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Life Processes Class 10 Extra Questions and Answers provides important exam-oriented questions from the Class 10 Science chapter Life Processes. These questions cover key topics such as nutrition, respiration, transportation, and excretion in plants and animals. The answers are written in simple and easy-to-understand language to help students revise concepts, practise important questions, and prepare effectively for CBSE board exams.
Life Processes Class 10 Extra Questions and Answers
Important Questions
Q. What are life processes? Name any four.
Answer: Life processes are the basic functions in living organisms that keep them alive. Examples: nutrition, respiration, transportation, and excretion.
Q. Why are molecular movements necessary for life?
Answer: Molecular movements repair and maintain the organised structure of living organisms. Without them, the body would break down and die.
Q. Define respiration. Why is it important for living organisms?
Answer: Respiration is the process of breaking down food to release energy. It is important because energy is needed for growth, repair, and all life activities.
Q. Why is excretion necessary in living beings?
Answer: Excretion removes harmful waste products like carbon dioxide and nitrogenous wastes. If not removed, these wastes can damage cells.
Q. What is nutrition? Why is it essential for living organisms?
Answer: Nutrition is the process of taking in food and using it for energy, growth, and repair. It is essential because organisms need energy and raw materials to survive.
Q. Define autotrophic and heterotrophic nutrition with examples.
Answer:
- Autotrophic nutrition: Organisms make their own food using simple substances. Example: green plants (photosynthesis).
- Heterotrophic nutrition: Organisms depend on others for food. Example: animals, fungi.
Q. Write the overall equation of photosynthesis.
Answer:
- 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
- (Carbon dioxide + Water → Glucose + Oxygen)
Q. What are the raw materials required for photosynthesis?
Answer: The raw materials are carbon dioxide, water, sunlight, and chlorophyll.
Q. Explain the role of stomata in photosynthesis.
Answer: Stomata are tiny pores on leaves. They allow carbon dioxide to enter and oxygen to exit during photosynthesis. They also help in transpiration.
Q. Describe the structure of the human alimentary canal with labelled parts.
Answer: The alimentary canal is a long tube from mouth to anus. It includes mouth, oesophagus, stomach, small intestine, large intestine, rectum, and anus. Each part is specialised for digestion and absorption.
Q. Explain the role of saliva in digestion of food.
Answer: Saliva contains salivary amylase enzyme which breaks down starch into sugar. It also moistens food for easy swallowing.
Q. Name the secretions of gastric glands and state their functions.
Answer: Gastric glands secrete:
- Hydrochloric acid – creates acidic medium, kills germs.
- Pepsin enzyme – digests proteins.
- Mucus – protects stomach lining.
Q. What is the role of villi in the small intestine?
Answer: Villi are finger‑like projections that increase surface area for absorption. They absorb digested food into blood vessels.
Q. Define respiration. Differentiate between aerobic and anaerobic respiration.
Answer: Respiration is the breakdown of food to release energy.
- Aerobic respiration: Uses oxygen, produces CO₂ and water, releases more energy.
- Anaerobic respiration: No oxygen, produces alcohol or lactic acid, releases less energy.
Q. Write the equation for breakdown of glucose in aerobic respiration.
Answer:
- C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy
Q. What is ATP? Why is it called the energy currency of the cell?
Answer: ATP (Adenosine Triphosphate) is a molecule that stores energy. It is called the energy currency because it provides energy for all cell activities.
Q. Explain the role of alveoli in human respiration.
Answer: Alveoli are tiny balloon‑like structures in lungs. They provide a large surface area for exchange of oxygen and carbon dioxide with blood.
Q. What is the function of haemoglobin in respiration?
Answer: Haemoglobin is a pigment in red blood cells. It carries oxygen from lungs to tissues and helps in transport of carbon dioxide.
Q. Describe the structure and function of the human heart with a labelled diagram.
Answer: The heart is a muscular organ with four chambers – two atria and two ventricles. It pumps oxygenated blood to the body and deoxygenated blood to the lungs. Valves prevent backflow of blood.
Q. What is double circulation? Why is it important in humans?
Answer: Double circulation means blood passes through the heart twice in one cycle – once for oxygenation, once for supply to body. It is important to keep oxygenated and deoxygenated blood separate.
Q. Define blood pressure. What are normal systolic and diastolic values?
Answer: Blood pressure is the force of blood against artery walls. Normal values: 120 mm Hg systolic / 80 mm Hg diastolic.
Q. Differentiate between arteries, veins, and capillaries.
Answer:
- Arteries: Thick walls, carry blood away from heart under high pressure.
- Veins: Thin walls, valves present, carry blood to heart.
- Capillaries: One‑cell thick walls, exchange of materials with tissues.
Q. What is the role of platelets in blood?
Answer: Platelets help in clotting of blood at injury sites to prevent blood loss.
Q. Define lymph. State its functions.
Answer: Lymph is a colourless fluid. Functions:
- Carries fats from intestine.
- Drains excess fluid from tissues back to blood.
Q. Name the two main components of the transport system in plants.
Answer: The two components are xylem (water and minerals) and phloem (food).
Q. Define transpiration. State its role in plants.
Answer: Transpiration is the loss of water vapour from leaves through stomata. It helps in upward movement of water and minerals and in cooling the plant.
Q. What is translocation? Which tissue is responsible for it?
Answer: Translocation is the transport of food (like sucrose) from leaves to other parts of the plant. It is done by phloem tissue.
Reason‑Based Questions
Q. Why is visible movement not a reliable characteristic of life?
Answer: Some living beings like plants may not show visible movement, and some animals breathe without visible movement. Life depends on molecular movements inside cells, not just visible ones.
Q. Why do multicellular organisms need a transportation system?
Answer: In multicellular organisms, all cells are not in direct contact with the environment. A transportation system is needed to carry food, oxygen, and wastes to and from every cell.
Q. Why is diffusion alone not enough for multicellular organisms?
Answer: Diffusion is too slow for large bodies. It cannot meet the needs of all cells. So multicellular organisms need specialised tissues and transport systems.
Q. Why is chlorophyll essential for photosynthesis?
Answer: Chlorophyll absorbs light energy from the sun and helps convert it into chemical energy. Without chlorophyll, photosynthesis cannot take place.
Q. Why do desert plants take in carbon dioxide at night?
Answer: Desert plants keep stomata closed during the day to prevent water loss. They take in carbon dioxide at night and store it, then use it during the day for photosynthesis.
Q. Why do herbivores have a longer small intestine than carnivores?
Answer: Herbivores eat grass which contains cellulose. Cellulose takes longer to digest, so herbivores need a longer small intestine. Carnivores eat meat which is easier to digest, so their intestine is shorter.
Q. Why is bile juice important for digestion of fats?
Answer: Bile juice breaks large fat globules into small ones (emulsification). This increases the efficiency of enzymes like lipase to digest fats.
Q. Why does lime water turn milky when we exhale into it?
Answer: Exhaled air contains carbon dioxide. Carbon dioxide reacts with lime water to form calcium carbonate, which makes it milky.
Q. Why do muscle cells form lactic acid during sudden activity?
Answer: During sudden activity, oxygen supply is less. In absence of oxygen, pyruvate is converted into lactic acid. This causes cramps in muscles.
Q. Why do fishes breathe faster than terrestrial animals?
Answer: Oxygen dissolved in water is less than oxygen in air. To get enough oxygen, fishes breathe faster through their gills.
Q. Why are rings of cartilage present in the human windpipe?
Answer: Rings of cartilage keep the windpipe open and prevent it from collapsing, so air can pass freely to the lungs.
Q. Why do ventricles have thicker muscular walls than atria?
Answer: Ventricles pump blood to lungs and the whole body. They need more force, so their walls are thicker than atria.
Q. Why is separation of oxygenated and deoxygenated blood useful in mammals and birds?
Answer: It ensures a high supply of oxygen to the body. This is important for animals like mammals and birds which need more energy to maintain body temperature.
Q. Why is transpiration called a “pull” mechanism?
Answer: Evaporation of water from leaves creates suction. This pulls water upward from roots through xylem. That’s why it is called a transpiration pull.
Q. Why is energy required for translocation in phloem but not for transport in xylem?
Answer:
- Xylem transport depends on physical forces like root pressure and transpiration pull, so no energy is needed.
- Phloem transport moves food using ATP energy, so energy is required.
Application‑Based Questions
Q. Explain how respiration provides energy for life processes.
Answer: Respiration breaks down food molecules like glucose. This releases energy in the form of ATP, which is used for growth, repair, and all life activities.
Q. Why is excretion important for maintaining life?
Answer: Excretion removes harmful wastes like carbon dioxide and urea. If not removed, these wastes can damage cells and disturb body functions.
Q. How can you experimentally prove that sunlight is necessary for photosynthesis?
Answer: Keep a plant in dark for three days. Then cover part of a leaf with black paper and place the plant in sunlight. Test the leaf with iodine. Only the uncovered part turns blue‑black, showing sunlight is necessary.
Q. How does potassium hydroxide help in proving that carbon dioxide is essential for photosynthesis?
Answer: Potassium hydroxide absorbs carbon dioxide. In an experiment, the plant kept with potassium hydroxide does not form starch, proving CO₂ is essential for photosynthesis.
Q. Explain how Amoeba obtains its food.
Answer: Amoeba uses finger‑like extensions called pseudopodia to surround food. A food vacuole is formed where enzymes digest food, and nutrients diffuse into the cytoplasm.
Q. How does Paramoecium take in food?
Answer: Paramoecium has cilia that move food particles to a specific spot. Food enters there and forms a food vacuole for digestion.
Q. How does the iodine test prove the action of saliva on starch?
Answer: If starch solution is mixed with saliva and tested with iodine, it does not turn blue‑black. This shows saliva breaks starch into sugar.
Q. Explain how bile salts increase the efficiency of fat digestion.
Answer: Bile salts break large fat globules into small ones (emulsification). This makes it easier for enzymes like lipase to act on fats.
Q. How does the pancreas help in digestion of proteins and fats?
Answer: The pancreas secretes pancreatic juice containing enzymes. Trypsin digests proteins, and lipase digests emulsified fats.
Q. How can you experimentally prove that exhaled air contains more carbon dioxide than inhaled air?
Answer: Pass normal air and exhaled air into lime water. Lime water turns milky faster with exhaled air, showing it has more carbon dioxide.
Q. How does the structure of alveoli make gas exchange efficient?
Answer: Alveoli are balloon‑like and very thin‑walled. They have a large surface area and are richly supplied with blood vessels, making gas exchange efficient.
Q. Explain how breathing movements (rib lifting and diaphragm flattening) help in inhalation.
Answer: When ribs lift and diaphragm flattens, the chest cavity becomes larger. This reduces pressure and air is sucked into the lungs.
Q. How does haemoglobin help in transport of oxygen?
Answer: Haemoglobin in red blood cells binds oxygen in the lungs and carries it to tissues. It also helps in carrying carbon dioxide back.
Q. Explain how valves in veins ensure one‑way flow of blood.
Answer: Valves in veins prevent blood from flowing backward. They ensure blood moves only towards the heart.
Q. Why do mammals and birds require double circulation but amphibians can manage with three chambers?
Answer: Mammals and birds need more oxygen for high energy and body temperature. Double circulation keeps oxygenated and deoxygenated blood separate. Amphibians have lower energy needs, so three chambers are enough.
Q. How does lymph help in absorption of fats from the intestine?
Answer: Lymph carries digested fats from the intestine to blood. It also drains excess fluid from tissues back into blood.
Q. How can you experimentally show that transpiration occurs in plants?
Answer: Cover a plant and a stick with plastic sheets in sunlight. Water droplets appear only on the sheet covering the plant, proving transpiration.
Q. Explain how sucrose is transported in phloem using ATP.
Answer: Sucrose is loaded into phloem using ATP energy. This increases osmotic pressure, water enters, and pressure moves sucrose to tissues where it is needed.
Case‑Based Questions
Q. Case Study: A student observed a dog running, a cow chewing cud, and a man shouting. Later, he saw them asleep but still considered them alive.
- Identify the property being observed.
- Explain how we know they are alive even without visible movement.
- What does this show about defining life?
Answer: The property being observed is movement and breathing, which are signs of life. Even when they are asleep, they are alive because molecular movements inside their cells continue and life processes like respiration go on. This shows that visible movement alone cannot define life; continuous life processes are the true criteria of being alive.
Q. Case Study: A student studied plants with green leaves and some with red leaves. He wondered how to know if both are alive.
- How can we confirm that plants are alive?
- Is leaf colour a reliable sign of life?
- What other evidence proves plants are living?
Answer: Plants can be confirmed alive because they grow, respire, and carry out photosynthesis. Leaf colour is not a reliable sign of life because some plants have red, yellow, or variegated leaves but are still living. Other evidence such as growth, respiration, reproduction, and molecular activities proves that plants are living organisms.
Q. Case Study: In an experiment, iron nails were placed in three test tubes: A (air + water), B (boiled water + oil), C (dry air + CaCl₂). Rusting occurred only in tube A.
- In which tube did rusting occur?
- What conditions are necessary for rusting?
- Suggest two methods to prevent rusting.
Answer: Rusting occurred only in tube A containing air and water. The necessary conditions for rusting are the presence of both oxygen and moisture. Rusting can be prevented by methods like painting, greasing, or galvanisation of iron objects.
Q. Case Study: A student kept a variegated leaf plant in the dark for three days, then exposed it to sunlight for six hours. After iodine test, only green parts of the leaf turned blue‑black.
- What does this experiment prove?
- Why were the non‑green parts not stained blue‑black?
- Which pigment is essential for photosynthesis?
Answer: This experiment proves that photosynthesis occurs only in the green parts of the leaf. The non‑green parts were not stained blue‑black because they do not contain chlorophyll and hence cannot make starch. The pigment essential for photosynthesis is chlorophyll.
Q. Case Study: Two potted plants were kept under bell‑jars. One jar had potassium hydroxide placed inside, the other did not. After two hours in sunlight, starch test was performed.
- Which plant showed starch formation?
- What does this experiment prove?
- Why was potassium hydroxide used?
Answer: Starch formation was seen only in the plant without potassium hydroxide. This proves that carbon dioxide is necessary for photosynthesis. Potassium hydroxide was used because it absorbs carbon dioxide from the air.
Q. Case Study: A student observed a cow eating grass and a lion eating flesh.
- Identify the mode of nutrition in both animals.
- How does the food source affect their nutritive apparatus?
- Why is the lion dependent on autotrophs indirectly?
Answer: The cow shows herbivorous mode of nutrition, while the lion shows carnivorous mode of nutrition. The food source affects their digestive system: cows have a longer small intestine for cellulose digestion, while lions have a shorter intestine for meat digestion. The lion is indirectly dependent on autotrophs because it eats herbivores, which in turn depend on plants.
Q. Case Study: A student performed an experiment with starch solution in two test tubes. Saliva was added to one tube, both were left for 20 minutes, and iodine was added.
- In which tube did starch disappear?
- What does this prove about the action of saliva?
- Which enzyme is responsible for this reaction?
Answer: Starch disappeared in the tube containing saliva. This proves that saliva breaks down starch into sugar. The enzyme responsible for this reaction is salivary amylase.
Q. Case Study: A patient suffers from indigestion due to lack of hydrochloric acid in the stomach.
- How will this affect protein digestion?
- What other function of hydrochloric acid will be disturbed?
- Why is mucus important in this condition?
Answer: Protein digestion will be affected because pepsin enzyme requires an acidic medium to act. Another function of hydrochloric acid, killing germs in food, will also be disturbed. Mucus is important because it protects the stomach lining from the action of acid.
Q. Case Study: A farmer observed that cows have a longer small intestine than tigers.
- Why do herbivores need a longer small intestine?
- Why is cellulose digestion more difficult than meat digestion?
- What does this show about adaptation in animals?
Answer: Herbivores need a longer small intestine because cellulose in grass takes longer to digest. Cellulose digestion is more difficult than meat digestion because special enzymes are needed to break cellulose. This shows that animals are adapted to their food habits.
Q. Case Study: A student performed an experiment by blowing air into lime water and also passing normal air into lime water. The lime water turned milky faster when exhaled air was used.
- What does this prove about exhaled air?
- Which gas is responsible for this change?
- Why does inhaled air not show the same effect?
Answer: This proves that exhaled air contains more carbon dioxide than inhaled air. The gas responsible for turning lime water milky is carbon dioxide. Inhaled air does not show the same effect because it has less carbon dioxide.
Q. Case Study: A runner experienced cramps in his legs after a race.
- What caused the cramps?
- Which compound was formed in the muscles?
- How can the cramps be relieved?
Answer: The cramps were caused by lack of oxygen in muscles. The compound formed in muscles is lactic acid. The cramps can be relieved by rest or massage, which increases oxygen supply to muscles.
Q. Case Study: A student observed fish in an aquarium opening and closing their mouths and gill‑slits rapidly.
- Why do fishes breathe faster than humans?
- What is the role of gills in respiration?
- How is oxygen taken up by blood in fishes?
Answer: Fishes breathe faster than humans because oxygen dissolved in water is less than oxygen in air. The role of gills is to absorb dissolved oxygen from water and remove carbon dioxide. Oxygen is taken up by blood in fishes through blood vessels present in the gills.
Q. Case Study: A patient was found to have blood pressure of 160/100 mm Hg.
- What is the normal blood pressure?
- What condition does the patient suffer from?
- Why is this condition dangerous?
Answer: The normal blood pressure is 120/80 mm Hg. The patient suffers from hypertension (high blood pressure). This condition is dangerous because it can rupture arteries, cause internal bleeding, and damage vital organs.
Q. Case Study: A student observed that when injured, bleeding stopped after some time due to clot formation.
- Which cells are responsible for clotting?
- Why is clotting important?
- What would happen if clotting did not occur?
Answer: The cells responsible for clotting are platelets. Clotting is important because it prevents excessive blood loss and protects the body. If clotting did not occur, the person would bleed continuously and may die.
Q. Case Study: A veterinary doctor measured haemoglobin levels in cows and buffaloes.
- How does haemoglobin content differ in male and female animals?
- Compare this with haemoglobin levels in humans.
- Why is haemoglobin important for oxygen transport?
Answer: Haemoglobin content differs in male and female animals, just as it differs in men and women. In humans, men generally have slightly higher haemoglobin levels than women. Haemoglobin is important because it carries oxygen from lungs to tissues and helps in respiration.
Q. Case Study: A student covered two pots, one with a plant and another with a stick, using plastic sheets. After half an hour in sunlight, water droplets were seen only in the pot with the plant.
- What process caused the droplets?
- Which plant tissue is involved in this process?
- What is the importance of this process for plants?
Answer: The droplets were caused by transpiration. The plant tissue involved is xylem, which carries water. Transpiration is important because it helps in upward movement of water and minerals and regulates temperature in plants.
Q. Case Study: In spring, sugar stored in roots is transported to buds.
- Which tissue is responsible for this transport?
- Why do buds need sugar at this time?
- How is this transport achieved in plants?
Answer: The tissue responsible is phloem. Buds need sugar at this time for growth and development. This transport is achieved by translocation using ATP energy in phloem sieve tubes and companion cells.
Competency‑Based Questions
Q. Explain how nutrition, respiration, transportation, and excretion together maintain life.
Answer: Nutrition provides food and raw materials to the body. Respiration breaks down food to release energy. Transportation carries food, oxygen, and wastes to and from cells. Excretion removes harmful waste products. Together these processes maintain life by supplying energy, materials, and removing wastes.
Q. Why do multicellular organisms develop specialised tissues for life processes?
Answer: In multicellular organisms, all cells are not in direct contact with the environment. Specialised tissues are needed to perform functions like nutrition, respiration, transportation, and excretion efficiently. This ensures that every cell gets food and oxygen and wastes are removed properly.
Q. Explain how different organs of the alimentary canal work together to complete digestion.
Answer: The mouth chews food and saliva digests starch. The oesophagus pushes food to the stomach. The stomach digests proteins with pepsin in acidic medium. The small intestine digests carbohydrates, proteins, and fats with help of bile and pancreatic juices. Villi in the small intestine absorb digested food. The large intestine absorbs water and removes waste. Thus, all organs work together to complete digestion.
Q. How do gastric glands, liver, and pancreas coordinate in digestion of food?
Answer: Gastric glands in the stomach secrete hydrochloric acid, pepsin, and mucus for protein digestion. The liver produces bile which emulsifies fats and makes food alkaline. The pancreas secretes enzymes like trypsin for proteins and lipase for fats. Together they help in complete digestion of food in the small intestine.
Q. Describe the process of absorption of digested food in the small intestine.
Answer: The inner lining of the small intestine has finger‑like projections called villi. Villi increase surface area for absorption. They are richly supplied with blood vessels which absorb glucose, amino acids, fatty acids, and glycerol. The absorbed food is carried by blood to all cells of the body.
Q. Explain the breakdown of glucose into pyruvate and its further pathways in aerobic, anaerobic, and muscle respiration.
Answer: Glucose (6‑carbon) breaks down into pyruvate (3‑carbon) in cytoplasm.
- In aerobic respiration (with oxygen), pyruvate breaks into carbon dioxide and water in mitochondria, releasing more energy.
- In anaerobic respiration (without oxygen, e.g. yeast), pyruvate converts into ethanol and carbon dioxide.
- In muscle cells (lack of oxygen), pyruvate converts into lactic acid, causing cramps.
Q. How does ATP act like a battery in the cell? Give examples of processes where ATP is used.
Answer: ATP stores energy released during respiration. When broken, it releases energy for cell activities. It acts like a battery because it can be used for many processes such as muscle contraction, protein synthesis, and conduction of nerve impulses.
Q. Describe the structure and function of alveoli in human lungs.
Answer: Alveoli are tiny balloon‑like structures at the end of lung passages. They have thin walls and a large surface area. They are surrounded by blood vessels. Oxygen from air diffuses into blood and carbon dioxide diffuses out. Thus, alveoli make gas exchange efficient.
Q. How does haemoglobin help in transport of oxygen to tissues?
Answer: Haemoglobin is a red pigment present in red blood cells. It has a high affinity for oxygen. It binds oxygen in the lungs and carries it to tissues. It also helps in carrying carbon dioxide back to the lungs.
Q. Explain the step‑by‑step flow of blood through the human heart during double circulation.
Answer: Deoxygenated blood from the body enters the right atrium, then moves to the right ventricle. The right ventricle pumps it to the lungs for oxygenation. Oxygenated blood from lungs enters the left atrium, then moves to the left ventricle. The left ventricle pumps it to the whole body. Thus, blood passes twice through the heart in one cycle, called double circulation.
Q. How do arteries, veins, and capillaries together ensure efficient transport of materials?
Answer: Arteries carry blood away from the heart under high pressure. Veins bring blood back to the heart with valves to prevent backflow. Capillaries are thin‑walled and allow exchange of materials between blood and tissues. Together they ensure efficient transport of oxygen, food, and wastes.
Q. Explain how transpiration pull and root pressure together help in upward movement of water.
Answer: Root pressure pushes water upward from roots into xylem. Transpiration causes evaporation of water from leaves, creating suction that pulls water upward. Together, root pressure and transpiration pull move water and minerals to the highest parts of the plant.
Q. Describe the mechanism of translocation in phloem with reference to osmotic pressure.
Answer: Food like sucrose is loaded into phloem using ATP. This increases osmotic pressure, causing water to enter phloem. The pressure moves food to tissues with lower pressure. Thus, phloem transports food to storage organs and growing parts according to plant needs.
HOTS Question
Q. Viruses do not show molecular movements until they infect a cell. Analyse why there is a controversy about whether viruses are truly alive or not.
Answer: Living organisms show continuous molecular movements to maintain life. Viruses do not show such movements outside a host cell. They only become active and multiply after infecting a living cell. This is why there is a controversy — some scientists consider them non‑living outside a host, while others consider them living because they reproduce inside a host.
Q. Viruses do not have their own nutrition. Analyse why this makes them dependent on host cells and discuss whether this supports or challenges their classification as living organisms.
Answer: Viruses cannot prepare or obtain food on their own. They depend completely on host cells for nutrition and energy. This supports the idea that they are not fully living organisms because independent nutrition is a basic life process. However, since they reproduce inside host cells, they also show a living characteristic. This dual nature challenges their classification as strictly living or non‑living.
Q. Dental caries is caused by bacteria acting on sugars to produce acids. Analyse how saliva and brushing teeth prevent tooth decay.
Answer: Bacteria in the mouth act on sugars and produce acids that damage tooth enamel, causing dental caries. Saliva helps neutralise acids and protect teeth. Brushing removes food particles and plaque, preventing bacteria from producing acids. Thus, saliva and brushing together prevent tooth decay.
Q. If diffusion alone were responsible for oxygen transport in humans, it would take years for oxygen to reach the toes. Analyse how haemoglobin solves this problem and makes respiration efficient.
Answer: Diffusion is too slow to carry oxygen to all parts of the human body. Haemoglobin in red blood cells binds oxygen in the lungs and quickly transports it to tissues. This makes oxygen transport fast and efficient, ensuring that all cells get oxygen in time for respiration.
Q. Analyse why birds and mammals with high energy needs require complete separation of oxygenated and deoxygenated blood, while fishes can survive with single circulation.
Answer: Birds and mammals need large amounts of energy to maintain constant body temperature. Complete separation of oxygenated and deoxygenated blood ensures a high supply of oxygen to tissues. Fishes have lower energy needs and their body temperature depends on the environment, so single circulation is sufficient for them.
Q. Analyse why tall trees like eucalyptus or pine cannot rely on diffusion alone for transport of water and minerals. How does the plant overcome this limitation?
Answer: In tall trees, the distance between roots and leaves is very large. Diffusion alone cannot move water and minerals over such long distances. Plants overcome this limitation by using xylem tissue and processes like root pressure and transpiration pull, which transport water and minerals efficiently to the highest parts of the plant.
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