IGCSE Biology 0610/62 October/November 2025 Past Paper with Answers

Question 1

A student measures the rate of respiration in yeast by reading the height of the yeast suspension in two large test-tubes after five minutes in a warm water-bath. The tube set up with 1% glucose solution gives a yeast-suspension height of 13 mm and the tube set up with 4% glucose solution gives a height of 23 mm. Which option describes a correct results table and the matching values?

1. a ruled table with a header line and column headings that include the unit mm, recording 13 mm for the 1% glucose tube and 23 mm for the 4% glucose tube
2. a ruled table with a header line and full headings, but recording 23 mm for the 1% glucose tube and 13 mm for the 4% glucose tube, with the two tubes swapped over
3. a ruled table with a header line and headings but no units anywhere, recording only the bare numbers 13 and 23 with nothing to show they are heights in mm
4. a single sentence of writing with no ruled columns and no header line, simply stating that one tube was taller than the other without any measured heights

Question 2

In the yeast investigation the yeast suspension reached 13 mm in the 1% glucose tube and 23 mm in the 4% glucose tube after five minutes, because respiring yeast releases gas that pushes the suspension up. What is the correct conclusion about the effect of glucose concentration on the rate of respiration in the yeast?

1. the higher the concentration of glucose, the greater the rate of respiration in the yeast
2. the higher the concentration of glucose, the lower the rate of respiration in the yeast
3. the concentration of glucose has no effect on the rate of respiration in the yeast
4. the yeast only respires in the tube with the lower concentration of glucose

Question 3

In the yeast investigation the student used a 1% and a 4% glucose solution and measured how far the yeast suspension rose in the large test-tube. Which option correctly states the independent variable and the dependent variable for this investigation?

1. independent variable: the concentration of the glucose solution; dependent variable: the height of the yeast suspension in the large test-tube
2. independent variable: the height of the yeast suspension in the large test-tube; dependent variable: the concentration of the glucose solution
3. independent variable: the temperature of the water-bath; dependent variable: the volume of yeast suspension used
4. independent variable: the time the tubes were left; dependent variable: the concentration of the glucose solution

Question 4 · Answer A

Step 1: To keep a temperature constant you need something that adds heat as the water cools. Step 2: A thermostatically controlled water-bath has a heater and a thermostat that switch on and off to hold the set temperature. Step 3: So using a thermostatically controlled water-bath keeps the temperature steady throughout.

Question 5 · Answer A

Step 1: The first syringe has been used to measure glucose solution, so some glucose is left inside it. Step 2: Re-using it would carry that glucose into the distilled water, changing the concentration. Step 3: A clean syringe avoids this contamination, keeping the glucose concentrations accurate.

Question 6 · Answer A

Step 1: The amount of glucose must be the same before and after dilution, so volume x 5% = 5 cm3 x 3%, giving volume x 5 = 15. Step 2: So the volume of 5% glucose needed is 15 / 5 = 3 cm3. Step 3: The distilled water makes the total up to 5 cm3, so 5 - 3 = 2 cm3 of water.

Question 7 · Answer A

Step 1: The food test for a reducing sugar uses Benedict’s solution. Step 2: The mixture must be heated, usually in a hot water-bath, for the reaction to occur. Step 3: A positive result is a colour change from blue to brick-red (orange), so adding Benedict’s and heating is the correct method.

Question 8 · Answer A

Step 1: In the emulsion test the food is mixed with ethanol and then added to water. Step 2: If fat is present, it forms tiny droplets in the water that scatter light. Step 3: This makes the mixture look cloudy and milky-white, which is the positive result.

Question 9 · Answer A

Step 1: Ethanol is highly flammable and its vapour can catch fire easily. Step 2: A naked flame near ethanol could ignite the vapour, so flames must be kept away. Step 3: Keeping the ethanol away from naked flames is therefore a suitable safety precaution.

Question 10 · Answer A

Step 1: The independent variable is exercise intensity, so only the intensity should change, using several levels such as walking, jogging and running for the same time. Step 2: The dependent variable is heart rate, measured after each exercise, letting the heart rate return to resting between tests. Step 3: The same person, duration and surroundings are kept constant and each intensity is repeated at least three times to find a reliable mean, with a sensible safety precaution.

Question 11 · 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 right number and place: five arms around an enclosed central shape that does not touch the edges. Step 3: It should also indicate where the colour changes along each arm, so a single large unshaded outline with these details is correct.

Question 12 · Answer A

Step 1: Rearranging the formula, actual diameter = length of line PQ / magnification. Step 2: That is 93 mm / 0.32 = 290.6 mm. Step 3: To two significant figures 290.6 mm rounds to 290 mm; because the magnification is less than one, the real starfish is larger than the photograph.

Question 13 · Answer A

Step 1: One clear difference is that the spiny starfish has spines along its arms while the necklace starfish has a smooth surface. Step 2: Another difference is the centre colour: the spiny starfish has a bright (light) centre while the necklace starfish has a dark centre. Step 3: A correct similarity is that both starfish have five tapering arms (radial symmetry), so the option giving these two differences and this similarity is correct.

Question 14 · Answer A

Step 1: To compare counts fairly, the sampling must be the same at every depth. Step 2: Photographing the same 20 m² area each time means the counts are from equal areas, and taking all photographs on the same day in the same region removes day-to-day and place differences. Step 3: So using the same area size and the same day and region makes the counts comparable.

Question 15 · Answer A

Step 1: Both axes must be labelled with their units, here depth / m and number of seven-armed starfish. Step 2: A suitable linear scale should let the data fill at least half the grid, and all five depth ranges must be plotted accurately. Step 3: Because the depth is in equal ranges, the bars are drawn equal in width with no gaps between them, which is what a histogram requires.

Question 16 · Answer A

Step 1: The depth range with the most starfish is the one with the largest count. Step 2: Comparing 337, 1486, 1243, 241 and 121, the largest is 1486. Step 3: That count belongs to the 10.0 to 19.9 m range, so most starfish were found there.

Question 17 · Answer A

Step 1: The total is the sum of all five counts: 337 + 1486 + 1243 + 241 + 121 = 3428 starfish. Step 2: The percentage in the 0.0 to 9.9 m range is 337 / 3428 x 100 = 9.83. Step 3: As a whole number this rounds to 10%, so the total is 3428 and 10% were in the 0.0 to 9.9 m range.