IGCSE Biology 0610/63 October/November 2025 Past Paper with Answers

Question 1

In an investigation into invertase, a student needs to measure the temperature of the liquid in the test-tubes after they have been in the water-bath. Which piece of laboratory equipment is used to measure temperature?

1. a thermometer
2. a measuring cylinder
3. a stop-clock
4. a top-pan balance

Question 2

A student adds Benedict’s solution to three test-tubes and records the final colours as: test-tube A is brick-red, test-tube B is green and test-tube W is blue. Which option describes a correct results table for these observations?

1. a ruled table with a header line and two columns headed test-tube and colour of liquid, recording A as brick-red, B as green and W as blue
2. a ruled table with a header line and full headings, but recording A as blue, B as green and W as brick-red, with the colours of A and W swapped over
3. a block of continuous writing with no ruled columns and no headings, simply stating that the tubes ended up as different colours
4. a ruled table with a header line and headings, but recording all three test-tubes A, B and W as the same brick-red colour

Question 3

In an invertase investigation, test-tube A with 100% invertase extract turns brick-red with Benedict’s solution (a lot of reducing sugar) while test-tube B with 10% invertase extract only turns green (less reducing sugar). What is the correct conclusion about the effect of invertase concentration on the reducing sugar produced?

1. the greater the concentration of invertase, the more reducing sugar is produced
2. the greater the concentration of invertase, the less reducing sugar is produced
3. the concentration of invertase has no effect on the amount of reducing sugar produced
4. reducing sugar is only produced when no invertase at all is added

Question 4 · Answer A

Step 1: Test-tube W has sucrose but no invertase, so it is the control. Step 2: It stays blue, showing that sucrose is not broken down into reducing sugar without invertase. Step 3: This means any reducing sugar found in A and B must be caused by the invertase, making the comparison valid.

Question 5 · Answer A

Step 1: The independent variable is the one the student deliberately changes. Step 2: Here the student changes the concentration of invertase extract (100% in one tube and 10% in another). Step 3: So the independent variable is the concentration of the invertase extract; the colour is the dependent variable and the rest are kept constant.

Question 6 · Answer A

Step 1: Enzymes such as invertase work fastest at a suitable warm temperature. Step 2: Placing all the tubes in the same warm water-bath keeps them at the same temperature and gives a high enough rate of reaction. Step 3: So the warm water-bath ensures a fair comparison and lets the invertase work quickly.

Question 7 · Answer A

Step 1: A syringe that has measured one solution still has some of it left inside. Step 2: Re-using it would carry that solution into the next tube and change its contents. Step 3: A clean syringe avoids this contamination, keeping each tube’s concentrations accurate.

Question 8 · Answer A

Step 1: The food test for protein uses biuret reagent. Step 2: A positive result is a colour change from blue to purple (lilac). Step 3: So biuret reagent is used to test for protein; the other reagents test for reducing sugar, starch and fat.

Question 9 · Answer A

Step 1: Controlled variables are the factors kept the same so they do not affect the result. Step 2: The volume of yeast suspension and the counting time must be kept constant at every temperature. Step 3: Temperature is deliberately changed (independent) and bubble number is measured (dependent), so neither of those can be a controlled variable.

Question 10 · Answer A

Step 1: Bubbles can vary in size and may be produced too quickly to count exactly, so counting them is not very accurate. Step 2: A better measure of the gas made is to collect it and measure its volume. Step 3: Measuring the volume of gas removes the problem of uneven or fast bubbles, improving the accuracy of the dependent variable.

Question 11 · Answer A

Step 1: Rate of bubble production = number of bubbles ÷ time = 79 ÷ 3 = 26.33 bubbles per minute. Step 2: The other table values are given to two significant figures. Step 3: So 26.33 rounds to 26 bubbles per minute, which matches the rest of the table.

Question 12 · Answer A

Step 1: Both axes must be labelled with units, here temperature / °C and rate of bubble production / bubbles per minute. Step 2: A suitable linear scale should let the points fill at least half the grid, and all six points must be plotted accurately. Step 3: The points are then joined with a smooth curve of best fit, which shows the rate rising to a peak and then falling.

Question 13 · Answer A

Step 1: From 10 °C to 50 °C the rate rises from 11 to 41 bubbles per minute. Step 2: The highest rate (the peak) is at 50 °C. Step 3: After 50 °C the rate falls to 12 at 60 °C, so the rate increases to a peak at 50 °C and then decreases.

Question 14 · Answer A

Step 1: Carbon dioxide is tested for using limewater. Step 2: When carbon dioxide is bubbled through limewater, the limewater turns cloudy (milky) as a white precipitate forms. Step 3: So bubbling the gas through limewater and seeing it turn cloudy confirms the gas is carbon dioxide.

Question 15 · Answer A

Step 1: A biological drawing uses a single clear continuous outline with no shading and should be drawn large. Step 2: It must show the real features in the correct positions: the bordered tear-shaped pale patch, the pale patch near the base of the beak and the lines on the beak. Step 3: So a large unshaded single-line drawing showing these details is correct.

Question 16 · Answer A

Step 1: Rearranging the formula, actual length = length of line AB / magnification. Step 2: That is 46 mm / 0.42 = 109.52 mm. Step 3: To one decimal place 109.52 mm rounds to 109.5 mm; because the magnification is less than one, the real beak is larger than its photograph.

Question 17 · Answer A

Step 1: One difference is the white patch around the eye: triangular and smaller in the gentoo penguin, semicircular and larger in the black-footed penguin. Step 2: Another difference is the beak: the gentoo penguin’s beak has no dark stripe, while the black-footed penguin’s beak carries a stripe. Step 3: So the option giving the triangular patch and the stripe-free beak for the gentoo penguin is correct.

Question 18 · Answer A

Step 1: The independent variable is the thickness of insulation, so only that should change, using at least two different thicknesses of the same material. Step 2: The dependent variable is heat loss, measured as the temperature fall (or the time for a set fall) of the hot water. Step 3: The volume of water, beaker type, starting temperature and surroundings are kept constant, each thickness is repeated for a mean, and a safety precaution is taken with the hot water.