GCSE Combined Science Digestion & enzymes questions by topic

Complete the table of digestive enzymes with substrates and products.

1. (a)Name the enzyme that digests starch.[1]
2. (b)Name the products of protein digestion.[1]
3. (c)Name the two products of lipid digestion.[2]

This question is about the food tests.

1. (a)Name the reagent used to test for starch and its positive colour.[2]
2. (b)Name the positive result of the biuret test.[1]
3. (c)State one safety precaution when heating Benedict’s samples.[1]

Put the levels of organisation in order and match them to digestion.

1. (a)Arrange in order of increasing size: organ, organelle, organ system, cell, tissue.[2]
2. (b)Name the organ system described in this chapter.[1]
3. (c)Give one organ that belongs to it.[1]

Describe the two roles of bile.

1. (a)State where bile is made and where it is stored.[2]
2. (b)Describe each of bile’s two roles.[2]

A student tests an unknown food sample.

1. (a)The sample turns Benedict’s solution orange after heating. What does this show, and why not brick-red?[2]
2. (b)A separate sample turns cloudy white with the ethanol test. What does this show?[1]
3. (c)Explain why a fresh sample is needed for each test.[1]

An amylase experiment gives the timings below.

1. (a)Identify the optimum pH from the data.[1]
2. (b)Calculate the rate at pH 7, giving the unit.[2]
3. (c)Describe the trend as pH moves away from the optimum.[1]

Explain how pH denatures an enzyme.

1. (a)Describe what pH change does to the enzyme molecule.[2]
2. (b)Explain why this stops the reaction.[2]

A class repeats the amylase practical three times at each pH.

1. (a)Explain why repeats improve the results.[2]
2. (b)State two other control variables in this practical.[2]

A student forgets the water bath and runs the pH 7 tube on an icy bench while the other tubes stay warm.

1. (a)Predict the effect on the pH 7 tube’s time and rate.[2]
2. (b)Explain your prediction using enzyme theory.[2]
3. (c)State how this error affects the conclusion about the optimum pH.[1]

Compare the digestion of a chip of boiled egg white (protein) and a drop of olive oil in the small intestine.

1. (a)Name the enzyme and products for each food.[4]
2. (b)Explain the extra step fats need before their enzyme can work well.[2]

A student claims: “Bile is an enzyme because it helps digest fat.”

1. (a)State whether the claim is correct.[1]
2. (b)Explain your answer using what bile actually does.[3]
3. (c)Name the enzyme that does digest fat and where it is made.[1]

Design a control to prove that the amylase result at pH 7 was not an accident of the iodine testing.

1. (a)Describe a suitable negative control tube.[2]
2. (b)State the expected result and what it proves.[2]