2026 Cambridge IGCSE Biology (0610) Practice Paper with Answers

A student investigated the effect of temperature on the rate of an enzyme-catalysed reaction. Which statement explains why the rate of reaction decreases rapidly at temperatures above the optimum temperature?

A piece of dialysis tubing containing a 10% sucrose solution is placed into a beaker of distilled water. Which row correctly describes the net movement of water molecules and the resulting change in the mass of the dialysis tubing?

Which hormone stimulates ovulation during the human menstrual cycle and where is it secreted?

Which process in the nitrogen cycle converts ammonium ions into nitrate ions in the soil?

A photomicrograph shows a palisade mesophyll cell. The measured width of the cell in the image is \(48\text{ mm}\). The actual width of the cell is \(80\ \mu\text{m}\). What is the magnification of the image?

Which sequence correctly shows the transfer of genetic information during the synthesis of a specific protein?

In a healthy human, which substance is completely reabsorbed from the renal filtrate back into the blood in the nephron?

Which chamber of the mammalian heart has the thickest muscular wall and generates the highest pressure to pump blood into the aorta?

A student investigated the rate of an enzyme-catalysed reaction at temperatures ranging from \(10\text{ }^\circ\text{C}\) to \(70\text{ }^\circ\text{C}\). At \(65\text{ }^\circ\text{C}\), the reaction ceased entirely. Which statement correctly explains why the reaction stopped?

Cylinders of potato tissue of equal initial mass were immersed in sucrose solutions of different concentrations (\(0.0\text{ mol/dm}^3\), \(0.2\text{ mol/dm}^3\), \(0.4\text{ mol/dm}^3\), and \(0.8\text{ mol/dm}^3\)) for 60 minutes. The cylinder in the \(0.8\text{ mol/dm}^3\) sucrose solution showed a significant decrease in mass. What caused this loss of mass?

Which row correctly identifies the hormone responsible for stimulating the repair and thickening of the uterine lining following menstruation, along with its primary site of secretion?

A micrograph shows a mammalian red blood cell with a measured image diameter of \(14\text{ mm}\). The magnification of the image is \(\times 2000\). What is the actual diameter of the red blood cell in micrometres (\(\mu\text{m}\))?

In a healthy human kidney, which substance passes from the blood into the renal capsule during ultrafiltration and is subsequently entirely reabsorbed into the capillaries from the nephron tubule?

Which statement correctly describes the action of the human heart during systemic circulation?

A double-stranded DNA molecule contains 120 base pairs. On one strand, there are 28 adenine (A) bases and 32 thymine (T) bases. What is the total number of cytosine (C) bases present in this entire double-stranded DNA molecule?

Why do natural food chains rarely contain more than five trophic levels?

An investigation was carried out into the effect of temperature on the rate of an enzyme-catalysed reaction. Which statement explains why the rate of reaction decreases rapidly above the optimum temperature?

Fresh plant tissue with a water potential equivalent to a \(0.3\text{ mol/dm}^3\) sucrose solution is placed into a concentrated \(0.8\text{ mol/dm}^3\) sucrose solution. Which row correctly describes the net movement of water and the resulting condition of the plant cells?

Which row correctly matches a hormone involved in the human menstrual cycle with its site of production and its primary role?

Why do food chains in natural ecosystems rarely consist of more than five trophic levels?

A photomicrograph shows a specialised human cell with an image diameter of \(28\text{ mm}\). The magnification of the image is \(\times 3500\). What is the actual diameter of the cell in micrometres (\(\mu\text{m}\))?

In a species of plant, petal colour is controlled by a single gene. The allele for purple petals (\(P\)) is dominant over the allele for white petals (\(p\)). A purple-flowered plant was crossed with a white-flowered plant, producing 49 purple-flowered offspring and 51 white-flowered offspring. What are the genotypes of the parent plants?

Which row correctly identifies substances filtered from the blood at the renal capsule (glomerulus) and a substance that is completely reabsorbed into the blood along the nephron in a healthy human?

Which heart chamber has the thickest muscular wall, and into which vessel does it directly pump oxygenated blood?

An experiment investigated the rate of an enzyme-catalysed reaction at different temperatures from \(10\text{ }^\circ\text{C}\) to \(60\text{ }^\circ\text{C}\).

Which statement explains why the rate of reaction decreases rapidly at temperatures above the optimum temperature?

Cylinders of potato tissue of identical length and mass were placed in test-tubes containing sucrose solutions of different concentrations: \(0.0\text{ mol}/\text{dm}^3\), \(0.4\text{ mol}/\text{dm}^3\), \(0.8\text{ mol}/\text{dm}^3\), and \(1.2\text{ mol}/\text{dm}^3\).

After two hours, in which concentration of sucrose solution will the potato cells have the highest turgor pressure?

Which row correctly identifies the site of secretion of luteinising hormone (LH) and its main function during the human menstrual cycle?

A woodland food chain is shown:

oak tree \(\rightarrow\) caterpillars \(\rightarrow\) blue tits \(\rightarrow\) sparrowhawk

The oak tree absorbs \(4\,000\,000\text{ kJ}\) of light energy, but only \(1\%\) is incorporated into biomass during photosynthesis.

Assuming a \(10\%\) efficiency of energy transfer between all subsequent trophic levels, how much energy is transferred to the sparrowhawk?

A photomicrograph shows a mammalian red blood cell with an observed image diameter of \(35\text{ mm}\).

The magnification of the image is \(\times 5\,000\).

What is the actual diameter of this red blood cell in micrometres (\(\mu\text{m}\))?

A mother with blood group A and a father with blood group B have a child who has blood group O.

What is the probability that their next child will have blood group AB?

Samples of fluid were extracted from three distinct regions of a healthy human kidney nephron:

- Region 1: blood in the afferent arteriole entering the glomerulus
- Region 2: filtrate inside the Bowman's capsule
- Region 3: urine exiting the collecting duct

Which row correctly shows the presence (+) or absence (-) of glucose and protein molecules in these samples?

Which set of events occurs during ventricular systole in the human cardiac cycle?

The effect of temperature on the rate of an amylase-catalysed reaction was investigated. The rate increased between \(10\,^{\circ}\text{C}\) and \(40\,^{\circ}\text{C}\), but decreased sharply above \(45\,^{\circ}\text{C}\).

Which statement explains why the rate of reaction decreases above the optimum temperature?

Four potato cylinders of equal mass (\(5.0\text{ g}\)) were placed into four different sucrose solutions, \(\text{P}\), \(\text{Q}\), \(\text{R}\), and \(\text{S}\). After two hours, their masses were measured again:

- Solution \(\text{P}\): \(5.8\text{ g}\)
- Solution \(\text{Q}\): \(5.0\text{ g}\)
- Solution \(\text{R}\): \(4.2\text{ g}\)
- Solution \(\text{S}\): \(3.6\text{ g}\)

In which solution was the initial water potential higher than that of the potato cells?

Which hormone is secreted by the developing follicle in the ovary to stimulate the repair and thickening of the endometrium during the human menstrual cycle?

The table compares the concentrations of three substances in blood plasma entering the glomerulus, filtrate in the renal capsule, and urine in a healthy human:

| Substance | Concentration in plasma / \(\text{g dm}^{-3}\) | Concentration in renal filtrate / \(\text{g dm}^{-3}\) | Concentration in urine / \(\text{g dm}^{-3}\) |
|---|---|---|---|
| 1 | 80.0 | 0.0 | 0.0 |
| 2 | 1.0 | 1.0 | 0.0 |
| 3 | 0.3 | 0.3 | 18.0 |

Which row correctly identifies substances 1, 2, and 3?

| | substance 1 | substance 2 | substance 3 |
|---|---|---|---|
| A | glucose | protein | urea |
| B | protein | glucose | urea |
| C | protein | urea | glucose |
| D | urea | glucose | protein |

Which sequence correctly traces the pathway of an oxygenated red blood cell leaving the lungs and travelling to the kidneys?

A strand of mRNA contains the triplet base sequence:

\(\text{AUG - CCA - UUC}\)

What was the base sequence on the template strand of the DNA molecule from which this mRNA sequence was transcribed?

A culture of bacteria is grown in a closed flask with a fixed volume of nutrient broth. After a period of exponential growth, the population enters the stationary phase.

Which statement correctly describes the population during the stationary phase?

A photomicrograph shows a palisade mesophyll cell. The length of the cell in the image is \(48\text{ mm}\). The actual length of the cell is \(60\,\mu\text{m}\).

What is the magnification of the photomicrograph?

Define the term enzyme.

Define the term osmosis.

Define the term homeostasis.

Define the term deamination and state the organ in which it occurs.

Define the term population.

Define the term gene.

Define the term pathogen.

Define the term translocation.

A student investigated the effect of \(\text{pH}\) on the activity of amylase.

Equal volumes of amylase and starch suspension were mixed at different \(\text{pH}\) values at a constant temperature of \(35\,^{\circ}\text{C}\). The time taken for starch to be completely broken down was recorded.

The results are shown in Table 1.1.

Table 1.1

| \(\text{pH}\) | Time taken to completely break down starch / s | Rate of reaction / \(\text{s}^{-1}\) |
| :--- | :--- | :--- |
| 4.0 | 250 | 0.004 |
| 5.0 | 100 | 0.010 |
| 6.0 | 40 | 0.025 |
| 7.0 | 25 | [A] |
| 8.0 | 50 | 0.020 |
| 9.0 | 200 | 0.005 |

(a) Calculate the rate of reaction at \(\text{pH}\) 7.0 to complete space [A] in Table 1.1.
$$\text{Rate} = \frac{1}{\text{time taken}}$$
Give your answer to two significant figures. [2]

(b) Explain why the rate of reaction was significantly lower at \(\text{pH}\) 9.0 than at \(\text{pH}\) 7.0. [2]

A student investigated osmosis using cylinders cut from a fresh potato tuber.

Cylinders of equal dimensions were immersed in sucrose solutions of various concentrations for 60 minutes.

The results are shown in Table 2.1.

Table 2.1

| Concentration of sucrose solution / \(\text{mol/dm}^3\) | Initial mass / g | Final mass / g | Change in mass / g | Percentage change in mass / \(\%\) |
| :--- | :--- | :--- | :--- | :--- |
| 0.0 | 3.20 | 3.68 | +0.48 | +15.0 |
| 0.2 | 3.20 | 3.44 | +0.24 | +7.5 |
| 0.4 | 3.20 | 3.20 | 0.00 | 0.0 |
| 0.6 | 3.20 | 2.96 | -0.24 | [B] |
| 0.8 | 3.20 | 2.72 | -0.48 | -15.0 |

(a) Calculate the percentage change in mass for the potato cylinder placed in the \(0.6\,\text{mol/dm}^3\) sucrose solution to complete space [B] in Table 2.1. Include the sign. [2]

(b) Using the data in Table 2.1, state the estimated concentration of sucrose inside the potato tuber cells and explain what occurs to the cells in the \(0.8\,\text{mol/dm}^3\) solution. [2]

Samples of blood plasma, glomerular filtrate, and urine were collected from a healthy individual and analysed for the concentration of various chemical components.

The findings are summarised in Table 3.1.

Table 3.1

| Substance | Concentration in blood plasma / \(\text{g/dm}^3\) | Concentration in glomerular filtrate / \(\text{g/dm}^3\) | Concentration in urine / \(\text{g/dm}^3\) |
| :--- | :--- | :--- | :--- |
| Protein | 75.0 | 0.0 | 0.0 |
| Glucose | 1.0 | 1.0 | [C] |
| Urea | 0.3 | 0.3 | 18.0 |
| Mineral ions | 8.0 | 8.0 | 16.0 |

(a) State the concentration value that should be recorded in space [C] for glucose in urine and explain why this value is observed in a healthy person. [2]

(b) Calculate how many times more concentrated urea is in the urine compared to the glomerular filtrate. [2]

A culture of yeast cells was grown in a nutrient broth in a closed conical flask over a 24-hour period. The population density was recorded every 4 hours.

The results are presented in Table 4.1.

Table 4.1

| Time / \(\text{hours}\) | Population density / \(\times 10^4\text{ cells/cm}^3\) |
| :--- | :--- |
| 0 | 4.0 |
| 4 | 6.0 |
| 8 | 18.0 |
| 12 | 54.0 |
| 16 | 90.0 |
| 20 | 96.0 |
| 24 | 96.0 |

(a) Calculate the percentage increase in yeast population density between hour 4 and hour 12. Show your working. [2]

(b) Identify the growth phase occurring between 20 and 24 hours and explain why the yeast population stops increasing during this phase. [2]

A student investigated their ventilation during different levels of physical activity.

Minute ventilation is the total volume of air inspired per minute and is calculated using the equation:
$$\text{Minute ventilation} = \text{Breathing rate} \times \text{Tidal volume}$$

Table 5.1 displays the collected data.

Table 5.1

| Activity state | Breathing rate / \(\text{breaths/min}\) | Tidal volume / \(\text{dm}^3\) | Minute ventilation / \(\text{dm}^3\text{/min}\) |
| :--- | :--- | :--- | :--- |
| At rest | 14 | 0.50 | 7.0 |
| Running on treadmill | 28 | 2.25 | [D] |
| 10 min post-exercise recovery | 18 | 0.75 | 13.5 |

(a) Calculate the minute ventilation when running on the treadmill to complete space [D] in Table 5.1. [1]

(b) Explain why both breathing rate and tidal volume remain elevated at '10 min post-exercise recovery' compared to 'At rest'. [3]

The blood glucose concentration of a healthy human volunteer was measured over a period of 120 minutes following the consumption of a meal rich in starch.

The results are shown in Table 6.1.

Table 6.1

| Time after meal / \(\text{min}\) | Blood glucose concentration / \(\text{mmol/dm}^3\) |
| :--- | :--- |
| 0 | 4.8 |
| 30 | 8.4 |
| 60 | 6.6 |
| 90 | 5.2 |
| 120 | 4.8 |

(a) Calculate the rate of decrease in blood glucose concentration between 30 minutes and 90 minutes. State the correct units in your answer. [2]

(b) Describe the biological mechanism that brings about the decrease in blood glucose concentration between 30 minutes and 120 minutes. [2]

(a) Define the term gene. [1]

(b) State the role of mRNA in protein synthesis. [2]

(c) Explain how the sequence of bases in a gene determines the specific 3D shape and biological activity of an enzyme. [3]

A student investigated the effect of different concentrations of sucrose solution on cylinders cut from a sweet potato (Ipomoea batatas).

Method:
1. A cork borer was used to cut six cylinders of tissue from the same sweet potato.
2. A scalpel and ruler were used to cut each cylinder to an initial length of \(40\text{ mm}\).
3. Each cylinder was gently blotted with a paper towel and its initial mass was measured and recorded using an electronic balance.
4. Six boiling tubes were set up containing \(25\text{ cm}^3\) of sucrose solution of concentrations: \(0.0\), \(0.2\), \(0.4\), \(0.6\), \(0.8\), and \(1.0\text{ mol/dm}^3\).
5. One sweet potato cylinder was placed into each boiling tube and left for \(60\text{ minutes}\).
6. After \(60\text{ minutes}\), each cylinder was removed, blotted gently with a paper towel, and its final mass was measured and recorded.

The student recorded their results in Table 1.

Table 1

| Sucrose concentration / \(\text{mol/dm}^3\) | Initial mass / \(\text{g}\) | Final mass / \(\text{g}\) | Change in mass / \(\text{g}\) | Percentage change in mass / \(\%\) |
| :--- | :--- | :--- | :--- | :--- |
| \(0.0\) | \(3.20\) | \(3.68\) | \(+0.48\) | \(+15.0\) |
| \(0.2\) | \(3.15\) | \(3.40\) | \(+0.25\) | \(+7.9\) |
| \(0.4\) | \(3.25\) | \(3.28\) | \(+0.03\) | [A] |
| \(0.6\) | \(3.10\) | \(2.91\) | \(-0.19\) | \(-6.1\) |
| \(0.8\) | \(3.30\) | \(2.87\) | \(-0.43\) | [B] |
| \(1.0\) | \(3.20\) | \(2.62\) | \(-0.58\) | \(-18.1\) |

(a) (i) Calculate the percentage change in mass for the cylinders placed in the \(0.4\text{ mol/dm}^3\) and \(0.8\text{ mol/dm}^3\) sucrose solutions. Give your answers to one decimal place. [2]

(ii) State why calculating the percentage change in mass allows a more valid comparison than using the raw change in mass. [1]

(b) On the grid, plot a line graph of percentage change in mass against sucrose concentration. Draw a smooth curve or join the points with ruled straight lines. [4]

(c) (i) Use your graph to estimate the sucrose concentration that has an equivalent water potential to the sweet potato tissue. Indicate clearly on your graph how you determined this value. [2]

(ii) Explain the change in mass of the cylinder placed in the \(0.0\text{ mol/dm}^3\) sucrose solution. [2]

(d) (i) State two variables that were kept constant in this investigation. [2]

(ii) Identify one potential source of error in step 3 or step 6 of the method and suggest an improvement to minimize this error. [2]

Fig. 1.1 shows a photomicrograph of a transverse section through the root of a young dicotyledonous plant.

[Fig. 1.1: A transverse section of a dicotyledonous root showing an outer layer of epidermis, a wide cortex of parenchyma tissue, an inner endodermis ring, and a central vascular cylinder (stele) containing a 4-armed (x-shaped) core of xylem surrounded by patches of phloem. A straight line labelled XY runs horizontally across the total width of the root section, measuring 75 mm.]

(a) Make a large, labelled outline drawing of the root cross-section shown in Fig. 1.1.
Do not draw individual cells.

(b) (i) Measure the length of line XY on Fig. 1.1.

Length of line XY = .................................................... mm

(ii) The magnification of the image in Fig. 1.1 is \(\times 25\).
Calculate the actual diameter of the root along line XY.
Give your answer in micrometres (\(\mu\text{m}\)).

Show your working.

Pectinase is an enzyme widely used in the food industry to break down cell wall components in fruit pulp and increase the yield of extracted juice.

Plan an investigation to determine the effect of temperature on the volume of fruit juice produced from apple purée using pectinase.

You are provided with apple purée, a 1% solution of pectinase enzyme, standard laboratory glassware, and access to thermostatically controlled water-baths.

Your plan should include:
- the independent variable and how you will change it, including the range and values you will use
- the dependent variable and the method you will use to measure it
- the variables that must be kept constant and how you will control them
- a safety precaution
- how you will ensure the reliability of your results.

Pectinase is an enzyme widely used in the food industry to break down cell wall components in fruit pulp and increase the yield of extracted juice.

Plan an investigation to determine the effect of temperature on the volume of fruit juice produced from apple purée using pectinase.

You are provided with apple purée, a 1% solution of pectinase enzyme, standard laboratory glassware, and access to thermostatically controlled water-baths.

Your plan should include:
- the independent variable and how you will change it, including the range and values you will use
- the dependent variable and the method you will use to measure it
- the variables that must be kept constant and how you will control them
- a safety precaution
- how you will ensure the reliability of your results.

A student investigated the distribution and population size of a plant species, hoary plantain (Plantago media), growing across a meadow bordering a dense woodland.

A 50 m tape measure was laid out as a line transect perpendicular to the woodland edge into the meadow.
A $0.5\text{ m} \times 0.5\text{ m}$ ($0.25\text{ m}^2$) quadrat was placed at 10 m intervals along the transect line, and the number of individual hoary plantain plants inside each quadrat was counted.

The results are shown in Table 1.1.

Table 1.1

| Distance from woodland edge / m | Number of plants per $0.25\text{ m}^2$ quadrat |
| :--- | :--- |
| 0 | 2 |
| 10 | 6 |
| 20 | 11 |
| 30 | 17 |
| 40 | 24 |
| 50 | 32 |

(a) Plot a line graph on the grid of the number of plants per $0.25\text{ m}^2$ quadrat against the distance from the woodland edge. [4]

(b) (i) Describe the relationship between the distance from the woodland edge and the number of plants per quadrat. [1]

(ii) Use your graph to estimate the number of plants per quadrat at a distance of 25 m from the woodland edge. Show clearly on your graph how you obtained your answer. [2]

(c) The open meadow at the far end of the transect has a total area of $1200\text{ m}^2$.
To estimate the total population of hoary plantain in this open meadow, the student threw ten $0.25\text{ m}^2$ quadrats at random across the meadow.
The total number of hoary plantain plants counted across all 10 quadrats combined was 310.

Calculate the estimated total population of hoary plantain plants in the $1200\text{ m}^2$ meadow.

Show your working. [2]

(d) State two ways the student could improve the accuracy or reliability of the population estimate in (c). [2]