On the cladogram, label with an M, the point at which a mutation occurred, preventing the gibbon from synthesizing ascorbic acid.

Outline the reason for ascorbic acid being described as an essential nutrient in the diet of humans.

A small box of orange juice contains these details on the side of the package:

[Source: © International Baccalaureate Organization 2020.]

Calculate the volume of juice needed to obtain the recommended daily requirement of vitamin C.

. . . . . . . . . . . . . . . . . . .mL

The apparatus used to measure energy content of food contains some water. Explain how this water is used when measuring the energy content of a food.

cannot be synthesized by the body;

250 (mL)

a. the volume/mass of water is measured;

b. the energy from the burning food raises the temperature/heats the water;

c. knowing the specific heat of water allows energy of the food to be calculated
OR
4.2J of heat energy causes a 1°C rise in 1g of water;

Most candidates could label the correct point on the cladogram where a mutation occurred and state the reason ascorbic acid is described as an essential nutrient.

The calculation of how much juice was needed was difficult for many candidates. Common incorrect answers were 160 ml and 240 ml.

Stronger candidates could explain how water is used in a calorimeter. Many candidates suggested burning the food in the water and others answered all they knew about calorimeters without answering the question directly.