Biological Molecules (Cambridge O Level Biology)

This question is about biological molecules.

Choose words or phrases from the list to complete the sentences.

Each word or phrase may be used once, more than once, or not at all.

Fats are composed of the elements .............................................. , hydrogen and .............................................. only. All proteins contain these three elements and the element .............................................. .

Glucose is a type of ............................................... . Animals store excess glucose as .............................................. in the liver.

Plants store excess glucose as .............................................. . Plants also convert glucose to .............................................. which is used to make cell walls. 

[7 marks]

Table 1 contains some statements about biological molecules.

Table 1

Place ticks (✓) in Table 1 to indicate statements that apply to carbohydrates.

Compare the chemical elements found in carbohydrates and proteins.

Fig. 3 shows groups of biological molecules and the building blocks that make them up.

Fig. 3

Join the boxes in an appropriate manner using straight lines. 

Fig. 1 shows the components of fats and oils as shapes.

Using these shapes, sketch the appearance of a triglyceride molecule that would be found in fats and oils.

Fig. 1

Describe the test that would be used to show a positive result for the presence of protein in a sample of food.

Table 1

Explain the purpose of the test tube containing just water in the experiment shown in Table. 1.

Explain why the test for lipids is known as an emulsion test.

Table 2

DNA controls cell function by controlling the production of proteins.

These proteins determine the phenotype of an organism, including blood group in humans.

Describe the structure of a DNA molecule.