Carbohydrates & Water - exam practice

Lactose is formed by a reaction between glucose and galactose, both of which have the chemical formula C₆H₁₂O₆.

Which option shows the correct chemical formula for lactose?

Carbohydrates, such as starch, are made from monosaccharides joined together.

Which bond joins monosaccharides together?

What can occur during condensation of carbohydrates?

What occurs when sucrose is broken down to monosaccharides?

X and Y show the structures of two hexose sugars.

Which statement is correct?

A sample of milk is tested with Benedict’s solution. After boiling, a yellow colour is observed.

Which conclusion is correct?

Which carbohydrate gives a brick red colour when boiled with Benedict’s solution?

Tests were performed on samples from a mixture of biological molecules.

When iodine in potassium iodide solution was added to a sample, the mixture turned black.

When the biuret test was carried out on another sample, the mixture turned purple.

Which biological molecules were in the mixture?

The structure of a biological molecule is shown below.

Which option correctly describes the molecule?

An unknown solution of a single sugar was tested. After Benedict's test for reducing sugars, the colour observed was blue. After Benedict's test for non-reducing sugars, the colour observed was brick red.

Identify the unknown sugar.

Why may fish living in ponds survive temperatures below 0°C in winter?

Polar molecules form hydrogen bonds with each other.

Which properties of water result from its molecules being polar?

1 - good solvent

2 - high specific heat capacity

3 - high surface tension

4 - cohesive

Which properties of water are important for transport in xylem?

1 - cohesion

2 - adhesion

3 - high energy requirement for evaporation

4 - good solvent properties

A student wrote the following statement:

‘Water is polar because the oxygen side of the molecule is slightly positive in charge.’

Which option explains why this statement is not correct?