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PSLCE Primary Science study materials
PSLCE Primary Science study resources

PSLCE Primary Science practice questions

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First 50 of 199 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

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Question 1Living things and life processes

Which part of a plant is mainly responsible for absorbing water and dissolved minerals from the soil?

  1. The stem
  2. The leaves
  3. The flowers
  4. The roots Correct answer.

Explanation

Roots are adapted for absorption: they branch finely and bear root hairs that greatly increase the surface area in contact with soil water. Water and dissolved minerals enter through these surfaces and are carried upward to the rest of the plant.

Question 2Living things and life processes

A pupil places a healthy potted plant in a dark cupboard for one week and waters it normally. What is the most likely observation?

  1. The roots stop absorbing water completely
  2. The plant grows taller than an identical plant in light
  3. The leaves turn pale and the plant stops making new food Correct answer.
  4. The leaves become darker green than before

Explanation

Light is needed for photosynthesis, which produces the food and the green pigment chlorophyll. In darkness the plant cannot photosynthesise, so existing chlorophyll breaks down and leaves look pale, and growth slows. Water uptake by roots continues even without light.

Question 3Living things and life processes

Which statement best describes the function of the heart in the human body?

  1. It takes oxygen directly from the air into the blood
  2. It pumps blood around the body through blood vessels Correct answer.
  3. It stores food before it is digested
  4. It filters waste from the blood to make urine

Explanation

The heart is a muscular pump. Its contractions push blood through arteries, capillaries and veins so that oxygen, nutrients and wastes are transported around the body.

Question 4Living things and life processes

Which set of teeth is best suited to cutting and biting food?

  1. The premolars
  2. The incisors Correct answer.
  3. The molars
  4. The canines

Explanation

Incisors are the flat, chisel-shaped front teeth used for biting and cutting pieces of food. Each type of tooth has a shape matched to its job in the mouth.

Question 5Living things and life processes

A tadpole hatches in a pond and later becomes a frog. Which statement about this change is correct?

  1. The young is identical to the adult except in size
  2. The young lives on land throughout its development
  3. The young differs greatly from the adult in body form and breathing organ Correct answer.
  4. The young breathes with lungs from the moment it hatches

Explanation

Frogs undergo metamorphosis: the tadpole has a tail, no legs and gills, while the adult has legs, no tail and lungs. This is a striking change in body form during the life cycle.

Question 6Living things and life processes

Which of these is a characteristic shared by all living things?

  1. They can move from place to place
  2. They have green leaves
  3. They can grow and reproduce Correct answer.
  4. They have eyes

Explanation

Growth and reproduction are part of the set of life processes shared by all organisms, along with nutrition, respiration, excretion and sensitivity. Features such as leaves, eyes or whole-body movement occur only in some groups.

Question 7Living things and life processes

Which organ system is mainly responsible for taking oxygen into the body and removing carbon dioxide?

  1. The respiratory system Correct answer.
  2. The excretory system
  3. The digestive system
  4. The skeletal system

Explanation

The respiratory system, especially the lungs, exchanges gases with the air: oxygen is taken into the blood and carbon dioxide is released. Breathing movements move air in and out of the lungs.

Question 8Living things and life processes

Which of these is a non-living thing that shows some features of living things, such as growth in size?

  1. A mushroom that produces spores
  2. A seedling that grows towards light
  3. A tadpole that develops legs
  4. A crystal that grows as salt is added to its solution Correct answer.

Explanation

A growing crystal increases in size but does not feed, respire, excrete or reproduce, so it is non-living. Growth alone is not enough to classify something as alive; all the life processes must be present.

Question 9Living things and life processes

A plant is kept in a sealed clear jar with a little water and placed in sunlight. After a few hours, what change in the air inside the jar is expected?

  1. The amount of carbon dioxide increases greatly
  2. The amount of oxygen decreases steadily to zero
  3. The amount of oxygen increases Correct answer.
  4. The air inside does not change at all

Explanation

In sunlight the green plant photosynthesises faster than it respires, so it releases oxygen into the enclosed air. The oxygen level therefore rises while carbon dioxide is used up.

Question 10Living things and life processes

Which explanation best accounts for a plant wilting on a hot, sunny day when its soil is dry?

  1. Chlorophyll is destroyed by sunlight within one day
  2. The plant stops respiring completely in the heat
  3. Cells lose water faster than roots can replace it, so the stem loses firmness Correct answer.
  4. Roots absorb too much water and swell up

Explanation

Water evaporates from leaves through transpiration, and when the soil is dry the roots cannot replace it quickly enough. The plant's cells lose turgor pressure, so stems and leaves droop.

Question 11Living things and life processes

Which statement correctly compares breathing and respiration?

  1. Both terms mean exactly the same process in the body
  2. Respiration happens only in the lungs and breathing only in cells
  3. Breathing releases energy from food; respiration moves air in and out
  4. Breathing moves air in and out; respiration releases energy from food inside cells Correct answer.

Explanation

Breathing, or ventilation, is the mechanical movement of air into and out of the lungs. Respiration is the chemical process in cells that breaks down food to release energy. They are related but distinct.

Question 12Living things and life processes

A student measures the pulse rate of a classmate at rest, then after one minute of running. Which result would be expected and why?

  1. Pulse rate rises because muscles need more oxygen and faster blood flow Correct answer.
  2. Pulse rate stays exactly the same because blood volume is unchanged
  3. Pulse rate rises because the body stops respiring
  4. Pulse rate falls because running slows the heart

Explanation

During exercise muscles respire faster and need more oxygen and glucose, so the heart beats faster to deliver them and remove carbon dioxide. The pulse rate reflects this increased heart rate.

Question 13Living things and life processes

Which sequence shows the correct order of the main parts of the human digestive tract?

  1. Oesophagus, mouth, small intestine, stomach, large intestine
  2. Stomach, mouth, oesophagus, small intestine, large intestine
  3. Mouth, stomach, oesophagus, large intestine, small intestine
  4. Mouth, oesophagus, stomach, small intestine, large intestine Correct answer.

Explanation

Food enters the mouth, passes down the oesophagus to the stomach, then enters the small intestine where most digestion and absorption occur, and finally the large intestine. The order follows the path food takes.

Question 14Living things and life processes

Which feature of a fish is best explained as an adaptation for life in water?

  1. Feathers that keep the body warm
  2. Lungs that fill with air on land
  3. Dry scaly skin that prevents water loss
  4. Streamlined body shape that reduces resistance when swimming Correct answer.

Explanation

A streamlined shape reduces drag as the fish moves through water, saving energy. Fish also have gills for taking oxygen dissolved in water, matching their aquatic habitat.

Question 15Living things and life processes

A seed is planted and kept warm and moist but given no light. It still sprouts a small shoot. Which explanation is best?

  1. The seed uses stored food and grows until light is needed for further healthy growth Correct answer.
  2. The shoot makes its own food without any light
  3. The shoot respires but never needs light at any stage
  4. The seed absorbs food from the surrounding air

Explanation

A seed contains stored food that supports early germination before leaves form. Once the shoot emerges and opens leaves, light is needed for photosynthesis to continue healthy growth.

Question 16Living things and life processes

Which statement about the life cycle of a flowering plant is correct?

  1. Seeds are produced by leaves without any flowers
  2. Flowers form after seeds have germinated
  3. Fertilisation happens in the soil before germination
  4. Seeds form after fertilisation and can grow into new plants Correct answer.

Explanation

In flowering plants, pollen transfers to the stigma and fertilisation occurs in the flower, after which seeds develop. These seeds can germinate and grow into new plants, completing the cycle.

Question 17Living things and life processes

Which observation would best show that a green plant has been photosynthesising?

  1. The plant has lost mass overnight
  2. Starch is present in a leaf that was kept in light Correct answer.
  3. The soil around the plant has become wetter
  4. The plant has gained water in its stem

Explanation

Photosynthesis produces glucose, which is stored as starch in the leaves. Testing a light-exposed leaf with iodine and finding starch indicates that photosynthesis has occurred.

Question 18Living things and life processes

Which grouping correctly places a mushroom, a fern and a human?

  1. Mushroom in fungi, fern in plants, human in animals Correct answer.
  2. Mushroom in animals, fern in plants, human in fungi
  3. Mushroom in fungi, fern in animals, human in plants
  4. Mushroom in plants, fern in fungi, human in animals

Explanation

Organisms are grouped by shared features: mushrooms absorb nutrients and lack chlorophyll, so they are fungi; ferns are green plants; humans are animals that feed on other organisms.

Question 19Living things and life processes

Two identical plants are placed in sealed clear containers. Plant A is in bright light; Plant B is in complete darkness. Both are kept at the same temperature. Which comparison of the air in the containers after several hours is most likely?

  1. Both containers have equal oxygen because both plants respire
  2. Container A has more oxygen than container B Correct answer.
  3. Container A has more carbon dioxide than container B
  4. Container B has more oxygen than container A

Explanation

In light, Plant A photosynthesises and releases oxygen faster than it uses it in respiration, so oxygen rises. In darkness Plant B only respires, using oxygen and releasing carbon dioxide, so its oxygen falls.

Question 20Living things and life processes

A student claims that a plant's roots only anchor it in the soil. Which evidence best challenges this claim?

  1. Roots are found below the soil surface
  2. A plant whose roots are removed quickly wilts even when placed in water Correct answer.
  3. Roots grow longer as the plant ages
  4. Roots are white in many plants

Explanation

If removing the roots causes rapid wilting, the roots must normally supply water to the shoot. This shows roots absorb water, not merely anchor the plant.

Question 21Living things and life processes

A pupil breathes out onto a cold mirror and a mist forms, then clears. Which conclusion is best supported?

  1. Exhaled air is pure carbon dioxide
  2. Exhaled air contains water vapour that condenses on the cold surface Correct answer.
  3. Exhaled air is warmer than inhaled air only because of the mirror
  4. Exhaled air contains no oxygen at all

Explanation

The mist is condensation of water vapour from exhaled air when it meets the cold mirror. This shows that exhaled air carries water vapour, a product of respiration.

Question 22Living things and life processes

A gardener covers the underside of a leafy shoot with a thin layer of grease. What is the most likely effect and reason?

  1. Transpiration decreases because most stomata are blocked Correct answer.
  2. Photosynthesis stops immediately because roots are sealed
  3. Water uptake by roots stops because the soil is dry
  4. Respiration in the stem increases because gas exchange is easier

Explanation

Most stomata are on the lower leaf surface, and they are the main route for water vapour leaving the leaf. Blocking them with grease reduces transpiration, though it may also limit gas exchange for photosynthesis.

Question 23Living things and life processes

A child has an illness that damages the small intestine so that it cannot absorb nutrients well. Which prediction is most reasonable?

  1. The child will digest food faster and gain weight
  2. The child may lose weight even if eating normally Correct answer.
  3. The child's heart will stop pumping blood
  4. The child will no longer need to breathe

Explanation

Most digested nutrients are absorbed through the small intestine into the blood. If absorption is poor, nutrients are lost in faeces and the body cannot obtain enough energy and materials, so weight may fall despite eating.

Question 24Living things and life processes

A pond contains water fleas that feed on green algae, small fish that eat the water fleas, and herons that eat the fish. If the algae are removed, which short-term change is most likely?

  1. All organisms in the pond die within one hour
  2. Heron numbers rise immediately because fish are easier to catch
  3. Water flea numbers rise because there is less competition
  4. Water flea numbers fall, then fish numbers fall Correct answer.

Explanation

Algae are the producers at the base of this food chain. Without them the water fleas lose their food supply and decline, and the fish that eat them then also decline.

Question 25Living things and life processes

Which statement best explains why a person's breathing rate increases during vigorous exercise?

  1. The lungs grow larger to store extra air permanently
  2. The body needs to cool down by taking in cold air
  3. Cells respire faster, so more oxygen is needed and more carbon dioxide must be removed Correct answer.
  4. The blood stops carrying oxygen during exercise

Explanation

Working muscles respire more rapidly, using oxygen and producing carbon dioxide. Faster and deeper breathing supplies the extra oxygen and helps expel the extra carbon dioxide.

Question 26Living things and life processes

A pupil places a small piece of onion skin on a glass slide, adds a drop of water, lowers a cover slip and looks at it with a light microscope. Which part of the onion skin cell is the thin outer boundary that controls what enters and leaves the cell?

  1. The nucleus
  2. The cell membrane Correct answer.
  3. The chloroplast
  4. The cell wall

Explanation

The cell membrane is the thin living boundary around the cytoplasm, and it controls the movement of substances into and out of the cell. The cell wall lies outside it and is made of cellulose, which gives shape and support rather than selective control.

Question 27Living things and life processes

Which statement describes the correct order in which air passes through the human breathing system when a person breathes in?

  1. Nose, bronchi, trachea, alveoli, bronchioles
  2. Nose, trachea, bronchi, bronchioles, alveoli Correct answer.
  3. Trachea, nose, bronchioles, bronchi, alveoli
  4. Nose, bronchioles, bronchi, trachea, alveoli

Explanation

Inhaled air enters through the nose, passes down the windpipe (trachea), and then divides into the two bronchi. These branch into many narrower bronchioles, which end in tiny air sacs called alveoli where gas exchange takes place.

Question 28Living things and life processes

A pupil compares a named plant with a named animal and writes a list of differences. Which difference is correct for the plant but not for the animal?

  1. It respires to release energy from food
  2. It grows during its life
  3. It makes its own food using light energy Correct answer.
  4. It responds to touch or other stimuli

Explanation

Green plants contain chlorophyll and can photosynthesise, using light energy to make food from carbon dioxide and water. Animals cannot do this and must take in ready-made food, so this feature separates the two groups.

Question 29Living things and life processes

A pupil sorts living things into groups and places a frog, a snake and a lizard together. Which feature do all three animals share?

  1. They have moist skin and live partly in water
  2. They have dry scales covering the body
  3. They lay their eggs on dry land
  4. They have a backbone and an internal skeleton Correct answer.

Explanation

Frogs, snakes and lizards are all vertebrates, meaning they have a backbone and an internal skeleton made of bone. The other options describe features of only some of these animals, not all three.

Question 30Living things and life processes

Which statement correctly describes what happens during germination of a bean seed?

  1. The seed needs light before it can begin to germinate
  2. The seed makes food by photosynthesis before the root appears
  3. The seed takes in water, the shoot appears first and grows downwards, then the root grows upwards
  4. The seed takes in water, the root appears first and grows downwards, then the shoot grows upwards Correct answer.

Explanation

Germination starts when the seed absorbs water and the stored food is used for growth. The young root emerges first and grows downwards, anchoring the plant, and the shoot then grows upwards towards the light.

Question 31Living things and life processes

Which statement best explains why a green plant is described as a producer in a food chain?

  1. It breaks down dead material and releases nutrients into the soil
  2. It supplies energy to animals without needing any energy itself
  3. It makes its own food from carbon dioxide and water using light energy Correct answer.
  4. It obtains its food by eating other living things

Explanation

A producer makes its own food by photosynthesis, using light energy trapped by chlorophyll to combine carbon dioxide and water. This stored chemical energy is then passed along the food chain to consumers.

Question 32Living things and life processes

A pupil places a piece of potato in a strong sugar solution. After an hour the potato feels softer and has lost mass. Which explanation fits this result?

  1. The potato cells have stopped respiring because of the sugar
  2. Sugar has moved from the potato into the solution
  3. Water has moved into the potato cells from the solution
  4. Water has moved out of the potato cells into the stronger sugar solution Correct answer.

Explanation

Water moves across a cell membrane from a weaker solution to a stronger one, so water leaves the potato cells and enters the more concentrated sugar solution. The cells lose water and become flaccid, so the potato softens and its mass falls.

Question 33Living things and life processes

A person eats a meal containing bread, butter and chicken. Which row correctly matches each nutrient with its main function in the body?

  1. Carbohydrate for growth and repair, fat for insulation, protein for energy
  2. Carbohydrate for insulation, fat for growth and repair, protein for energy
  3. Carbohydrate for growth and repair, fat for energy, protein for insulation
  4. Carbohydrate for energy, fat for energy and insulation, protein for growth and repair Correct answer.

Explanation

Carbohydrates are the body's main energy source, fats store energy and provide insulation, and proteins are needed for growth and repair of tissues. Each nutrient has a main role, though all three can supply energy.

Question 34Living things and life processes

A pupil keeps a small pond snail in a jar of pond water with green weed and leaves it in bright light. Which combination of changes shows that the snail and the weed are both respiring?

  1. Oxygen rises in light and falls in light at the same rate
  2. Carbon dioxide falls only when the weed is present
  3. Oxygen in the water falls in darkness and carbon dioxide rises Correct answer.
  4. Oxygen in the water rises and carbon dioxide falls in darkness

Explanation

Respiration uses oxygen and releases carbon dioxide, and it happens all the time in both the snail and the weed. In darkness photosynthesis stops, so the net effect is oxygen being used up and carbon dioxide increasing.

Question 35Living things and life processes

A child's hand is accidentally placed near a hot pan and the child pulls the hand away very quickly, before feeling the pain. Which statement best explains this?

  1. The muscles of the arm detect the heat and move without any nerve signal
  2. The pain receptors in the skin pull the muscles directly
  3. A reflex action uses a fast pathway through the spinal cord without waiting for the brain to decide Correct answer.
  4. The brain decides to move the hand before any signal reaches it

Explanation

A reflex action is a rapid, automatic response in which the nerve signal passes through a relay in the spinal cord and straight back to the muscle. This shortens the pathway, so the hand is withdrawn before the brain has processed the signal as pain.

Question 36Living things and life processes

A pupil looks at a slide of human cheek cells and a slide of onion skin cells under the same microscope. Which difference would the pupil expect to see?

  1. The onion cells have a firm regular shape because of a cell wall, while the cheek cells have an irregular flexible shape Correct answer.
  2. The cheek cells have a cell wall while the onion cells do not
  3. The onion cells have no nucleus while the cheek cells do
  4. The cheek cells have chloroplasts while the onion cells do not

Explanation

Plant cells have a cellulose cell wall outside the membrane, which keeps them firm and gives them a regular box-like shape. Animal cells such as cheek cells lack a cell wall, so their membrane gives them an irregular, flexible outline.

Question 37Living things and life processes

A farmer notices that a crop grown in a field for many years produces smaller yields, and the soil is found to lack nitrates. Which explanation is most likely?

  1. Nitrates are used only to make the cell wall, so shortage makes stems woody
  2. Nitrates are needed for photosynthesis, so shortage stops carbon dioxide entering
  3. Nitrates are needed to make chlorophyll, so shortage stops all water uptake
  4. Nitrates are needed to make proteins for growth, so shortage limits new plant tissue Correct answer.

Explanation

Plants absorb nitrate ions from the soil and use the nitrogen to build amino acids, which are joined to make proteins for growth. Without enough nitrate, new leaves and stems cannot form properly, so growth and yield are reduced.

Question 38Living things and life processes

Two similar potted plants are kept in the same room. Plant P has its leaves wiped with oil so the stomata are blocked; plant Q is untreated. Both are well watered and given light. Which result is most likely after a day?

  1. Plant P wilts less because it cannot lose water, but its photosynthesis slows because carbon dioxide cannot enter Correct answer.
  2. Plant P wilts more because blocked stomata stop water being taken up by the roots
  3. Both plants show identical growth because stomata do not affect gas exchange
  4. Plant Q wilts because untreated leaves cannot lose water vapour

Explanation

Stomata are the pores through which water vapour leaves the leaf and carbon dioxide enters for photosynthesis. Blocking them reduces water loss, so wilting is less likely, but it also cuts the carbon dioxide supply, so photosynthesis slows.

Question 39Living things and life processes

A student is told that a certain animal has moist skin, lays jelly-covered eggs in water, and its young feed on milk from the mother. Which conclusion about this animal is correct?

  1. The animal is a mammal, because it feeds its young on milk
  2. The animal is a fish, because it lays eggs in water
  3. The description is inconsistent, because no animal combines all these features Correct answer.
  4. The animal is an amphibian, because it has moist skin

Explanation

Each feature belongs to a different group: moist skin and jelly-covered eggs are amphibian features, while feeding young on milk is a mammalian feature. No single animal has all of these together, so the description cannot describe one real animal.

Question 40Living things and life processes

A pupil counts the number of stomata on the upper and lower surfaces of a leaf using a microscope and finds far more on the lower surface. Which explanation is most reasonable?

  1. Stomata on the lower surface are larger and each one counts as many
  2. The lower surface receives more sunlight, so it needs more stomata for photosynthesis
  3. The upper surface has no living cells, so it cannot have stomata
  4. The lower surface is shaded, so fewer stomata there reduce water loss while still allowing gas exchange Correct answer.

Explanation

Most water vapour is lost through stomata, and the lower surface of a leaf is usually cooler and more shaded than the upper surface. Having more stomata there reduces water loss while still allowing enough carbon dioxide in for photosynthesis.

Question 41Living things and life processes

A girl measures her breathing rate at rest and then holds her breath for as long as she can. Immediately after she starts breathing again, her breathing rate is higher than at rest. Which explanation is best?

  1. Carbon dioxide built up in the blood during the hold, and faster breathing removes it Correct answer.
  2. Oxygen built up in the blood during the hold, and faster breathing uses it up
  3. Her lungs had filled with water during the hold
  4. Her muscles needed more energy because she was holding her breath

Explanation

During breath-holding, respiration continues and carbon dioxide accumulates in the blood because it is not being removed by the lungs. The higher concentration of carbon dioxide stimulates faster and deeper breathing to remove it and restore the balance.

Question 42Living things and life processes

In a woodland, caterpillars feed on oak leaves, blue tits eat the caterpillars, and sparrowhawks eat the blue tits. A disease greatly reduces the number of caterpillars. Which prediction about the food chain is most likely in the short term?

  1. Oak trees will die because nothing is eating their leaves
  2. Blue tits will increase because there is less competition for caterpillars
  3. Blue tits may decline because their food supply falls, and sparrowhawks may then also decline Correct answer.
  4. Sparrowhawks will increase because there are fewer caterpillars

Explanation

Each consumer depends on the level below it for food, so a fall in caterpillars reduces the food available to blue tits. Fewer blue tits then means less food for sparrowhawks, so their numbers are also likely to fall.

Question 43Living things and life processes

A pupil sets up a test tube containing pond weed in water and places it in bright light. Bubbles of gas collect at the top. The pupil then moves the tube closer to the lamp and the bubbles appear faster. Which conclusion is best supported?

  1. The rate of photosynthesis increases as light intensity increases Correct answer.
  2. The gas collected is carbon dioxide released by respiration
  3. The weed is respiring faster because the lamp warms the water
  4. The weed is absorbing more oxygen as the light gets brighter

Explanation

The bubbles are oxygen released by photosynthesis, and their rate shows how fast the process is happening. Moving the lamp closer increases light intensity, so more oxygen is produced and the bubbles appear faster.

Question 44Living things and life processes

A pupil claims that a seed's stored food is used only after the young plant has green leaves. Which observation best challenges this claim?

  1. A dry seed placed in a sealed dry jar does not sprout
  2. A seedling grown in the dark increases in size while its seed becomes lighter and softer Correct answer.
  3. A seed soaked in water swells and its seed coat splits
  4. A seedling grown in the light turns green within a few days

Explanation

If the stored food were used only after green leaves formed, a seedling in the dark could not grow. The seed losing mass while the seedling gains size shows that the stored food is being transferred to the growing plant before photosynthesis begins.

Question 45Plants and their structures, growth and reproduction

Which part of a flowering plant absorbs most of the water it needs from the soil?

  1. The anthers
  2. The root hairs Correct answer.
  3. The leaf veins
  4. The petals

Explanation

Root hairs are fine extensions of root cells that greatly increase the surface area for absorbing water and dissolved minerals from the soil. Leaves, petals and anthers are above ground and are not adapted for water uptake.

Question 46Plants and their structures, growth and reproduction

A seed is planted and kept warm and moist but given no light. Which observation is most likely after one week?

  1. The seed rots because warmth prevents germination
  2. The seed sprouts a pale shoot that grows towards the dark Correct answer.
  3. The seed sprouts green leaves immediately
  4. The seed remains hard because light is needed to start germination

Explanation

Seeds need water, warmth and oxygen to germinate; light is not required for the first stage. A shoot grown in darkness is pale and elongated because chlorophyll and normal leaf growth depend on light.

Question 47Plants and their structures, growth and reproduction

Which statement correctly describes the job of the flower's stigma?

  1. It protects the growing seed
  2. It produces the pollen grains
  3. It receives pollen grains during pollination Correct answer.
  4. It holds the flower open to the sun

Explanation

The stigma is the sticky tip of the carpel where pollen grains land and stick during pollination. Pollen is made in the anthers, and the ovary protects the developing seed.

Question 48Plants and their structures, growth and reproduction

A pupil covers one leaf of a healthy plant with a black paper bag for three days. What is the most likely result when that leaf is tested for starch?

  1. No starch is found because the leaf was kept in the dark Correct answer.
  2. The leaf turns brown because it dried out
  3. More starch is found because the leaf was protected
  4. Starch is found only in the covered leaf

Explanation

Photosynthesis, which makes starch, requires light. A leaf kept in darkness cannot photosynthesise, so a starch test on it should give a negative result compared with leaves left in light.

Question 49Plants and their structures, growth and reproduction

Which change happens to a plant stem when it grows taller over a season?

  1. Old cells at the base are pushed upwards
  2. The existing cells simply stretch longer without dividing
  3. New cells are added at the tips and the stem thickens Correct answer.
  4. The stem stops making xylem as it grows

Explanation

Growth in length comes mainly from cell division in the shoot tip, while thickening comes from new tissue added inside the stem. Existing cells enlarge but do not stretch indefinitely.

Question 50Plants and their structures, growth and reproduction

Which feature of an insect-pollinated flower is most likely?

  1. Sticky pollen and a scent Correct answer.
  2. Large feathery stigmas hanging outside the flower
  3. Small dull petals and no nectar
  4. Very light pollen carried by the wind

Explanation

Insect-pollinated flowers usually offer nectar and scent to attract insects, and their pollen is sticky so it clings to the insect's body. Wind-pollinated flowers have small dull petals, no scent, and light pollen with feathery stigmas.