Life Processes · Class 10 Science: 216 MCQs with answers

Q1. Fats are finally broken into:

Q2. Why is nutrition necessary for an organism even when it is not growing?

Q3. Write the equation of photosynthesis and name the three events involved.

Q4. How do guard cells regulate the opening and closing of stomata?

Q5. Distinguish between saprophytic and parasitic nutrition with one example each.

Q6. Describe nutrition in Amoeba.

Q7. What part does saliva play in digesting food?

Q8. Distinguish between breathing and respiration.

Q9. Why do we get muscle cramps after sudden vigorous exercise, and how does a massage help?

Q10. What is ATP and why is it called the energy currency?

Q11. How are oxygen and carbon dioxide transported in human blood?

Q12. Why do terrestrial organisms have an advantage over aquatic ones in obtaining oxygen?

Q13. List the components of blood and state one function of each.

Q14. Differentiate between arteries and veins (any three points).

Q15. Describe double circulation in human beings. Why is it called 'double'?

Q16. What is lymph? State its two functions.

Q17. What are the functions of platelets, and what would happen without them?

Q18. What is blood pressure? Name the instrument that measures it and the danger of persistently high readings.

Q19. The energy currency point of photosynthesis's water-splitting step is that water yields:

Q20. Desert plants take in CO₂ at night because:

Q21. Nitrogen for plant proteins comes from:

Q22. Mushrooms and yeast share which feeding style?

Q23. Paramoecium moves food to its mouth-spot using:

Q24. Chewing a rice morsel long makes it sweet because:

Q25. Pepsin works best in a medium that is:

Q26. The sphincter muscle at the stomach's exit:

Q27. Emulsification of fats means:

Q28. Pancreatic juice contains which enzyme pair (among others)?

Q29. Why does the food entering the intestine need to become alkaline?

Q30. What are the functions of HCl, pepsin and mucus in the stomach?

Q31. State the two functions of bile juice. Does bile digest anything itself?

Q32. How is the small intestine designed to absorb digested food?

Q33. Why do herbivores have longer small intestines than carnivores?

Q34. Which pathway yields the MOST energy per glucose?

Q35. Pyruvate carries how many carbon atoms?

Q36. The total alveolar surface in humans is about:

Q37. Residual volume ensures:

Q38. Fermentation by yeast happens in the:

Q39. Which sequence is correct for air flow?

Q40. In plants at night, the dominant gas released is:

Q41. Amoeba exchanges gases through:

Q42. Alcohol production industries essentially harness:

Q43. Describe the three pathways by which pyruvate is further broken down.

Q44. How are the lungs designed to maximise gas exchange?

Q45. Explain the mechanism of breathing in humans.

Q46. Describe how respiration occurs in plants.

Q47. Why is diffusion alone insufficient to meet the oxygen requirements of large multicellular organisms like humans?

Q48. Blood passes through the human heart per complete circuit:

Q49. Separation of oxygenated and deoxygenated blood mainly serves:

Q50. Three-chambered hearts are typical of:

Q51. Lymph carries which nutrient class from the intestine?

Q52. The energy for loading sucrose into phloem comes from:

Q53. Water rises in tall trees mainly due to:

Q54. At night, water movement in plants relies mostly on:

Q55. Phloem sap moves:

Q56. Hypertension results from:

Q57. Which sequence for oxygenated blood is correct?

Q58. Selective advantage of 4 chambers over 3 is:

Q59. Why is the separation of oxygenated and deoxygenated blood necessary in birds and mammals?

Q60. How does water move upward in tall plants?

Q61. What is translocation in plants and why does it need energy?

Q62. Compare transport in xylem and phloem.

Q63. In dialysis, urea leaves the blood by:

Q64. The dialysing fluid contains glucose and salts at blood-normal levels so that:

Q65. A key process the artificial kidney LACKS versus a real one:

Q66. Some plant wastes are secreted into the:

Q67. Why can plants manage without kidneys?

Q68. Consider these statements about life processes. I. Nutrition, respiration, transportation and excretion are all life processes. II. They go on even when an organism is asleep and doing nothing visible. III. Their purpose is to maintain and repair the body. IV. Movement is the surest single proof that something is alive. Which statements are correct?

Q69. Which is the correct explanation of why every food chain must begin with an autotroph?

Q70. A leaf with green and white patches is tested for starch with iodine. Blue-black appears only on the parts that were green. This shows that:

Q71. Consider these statements about the events of photosynthesis. I. Chlorophyll absorbs light energy. II. Light energy splits water into hydrogen and oxygen. III. Carbon dioxide is reduced to carbohydrate. IV. All three steps must happen at the same time in the same place. Which statements are correct?

Q72. In photosynthesis the oxygen that is released comes from:

Q73. Which statement best explains why stomata close when the plant is short of water?

Q74. A plant is kept in a bell jar with a dish of potassium hydroxide and left in sunlight. Its leaves test negative for starch. This is because the potassium hydroxide has:

Q75. Consider these three ways of feeding. I. A mushroom breaks down dead matter outside its body and absorbs the products. II. A tapeworm takes ready-made food from the body of a living host. III. A cow takes solid food into its body and digests it inside. These three are respectively:

Q76. Assertion (A): Cuscuta is classed as a parasite even though it is a plant. Reason (R): It has no chlorophyll of its own and draws its food from the host plant it twines around.

Q77. Which sequence correctly describes how an Amoeba feeds?

Q78. Chewing a piece of plain bread for a minute makes it taste slightly sweet. The reason is that:

Q79. Which of these best explains why a person can swallow food while lying down or even standing on their head?

Q80. Consider these statements about gastric juice. I. It contains hydrochloric acid. II. The acid kills germs swallowed with the food. III. The acid provides the medium in which pepsin works. IV. The acid digests starch. Which statements are correct?

Q81. What is the best explanation of why the stomach is not digested by its own pepsin and acid?

Q82. Bile contains no digestive enzymes, yet fat digestion fails without it. Bile does TWO things — it:

Q83. Which is the correct explanation of why the small intestine is the longest part of the alimentary canal?

Q84. Which statement correctly distinguishes EGESTION from EXCRETION?

Q85. The villi of the small intestine and the alveoli of the lungs are built on the same principle. That principle is:

Q86. Carbohydrates, proteins and fats are finally broken down respectively into:

Q87. Which statement best explains why a leaf is boiled in alcohol before the iodine test for starch?

Q88. Consider these statements about the raw materials of photosynthesis. I. Carbon dioxide enters the leaf through the stomata. II. Water and minerals are absorbed by the roots. III. Nitrogen is taken up as nitrates and nitrites from the soil. IV. Plants absorb nitrogen gas directly from the air through their leaves. Which statements are correct?

Q89. Which of these best explains why a herbivore such as a cow has a much longer small intestine than a tiger?

Q90. What is the best explanation of why the sphincter muscle at the exit of the stomach releases food into the intestine a little at a time?

Q91. Herbivores have longer small intestines than carnivores because:

Q92. Assertion (A): Pepsin works in the stomach and pancreatic enzymes work in the small intestine, and neither would work in the other's place. Reason (R): Pepsin needs an alkaline medium while the pancreatic enzymes need an acidic one.

Q93. Assertion: Bile is essential for fat digestion. Reason: Bile contains lipase that digests fat.

Q94. A patient's gall bladder is removed; the digestion most affected is of:

Q95. In the leaf-starch experiment, the leaf is boiled in alcohol first to:

Q96. Explain autotrophic nutrition in detail: the equation, the three events of photosynthesis, the roles of chlorophyll and stomata, how desert plants differ, and the experiments proving chlorophyll and CO₂ are essential.

Q97. Describe human digestion organ by organ — mouth, oesophagus, stomach, small intestine, large intestine — naming every secretion, enzyme and product, and explain the roles of the liver and pancreas.

Q98. Compare the nutrition of a fungus (bread mould), a parasite (cuscuta), Amoeba and a human being — classify each mode, describe each mechanism, and state what all four have in common.

Q99. Design and explain the experiment to show that sunlight is necessary for photosynthesis, including destarching, the leaf-covering step, the iodine test procedure and the conclusion. Add why the leaf is boiled in water and then alcohol.

Q100. Which statement correctly distinguishes BREATHING from RESPIRATION?

Q101. Consider these statements about the breakdown of glucose. I. The first step, glucose to pyruvate, happens in the cytoplasm. II. This first step is common to all three respiratory pathways. III. What happens to the pyruvate afterwards depends on whether oxygen is available. IV. The first step requires oxygen. Which statements are correct?

Q102. Pyruvate has three carbon atoms and glucose has six. This tells us that in the first step of respiration one molecule of glucose gives:

Q103. Assertion (A): The mitochondrion is called the powerhouse of the cell. Reason (R): A mitochondrion has a folded inner membrane and carries its own DNA.

Q104. Three pathways break down pyruvate: aerobically in our cells, anaerobically in yeast, and in oxygen-starved muscle. Their products are respectively:

Q105. Which is the correct explanation of why bread dough rises when yeast is added?

Q106. A student sprints suddenly and gets a cramp in the leg. Which statement explains this and the remedy?

Q107. Which statement best explains why the energy from food is stored as ATP rather than used directly?

Q108. Consider these features of the human air passage. I. Hair and mucus in the nostrils trap dust. II. Rings of cartilage keep the trachea from collapsing. III. The passage branches into finer and finer tubes ending in alveoli. IV. Air is warmed and moistened on the way. Which statements are correct?

Q109. Which of these best explains why the trachea is reinforced with rings of cartilage?

Q110. The alveoli of the lungs together present a surface of about 80 square metres, roughly the floor of a small flat. This large area is needed because:

Q111. Which sequence correctly describes what happens during INHALATION?

Q112. Assertion (A): Carbon dioxide is carried by haemoglobin while oxygen travels mostly dissolved in the plasma. Reason (R): Carbon dioxide is far more soluble in water than oxygen is, so it needs no carrier molecule.

Q113. A closed room with a burning coal stove can kill the people sleeping in it. The chief reason is that:

Q114. What is the best explanation of why fish must pass a much larger volume of water over their gills than we pass air over our lungs?

Q115. Consider these statements about gas exchange in plants. I. Leaves exchange gases through stomata. II. Roots take in oxygen from air spaces between soil particles. III. Each plant part largely looks after its own needs. IV. Plants respire only at night. Which statements are correct?

Q116. Which is the correct explanation of why aerobic respiration releases much more energy from a glucose molecule than fermentation does?

Q117. An athlete continues to pant for some minutes after a race has finished. The best explanation is that:

Q118. Which statement best explains why diffusion alone cannot supply oxygen to the cells of a human being, though it suffices for an Amoeba?

Q119. Which of these best explains why the human respiratory system delivers oxygen in two stages — breathing and then blood transport — rather than one?

Q120. Consider these statements about the human breathing mechanism. I. Air is drawn in because the pressure inside the chest falls below that outside. II. The lungs have no muscle of their own. III. Some air always remains in the lungs after breathing out. IV. That residual air lets gas exchange continue between breaths. Which statements are correct?

Q121. If a cell's mitochondria stopped working altogether, the cell could still obtain a little energy by:

Q122. The common product of ALL three glucose pathways is:

Q123. Assertion: Aquatic animals breathe faster than terrestrial ones. Reason: Water contains less dissolved oxygen than air contains oxygen.

Q124. Assertion: Plants photosynthesise by day, so they do not respire by day. Reason: Respiration and photosynthesis cannot co-occur.

Q125. What is the best explanation of why milk turns to curd and why a sprinter's muscles ache, though the two seem unrelated?

Q126. If mitochondria stopped working, the cell could still produce energy by:

Q127. Mountain climbers at high altitude tire quickly because:

Q128. Yoghurt-making bacteria souring milk relates to which molecule?

Q129. The lime-water test after exhaling into it shows milkiness FASTER than room air because exhaled air:

Q130. Which is the correct explanation of why brewing and baking are described as the same process put to two different ends?

Q131. Draw up the complete picture of glucose breakdown: the common first step, the three alternative fates of pyruvate with sites, products and energy comparison, and one everyday application or consequence of each pathway.

Q132. Describe the human respiratory system: the complete air passage with the protective/structural feature at each stage, the alveolar design for exchange, the mechanics of inhalation-exhalation, and the transport of both gases in blood.

Q133. Compare how gas exchange is achieved in Amoeba, fish, terrestrial mammals and flowering plants, and explain the design principle that unites all four solutions.

Q134. A student sets up: (a) a flask of yeast in sugar solution fitted with a tube dipping into lime water, and (b) a mouse in a ventilated cage beside a potted plant kept in the dark. Predict and explain every observation, and connect each to the respiration concepts involved.

Q135. Consider these statements about the composition of blood. I. Plasma is the fluid part and carries food, carbon dioxide and wastes in solution. II. Red cells carry oxygen using haemoglobin. III. White cells defend against infection. IV. Platelets carry oxygen when the red cells are full. Which statements are correct?

Q136. Which statement best explains why a deep cut stops bleeding on its own after a few minutes?

Q137. Which of these best explains why arteries have thick elastic walls while veins have thinner walls with valves?

Q138. Assertion (A): The pulmonary artery carries deoxygenated blood although it is called an artery. Reason (R): A vessel is named an artery because it carries blood away from the heart, not because of the blood it contains.

Q139. Which sequence correctly traces a drop of blood from the body back to the body again?

Q140. What is the best explanation of why the wall of the left ventricle is the thickest of the four chambers?

Q141. Fish have two-chambered hearts, amphibians three and birds and mammals four. Which statement explains the pattern?

Q142. Consider these statements about double circulation. I. Blood passes through the heart twice in one complete round of the body. II. One circuit goes to the lungs and back, the other to the body and back. III. It keeps oxygenated and deoxygenated blood from mixing. IV. It means the blood is pumped only once per circuit. Which statements are correct?

Q143. Which is the correct explanation of why the exchange of gases and nutrients with the tissues happens in the capillaries rather than in arteries or veins?

Q144. Which statement best explains what LYMPH is and what it does?

Q145. A reading of 120/80 mm Hg is described as normal blood pressure. The two numbers are respectively:

Q146. Which statement best explains why persistently high blood pressure is dangerous even though a person may feel nothing?

Q147. Consider these statements about transport in plants. I. Xylem carries water and minerals upward from the roots. II. Phloem carries food made in the leaves to wherever it is needed. III. Phloem can move material both up and down the plant. IV. Xylem transport requires energy at every step. Which statements are correct?

Q148. Sugar stored in the roots of a tree in winter moves upward to the buds in spring. This proves that:

Q149. Which statement best explains how water reaches the top of a tall tree without any pump?

Q150. Which of these is NOT a function of transpiration?

Q151. A plant wilting in the hot noon sun recovers by evening without being watered. This shows that:

Q152. Drops of water appear at the tips of grass blades on a still morning. This is caused by:

Q153. Which of these best explains why loading sugar into the phloem requires energy from ATP?

Q154. Which pair correctly matches a vessel to the pressure it is built to handle?

Q155. Consider these statements about transpiration. I. It creates the pull that draws water up the xylem. II. It cools the plant on a hot day. III. It helps minerals move up with the water. IV. It supplies the leaf with the carbon dioxide it needs. Which statements are correct?

Q156. Assertion: Veins have valves. Reason: Blood in veins is under low pressure and could flow backward.

Q157. Assertion: The pulmonary artery is still called an artery though it carries CO₂-rich blood. Reason: Arteries are defined by carrying blood away from the heart, not by oxygen content.

Q158. Removing a complete ring of bark (girdling) eventually kills a tree because:

Q159. Morning droplets at grass-blade tips demonstrate:

Q160. A person with a torn heart valve would most directly suffer from:

Q161. In hot noon sun, a wilting plant recovering by evening shows the role of:

Q162. Sugar stored in roots in winter moving upward in spring proves:

Q163. Which pair correctly matches vessel to pressure-handling design?

Q164. Describe the structure and working of the human heart: chambers, valves, the complete path of blood, why chamber walls differ in thickness, and how double circulation serves warm-blooded life.

Q165. Explain the composition of blood and the roles of each component, the three vessel types with their structural adaptations, and the origin and functions of lymph.

Q166. Explain in full how a tall tree gets water to its top leaves and food to its deepest roots: the xylem mechanism (both forces), the phloem mechanism, and the key contrasts between the two transport systems.

Q167. A doctor examines three patients: one with a low platelet count, one with hypertension, and one with a congenital hole between the two ventricles. Explain the specific problem each condition creates, connecting each to the transport concepts of this chapter.

Q168. Consider these statements about excretion in humans. I. Urea is the chief nitrogenous waste. II. It is made in the liver from excess amino acids. III. It is carried by the blood to the kidneys. IV. It is made by the kidneys themselves. Which statements are correct?

Q169. What is the best explanation of why the body converts surplus amino acids into urea rather than storing them?

Q170. Which sequence correctly traces a molecule of urea from where it is made to where it leaves the body?

Q171. Which statement best explains what drives filtration at the glomerulus?

Q172. Assertion (A): About 180 litres of fluid are filtered into the Bowman's capsules each day, yet only one to two litres of urine are passed. Reason (R): Almost all the water, and all the useful substances in the filtrate, are reabsorbed as it travels along the tubule.

Q173. Which substance is present in the glomerular filtrate but normally absent from urine?

Q174. Which is the correct explanation of why each kidney contains about a million nephrons rather than one large filter?

Q175. Consider these statements about selective reabsorption in the tubule. I. Glucose and amino acids are taken back completely. II. Most of the water is taken back. III. How much water is taken back depends on how much the body has to spare. IV. Urea is taken back along with the glucose. Which statements are correct?

Q176. A person sweats heavily on a hot day and drinks little. Their urine will be:

Q177. Which statement best explains why the bladder exists at all, when the kidneys produce urine continuously?

Q178. Glucose appearing in a person's urine report most likely indicates that:

Q179. Besides the kidneys, which two organs also remove wastes from the human body, and what do they remove?

Q180. Consider these statements about how plants deal with their wastes. I. Oxygen and carbon dioxide diffuse out through the stomata. II. Excess water is lost by transpiration. III. Many wastes are stored in cells or in resins and gums. IV. Old leaves carry wastes away when they fall. Which statements are correct?

Q181. Amber, in which ancient insects are sometimes found preserved, is:

Q182. Which of these best explains why autumn leaf-fall serves a plant as a form of excretion?

Q183. Which statement correctly distinguishes excretion from egestion in a human being?

Q184. What is the best explanation of why a person on dialysis must attend the hospital several times a week rather than once a month?

Q185. Assertion (A): A kidney transplant is preferred to long-term dialysis where it is possible. Reason (R): A transplant requires a matched donor and lifelong medicines to prevent rejection.

Q186. Which is the correct explanation of why the kidneys receive a very large share of the blood pumped by the heart?

Q187. Consider these statements about what crosses into the Bowman's capsule. I. Water, glucose, amino acids, salts and urea pass through. II. Blood cells do not pass through. III. Large proteins do not pass through. IV. The filtrate is identical in composition to the blood. Which statements are correct?

Q188. Which statement best explains why the nephron filters everything out first and then takes most of it back, rather than removing only the wastes directly?

Q189. Assertion (A): The amount of water reabsorbed in the kidney tubule is fixed and the same at every hour. Reason (R): The kidney's task is to keep the body's water and salt balance steady, not merely to remove wastes.

Q190. Which of these best explains why a routine urine test can reveal problems in organs other than the kidney?

Q191. Consider these statements comparing excretion in plants and animals. I. A plant's chemistry is slower, so wastes accumulate less quickly. II. A plant can store wastes harmlessly in cells, resins and gums. III. A plant can shed wastes with its leaves and bark. IV. A plant therefore needs no specialised excretory organ. Which statements are correct?

Q192. What is the best explanation of why a person who drinks a large quantity of water passes a large volume of pale urine soon afterwards?

Q193. Which is the correct explanation of why both a healthy kidney and a dialysis machine depend on a semi-permeable membrane?

Q194. The fluid filtered into Bowman's capsule per day is roughly:

Q195. Assertion: Urine of a healthy person is glucose-free. Reason: Glucose is completely reabsorbed in the nephron's tubule.

Q196. Assertion: Dialysis must be repeated every few days. Reason: Unlike kidneys, dialysis machines work only during sessions while urea is produced continuously.

Q197. A patient's damaged glomeruli leak proteins into urine. This shows glomeruli normally:

Q198. Marine fish excrete ammonia directly but land animals make urea because:

Q199. If tubular reabsorption stopped entirely, the immediate result would be:

Q200. Which sequence traces a urea molecule correctly?