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JCE General Science (Syllabus 43) study materials
JCE General Science (Syllabus 43) study resources

JCE General Science (Syllabus 43) practice questions

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Question 1Scientific skills and processes (investigation, measurement, data handling)

In a controlled experiment, which variable does the investigator deliberately change in order to observe its effect?

  1. A dependent variable
  2. A control variable
  3. An independent variable Correct answer.
  4. A random variable

Explanation

The independent variable is the one the investigator chooses to alter, for example the temperature at which a reaction is carried out. Its effect is seen on the dependent variable, which is measured at the end. Control variables are deliberately held constant so that the comparison between trials remains fair.

Question 2Scientific skills and processes (investigation, measurement, data handling)

Which quantity is measured in newtons?

  1. Force Correct answer.
  2. Volume
  3. Mass
  4. Density

Explanation

The newton is the SI unit of force, so a reading given in newtons describes a push or a pull. Mass is measured in kilograms, volume in cubic metres and density in kilograms per cubic metre. Confusing mass with force is a common error because mass is often loosely called weight.

Question 3Scientific skills and processes (investigation, measurement, data handling)

A student records the length of a seedling four times and obtains 12.4 cm, 12.5 cm, 12.4 cm and 12.3 cm. What is the best estimate of the seedling's length?

  1. 12.3 cm
  2. 12.65 cm
  3. 12.4 cm Correct answer.
  4. 12.5 cm

Explanation

The best estimate is the mean of the repeated readings, found by adding the four values and dividing by four, which gives 12.4 cm. Averaging repeated readings reduces the influence of small random errors in any single measurement. The two extreme readings are retained because neither is far enough away to be treated as an anomaly.

Question 4Scientific skills and processes (investigation, measurement, data handling)

A student records the temperature of cooling water every 30 seconds for ten minutes. Which display is most suitable for showing these results?

  1. A pie chart
  2. A bar chart
  3. A line graph Correct answer.
  4. A pictogram

Explanation

Both temperature and time are continuous quantities, and the readings are taken in a fixed sequence, so a line graph shows the cooling trend clearly. Joining the plotted points reveals the shape of the change and allows interpolated values to be read. Pie charts, pictograms and bar charts are designed for categorical or counted data rather than continuous measurements.

Question 5Scientific skills and processes (investigation, measurement, data handling)

A student times how long a marble takes to roll down a ramp in five trials and records 24 s, 25 s, 23 s, 52 s and 24 s. Which value should be treated as anomalous?

  1. 24 s
  2. 23 s
  3. 52 s Correct answer.
  4. 25 s

Explanation

Four readings cluster tightly between 23 s and 25 s, while 52 s is more than double the typical value, so it is almost certainly a measurement fault such as a mistimed start. An anomalous result should be checked and, if a clear fault is identified, repeated rather than averaged with the rest. The other readings lie within the normal spread of the data.

Question 6Scientific skills and processes (investigation, measurement, data handling)

Two groups investigate how light intensity affects the rate of photosynthesis in pondweed. Which factor must be kept the same in both groups?

  1. The temperature of the water Correct answer.
  2. The light intensity
  3. The distance of the lamp from the plant
  4. The rate of bubble production

Explanation

The light intensity is the independent variable, so everything else that could affect photosynthesis must be controlled, including water temperature and carbon dioxide supply. If temperature differed, any change in bubble rate could be caused by temperature rather than by light. Controlling such factors is what makes the comparison between the two groups valid.

Question 7Scientific skills and processes (investigation, measurement, data handling)

Why does a student take three repeat readings of a measurement and then calculate the mean?

  1. To increase the range of the data collected
  2. To remove all systematic error from the results
  3. To make the measuring instrument more precise
  4. To reduce the effect of random error Correct answer.

Explanation

Repeating a measurement and averaging the readings reduces the influence of random errors such as slight variations in judging a scale. It does not correct a systematic fault, such as a zero error or a mislabelled instrument, because that offset affects every reading equally. Nor does repeating a measurement widen the range, which depends on the values of the independent variable chosen.

Question 8Scientific skills and processes (investigation, measurement, data handling)

Group A grows plants on a sunny windowsill and adds fertiliser. Group B grows plants in a dark cupboard and adds no fertiliser. Why is this experiment not a fair test?

  1. Two variables were changed at once Correct answer.
  2. The plants were not measured accurately
  3. The experiment had no separate control group
  4. The results were not repeated

Explanation

Light and fertiliser both differ between the two groups, so any difference in growth cannot be attributed to fertiliser alone. A fair test changes only one variable while holding all others constant, which would require both groups to receive identical light. Group B does act as a comparison, but the confounding makes its result impossible to interpret.

Question 9Scientific skills and processes (investigation, measurement, data handling)

A ruler marked in millimetres is used to measure a 2.0 cm nail and a 20.0 cm rod, and each reading carries an uncertainty of about 0.1 cm. Which statement about these measurements is correct?

  1. The rod measurement has the larger percentage uncertainty of the two
  2. Percentage uncertainty cannot be compared for different lengths
  3. The nail measurement has the larger percentage uncertainty Correct answer.
  4. Both measurements have exactly the same percentage uncertainty

Explanation

Percentage uncertainty equals the absolute uncertainty divided by the reading, multiplied by one hundred. For the nail this is 0.1 divided by 2.0, giving about 5 per cent, whereas for the rod it is 0.1 divided by 20.0, giving only 0.5 per cent. The same absolute uncertainty therefore matters far more when the quantity being measured is small.

Question 10Scientific skills and processes (investigation, measurement, data handling)

Sugar dissolves in 120 s at 20 degrees Celsius, 95 s at 30 degrees, 75 s at 40 degrees and 60 s at 50 degrees. A student predicts that at 60 degrees the sugar will dissolve in 10 s. What is the strongest criticism of this prediction?

  1. Sugar does not dissolve faster in warmer water
  2. The temperatures were not measured accurately enough
  3. The prediction lies beyond the range of the data collected Correct answer.
  4. The experiment should have used a stopwatch

Explanation

All the measurements were made between 20 and 50 degrees, so a value at 60 degrees requires extrapolating the trend beyond the tested range. The pattern of decreasing times does not justify assuming the fall continues so steeply, because the relationship may change at higher temperatures. A sound conclusion must stay within the evidence available.

Question 11Scientific skills and processes (investigation, measurement, data handling)

A student writes four statements about plants. Which statement is a testable hypothesis?

  1. Plants are the most important living things on Earth.
  2. Adding 10 g of fertiliser each week makes tomato plants grow taller. Correct answer.
  3. Tomato plants enjoy being watered in the morning.
  4. Plants with more leaves look nicer than plants with fewer leaves.

Explanation

A hypothesis must predict a measurable link between two variables that an experiment can test. The fertiliser statement names a specific change and a measurable outcome (plant height), so data can support or reject it.

Question 12Scientific skills and processes (investigation, measurement, data handling)

A student records the mass of a mineral sample as 0.75 kg. What is this mass in grams?

  1. 7.5 g
  2. 75 g
  3. 750 g Correct answer.
  4. 7500 g

Explanation

There are 1000 grams in one kilogram, so a mass in kilograms is converted by multiplying by 1000. 0.75 multiplied by 1000 equals 750, so the sample has a mass of 750 g.

Question 13Scientific skills and processes (investigation, measurement, data handling)

A thermometer is marked in divisions of 2 degrees Celsius. The liquid level is exactly halfway between the 20 degrees mark and the 22 degrees mark. What value should the student record?

  1. 22 degrees Celsius
  2. 20 degrees Celsius
  3. 21 degrees Celsius Correct answer.
  4. 23 degrees Celsius

Explanation

Each small division on the scale represents 2 degrees, so a point halfway between two marks is 1 degree above the lower mark. The level is 1 degree above 20 degrees, giving 21 degrees; estimating between marks improves precision.

Question 14Scientific skills and processes (investigation, measurement, data handling)

A student uses an electronic balance to find the mass of a 5.30 g object. The readings are 4.98 g, 4.99 g, 4.98 g and 4.99 g. Which description fits these results?

  1. They are precise but not accurate. Correct answer.
  2. They are accurate but not precise.
  3. They are neither accurate nor precise.
  4. They are both accurate and precise.

Explanation

Precision describes how closely repeated readings agree with each other, while accuracy describes how close they are to the true value. The readings cluster within 0.01 g of each other but sit about 0.3 g below 5.30 g, so they are precise but not accurate.

Question 15Scientific skills and processes (investigation, measurement, data handling)

A student adds different masses of magnesium ribbon to 50 cubic centimetres of dilute acid and times how long the metal takes to disappear completely. Which is the dependent variable?

  1. How long the metal takes to dissolve Correct answer.
  2. The mass of magnesium ribbon added to the acid
  3. The volume of dilute acid used in the experiment
  4. The concentration of the acid used

Explanation

The dependent variable is the quantity that is measured in response to the change the investigator makes. Here the mass of magnesium is changed and the time to dissolve is measured, so time is the dependent variable.

Question 16Scientific skills and processes (investigation, measurement, data handling)

A student measures the volume of gas collected every minute and records 12, 22, 30, 36, 40 and 42 cubic centimetres. Which statement best describes the results?

  1. The gas is produced at a steady rate throughout the experiment.
  2. No gas is produced after the fourth minute of the experiment.
  3. The volume increases and the rate of production rises.
  4. The volume increases, but the rate of production falls. Correct answer.

Explanation

The volume rises by 10, 8, 6, 4 and 2 cubic centimetres in successive minutes. The total volume is still increasing, but the size of each increase is falling, so the rate of gas production decreases over time.

Question 17Scientific skills and processes (investigation, measurement, data handling)

A student needs to measure the diameter of a thin copper wire as accurately as possible. Which instrument is most suitable?

  1. A metre rule marked in millimetres
  2. A 50 cubic centimetre measuring cylinder
  3. A top-pan balance
  4. A micrometer screw gauge Correct answer.

Explanation

A micrometer screw gauge has a very fine scale, usually reading to 0.01 mm, and small jaws that grip a thin wire. A millimetre rule is too coarse for such a small diameter.

Question 18Scientific skills and processes (investigation, measurement, data handling)

A student wants to estimate the number of daisy plants in a large field. Which method gives the most reliable estimate?

  1. Estimate the number by looking at the field from a hill.
  2. Count every daisy along one straight line across the field.
  3. Count the daisies in several random quadrats. Correct answer.
  4. Count the daisies in one small area near the gate.

Explanation

Random quadrats avoid the bias of choosing convenient spots and give several samples that can be averaged. Multiplying the mean count per quadrat by the number of quadrats that fit the field estimates the total.

Question 19Scientific skills and processes (investigation, measurement, data handling)

A student uses a thermometer that reads 3 degrees Celsius too high at every temperature, so every reading in the experiment is affected in the same way. What type of error is this, and how could it be reduced?

  1. Random error; repeat each reading and calculate a mean value.
  2. Random error; use a thermometer with a wider scale.
  3. Systematic error; take many readings and average them.
  4. Systematic error; calibrate against a known standard. Correct answer.

Explanation

The fault shifts every reading in the same direction by the same amount, which is the signature of a systematic error. Repeating readings or averaging cannot remove a constant offset; comparing the thermometer with a known standard and adjusting for the offset can.

Question 20Scientific skills and processes (investigation, measurement, data handling)

A survey finds that towns which sell more ice cream also record more incidents at swimming pools. Which conclusion is best supported by this evidence?

  1. Eating ice cream causes people to have accidents in pools.
  2. The two measurements are unrelated because they are different quantities.
  3. Swimming pool incidents cause higher ice cream sales.
  4. The two are linked, but causation is not shown. Correct answer.

Explanation

The survey shows that the two measurements vary together, which is a correlation. Without an experiment that changes one factor while controlling others, the data cannot establish which factor, if either, causes the other.

Question 21Scientific skills and processes (investigation, measurement, data handling)

A student notices that a metal can feels cold when touched. Which statement is an observation rather than an inference?

  1. The room is colder than the can.
  2. The can feels cold to the touch. Correct answer.
  3. The metal is a good conductor of heat.
  4. The can must contain ice.

Explanation

An observation records what is directly detected with the senses or an instrument, while an inference is an explanation built from observations. Feeling cold is a direct sensation, whereas saying why it feels cold requires interpretation. The other statements offer possible reasons rather than describing the sensation itself.

Question 22Scientific skills and processes (investigation, measurement, data handling)

A ruler has markings every 1 mm. A student uses it to measure the length of a pencil. To what precision can the student read the ruler directly?

  1. to the nearest 1 mm Correct answer.
  2. to the nearest 0.01 mm
  3. to the nearest 10 mm
  4. to the nearest 1 cm

Explanation

The smallest marked division on the ruler is 1 mm, so a direct reading can be made to the nearest millimetre. Estimating between marks may allow a fraction of a millimetre, but not the much finer precision of 0.01 mm. Readings to 1 cm or 10 mm would ignore the available markings.

Question 23Scientific skills and processes (investigation, measurement, data handling)

Which piece of apparatus is most suitable for measuring exactly 25.0 cm³ of water?

  1. a test tube with no volume markings
  2. a conical flask marked in 25 cm³ divisions
  3. a measuring cylinder with 1 cm³ markings Correct answer.
  4. a beaker marked in 10 cm³ divisions

Explanation

A measuring cylinder with 1 cm³ markings allows the volume to be read close to the required value with reasonable precision. Beakers and flasks have coarse or single markings, so they cannot measure 25.0 cm³ accurately. A test tube without markings cannot measure volume at all.

Question 24Scientific skills and processes (investigation, measurement, data handling)

A student investigates how the height of a ramp affects the distance a toy car travels along the floor. The same car and floor are used each time. Which is the dependent variable?

  1. the mass of the toy car used
  2. the distance the car travels Correct answer.
  3. the vertical height of the ramp
  4. the type of floor surface used

Explanation

The dependent variable is the quantity measured in response to a deliberate change. Here the ramp height is changed, and the distance travelled is measured as the outcome. The car mass and floor surface are controlled so they do not affect the result.

Question 25Scientific skills and processes (investigation, measurement, data handling)

A student times 20 complete swings of a pendulum three times and records 31.2 s, 31.4 s and 31.6 s. What is the best estimate of the time for one complete swing?

  1. 31.4 s
  2. 15.7 s
  3. 1.56 s
  4. 1.57 s Correct answer.

Explanation

First find the mean time for 20 swings: (31.2 + 31.4 + 31.6) ÷ 3 = 31.4 s. Then divide by 20 to find the time for one swing: 31.4 ÷ 20 = 1.57 s. The other values either use the total time or apply an incorrect division.

Question 26Scientific skills and processes (investigation, measurement, data handling)

A class records the favourite fruit chosen by each student from five options. Which type of graph is most suitable for comparing the number of students choosing each fruit?

  1. a pie chart showing temperature changes
  2. a scatter graph of fruit against number of students
  3. a bar chart with one bar for each fruit Correct answer.
  4. a line graph with fruit on the horizontal axis

Explanation

Favourite fruit is categorical data, so a bar chart is appropriate for comparing counts in separate categories. Line graphs and scatter graphs are designed for numerical data where order or trends matter. A pie chart showing temperature changes does not display the fruit counts.

Question 27Scientific skills and processes (investigation, measurement, data handling)

A student tests whether a new fertiliser increases plant growth. Ten plants receive fertiliser and ten identical plants receive only water. All plants are kept in the same light and temperature. Which group is the control group?

  1. the plants kept in the same light
  2. the ten plants that receive only water Correct answer.
  3. all twenty plants together
  4. the ten plants that receive fertiliser

Explanation

The control group is the standard treatment used for comparison, and here it is the group given only water. Any difference in growth can then be linked to the fertiliser rather than to other factors. Keeping light and temperature the same applies to both groups and is not itself a control group.

Question 28Scientific skills and processes (investigation, measurement, data handling)

A burette reading is 23.40 cm³ before adding liquid and 27.10 cm³ after. What volume of liquid was delivered?

  1. 3.70 cm³ Correct answer.
  2. 50.50 cm³
  3. 4.30 cm³
  4. 23.40 cm³

Explanation

The delivered volume is found by subtracting the initial reading from the final reading: 27.10 − 23.40 = 3.70 cm³. Adding the readings gives the total of both values, not the amount delivered. Using only the initial reading ignores the liquid added.

Question 29Scientific skills and processes (investigation, measurement, data handling)

A student measures the period of a pendulum five times and obtains 1.98 s, 2.01 s, 2.00 s, 1.99 s and 2.00 s. The accepted value is 2.00 s. Which statement best describes these measurements?

  1. They are both precise and accurate. Correct answer.
  2. They are accurate but not precise.
  3. They are precise but not accurate.
  4. They are neither precise nor accurate.

Explanation

Precision describes how closely repeated measurements agree with each other, and accuracy describes how close they are to the accepted value. The five readings are tightly clustered and their mean is essentially 2.00 s. Therefore the set is both precise and accurate.

Question 30Scientific skills and processes (investigation, measurement, data handling)

A student plots a graph of extension against force for a spring. The points form a straight line that passes through the origin. What does this show?

  1. Extension is directly proportional to force. Correct answer.
  2. The spring is not behaving elastically.
  3. The spring has reached its elastic limit.
  4. Force increases but extension stays constant.

Explanation

A straight line through the origin on an extension–force graph means extension changes by the same factor as force, which is direct proportionality. This is expected for a spring behaving elastically within its limit. A curve or a line not through the origin would show a different relationship.

Question 31Scientific skills and processes (investigation, measurement, data handling)

In a scientific investigation, what is meant by the dependent variable?

  1. The variable that has no connection with the investigation
  2. The variable that the investigator deliberately changes
  3. The variable that is measured in response to a change Correct answer.
  4. The variable that is kept constant throughout the investigation

Explanation

The dependent variable is the quantity that responds to the change the investigator makes, so it is the one measured or observed at each setting. The variable deliberately changed is the independent variable, while quantities held fixed are control variables. Identifying each role correctly is essential when planning a fair test.

Question 32Scientific skills and processes (investigation, measurement, data handling)

A student records the temperature of a cooling liquid every minute for ten minutes. Which type of graph is most suitable for displaying these results?

  1. A table of values with no axes labelled
  2. A line graph with time on the horizontal axis Correct answer.
  3. A pie chart showing the share of each temperature
  4. A bar chart with a separate bar for each minute

Explanation

Temperature changes continuously as time passes, so a line graph reveals the trend and allows values between readings to be estimated. Bar charts are used for categories and pie charts show proportions of a whole, so neither shows how one continuous quantity varies with another.

Question 33Scientific skills and processes (investigation, measurement, data handling)

A stopwatch shows a time of 1 minute 45 seconds. What is this time in seconds?

  1. 165 s
  2. 45 s
  3. 105 s Correct answer.
  4. 145 s

Explanation

Times must be converted to a single unit before being recorded, compared or averaged, and one minute contains 60 seconds. Adding the 60 s in the minute to the 45 s gives 105 s.

Question 34Scientific skills and processes (investigation, measurement, data handling)

When reading the volume of a liquid in a measuring cylinder, which procedure gives the most accurate reading?

  1. Looking down at the scale from above while the cylinder is held up
  2. Holding the cylinder at arm's length and reading the top of the liquid
  3. Looking up at the scale from below through the base of the cylinder
  4. Reading the meniscus at eye level with the cylinder on the bench Correct answer.

Explanation

For most liquids the reading is taken at the bottom of the curved meniscus, with the eye level with that point so the line of sight is perpendicular to the scale. Viewing from above or below produces a parallax error, making the recorded volume too high or too low.

Question 35Scientific skills and processes (investigation, measurement, data handling)

A student plots temperatures ranging from 20 degrees Celsius to 48 degrees Celsius and has a grid with 10 major divisions on the vertical axis. Which scale allows the points to be plotted most precisely?

  1. 0 to 100 degrees Celsius with each major division representing 10 degrees
  2. 0 to 50 degrees Celsius with each major division representing 5 degrees Correct answer.
  3. 50 to 100 degrees Celsius with each major division representing 5 degrees
  4. 0 to 20 degrees Celsius with each major division representing 2 degrees

Explanation

A good scale covers the whole range of the readings and uses the full grid so that each point can be placed precisely. A scale with coarser divisions loses precision, and a scale that does not include all the readings cannot be used at all.

Question 36Scientific skills and processes (investigation, measurement, data handling)

A student measures the boiling point of pure water five times and obtains 97 degrees Celsius every time. The accepted value is 100 degrees Celsius. Which statement best describes these results?

  1. They are accurate but not precise
  2. They are neither precise nor accurate
  3. They are both accurate and precise
  4. They are precise but not accurate Correct answer.

Explanation

Precise results agree closely with each other, while accurate results lie close to the true value. All five readings agree exactly, so they are precise, but they are 3 degrees below the accepted boiling point, showing a systematic error that makes them inaccurate.

Question 37Scientific skills and processes (investigation, measurement, data handling)

In an experiment, 24.0 cubic centimetres of gas is collected in 40 seconds. What is the average rate of gas production?

  1. 0.30 cubic centimetres per second
  2. 1.7 cubic centimetres per second
  3. 0.60 cubic centimetres per second Correct answer.
  4. 960 cubic centimetres per second

Explanation

A rate is the quantity produced divided by the time taken, so the volume is divided by the time: 24.0 divided by 40 gives 0.60 cubic centimetres per second. Recording the unit per second confirms the calculation has been set up the right way round.

Question 38Scientific skills and processes (investigation, measurement, data handling)

A seedling's mass increases from 2.4 g to 3.0 g over one week. What is the percentage increase in mass?

  1. 125%
  2. 25% Correct answer.
  3. 80%
  4. 20%

Explanation

Percentage change is the increase divided by the original value, multiplied by 100. The increase is 0.6 g, and 0.6 divided by 2.4 gives 0.25, which is 25%.

Question 39Scientific skills and processes (investigation, measurement, data handling)

Two students compare the absorbency of two brands of paper towel. They pour 20 cubic centimetres of water onto brand A and 40 cubic centimetres onto brand B, then measure how much water each towel soaks up. Why can they not conclude that brand B is more absorbent?

  1. The test was carried out at room temperature
  2. Water was used rather than another liquid
  3. The towels were the same size and shape
  4. A larger volume of water was poured onto brand B Correct answer.

Explanation

A fair test changes only the variable being investigated, which here is the brand of towel. Because brand B received twice as much water, any difference in uptake could be caused by the extra water available rather than by the towel itself, so absorbency cannot be compared.

Question 40Scientific skills and processes (investigation, measurement, data handling)

A student records the mass of an open dish of water every 5 minutes: 50.0 g, 48.5 g, 47.0 g, 45.6 g and 44.1 g. Which conclusion is best supported by these data?

  1. Water is lost at a steady rate of about 1.5 g per 5 minutes Correct answer.
  2. No water is lost during the first ten minutes of the experiment
  3. The rate of water loss increases steadily as the experiment continues
  4. The rate of water loss decreases steadily as the experiment continues

Explanation

The drops between successive readings are 1.5 g, 1.5 g, 1.4 g and 1.5 g, which are the same within the uncertainty of the balance. A constant loss in each equal time interval means the rate is steady. If the rate were changing, the drops would grow or shrink consistently.

Question 41Biology and life processes

Which cell structure controls the movement of substances into and out of a cell?

  1. Cell membrane Correct answer.
  2. Endoplasmic reticulum
  3. Nucleus
  4. Vacuole

Explanation

The cell membrane is a thin partially permeable layer that surrounds the cell. It allows some molecules, such as oxygen and water, to pass through while restricting others. This selective barrier controls exchange with the surroundings.

Question 42Biology and life processes

Root hair cells absorb water from the soil mainly by which process?

  1. Osmosis Correct answer.
  2. Translocation
  3. Active transport
  4. Respiration

Explanation

Soil water contains a lower concentration of dissolved solutes than the cell sap inside a root hair cell. Water therefore moves down its concentration gradient through the partially permeable cell membrane. This passive movement of water is called osmosis.

Question 43Biology and life processes

Which gas is released by a green plant during photosynthesis?

  1. Oxygen Correct answer.
  2. Water vapour
  3. Carbon dioxide
  4. Nitrogen

Explanation

In photosynthesis, green plants use light energy to combine carbon dioxide and water into glucose. Oxygen is produced as a by-product when water molecules are split. The oxygen diffuses out of the leaf through the stomata.

Question 44Biology and life processes

An enzyme-catalysed reaction is fastest at 37 °C. Which change is most likely to slow the reaction by altering the shape of the enzyme?

  1. Lowering the temperature to 20 °C
  2. Raising the temperature to 70 °C Correct answer.
  3. Adding more substrate
  4. Adding more enzyme

Explanation

Enzymes have a specific active site whose shape is held by bonds that are sensitive to temperature. Very high temperatures break these bonds, so the active site loses its shape and the enzyme is denatured. The substrate can then no longer bind, and the reaction rate falls sharply.

Question 45Biology and life processes

Which part of the digestive system absorbs most of the remaining water from undigested food before it is stored as faeces?

  1. Stomach
  2. Small intestine
  3. Oesophagus
  4. Large intestine Correct answer.

Explanation

By the time digested food reaches the large intestine, most nutrients have already been absorbed in the small intestine. The large intestine absorbs much of the remaining water, turning the waste into a more solid mass. This material is then stored in the rectum before being egested.

Question 46Biology and life processes

Which blood component carries oxygen from the lungs to respiring tissues?

  1. White blood cells
  2. Platelets
  3. Red blood cells Correct answer.
  4. Plasma

Explanation

Red blood cells contain haemoglobin, which binds oxygen in the lungs and releases it in tissues where oxygen concentration is low. Their biconcave shape gives a large surface area for gas exchange. This makes them the main oxygen-carrying component of blood.

Question 47Biology and life processes

Which sequence correctly describes the pathway of a reflex action when a person touches a hot object?

  1. receptor → sensory neurone → relay neurone → motor neurone → effector Correct answer.
  2. receptor → relay neurone → sensory neurone → effector → motor neurone
  3. effector → sensory neurone → relay neurone → motor neurone → receptor
  4. receptor → motor neurone → relay neurone → sensory neurone → effector

Explanation

A reflex arc begins with a receptor detecting the stimulus and generating an impulse. The impulse travels along a sensory neurone to a relay neurone in the spinal cord, then along a motor neurone to an effector. The muscle contracts quickly, often before the brain produces the sensation of pain.

Question 48Biology and life processes

In a cross between two heterozygous tall pea plants (Tt), what is the expected ratio of tall to short offspring?

  1. 1:1
  2. 3:1 Correct answer.
  3. 4:0
  4. 1:3

Explanation

Each heterozygous parent can pass on either a T allele or a t allele. A Punnett square gives TT, Tt, Tt and tt in equal proportions. Tall is dominant, so the three offspring with at least one T are tall and only tt is short, giving a 3:1 ratio.

Question 49Biology and life processes

On a hot day, which pair of responses helps a person lose heat?

  1. Metabolic rate increases and urine output increases.
  2. Sweating decreases and arterioles near the skin surface narrow.
  3. Shivering increases and hairs on the skin stand up.
  4. Sweating increases and arterioles near the skin surface widen. Correct answer.

Explanation

When body temperature rises, sweat glands release more sweat, and evaporation of sweat removes heat from the skin. At the same time, arterioles near the skin surface widen, so more warm blood flows close to the surface and heat is lost by radiation. These responses together increase heat loss and help restore normal body temperature.

Question 50Biology and life processes

During vigorous exercise, why does lactic acid build up in muscles?

  1. Lactic acid is converted to glucose in the muscles during exercise.
  2. Glucose is completely broken down with oxygen to carbon dioxide and water.
  3. Glucose is partly broken down without oxygen, producing lactic acid. Correct answer.
  4. Carbon dioxide is converted to lactic acid when oxygen is plentiful.

Explanation

During strenuous exercise, muscles may use oxygen faster than it can be supplied. Anaerobic respiration then breaks down glucose only partly, producing lactic acid instead of carbon dioxide and water. The lactic acid accumulates and can cause muscle fatigue until oxygen is available to break it down.