|Table of contents|
|Multiple Choice Questions|
|Short Answer Type Questions|
|Long Answer Type Questions|
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Q.1. Which of the following statements about the autotrophs is incorrect?
(a) They synthesise carbohydrates from carbon dioxide and water in the presence of sunlight and chlorophyll
(b) They store carbohydrates in the form of starch
(c) They convert carbon dioxide and water into carbohydrates in the absence of sunlight
(d) They constitute the first trophic level in food chains
Q.2. In which of the following groups of organisms, food material is broken down outside the body and absorbed?
(a) Mushroom, green plants, Amoeba
(b) Yeast, mushroom, bread mould
(c) Paramecium, Amoeba, Cuscuta
(d) Cuscuta, lice, tapeworm
Q.3. Select the correct statement
(a) Heterotrophs do not synthesise their own food
(b) Heterotrophs utilise solar energy for photosynthesis
(c) Heterotrophs synthesise their own food
(d) Heterotrophs are capable of converting carbon dioxide and water into carbohydrates
Q.4. Which is the correct sequence of parts in human alimentary canal?
(a) Mouth → stomach → small intestine → oesophagus → large intestine
(b) Mouth →oesophagus → stomach → large intestine → small intestine
(c) Mouth → stomach → oesophagus → small intestine → large intestine
(d) Mouth → oesophagus → stomach → small intestine → large intestine
Q.5. If salivary amylase is lacking in the saliva, which of the following events in the mouth cavity will be affected?
(a) Proteins breaking down into amino acids
(b) Starch breaking down into sugars
(c) Fats breaking down into fatty acids and glycerol
(d) Absorption of vitamins
Q.6. The inner lining of stomach is protected by one of the following from hydrochloric acid. Choose the correct one
(c) Salivary amylase
Q.7. Which part of alimentary canal receives bile from the liver?
(b) Small intestine
(c) Large intestine
Q.8. A few drops of iodine solution were added to rice water. The solution turned blue-black in colour. This indicates that rice water contains
(a) complex proteins
(b) simple proteins
Q.9. In which part of the alimentary canal food is finally digested?
(b) Mouth cavity
(c) Large intestine
(d) Small intestine
Q.10. Choose the function of the pancreatic juice from the following
(a) trypsin digests proteins and lipase carbohydrates
(b) trypsin digests emulsified fats and lipase proteins
(c) trypsin and lipase digest fats
(d) trypsin digests proteins and lipase emulsified fats
Q.11. When air is blown from mouth into a test-tube containing lime water, the lime water turned milky due to the presence of
(b) carbon dioxide
(d) water vapour
Q.12. The correct sequence of anaerobic reactions in yeast is
Q.13. Which of the following is most appropriate for aerobic respiration?
Q.14. Which of the following statement(s) is (are) true about respiration?
(i) During inhalation, ribs move inward and diaphragm is raised
(ii) In the alveoli, exchange of gases takes place i.e., oxygen from alveolar air diffuses into blood and carbon dioxide from blood into alveolar air
(iii) Haemoglobin has greater affinity for carbon dioxide than oxygen
(iv) Alveoli increase surface area for exchange of gases
Choose the correct option:
(a) (i) and (iv)
(b) (ii) and (iii)
(c) (i) and (iii)
(d) (ii) and (iv)
Q.15. Which 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
Q.16. During respiration exchange of gases take place in
(a) trachea and larynx
(b) alveoli of lungs
(c) alveoli and throat
(d) throat and larynx
Q.17. Which of the following statement (s) is (are) true about heart?
(i) Left atrium receives oxygenated blood from different parts of body while right atrium receives deoxygenated blood from lungs
(ii) Left ventricle pumps oxygenated blood to different body parts while right ventricle pumps deoxygenated blood to lungs
(iii) Left atrium transfers oxygenated blood to right ventricle which sends it to different body parts
(iv) Right atrium receives deoxygenated blood from different parts of the body while left ventricle pumps oxygenated blood to different parts of the body
Choose the correct option:
(c) (ii) and (iv)
(d) (i) and (iii)
Q.18. What prevents backflow of blood inside the heart during contraction?
(a) Valves in heart
(b) Thick muscular walls of ventricles
(c) Thin walls of atria
(d) All of the above
Q.19. Single circulation i.e., blood flows through the heart only once during one cycle of passage through the body, is exhibited by
(a) Labeo, Chameleon, Salamander
(b) Hippocampus, Exocoetus, Anabas
(c) Hyla, Rana, Draco
(d) Whale, Dolphin, Turtle
Ans: . (b)
Q.20. In which of the following vertebrate group/groups, heart does not pump oxygenated blood to different parts of the body?
(a) Pisces and amphibians
(b) Amphibians and reptiles
(c) Amphibians only
(d) Pisces only
Q.21. Choose the correct statement that describes arteries.
(a) They have thick elastic walls, blood flows under high pressure; collect blood from different organs and bring it back to the heart
(b) They have thin walls with valves inside, blood flows under low pressure and carry blood away from the heart to various organs of the body
(c) They have thick elastic walls, blood flows under low pressure; carry blood from the heart to various organs of the body
(d) They have thick elastic walls without valves inside, blood flows under high pressure and carry blood away from the heart to different parts of the body.
Q.22. The filtration units of kidneys are called
Q.23. Oxygen liberated during photosynthesis comes from
(c) carbon dioxide
Q.24. The blood leaving the tissues becomes richer in
(a) carbon dioxide
Q.25. Which of the following is an incorrect statement?
(a) Organisms grow with time
(b) Organisms must repair and maintain their structure
(c) Movement of molecules does not take place among cells
(d) Energy is essential for life processes
Q.26. The internal (cellular) energy reserve in autotrophs is
(d) fatty acid
Q.27. Which of the following equations is the summary of photosynthesis?
(a) 6CO2 + 12H2O → C6H12O6 + 6O2+ 6H2O
(b) 6CO2 + H2O + Sunlight→ C6H12O6 + O2 + 6H2O
(c) 6CO2 + 12H2O + Chlorophyll + Sunlight→ C6H12O6 + 6O2 + 6H2O
(d) 6CO2 + 12H2O + Chlorophyll + Sunlight→ C6H12O6 + 6CO2 + 6H2O
Q.28. Choose the event that does not occur in photosynthesis
(a) Absorption of light energy by chlorophyll
(b) Reduction of carbon dioxide to carbohydrates
(c) Oxidation of carbon to carbon dioxide
(d) Conversion of light energy to chemical energy
Q.29. The opening and closing of the stomatal pore depends upon
(c) water in guard cells
(d) concentration of CO2 in stomata
Q.30. Choose the forms in which most plants absorb nitrogen
(ii) Nitrates and Nitrites
(iv) Atmospheric nitrogen
Choose the correct option:
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iv)
Q.31. Which is the first enzyme to mix with food in the digestive tract?
Q.32. Which of the following statement(s) is (are) correct?
(i) Pyruvate can be converted into ethanol and carbon dioxide by yeast
(ii) Fermentation takes place in aerobic bacteria
(iii) Fermentation takes place in mitochondria
(iv) Fermentation is a form of anaerobic respiration
Choose the correct option:
(a) (i) and (iii)
(b) (ii) and (iv)
(c) (i) and (iv)
(d) (ii) and (iii)
Q.33. Lack of oxygen in muscles often leads to cramps among cricketers. This results due to
(a) conversion of pyruvate to ethanol
(b) conversion of pyruvate to glucose
(c) non conversion of glucose to pyruvate
(d) conversion of pyruvate to lactic acid
Q.34. Choose the correct path of urine in our body
(a) kidney → ureter → urethra → urinary bladder
(b) kidney → urinary bladder → urethra → ureter
(c) kidney → ureters → urinary bladder → urethra
(d) urinary bladder → kidney → ureter → urethra
Q.35. During deficiency of oxygen in tissues of human beings, pyruvic acid is converted into lactic acid in the
(d) golgi body
Q.36. Name the following:
(a) The process in plants that links light energy with chemical energy.
(b) Organism that can prepare their own food.
(c) The cell organelle where photosynthesis occurs.
(d) Cells that surround a stomatal pore.
(e) Organisms that cannot prepare their own food.
(f) An enzyme secreted from gastric glands in stomach thact acts on proteins.
Ans: (a) Photosynthesis
(d) Guard cells
Q.37. “All plants give out oxygen during day and carbon dioxide during night”. Do yo agree with this statement? Give reason.
Ans: Yes, respiration takes place throughout day and night but photosynthesis occurs only during the day. During daytime, plants give out oxygen which is a product of photosynthesis. Thus, during night when there is no photosynthesis, plants liberate carbon dioxide.
Q.38. How do the guard cells regulate opening and closing of stomatal pores?
Ans: The swelling of guard cells due to absorption of water causes opening of stomatal pores while shrinking of guard cells closes the pores. Opening and closing of stomata occurs due to turgor changes in guard cells. When guard cells are turgid, stomatal pore is open while in flaccid conditions, the stomatal aperture closes.
Q.39. Two green plants are kept separately in oxygen free containers. One in dark and other in continuous light which one will longer? Give reasons.
Ans: The plant which kept in continuous light will live longer because in light, the plant will be able to undergo photosynthesis and able to convert carbon dioxide into oxygen whereas the plant in dark cannot perform photosynthesis and lack of oxygen will kill the plant.
Q.40. If a plant is releasing carbon dioxide and taking in oxygen during the day, does it mean that there is no photosynthesis occurring? Justify your answer.
Ans: Release of CO2 and intake of O2 gives evidence that either photosynthesis is not taking place or its rate is too low. Normally during day time, the rate of photosynthesis is much more than the rate of respiration. So, CO2 produced during respiration is used up for photosynthesis hence CO2 is not released.
Q 41. Why do fishes die when taken out of water?
Ans: Fishes die when taken out of water because they cannot obtain gaseous oxygen.
They breath through gills, which are richly supplied with blood capillaries and can readily absorb oxygen dissolved in water.
Q.42. Differentiate between an autotroph and a heterotroph.
Q.43. Is ‘nutrition’ a necessity for an organism? Discuss.
Ans. Yes, ‘nutrition’ is a necessity for an organism because:
Q.44. What would happen if green plants disappear from the earth?
Ans: If green plants disappear from the earth, then the herbivores will die of starvation followed by carnivores and then decomposers.
Q.45. Leaves of a healthy potted plant were coated with vaseline will this plant remain healthy for long? Give reasons for your answer.
Q.46. How does aerobic respiration differ from anaerobic respiration?
Q.47. Match the words of Column (A) with that of Column (B)
Ans: (a) Phloem - (ii) Translocation of food
(b) Nephron - (i) Excretion
(c) Veins - (iv) Deoxygenated blood
(d) Platelets - (iii) Clotting of blood
Q.48. Differentiate between an artery and a vein.
Q.49. What are the adaptations of leaf for photosynthesis?
Ans: The adaptations of leaf for photosynthesis are as follows:
Q.50. Why is the small intestine in herbivores longer than in carnivores?
Ans: Herbivores eat grass and need a longer small intestine to allow complete digestion of cellulose. But carnivores cannot digest cellulose, and therefore they have a shorter intestine.
Q.51. What will happen if the mucus is not secreted by the gastric glands?
Ans: If the mucus is not secreted by the gastric glands, it will lead to corrosion of the inner lining of the stomach, causing excessive acidity, ulcers, and extreme discomfort as mucus protects the inner lining of the stomach from the action of hydrochloric add and enzyme pepsin.
Q.52. What is the significance of emulsification of fats?
Ans: Fats are present in food in the form of large globules which makes it difficult for enzymes to act on them. Bile salts present in bile break them down mechanically into smaller globules which increases the efficiency of fat digesting enzymes.
Q.53. What causes movement of food inside the alimentary canal?
Ans: The wall of alimentary canal contains muscle layers. Rhythmic contraction and relaxation of these muscles pushes the food forward. This is called peristalsis, which occurs all along the gut.
Q.54. Why does absorption of digested food occur mainly in the small intestine?
Ans: Absorption of digested food occurs mainly in the small intestine because:
(i) Digestion of food is completed in the small intestine.
(ii) Inner lining of the small intestine bears a number of finger-like projections called villi, which increases the surface area for absorption.
(iii) Wall of the intestine has blood vessels for carrying the absorbed food to different parts of the body.
Q.55. Match Group (A) with Group (B)
Ans: (a) Autotrophic nutrition- (iv) Green plant
(b) Heterotrophic nutrition - (iii) Deer
(c) Parasitic nutrition - (i) Leech
(d) Digestion in food vacuoles - (ii) Paramoecium
Q.56. Why is the rate of breathing in aquatic organisms much faster than in terrestrial organisms?
Ans: The rate of breathing in aquatic organisms is much faster than in terrestrial organisms because the amount of dissolved oxygen in water is low as compared to the amount of oxygen in the air. Aquatic animals take in water through their mouths and past it to the gills where the dissolved oxygen is taken up by the blood.
Q.57. Why is blood circulation in human heart called double circulation?
Ans: The blood circulation in human heart is called double circulation because the blood passes through the heart twice in one complete cycle of the body – once through the right half in the form of deoxygenated blood and once through the left half in the form of oxygenated blood.
Q.58. What is the advantage of having a four-chambered heart?
Ans: The advantage of having a four-chambered heart is that it prevents oxygenated and deoxygenated blood from mixing, as the left half of the four-chambered heart is completely separated from the right half by septa. This mechanism is useful to animals with high energy needs such as birds and mammals. In this way, a highly efficient supply of oxygenated blood is passed to all parts of the body.
Q.59. Mention the major events during photosynthesis
Ans: The major events during photosynthesis are
(a) absorption of light energy by chlorophyll
(b) conversion of light energy to chemical energy
(c) splitting of H2O into H2, O2 and e–
(d) reduction of CO2 to carbohydrates
Q.60. In each of the following situations what happens to the rate of photosynthesis?
(a) Cloudy days
(b) No rainfall in the area
(c) Good manuring in the area
(d) Stomata gets blocked due to dust.
Ans: (a) On cloudy days, photosynthesis is reduced due to low light intensity.
(b) In case of no rainfall in the area, rate of photosynthesis decreases.
(c) With good manuring in the area, rate of photosynthesis increases, it increases soil fertility.
(d) When stomata gets blocked due to dust, photosynthesis decreases by reducing gaseous exchange.
Q.61. Name the energy currency in the living organisms. When and where is it produced?
Ans: Adenosine triphosphate (ATP) is the energy currency of the living organisms. It is produced during respiration in living organisms and also during photosynthesis in plants.
Q.62. What is common for cuscuta, ticks and leeches?
Ans: All are parasites and they derive their nutrition from their hosts directly without killing them.
Q.63. Explain the role of mouth in digestion of food.
Ans: (a) Food is crushed into small pieces by the teeth.
(b) It mixes with saliva and the enzyme amylase (found in saliva) breaks down starch into sugars
(c) Tongue helps in thorough mixing of food with saliva.
Q.64. What are the functions of gastric glands present in the wall of the stomach?
Ans: Functions of the gastric glands present in the wall of the stomach are as follows:
(i) Secretion of mucus for protection of inner lining of stomach.
(ii) Secretion of HCI which makes the food soft and acidified for pepsin to act upon food.
(iii) Secretion of pepsin enzyme that digests proteins.
Q.65. Match the terms in Column (A) with those in Column (B)
Ans: (a) Trypsin - (i) Pancreas
(b) Amylase- (iv) Saliva
(c) Bile - (ii) Liver
(d) Pepsin- (iii) Gastric glands
Q.66. Name the correct substrates for the following enzymes
Ans: (a) Trypsin - Protein
(b) Amylase - starch
(c) Pepsin -Protein
(d) Lipase - Fat
Q.67. Why do veins have thin walls as compared to arteries?
Ans: Arteries carry blood from the heart to various organs of the body under high pressure so they have thick and elastic walls. Veins collect the blood from different organs and bring it back to the heart. The blood is no longer under pressure so the walls are thin with valves to ensure that blood flows only in one direction.
Q.68. What will happen if platelets were absent in the blood?
Ans: In the absence of platelets, the process of clotting will be affected.
Q.69. Plants have low energy needs as compared to animals. Explain.
Ans: Plants have low energy needs as compared to animals because plants do not move and most of their body is made up of dead cells like sclerenchyma. But animals move about in search of food, mate and shelter.
Q.70. Why and how does water enter continuously into the root xylem?
Ans: Cells of root are in close contact with soil and so actively take up ions. Ions pass inward increasing osmotic concentration of xylem. Because of it water from the soil continuously pass into the root xylem.
Q.71. Why is transpiration important for plants?
Ans: Transpiration is important because
(a) it helps in absorption and upward movement of water and minerals from roots to leaves
(b) it prevents the plant parts from heating up.
Q.72. How do leaves of plants help in excretion?
Q.73. Explain the process of nutrition in Amoeba.
Ans: Amoeba shows holozoic nutrition which Is comprised of the following steps: Ingestion, Digestion, Absorption. Assimilation and Egestion.
Q.74. Describe the alimentary canal of man.
Ans: Alimentary canal in man is 9 meters long and consists of the following parts:
Q.75. Explain the process of breathing in man.
Ans: Breathing involves two step, namely. inhalation and exhalation.
Q.76. Explain the importance of soil for plant growth.
Ans: Importance of soil for plant growth:
Q.77. Draw the diagram of alimentary canal of man and label the following parts.
Mouth, Oesophagus, Stomach, Intestine
Q.78. How do carbohydrates, proteins and fats get digested in human beings?
Q.79. Explain the mechanism of photosynthesis.
Ans: Photosynthesis is a process in which the light energy obtained from the sunlight is used in the manufacture of oxygen and sugar molecules in the presence of carbon dioxide and water. The mechanism of photosynthesis involves two processes; the light reaction that takes place in the thylakoid membrane that leads to the production of NADPH and ATP. Another important reaction involves the light-independent reaction also known by the name ‘Calvin cycle’ that occurs in the stroma of the chloroplasts which is the final step that produces sugar. The NADP and ATP energy-rich molecules play an important role in light-independent reactions to fix the carbon dioxide in order to synthesize glucose molecules.
Q.80. Explain the three pathways of breakdown in living organisms.
Ans: In all organisms, glucose is first converted into pyruvate. Glucose is a 6-carbon molecule, while pyruvate is a 3-carbon molecule. This step is same in all organisms and it happens in the cytoplasm. Further breakdown of pyruvate can happen in any of the following ways:
Q.81. Describe the flow of blood through the heart of human beings.
Ans: Flow of blood through heart:
(a) Deoxygenated blood from different organs comes to the right atrium through the vena cava.
(b) From the right atrium, blood goes to the right ventricle. The tricuspid valve between the right atrium and right ventricle prevents the backflow of blood.
(c) From the right ventricle, blood goes to the lungs through the pulmonary artery. Inside the lungs, carbon dioxide is removed from the blood and oxygen enters the blood.
(d) From the lungs, blood goes to the left atrium through the pulmonary vein.
(e) From the left atrium, blood goes to the left ventricle.
(f) From the left ventricle, blood is pumped into the aorta so that it can be supplied to different organs.
Q.82. Describe the process of urine formation in kidneys.
Ans: Urine is formed in the kidneys in the nephron , i.e., the structural and functional unit of kidney. Blood at high pressure travels into these tubules by the tuft of blood capillaries called glomerulus.
The following steps are involved in the process:
(i) Filtration Blood enters the glomerulus through the afferent arterioles, it passes under pressure that results in filtration of blood . Water and small molecules are forced out of glomerular capillary walls and Bowman's capsule. Large molecules remain in the blood of the glomerulus.
(ii) Selective reabsorption Some molecules are selectively reabsorbed into the blood. The glomerular filtrate flows through the proximal convoluted tubule, the U- shaped Henle's loop and distal convoluted tubule. The useful substances present such as glucose , amino acids and salts are reabsorbed by a process , which requires energy . The filtrate now contains urea, some salts and The water is then resbsorbed into blood by osmosis (osmoregulation).
(iii) Tubular secretion Some nitrogenous waste products like creatinine and some other substances like K+ are removed from blood by DCT (Distal convulated tubule), and are added to urine. The urine formed is collection in the urinary bladder.