# Inheritance, variation and evolution - One- to two-mark questions

One- to two-mark questions will start with command words such as ‘describe’ or ‘explain’. Some command words are easy to understand such as:

• 'calculate' or 'determine' for maths questions
• 'complete' to fill in a gap in a table or graph
• 'define' to give the meaning of an important word
• 'suggest' where you use your knowledge in an unfamiliar situation

The command words 'describe' and 'explain' can be confusing. If you are asked to describe a graph, you will be expected to write about its overall shape, whether it is linear or curved, the slope of gradients etc. If you are asked to explain why a pattern or trend is seen in a graph, you will be expected to use your science knowledge, not just say what you see (which is a description), eg the graph shows a steep linear increase for the first three hours because…

Explain how and why questions often have the word 'because' in their answer. Describe questions don't.

The number of marks per question part is given in this form '[2 marks]'. It is essential that you give two different answers if a question is worth two marks. Sometimes you can gain a second mark by giving the units in a calculation or stating specific data points, eg during the first two years the number of lions deceased by seven.

You will be expected to write in more depth for three and four mark questions. They might ask you about a process such as the carbon cycle or the method you would use in an experiment.

## Question 1 - Foundation

Question

The grid shows the inheritance of X and Y chromosomes.

Draw a tick on the part of the diagram that shows a sperm cell. [1 mark]

This question is AQA material which is reproduced by permission of AQA.

On the diagram, a tick drawn next to X and / or Y from Parent 1. 

## Question 2 - Foundation

Question

What is the difference between genotypes and phenotypes? Give an example of each in your answer. [4 marks]

This question has been written by a Bitesize consultant as a suggestion to the type of questions that may appear in an exam paper.

• Genotypes are letters used to determine characteristics.
• BB, Bb, bb for eye colour (accept other suitable examples).
• Phenotypes are physical descriptions using words that describe genotypes.
• So BB and Bb are brown eyes and bb is blue eyes (accept other suitable examples).

## Question 3 - Higher

Question

Using the tree below, which primate evolved first? [1 mark]

Tip: the tree shows an evolutionary relationship between the organisms contained. Consider the roots being at the start moving up towards the leaves.

This question is AQA material which is reproduced by permission of AQA.

Lemur. 

## Question 4 - Higher

Question

DNA fingerprinting can be used to identify people. One example of the use of DNA fingerprinting is to find out which man is the father of a child. The diagram shows the DNA fingerprints of a child, the child’s mother and two men who claim to be the child’s father. The numbers refer to the bars on the DNA fingerprints.

Only half the bars of the child's DNA fingerprint match the mother's DNA fingerprint. Explain why. [2 marks]

Tip: key point here is 'half the bars' of the child match the mother. Think - which process produces offspring? What happened to the DNA?

This question is AQA material which is reproduced by permission of AQA.

Eggs are produced by meiosis. 

Therefore, they only contain half of the mother's DNA.