Set B (AQA GCSE Biology): Exam Questions

Figure 1 shows a cross section of a leaf.

Figure 1

Which of the options below correctly describes the organisational structure of a leaf?

Name structure X and Y in Figure 1.

Describe how structure X (in Figure 1) helps control gas exchange in response to changing environmental conditions.

Which feature of palisade mesophyll cells makes them adapted for efficient photosynthesis?

Which of the following options is not a non-specific defence against pathogens?

Figure 1 shows the process of phagocytosis. 

Figure 1

Describe the stages of phagocytosis shown in the image. 

Table 1 shows how the number of white blood cells in the blood changes before and during an infection with a pathogen. 

Table 1

Calculate the difference in the number of white blood cells per dm³ of blood before and during an infection. 

State two roles of white blood cells during an infection other than phagocytosis.

Describe and explain the changes that occur in the body during exercise.

A group of athletes carried out a 9-month training programme.

Figure 1 shows the effect of the same type and amount of exercise on one of the athlete’s heart rate before and after the training programme.

Figure 1

Calculate the percentage change in the athletes heart rate 10 minutes after the start of exercise.

Show your working.

The volume of blood pumped out of the left side of the heart in one beat is the stroke volume.

Figure 2 shows the relationship between the athlete's stroke volume and heart rate in beats per minute both before and after completing the training programme.

Figure 2

The cardiac output of the heart can be calculated by:

cardiac output = heart rate × stroke volume

Calculate the difference in cardiac output of the athlete 20 minutes after the start of exercise before and after the training programme. 

Show clearly how you calculated your answer.

Figure 1 shows that the heart of the athlete after completing the training programme beats more slowly than before the training programme.

Use information from Figure 2 to explain why.

Explain how an increased cardiac output helps the athlete to maximise their performance.

A student set up an investigation into the limiting factors of photosynthesis.

His set up is shown in Figure 5 below:

Figure 5

Identify the limiting factor being investigated in this practical.

The student carried out an investigation to find out the effect of light intensity on the rate of photosynthesis by moving the light source further and further away from the aquatic plant and counting the bubbles produced per minute at each distance.

The results can be seen in Table 1 below:

Table 1

One of the results recorded was an anomaly.

Identify which result was anomalous and explain your choice.

Describe the trend shown by the data in Table 1.

The student evaluated his method and decided that counting bubbles is an inaccurate way of measuring the rate of photosynthesis for two reasons.

1. It does not take into account the fact that there may be bubbles of different sizes

2. Tiny bubbles may be hard to see and so may not be counted at all

Suggest a more accurate method which could be used to collect information about the amount of oxygen gas produced as the aquatic plant photosynthesizes.

Both muscle and sperm cells are specialised animal cells. The nucleus of a muscle cell is different to the nucleus of a sperm cell.

Describe one way in which the nucleus is different between these two cells.

All specialised cells are adapted to carry out their function. 

Explain two adaptations of a sperm cell that enables it to carry out its function. 

Specialised cells develop from unspecialised cells by differentiation when an organism develops.

Describe what happens when a cell differentiates.

Compare the process of differentiation in animals and plants.

Listing the key structures, describe the path of air from the trachea to the lung capillaries.

Explain the changes that occur in the thorax (chest cavity) when a person breathes in.

During inhalation and exhalation, the intercostal muscles work as antagonistic pairs.

With reference to the intercostal muscles, explain what antagonistic pairs are and how they work.

The internal intercostal muscles are predominantly active during strenuous activity.

Why is this?

Between 2013 and 2016, the Ebola virus was responsible for around 12 000 deaths.

Almost all of the victims were in Western Africa.

There is currently no clinically approved medicine available to treat individuals infected with the Ebola virus. 

Drug companies have developed a new drug to treat Ebola.

Describe the stages of testing this new drug must go through before it can be used on patients. 

How are new drug compounds discovered?

A potential vaccine for Ebola began development in 2003.

In 2014, the World Health Organisation ruled that it would approve the vaccine for use on individuals recently infected with Ebola.

At that time the vaccine had not yet been tested on humans.

Suggest two reasons reason why the World Health Organisation deemed it ethical to use the vaccine on infected individuals despite it not having been tested on humans.

Figure 4 shows two guard cells surrounding an open stoma and two guard cells surrounding a closed stoma.

Figure 4

When light intensity is low, the stoma closes.

Describe how the stoma close.

Guard cells have cell walls with unevenly distributed cellulose.

Suggest why this is important.

A student investigated the effect of varying concentrations of salt solution on the opening of stomata on the lower epidermis of a leaf.

Her results are shown in Table 2.

Table 2

The student calculated one of the percentages for open stomata in the field of view incorrectly.

Identify for which solution the result was incorrect and give the correct value.

Write a conclusion for the results of the experiment as shown in Table 2.

The student measured the real diameter for the field of view to be 0.475 mm.

Calculate the total number of stomata per mm² of the leaf epidermis placed in 0.8 mol / dm³ salt solution if the value of π (pi) is 3.14.

Show your working.

The liver has many roles in the body.

As well as detoxifying a number of substances, the liver also produces bile, a yellowish-brown fluid that is stored in the gallbladder.

One of the main components of bile is bilirubin.

The liver produces this yellow-brown pigment when it breaks down haemoglobin released from broken down red blood cells.

Explain how red blood cells transport oxygen from the alveoli to other parts of the body.

The liver is also responsible for producing much of the body’s cholesterol.

If levels of cholesterol in the body are too high, there is a risk that solid ‘gallstones’ may form in the liquid bile.

The gallbladder is connected to the small intestine by a narrow duct (tube) which can become blocked by these gallstones.

It is not uncommon for individuals with gallstones to form very pale faeces.

Suggest why.

One form of cholesterol found in the blood is LDL.

Suggest the consequences of an individual having too high a level of LDL cholesterol in their blood.

Figure 1 shows two plant cells.

Figure 1

Which of the plant cells above was placed in a solution with a lower solute concentration than the cell contents?

Explain what has happened to the plant cell you identified in part (a).

When placed in different solutions, animal cells will also change.

Figure 2 below shows a red blood cell.

Figure 2

Describe what would happen if a red blood cell was put into a solution with a lower solute concentration than the cell contents and explain why this would be different from what would happen to a plant cell.

Hereditary spherocytosis is a rare inherited condition that produces red blood cells with an abnormal spherical shape, as shown in Figure 3.

Figure 3

Suggest the possible impact of this condition on a sufferer.