes under water, it cannot survive for a long time unless carrying an oxygen cylinder. On the other hand, the organism Y having breathing organs B always lives in water and if taken out of water; it dies after a short while. A third organism Z having. breathing organs C and D which lives on the banks of ponds, lakes and rivers can survive on land as well as in water equally well.
(a) What could organism X be ? Name the breathing organs A.
(b) What could organism Y be ? Name the breathing organs B.
(c) What could organism Z be? Name the breathing organs C and D.
(d) Out of X, Y and Z, which organism is (i) amphibian, (ii) aquatic, and (iii) terrestrial ?

Answer

→ (a) Organism X could be man. Man (X) have the lungs (A) as breathing organ.
(b) Organism Y could be Fish. Fish has the gills (B) as breathing organ.
(c) Organism Z could be frog. Frog has lungs (C) and skin (D) as breathing organs.
(d) (i) Organism Z (ii) Organism Y (iii) Organism X

Very Short Answer Type Questions-Pg-72

1. What is the name of tissues which transport:
(a) food in a plant?
(b) water and minerals in a plant?

Answer

→(a) Phloem is a plant tissue which transport food from the leaves to other parts of the plant.
(b) Xylem is a plant tissue which transport water and minerals from the soil to the various parts of the plant body.

2. What substance/substances are transported in plants by:
(a) xylem vessels and tracheids?
(b) sieve tubes (or phloem)?

Answer

→ (a) Xylem vessels and tracheids are two elements of xylem tissue which help in the transportation of water.
(b) The cells of phloem are called sieve tubes. Sieve tubes are conducting element of phloem which is responsible for transportation of food.

3. Which organ acts as a pump in the circulatory system?

Answer

→ Heart is a muscular organ which act as a pumping organ in the circulatory system.

4. Veins and arteries carry blood. Which of these carry blood :
(a) away from the heart?
(b) back to the heart?

Answer

→ (a) Arteries carry blood from the heart to different organs.
(b) Veins carry blood from different organs to the heart.

5. Where does blood absorb oxygen?

Answer

The exchange of various materials like carbon dioxide, oxygen, etc., between the blood and the body cells takes place through capillaries.

6. What stops blood from flowing backwards through the heart?

Answer

→ The valves present in the heart prevent the blood flowing backward through the heart.

7. Name (i) largest artery, and (ii) largest vein, in our body.

Answer

→ (i) The aorta is the largest blood (artery) vessel in the body.
(iii) The vena cava is the largest vein in the body.

8. What gaseous waste products are excreted by plants?

Answer

→ The main waste products of plants are carbon dioxide, oxygen and water vapour.

9. Where is the dirty blood in our body filtered?

Answer

The dirty blood in our body is filtered in glomerulus present in the kidney.

10. Name the procedure used in the working of artificial kidney.

Answer

→ Dialysis is the artificial process which is used in artificial kidney to get rid of waste and unwanted water from the blood.

11. From the following terms, choose one term which includes the other four: Plasma, Platelets, Blood, RBC, WBC.

Answer

→ Blood is a fluid connective tissue which is composed of plasma, platelets, RBC and WBC.

12. What are the components of the transport system in highly organized plants?

Answer

→ There are two components of the transport system in plants namely xylem and phloem.

13. Out of xylem and phloem, which one carries materials:
(a) upwards as well as downwards?
(b) only upwards?

Answer

→ (a) Phloem carries food from leaves in both the directions, upwards as well as downwards, depending on the requirement of the plant.
(b) Xylem carries water and dissolved minerals only in upward direction from roots to the leaves of plant.

14. Name two liquids which help in the transport of substances in the human body.

Answer

→ Blood and lymph are two liquid of human circulatory system which help in the transportation of substances in the human body.

15. What is the other name of main vein?

Answer

→ The main vain carries deoxygenated blood from all the parts of the body to heart. It is also known as Vena cava.

16. Name the conducting tissue of plants which is made of sieve tubes along with companion cells.

Answer

→ Phloem is a conducting tissue of plant which is made of two elements i.e. sieve tube and companion cells.

17. Name the conducting tissue in plants which is made of
(a) living cells, and
(b) dead cells.

Answer

→ (a) Phloem is a conducting tissue of a plant which is made up of sieve tubes. Sieve tubes are living cells which contain cytoplasm.
(b) Xylem is made up of xylem vessels and tracheids which are non-living cells.

18. State the term used for the transport of food from leaves to other parts of plant.

Answer

→ The transport of food from leaves to other parts of the plant is called translocation.

19. Which process in a plant is accomplished by utilising energy from ATP : transport of water and minerals or transport of food ?

Answer

→ The transport of food in a plant is accomplished by utilizing energy from ATP.

20. Name the two types of transport systems in the human beings.

Answer

→ There are two types of transport systems in the human beings:
(i) Blood circulatory system
(ii) Lymphatic system

21. Name a waste gas released by the plants (a) only during the day time, and
(b) only during the night time.

Answer

→ (a) Plants excrete oxygen as waste product by the process of photosynthesis only during the day time.
(b) Plant release carbon dioxide as waste product by the process of respiration during the night time.

22. Name one animal having single circulation of blood and another having double circulation.

Answer

→ The single circulation of blood is found in only fishes whereas the double circulation of blood is found in human beings.

23. State whether the following statements are true or false :
(a) Some organisms store wastes in body parts.
(b) The value of systolic pressure is always lower than that of diastolic pressure.

Answer

→ (a) True
(b) False

24. Name the two parts of a plant through which its gaseous waste products are released into the air.

Answer

→ Plant releases its gaseous waste products into the air through stomata, present in the leaves, and lenticels, present in the stems.

25. What happens to the glucose which enters the nephron tubule along with the filtrate?

Answer

→ When glucose passes through the nephron tubule along with the glomerular filtrate, it gets collected in the Bowman's capsule.

26. Name the two waste products of the human body which are produced in the body cells.

Answer

→ Carbon dioxide and urea are two waste products which are produced in the body cells of human beings.

27. What is the role of glomerulus in the kidney?

Answer

→ Glomerulus, in the kidney, helps in the filtration of blood and resulting in urine formation.

28. What is the other name of 'high blood pressure' ?

Answer

High blood pressure is also known as hypertension.

29. Fill in the following blanks with suitable words :
(a) Gums and resins are the ................. products of plants.
(b) Bowman's capsule and tubule taken together make a...................
(c) The organs which extract the nitrogenous wastes from the blood are ..................
(d) The extracellular fluid which always flows from body tissues to the heart is called..................
(e) The ............blood cells make antibodies whereas............. blood cells help in respiration.

Answer

→ (a) Waste.
(b) Nephron.
(c) Kidneys.
(d) Lymph.
(e) White, red.

Short Answer Type Questions-Pg-73

30. What is xylem tissue? Name the two kinds of cells in xylem tissue. State whether these cells are living or dead.

Answer


→ Xylem is a conducting tissue of plants which carry water and minerals from the soils to the various of the plant body. Xylem is made up of xylem vessels and tracheids which are non-living cells.

31. What is phloem tissue? Phloem contains two types of cells joined side by side. Name these two types of cells. State whether these cells are living or dead.

Answer

→ Phloem is a vascular tissue which transports food from leaves to the other parts of the plant. Phloem is made up of many cells joined end to end to form long tube. Phloem contains two type of cells which are associated with each other. These cells are sieve tubes and companion cell. Both cells are living.

32A. What is transpiration?

Answer

→ The loss of water in the form of vapour from the aerial parts of the plant is known as transpiration.

32B. What do you mean by 'translocation' with respect to transport in plants?

Answer

→ The transport of food from leaves to other parts of the plant is called translocation.

32C. Which plant tissue is involved in translocation : xylem or phloem ?

Answer

→ Phloem is a vascular tissue which transports food from leaves to the other parts of the plant.

33A. (a) Draw a labelled diagram of
(i) a xylem vessel, and
(ii) a sieve tube (or phloem).

Answer

→ (a) (i) and (ii)


33B. What are the differences between the transport of materials in xylem and phloem?

Answer

→ Differences between the transport of materials in xylem and phloem
Xylem

Phloem
It transports water and minerals from roots to the other parts of the 
plant.
It transports the food from leaves to the other parts of the plant.
It transports materials only in upward direction.
It transports materials in both the directions upward as well as downward.

34. Match the terms in column I with their uses in column II
Column I
Column II

(i) Heart

(a) Pipes for transport in humans

(ii) Arteries and Veins

(b) Clotting of blood

(iii) Xylem vessels

(c) Pumping organ

(iv) RBC

(d) Water transport in plants

(v) Platelets

(e) Carrier of oxygen


Answer

→ (i) c - Explanation: Heart is a pumping organ, its function is to pump blood from different parts of the body.
(ii) a - Explanation: Arteries and Veins transport blood to different parts of the body.
(iii) d - Explanation: Xylem vessels  responsible for transport water in plant body.
(iv) e - Explanation: RBC(Red blood cells) found in blood is use to transport oxygen to different part of the body.
(v) b - Explanation: Platelets is responsible for Clotting of blood.

35. Define excretion. Name the excretory unit of a kidney.

Answer

→ The biological process of removable of harmful metabolic wastes from the body of a living organism is called excretion.
The excretory unit of a kidney is called nephrons.

36A. What job is done by the kidneys ?

Answer

→ The kidneys are bean-shaped organs which filter the wastes from the blood by forming a yellowish liquid called urine.

36B. What do kidneys excrete?

Answer

→ Kidneys excrete urea from the body.

36C. What is the name of the tubes which connect the kidneys to bladder?

Answer

→ Each kidney enters a long tube called ureter which connects kidney to urinary bladder.

36D. What does the bladder in our body do?

Answer

→ Urinary bladder is a large muscular bag-like structure which stores the urine temporarily till it is excrete out.

37. Why do some people need to use a dialysis machine ? What does the machine do?

Answer

→ Some people need to use a dialysis machine because one or both of their kidneys fail to work. Dialysis machine cleans the blood of a person by removing the nitrogenous wastes from the blood.

38. What is the liquid part of the blood called? What is the function of platelets in the blood?

Answer

→ The liquid part of the blood is called plasma. The main function of platelets is to prevent bleeding. Platelets helps in the coagulation of blood (clotting of blood) in a cut or wound.

39A. How many types of blood vessels are there in the human body? Name them.

Answer

→ There are three types of blood vessels are found in human body. These are arteries, veins and capillaries.

39B. Why does the heart need valves?

Answer

→ Heart needs valves to prevent back flow of blood. Valves allow flow of blood in only one direction.

40. A dialysis machine contains long tubes coiled in a tank containing dialysing
(i) Of what substance are the tubes made ?
(ii) What does the dialysing solution contain?
(iii) Name the main waste which passes into the dialysing solution.

Answer

→ (i) The tubes of dialysis machine are made up of semipermeable membrane (cellulose).
(ii) Dialysing solution contain water, glucose and salt.
(iii) The main waste is urea which passes into the dialysing solution.

41. State the differences between artery, vein and capillary.

Answer

→ Artery
• Thick-walled blood vessel
• Blood flows from the heart to different parts of the body
• Blood flows with high pressure with a high speed
• Valves are absent
Vein
• Thin walled blood vessel.
• Brings blood from the different parts of the body to the heart.
• Blood flows with low pressure and with a low speed.
• Contains valves which permit blood flow only towards the heart.
Capillary
• Thin walled and extremely narrow blood vessel.
• Capillary forms an extensive network throughout all living cells in the body.
• Capillaries connect arteries and veins.
• Valves are absent

42A. What are the upper parts of the heart called?

Answer

→ The upper part of the heart is called atria.

42B. What are the lower parts of the heart called?

Answer

→ The lower part of the heart is called ventricles.

42C. What is the name of blood vessels which connect arteries to veins?

Answer

→ Capillaries are thin-walled blood vessels which connect arteries to veins.

42D. (i) Which side of the heart pumps blood into the lungs ?
(ii) Which side of the heart pumps blood into entire body (except the lungs)?

Answer

→ (i) Right side of the heart pumps blood into the lungs.
(ii) Left side of the heart pumps blood into the entire body except the lungs.

43A. What are the methods used by plants to get rid of their waste products ?

Answer

→ There are various methods that are used by the plants to get rid of their waste products:
(i) Gaseous waste products are thrown out through the stomata, present on leaves and lenticels, present on stem of the plants.
(ii) Solid and liquid wastes are thrown out by shedding off leaves, peeling of bark and falling of fruits.
(iii) Plants excrete some waste products into the soil around them.
(iv) By secreting gums and resins.

43B. How are waste products excreted in Amoeba?

Answer

→ Amoeba is a unicellular organism which removes carbon dioxide from the body through its cell membrane by diffusion whereas it removes nitrogenous waste and water from the body by contractile vacuole.

44A. What is lymph? State two major functions of lymph.

Answer

→ Lymph is a colorless or slightly yellowish fluid. It is a medium of circulation in human body which flows only in one direction - from body tissues to the heart.
The functions of lymph are:
(i) Lymph helps in removing the waste products.
(ii) Lymph carries digested fat from the small intestine to the entire body.
(iii) Lymph nodes contain lymphocytes which kill the germs or foreign bodies.


44B. What is meant by saying that the blood pressure of a person is 120/80?

Answer

→ The blood pressure of a person is 120/80 which means that the systolic pressure is 120 mm Hg and diastolic pressure is 80 mm Hg.

45. What is hypertension? Why is it caused? What harm can it do?

Answer

→ High blood pressure is also called hypertension. Hypertension is caused by the constriction of arterioles (small arteries), resulting in increased resistance to blood flow. Very high pressure can cause internal bleeding and rupturing of artery.

46. What are the various components of blood? State their functions.

Answer

→ Blood is a red colour liquid which circulates in our body. The main components of blood are:
•Plasma
•RBC (Red blood cells)
•WBC (White blood cells), and
•Platelets
Functions:
•Plasma-It is liquid part of the blood. It contains about 90 percent water. Plasma carries dissolved substances like proteins, digested food, waste products, etc. one part of the body to the other parts.
•RBC : It carries oxygen from the lungs to all the cells of the body.
•WBC : Which blood cells (WBC) protect us from diseases. WBC make a chemical, antibodies which help to fight against infection.
•Platelets : The main function of platelets is to prevent bleeding. Platelets helps in the coagulation of blood (clotting of blood) in a cut or wound.

47. With which human organ systems (or human systems) are the following associated?
(i) vena cava
(ii) glomerulus
(iii) alveoli
(iv) villi

Answer

→ (i) Vena cava is associated with human circulatory system.
(ii) Glomerulus is associated with human excretory system.
(iii) Alveoli is associated with human respiratory system.
(iv) Villi is associated with human digestive system.

48. What is meant by 'systolic pressure' and 'diastolic pressure'? What are their normal values?

Answer

→ Systolic pressure: The pressure of blood inside the artery during ventricular systole (contraction) is called systolic pressure.
Diastolic pressure: The pressure of blood inside the artery during ventricular diastole (relaxation) is called diastolic pressure.
The normal value of systolic pressure is about 120 mm of Hg and the value of diastolic pressure is 80 mm of Hg.

49A. What is meant by 'heart beat' ? What is the usual heart beat rate at rest?

Answer

→ One heart beat includes one complete contraction (systole) and relaxation (diastole) of heart. The normal heart beat rate at rest is 72 times /minute.
(b) When a person runs for a while, his heart beat becomes faster because he needs more energy to run.

49B. What change occurs in heart beats if a person runs for a while? Why?

Answer

→ When a person runs for a while, his heart beat becomes faster because he needs more energy to run.

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