Biology 9700 · AS & A Level · Carbohydrates and lipids

Carbohydrates and lipids — practice question

The human pancreas makes and releases several different digestive enzymes. Their action takes place in the small intestine. Pancreatic lipase works by splitting the bond between glycerol and fatty acids in triglycerides.
(a)[1]

State the term used for an enzyme that is released outside the cell and acts there.

(b)

Fig. 2.1 shows one of the triglycerides present in olive oil.

(b(i))[1]

On Fig. 2.1, draw an arrow to show where lipase digestion breaks the bond between the glycerol residue and the stearic acid residue.

(b(ii))[2]

State the type of reaction that produces stearic acid from this triglyceride and name the type of bond that is broken. Type of reaction Type of bond

(c)[2]

The activity of the bacterial lipase was measured at $37\,^{\circ}\text{C}$ using different concentrations of olive oil as the substrate. The results were used to obtain a Michaelis-Menten constant $(K_m)$ of $91.76\,\text{mmol dm}^{-3}$. Explain what is meant by a $K_m$ of $91.76\,\text{mmol dm}^{-3}$.

(d)

Fig. 2.2 presents the findings of an investigation into how temperature affects the activity of bacterial lipase.

(d(i))[4]

Describe and explain the pattern shown in Fig. 2.2.

(d(ii))[2]

An investigation using human pancreatic lipase over the same temperature range would give results that differ from those in Fig. 2.2. Predict how the trend would differ from the one shown in Fig. 2.2.

(c(i))[4]

Describe and explain the results presented in Fig. 2.2.

(c(ii))[2]

An investigation using human pancreatic lipase across the same temperature range would produce results unlike those in Fig. 2.2. Predict how the trend would differ from the one shown in Fig. 2.2.

Worked solution & mark scheme

This 18-mark question has a full step-by-step worked solution and mark scheme. One marking point: It is an extracellular enzyme.

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI