0610 Biology November 2025 Question Paper 63

1 Yeast cells produce an enzyme called invertase. Invertase catalyses the breakdown of sucrose into reducing sugars. Sucrose is not a reducing sugar.

A student investigated the effect of two different concentrations of invertase extract on a sucrose solution.

The student used this method:

Step 1 Label three test-tubes A, B and W.

Step 2 Use a syringe to put 2 cm3 of sucrose solution into all three test-tubes.

Step 3 Use a clean syringe to put 2 cm3 of 100% invertase extract into test-tube A.

Step 4 Use a clean syringe to put 2 cm3 of 10% invertase extract into test-tube B.

Step 5 Use a clean syringe to put 2 cm3 of distilled water into test-tube W.

Step 6 Put all three test-tubes in a warm water-bath at 40 °C for 15 minutes.

Step 7 Measure the temperature of the liquid in the test-tubes.

(a) State the name of the piece of equipment that is used to measure temperature [1]

Step 8 Use a clean syringe to add 4 cm3 of Benedict’s solution to all three test-tubes.

Step 9 Place all three test-tubes into a hot water-bath for five minutes.

Step 10 After five minutes, record the colour of the liquid in each test-tube.

Fig. 1.1 shows the notes the student made about their observations in step 10. the liquid in test-tube A is brick-red the liquid in test-tube B is green W remains blue Fig. 1.1 , ,

(b) Prepare a table and record the results of this investigation using the information in Fig. 1.1.

[3]

(c) State a conclusion for the results shown in test-tube A and test-tube B [1]

(d) Explain the purpose of test-tube W [2]

(e) State the independent variable in this investigation [1]

(f) Explain why the test-tubes were placed in the warm water-bath in step 6 [1] , ,

(g) Explain why a clean syringe was used in steps 3, 4 and 5 [1]

(h) Invertase is a protein.

State the reagent used to test for the presence of protein [1]

[Total: 11] , ,

2 A student investigated the effect of temperature on the rate of respiration in yeast cells.

They used the apparatus shown in Fig. 2.1. clamp measuring cylinder water water-bath yeast suspension Fig. 2.1

The student used this method: • Put 25 cm3 of yeast suspension into a test-tube. • Put the test-tube into a water-bath and add water at 10 °C to the water-bath. • Leave the apparatus for five minutes before moving on to the next step. • Start a stop-clock and count the number of bubbles produced by the respiring yeast cells in three minutes. • Repeat the procedure using a water-bath maintained at different temperatures.

(a) (i) State two variables that the student kept constant in this investigation. 1 2 [2]

(ii) State one possible source of error when measuring the dependent variable and suggest an improvement to this method of measuring. error improvement [2] , ,

(b) Table 2.1 shows the results of the investigation. Table 2.1 water-bath temperature / °C number of bubbles produced in 3 minutes rate of bubble production / bubbles per minute 10 33 11 20 45 15 30 79 40 112 37 50 124 41 60 37 12

(i) Calculate the rate of bubble production at 30 °C.

Give your answer to an appropriate number of significant figures.

Space for working bubbles per minute [2] , ,

(ii) Plot the data in Table 2.1 on the grid to show the effect of temperature on the rate of bubble production.

[4]

(iii) Describe the results of this investigation [2]

(c) Describe how the student could confirm that the gas produced is carbon dioxide [2]

[Total: 14] , ,

3 (a) Fig. 3.1 is a photograph of the head of a king penguin. A B magnification ×0.42 Fig. 3.1

(i) Make a large drawing of the head of the king penguin shown in Fig. 3.1. [4] , ,

(ii) The length of line AB represents the length of the penguin’s beak.

Measure the length of line AB in Fig. 3.1.

length of line AB mm

Use your measurement and the formula to calculate the actual length of the penguin’s beak. magnification = length of line AB in Fig. 3.1 actual length of the penguin’s beak

Give your answer to one decimal place.

Space for working mm

[3] , ,

(b) Fig. 3.2 shows the heads of a gentoo penguin and a black-footed penguin. gentoo black-footed not to scale Fig. 3.2

Other than size, state two ways the gentoo penguin differs from the black-footed penguin in Fig. 3.2. 1 2 [2] , ,

(c) Penguins are covered in feathers. The feathers reduce heat loss by insulating the birds from the cold.

A beaker of hot water can be used to represent a penguin.

Plan an investigation to determine the effect of the thickness of an insulating material on heat loss in a beaker of hot water [6]

[Total: 15] , ,