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Life Processes — Homi Bhabha Class 9 Biology MCQs with Solutions
Free Homi Bhabha Class 9 Biology Life Processes MCQs with step-by-step solutions covering Nutrition, Respiration, Transportation, Excretion. Practise online on Prepizo — no login needed.
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Sample questions with solutions
Q1 — Nutrition · easy · theory
Which process do green plants use to prepare their own food?
A. Respiration
B. Transpiration
C. Digestion
D. Photosynthesis ✓ Correct
Solution: Green plants are autotrophs. They use photosynthesis to make food (glucose) from carbon dioxide and water in the presence of sunlight and chlorophyll.
Q2 — Nutrition · easy · theory
The two raw materials that a leaf takes in for photosynthesis are:
A. Nitrogen and water
B. Carbon dioxide and water ✓ Correct
C. Oxygen and glucose
D. Carbon dioxide and oxygen
Solution: Photosynthesis uses carbon dioxide (from air, through stomata) and water (from soil, through roots), converting them into glucose and releasing oxygen.
Q3 — Respiration · easy · theory
During heavy exercise, the muscles of humans may respire without enough oxygen. The end product formed is:
A. Lactic acid ✓ Correct
B. Ethanol and carbon dioxide
C. Carbon dioxide and water
D. Only pyruvate
Solution: When oxygen is limited, muscle cells break down pyruvate anaerobically into lactic acid. Its build-up causes muscle cramps and fatigue.
Q4 — Respiration · easy · theory
In which cell organelle does aerobic respiration mainly take place?
A. Nucleus
B. Ribosome
C. Chloroplast
D. Mitochondria ✓ Correct
Solution: Mitochondria are the site of aerobic respiration, where pyruvate is broken down using oxygen to release a large amount of energy. They are called the powerhouse of the cell.
Q5 — Transportation · easy · theory
In humans, the blood vessels that carry blood AWAY from the heart are called:
A. Venules
B. Capillaries
C. Arteries ✓ Correct
D. Veins
Solution: Arteries carry blood away from the heart and have thick, elastic walls to withstand high pressure. Veins carry blood back towards the heart.
Q6 — Excretion · easy · theory
The basic filtration unit of the human kidney is the:
A. Neuron
B. Alveolus
C. Villus
D. Nephron ✓ Correct
Solution: Each kidney contains about a million nephrons. A nephron filters the blood and forms urine. Neurons are nerve cells, alveoli are in the lungs and villi are in the small intestine.
Q7 — Excretion · easy · theory
The main nitrogenous waste removed from the human body in urine is:
A. Glucose
B. Amino acids
C. Proteins
D. Urea ✓ Correct
Solution: The liver converts excess amino acids into urea, which is carried by blood to the kidneys and removed in urine. Glucose and amino acids are useful and are normally reabsorbed.
Q8 — Nutrition · hard · theory
The tiny pores on the surface of leaves through which gases are exchanged are called:
A. stomata ✓ Correct
B. veins
C. lenticels
D. root hairs
Solution: Stomata allow the exchange of CO₂ and O₂ and also the loss of water vapour.
Q9 — Nutrition · hard · theory
Amoeba takes in its food by surrounding it with finger-like extensions called:
A. tentacles
B. pseudopodia ✓ Correct
C. flagella
D. cilia
Solution: Amoeba engulfs food using pseudopodia in a process called phagocytosis.
Q10 — Nutrition · hard · theory
A plant like Cuscuta (Amarbel), which takes food from another living plant, shows:
A. parasitic nutrition ✓ Correct
B. saprophytic nutrition
C. holozoic nutrition
D. autotrophic nutrition
Solution: Cuscuta is a parasite that draws nutrients from a host plant.
Q11 — Nutrition · hard · theory
In humans, the chemical substances that speed up the digestion of food are called:
A. minerals
B. vitamins
C. hormones
D. enzymes ✓ Correct
Solution: Digestive enzymes break down complex food molecules into simpler absorbable forms.
Q12 — Respiration · hard · theory
Anaerobic respiration in yeast produces carbon dioxide and:
A. water only
B. lactic acid
C. oxygen
D. ethanol (alcohol) ✓ Correct
Solution: Yeast carries out fermentation, producing ethanol and CO₂.
Q13 — Respiration · hard · theory
During vigorous exercise, the anaerobic respiration in our muscles produces:
A. carbon dioxide only
B. glucose
C. lactic acid ✓ Correct
D. ethanol
Solution: When oxygen is scarce, muscle cells form lactic acid, which causes cramps.
Q14 — Respiration · hard · theory
Which statement correctly distinguishes breathing from respiration?
A. Breathing is a physical process; respiration is a chemical process that releases energy ✓ Correct
B. They are exactly the same
C. Breathing releases energy from food
D. Respiration is only physical
Solution: Breathing is the physical exchange of gases, while respiration is the chemical breakdown of food to release energy.
Q15 — Respiration · hard · theory
Which of the following is TRUE about plants?
A. Plants only photosynthesise
B. Plants respire all the time, taking in oxygen and giving out carbon dioxide ✓ Correct
C. Plants respire only in sunlight
D. Plants never respire
Solution: Plants respire continuously (day and night), while photosynthesis occurs only in light.
Q16 — Transportation · hard · theory
Blood vessels that carry blood away from the heart are called:
A. arteries ✓ Correct
B. veins
C. nerves
D. capillaries only
Solution: Arteries carry blood away from the heart; veins bring it back.
Q17 — Transportation · hard · theory
The loss of water vapour from the leaves of a plant, which helps pull water upward, is called:
A. transpiration ✓ Correct
B. translocation
C. photosynthesis
D. respiration
Solution: Transpiration creates a suction (pull) that draws water up through the xylem.
Q18 — Transportation · hard · theory
Human beings have double circulation, which means the blood passes through the heart:
A. never
B. twice in one complete cycle ✓ Correct
C. once in one complete cycle
D. only through the lungs
Solution: Blood flows through the heart twice per cycle (pulmonary and systemic circulation).
Q19 — Transportation · hard · theory
The colourless fluid that flows in lymph vessels and helps in defence and transport is:
A. bile
B. plasma only
C. urine
D. lymph ✓ Correct
Solution: Lymph transports digested fats and helps fight infection.
Q20 — Excretion · hard · theory
The functional (structural) unit of the kidney is the:
A. neuron
B. nephron ✓ Correct
C. alveolus
D. nephridium
Solution: Each kidney contains about a million nephrons that filter the blood and form urine.
Q21 — Excretion · hard · theory
Which organ, besides the kidneys, helps in excretion by removing carbon dioxide?
A. pancreas
B. lungs ✓ Correct
C. heart
D. stomach
Solution: The lungs excrete carbon dioxide (and some water vapour) during breathing.
Q22 — Excretion · hard · theory
Plants get rid of some waste products by:
A. urinating
B. shedding leaves and storing wastes in cells ✓ Correct
C. sweating like animals
D. using kidneys
Solution: Plants excrete wastes by shedding leaves/bark, releasing gases through stomata, and storing wastes in cells or resins.
Q23 — Nutrition · hard · theory
The pancreas of a person is damaged and secretes very little pancreatic juice. Which digestive activity in the small intestine would be MOST affected?
A. Absorption of water in the large intestine
B. Only protein digestion
C. Only starch digestion in the mouth
D. Digestion of proteins, fats and carbohydrates together in the small intestine ✓ Correct
Solution: Pancreatic juice contains trypsin (proteins), lipase (fats) and pancreatic amylase (carbohydrates). With little of it, the digestion of all three types of food in the small intestine is affected together.
Q24 — Respiration · hard · theory
Fish breathe much faster than land animals of a similar size. The BEST reason for this is:
A. The amount of oxygen dissolved in water is much lower than the oxygen available in air ✓ Correct
B. Water contains no oxygen at all
C. Fish need far more oxygen than land animals
D. Air contains less oxygen than water
Solution: The concentration of dissolved oxygen in water is much lower than the oxygen content of air. To obtain enough oxygen, fish must pass large amounts of water over their gills, so their breathing rate is high.
Q25 — Transportation · hard · numerical
The heart of a person beats about 72 times per minute and pumps about 70 mL of blood with each beat. Approximately how much blood does the heart pump in one minute?
A. About 50 litres
B. About 14 litres
C. About 0.5 litres
D. About 5 litres ✓ Correct
Solution: Blood pumped per minute = 72 x 70 mL = 5040 mL, which is about 5 litres. This is roughly equal to the total blood volume of an adult, so the whole blood supply circulates about once a minute at rest.
Q26 — Transportation · hard · theory
In a tall tree during the daytime, the major force that pulls water upward from the roots to the leaves through the xylem is:
A. Root pressure acting alone
B. Active pumping of water by the phloem
C. Transpiration pull created by evaporation of water from the leaves ✓ Correct
D. The force of gravity
Solution: As water evaporates from leaf cells (transpiration), it creates a suction, or transpiration pull, that draws a continuous column of water up the xylem. This is the main upward force in tall plants during the day.
Q27 — Excretion · hard · theory
The kidneys of a patient have stopped working. The artificial process used to remove nitrogenous wastes from the blood is called:
A. Transamination
B. Transpiration
C. Dialysis ✓ Correct
D. Osmosis
Solution: Dialysis uses an artificial kidney machine to filter wastes such as urea from the blood when the kidneys fail. Transpiration and osmosis are natural processes, and transamination relates to amino acids.
Q28 — Excretion · hard · theory
Unlike animals, plants have no special excretory organs. They can still get rid of many waste products because:
A. Plants convert all their wastes back into food
B. Gaseous wastes diffuse out, some wastes are stored in leaves and bark that fall off, and others are stored harmlessly in cells ✓ Correct
C. Plants possess a pair of kidneys
D. Plants produce no waste products at all
Solution: Plants remove gaseous wastes (oxygen, carbon dioxide) by diffusion through stomata, store some wastes in old leaves and bark that are shed, and lock others in vacuoles or as resins and gums. So they manage without excretory organs.
Q29 — Nutrition · medium · theory
Organisms that make their own food from simple substances are called:
A. parasites
B. heterotrophs
C. decomposers
D. autotrophs ✓ Correct
Solution: Autotrophs (e.g. green plants) synthesise their own food by photosynthesis.
Q30 — Nutrition · medium · theory
The raw materials required for photosynthesis are carbon dioxide and:
A. nitrogen
B. oxygen
C. water ✓ Correct
D. glucose
Solution: Plants use CO₂ and water, in the presence of sunlight and chlorophyll, to make glucose and oxygen.