Biological Molecules (Cambridge (CIE) IGCSE Biology): Exam Questions

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A strand of DNA is shown below:

T ― G ― A ― A ― C ― T ― A ― G ― C ― C

What would the correct order of bases be on the complementary strand of DNA?

Three statements about proteins are given below. 

1. Different sequences of amino acids give different shapes to protein molecules.

2. Amylase is made from a sequence of amino acids joined together forming a non-specific 3D shape. 

3. When mixed with Biuret solution, there is a colour change from blue to purple. 

Which of the statements above are true?

The table below lists three large molecules found in living organisms. 

Which row correctly describes the smaller molecules these substances are made from?

Four statements about large biological molecules are given below:

1. Proteins are made from a number of different amino acids.

2. Both glycogen and starch are made from simple sugar base units.

3. Fats are made from glycerol and fatty acids.

4. Oils are made from glycerol only. 

Which of the four statements above is/are false?

A student carried out two food tests on solution F to determine what food groups it contains.

What food molecules does solution F contain?

A student mixes a food reagent with solution X in a test tube. 

They observe a positive test result when a cloudy emulsion forms. 

Which row of the table below identifies the reagent used and molecule present in Solution X?

Which row of the table below correctly describes the role of cellulose, proteins and water in living organisms? 

The image below shows two molecules before and after chemical digestion by enzymes in the alimentary canal. 

Which letter(s) identify the product(s) of complete starch digestion?

The data shows the concentrations of sugar and starch in an onion.

The onion is tested with Benedict’s solution and iodine solution.

Which set of results is correct?

The diagram shows a short section of a single strand of DNA. 

Which strand of DNA will combine with this strand to form part of a double helix?  

A group of students tested four different foods using some common food tests.

Their results are shown in the table below.

Which food contains reducing sugar and Vitamin C but not protein or starch?

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The table below shows the elements and basic units used by cells to make large biological molecules. 

Which row of the table is correct?

Four foods were tested for the following food molecules:

• reducing sugar using Benedict’s reagent

• protein using Biuret solution

• fat using ethanol

• Vitamin C using DCPIP

Which food contains sugar and Vitamin C?

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The shape and structure of molecules allows them to carry out their specific functions. 

Which row of the table below correctly describes a feature of each molecule that makes it specific?

Which drawing represents the general structure of an amino acid molecule that would be found in Nature?

The diagram shows two food tests being carried out on solution X. 

Which nutrients are present in solution X?

In a length of DNA, 20% of the bases were T. 

What is the percentage of base G in this length of DNA?