Class 10 · Science · Chapter 5: Life Processes
Bihar Board · NCERT · CBSE
All 75 objective questions (MCQ) of this chapter — solve first, then tap “Show answer”. Each question shows its source label: «BSEB 2025 · board paper» = verified from the official board paper; «Board-style (practice)» = Study With Me's own practice questions.
← Chapter 5: Life Processes — full notes, video, questions
In photosynthesis, what does the chlorophyll part become with iodine?
Correct answer: (B) Blue-black
Starch turns blue-black with iodine. That colour appears in the green part.
Why is potassium hydroxide kept in the bell jar?
Correct answer: (B) To absorb carbon dioxide
KOH absorbs carbon dioxide, so photosynthesis stops.
In Activity 5.2, what does the black paper block?
Correct answer: (A) Sunlight
Black paper blocks sunlight. Without sunlight, starch does not form.
From where does a land plant take the water for photosynthesis?
Correct answer: (B) From the soil, through the roots
Water is taken from the soil by the roots.
In Activity 5.3, which tube gives the blue-black colour with iodine?
Correct answer: (B) Only B, which has no saliva
Starch remains in B, so the colour is blue-black. In A the starch has become sugar.
The protein-digesting enzyme in the stomach is —
Correct answer: (B) Pepsin
Pepsin digests protein. HCl makes its medium.
Which secretion breaks large fat globules into smaller ones?
Correct answer: (B) Bile
Bile salts emulsify fats.
In Activity 5.4, which air turns lime water milky sooner?
Correct answer: (B) Air blown from the mouth
Blown air contains more carbon dioxide, so the milky colour comes sooner.
Pyruvate is formed from glucose in the —
Correct answer: (B) Cytoplasm
The breakdown of glucose to pyruvate happens in the cytoplasm.
About how much energy is released when the terminal phosphate of ATP breaks?
Correct answer: (B) 30.5 kJ/mol
About 30.5 kJ/mol of energy is released.
Where does a fish take up the oxygen dissolved in water?
Correct answer: (B) At the gills
Water passes over the gills and the blood takes up oxygen.
What does the diaphragm do when we breathe in?
Correct answer: (B) It flattens
The diaphragm flattens and the ribs lift, so air is drawn in.
In humans, what mainly carries oxygen?
Correct answer: (B) Haemoglobin of the red blood cell
Haemoglobin in the red blood cell binds oxygen and carries it.
In one cycle, how many times does human blood pass through the heart?
Correct answer: (B) Twice
Blood passes through the heart twice. In a fish it passes only once.
In Activity 5.8, on which cover do water drops appear?
Correct answer: (B) On the pot with the plant
Drops form on the cover of the plant. This is transpiration.
About how much filtrate does a healthy adult form in a day?
Correct answer: (D) 180 litres
The filtrate is about 180 litres. Only one or two litres remain as urine.
The uppermost layer of human teeth is—
Correct answer: (C) Enamel
The hard outermost layer of a tooth is enamel; dentine lies under it. The book's «More to know» box on dental caries: bacterial acid softens enamel and dentine (lesson 4).
Gastric glands are found in the—
Correct answer: (C) Stomach
Gastric glands in the wall of the stomach release HCl, pepsin and mucus (lesson 4).
Which of the following helps in the digestion of fat?
Correct answer: (A) Lipase
Lipase of pancreatic juice breaks emulsified fat into fatty acids and glycerol. Ptyalin = salivary amylase (acts on starch).
Respiration takes place in plants—
Correct answer: (D) all of these
Every living cell of every part of a plant respires; roots, stems and leaves exchange gases by diffusion (lesson 5).
Which gas is released by green plants at night?
Correct answer: (A) CO2
At night there is no photosynthesis, only respiration — so CO2 is released. By day the CO₂ is used up in photosynthesis and O₂ is released (lesson 5).
How many ATPs are produced as a result of fermentation?
Correct answer: (A) 02
Fermentation (anaerobic respiration) gives only 2 ATP per glucose; aerobic respiration gives far more (about 36–38 ATP) — lesson 5.
Normal diastolic blood pressure is—
Correct answer: (A) 80 mm Hg
Normal blood pressure is 120/80 mm Hg — 120 systolic, 80 diastolic. It is measured with a sphygmomanometer (lesson 7).
In which organ does transpiration take place in plants?
Correct answer: (B) In the leaf
Transpiration is mainly the loss of water vapour through the stomata of the leaf (lesson 8, Activity 5.8).
Plant wastes are stored in—
Correct answer: (D) All of these
Book: wastes are stored in cellular vacuoles, in leaves that fall off, and as resins and gums in old xylem; bark is shed too — so all of these (lesson 8).
The structural and functional unit of the kidney is called—
Correct answer: (C) Nephron
The nephron is the basic filtration unit of the kidney; the glomerulus and Bowman's capsule are its parts (lesson 8).
The excretory substances of plants are—
Correct answer: (D) All of these
Tannin, resin and gum are all plant wastes; gums and resins collect in old xylem (lesson 8).
Which method of nutrition is found in fungi?
Correct answer: (A) Saprotrophic
Fungi (bread mould, yeast, mushrooms) break food down outside the body and absorb it — saprotrophic nutrition (lesson 3).
Digestion in human beings begins in the—
Correct answer: (A) buccal cavity
In the mouth, salivary amylase starts breaking starch into sugar (lesson 3, Activity 5.3).
The biological processes found in living organisms are—
Correct answer: (D) all of these
Nutrition, respiration, transport, excretion — and reproduction too — are processes of living things; the board answer is all of these (lesson 1).
Fermentation takes place in—
Correct answer: (C) Yeast
Yeast turns pyruvate into ethanol + CO₂ without oxygen — fermentation (lesson 5, Activity 5.5).
Which gas is taken in during aerobic respiration?
Correct answer: (D) O2
Aerobic = in the presence of oxygen; in mitochondria pyruvate → CO₂ + H₂O + energy (lesson 5).
What is called cellular fuel?
Correct answer: (C) Glucose
In respiration glucose is oxidised to make ATP — so glucose is called the cellular fuel (lesson 5).
In which organ does transpiration mainly take place in plants?
Correct answer: (C) leaves
Mainly through the stomata of the leaves (lesson 8).
The human heart is a part of which system?
Correct answer: (D) circulatory system
The heart pumps blood — the circulatory (transport) system (lesson 7).
Which of the following helps in clotting of blood?
Correct answer: (B) Fibrinogen
Fibrinogen (a plasma protein) takes part in clotting. The book says platelets clot the blood at a cut; platelets are not an option, so fibrinogen (lesson 7).
Plant wastes are stored in—
Correct answer: (D) all of these
Vacuoles, leaves that fall, old xylem — all of these (lesson 8).
What is formed by the breakdown of amino acids?
Correct answer: (C) NH3
Breaking down proteins/amino acids gives nitrogenous wastes — ammonia (NH3), then urea or uric acid. Unicellular organisms remove them by diffusion (lesson 8).
The main function of the kidney is—
Correct answer: (B) excretion
Kidneys filter nitrogenous wastes such as urea out of the blood — excretion (lesson 8).
Why is there a debate about whether viruses are alive?
Correct answer: (B) They show no molecular movement until they infect a cell
Book: viruses show no molecular movement until they infect some cell.
In what form do plants store carbohydrate?
Correct answer: (B) Starch
Plants — starch; we (animals) — glycogen.
When do desert plants take in CO₂?
Correct answer: (B) At night
They take up CO₂ at night and make an intermediate; by day they act on it with light energy.
What controls the opening and closing of a stoma?
Correct answer: (B) Guard cells
Guard cells swell with water to open the pore and shrink to close it.
In what form do plants take nitrogen to make proteins?
Correct answer: (B) Nitrates/nitrites or organic compounds made by bacteria
From the soil as inorganic nitrates or nitrites, or as organic compounds made by bacteria from atmospheric N.
How does food reach a specific spot in Paramoecium?
Correct answer: (B) By movement of cilia
Paramoecium has a definite shape; cilia move the food to a specific spot.
Why do grass-eating herbivores have a longer small intestine?
Correct answer: (B) To digest cellulose
Cellulose takes longer to digest; carnivores (tiger) have a shorter intestine.
The main cause of dental caries is—
Correct answer: (B) Acid made from sugar by bacteria
Bacteria act on sugars to make acids that soften enamel and dentine; plaque stops saliva from reaching the acid.
During exercise, muscle cramps are caused by a build-up of—
Correct answer: (B) lactic acid
With too little O₂, pyruvate → lactic acid.
What prevents the trachea (air passage) from collapsing?
Correct answer: (B) Rings of cartilage
Rings of cartilage in the throat keep the air passage from collapsing.
How many chambers does a fish heart have?
Correct answer: (B) 2
Fish: two chambers, blood passes the heart once per cycle; amphibians and many reptiles: three chambers.
The instrument that measures blood pressure is the—
Correct answer: (B) sphygmomanometer
Sphygmomanometer; high blood pressure (hypertension) comes from constriction of arterioles.
At night, the main force moving water up the xylem is—
Correct answer: (B) root pressure
Stomata are closed at night, so root pressure; by day transpiration pull is the main force.
About how much filtrate do the kidneys form daily?
Correct answer: (B) 180 litres
About 180 litres of filtrate a day, but only 1–2 litres of urine; the rest is reabsorbed.
The kidneys in human beings are a part of the system for—
Correct answer: (C) excretion
Kidneys filter nitrogenous wastes out of blood — excretion.
The xylem in plants is responsible for—
Correct answer: (A) transport of water
Xylem: water and minerals from root to leaf; food and amino acids go by phloem.
The autotrophic mode of nutrition requires—
Correct answer: (D) all of the above
CO₂, water, chlorophyll and sunlight — all of them.
The breakdown of pyruvate to give carbon dioxide, water and energy takes place in—
Correct answer: (B) mitochondria
This aerobic step happens in the mitochondria; glucose → pyruvate happens in the cytoplasm.
The full sign of being alive is not only this —
Correct answer: (B) Visible movement
Visible movement alone is not enough.
An example of an autotroph is —
Correct answer: (B) A green plant
A green plant is an autotroph.
The reagent for the starch test is —
Correct answer: (B) Dilute iodine
Dilute iodine gives a blue-black colour with starch.
Black paper blocks —
Correct answer: (A) Sunlight
Black paper blocks sunlight.
The organism that gathers food with cilia is —
Correct answer: (B) Paramecium
Paramecium uses cilia.
The secretion that emulsifies fat is —
Correct answer: (B) Bile
Bile makes fat droplets smaller.
Aerobic breakdown of pyruvate happens in the —
Correct answer: (C) Mitochondria
The aerobic path is in the mitochondria.
When oxygen is short in muscle, pyruvate becomes —
Correct answer: (B) Lactic acid
Lactic acid is formed.
Aquatic organisms breathe faster because —
Correct answer: (B) Dissolved oxygen in water is scarce
Dissolved oxygen is scarce, so breathing is faster.
The heart of a fish has this many chambers —
Correct answer: (A) Two
A fish heart has two chambers.
Normal diastolic pressure is about —
Correct answer: (A) 80 mm Hg
Diastolic pressure is about 80 mm Hg.
Digested fat from the intestine is carried by —
Correct answer: (B) Lymph
Lymph carries the fat.
The main daytime pull on xylem water is —
Correct answer: (B) Transpiration
By day, transpiration pulls.
The Bowman capsule is part of which structure?
Correct answer: (B) A nephron
The Bowman capsule is in the nephron.
The kidney is an organ of which system?
Correct answer: (C) Excretion
The kidney is an organ of excretion.
The main job of xylem is —
Correct answer: (A) Transport of water
Xylem carries water and minerals.
A student kept two starch tubes. Saliva was added only to A. After 30 minutes iodine turned B blue-black, not A. The conclusion is —
Correct answer: (A) Saliva turns starch into sugar
No starch is left in A, so saliva broke it.
Half a leaf was covered with black paper. After iodine only the open part turned blue-black. This shows that what is essential is —
Correct answer: (B) Sunlight
The covered part made no starch, so sunlight is essential.
