4N Term 3 Revision WS 2 (Bio Molecules & Nutrition in Humans)

4N Term 3 Revision WS 2 (Bio Molecules & Nutrition in Humans)

By Sarah Ang

Open Ended

Describe and explain the relationship shown by the curve.

Let's start with 'At low temperature, the rate of reaction is...'

Open Ended

Describe and explain the relationship shown by the curve.

Let's carry on with 'As temperature increases from 10 to 40oC, the rate of reaction...'

Open Ended

Describe and explain the relationship shown by the curve.

Let's carry on with 'At 40oC, the rate of reaction...'

Open Ended

Describe and explain the relationship shown by the curve.

Let's end on with 'Beyond optimum temperature from 40oC, the rate of reaction...'

Multiple Choice

Identify the components X, Y and Z.

• X is sucrose.

  Y is fructose and glucose.

  Z is sucrase.

• X is fructose and glucose

  Y is sucrose.

  Z is sucrase.

• X is sucrase.

  Y is sucrose.

  Z is fructose and glucose.

Open Ended

Using the lock and key hypothesis, explain the action of sucrase on sucrose.

Using the lock and key hypothesis, explain the action of sucrase on sucrose.

Sucrase was the lock and sucrose was the key [0.5].

Sucrose has a shape complementary to the active site of sucrase [0.5] and thus binds to it to form the enzyme-substrate complex [0.5].

Sucrose is then broken down [0.5] to form the products fructose and glucose [0.5]. The products are then released and sucrase remains unchanged and is ready for the next reaction [0.5].

Open Ended

The optimum temperature of sucrase is 55 ^oC. What would happen if a mixture of sucrase and sucrose was placed in a water bath of 80 ^oC.

The optimum temperature of sucrase is 55 ^oC. What would happen if a mixture of sucrase and sucrose was placed in a water bath of 80 ^oC.

Sucrase would be denatured [1]. The active site would be altered [0.5]. Sucrose is not complementary to shape of active site [0.5]. Sucrose can no longer bind to it [0.5] and is thus not broken down [0.5].

Open Ended

Explain how reducing sugar may have appeared in the sample from A.

Explain how reducing sugar may have appeared in the sample from A.

Starch was broken down by salivary amylase in the mouth to form maltose.

Maltose is a reducing sugar.

Multiple Choice

What is one digestive enzyme which is responsible for the presence of amino acid in the sample from B.

• Protease

• Lipase

• Sucrase

• Amylase

Open Ended

The juice from duct X is boiled for 10 minutes and then mixed with peanut oil and water. The mixture is shaken vigorously for a while. State and explain what you expect to observe.

The juice from duct X is boiled for 10 minutes and then mixed with peanut oil and water. The mixture is shaken vigorously for a while. State and explain what you expect to observe.

A white emulsion is formed. [1] The juice from duct X contains bile which emulsifies fats into smaller fat droplets.[1] Since bile is not an enzyme, boiling has no effect on its activity. [1]

Poll

What colour will you observe in well W?

• Brown because all the starch has been digested.

• Blue Black because the starch has not been digested. There is no enzyme present in distilled water.

• Blue Black because the starch has not been digested. The enzyme has denatured.

Multiple Choice

What colour will you observe in well X?

• Brown because all the starch has been digested.

• Blue Black because the starch has not been digested. There is no enzyme present in distilled water.

• Blue Black because the starch has not been digested. The enzyme has denatured.

Multiple Choice

What colour will you observe in well Y?

• Brown because all the starch has been digested.

• Blue Black because the starch has not been digested. There is no enzyme present in distilled water.

• Blue Black because the starch has not been digested. The enzyme has denatured at high temperatures.

• Blue Black because starch has not been digested. The enzyme is denatured at alkali pH.

Multiple Choice

What colour will you observe in well Z?

• Brown because all the starch has been digested.

• Blue Black because the starch has not been digested. There is no enzyme present in distilled water.

• Blue Black because the starch has not been digested. The enzyme has denatured at high temperatures.

• Blue Black because starch has not been digested. The enzyme is denatured at alkali pH.