AQA GCSE Biology: Combined Science

Topic Questions

1.3 Transport in Cells

1a1 mark

Organisms must transport substances to and from the external environment.

Identify one substance which cells must transport across the cell membrane to support cell functions.

1b1 mark

Figure 1 shows particles of two gases.

Figure 1
diffusion-1

Complete Figure 1 by drawing the arrangement of the gas particles after 1 hour.

1c1 mark

Name the process shown in Figure 1.

1d1 mark

Which of the following is an example of simple diffusion?

  • Movement of water into the root of a plant

  • Movement of mineral ions into the root of a plant

  • Movement of oxygen into the leaf of a plant

  • Movement of glucose into the epithelial cells of villi in the small intestine

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2a4 marks

Complete each row of Table 1 with a  tick (✓) or a cross ( ✕ ) to indicate whether it is a feature of osmosis.

Table 1

Feature

✓ /  ✕
Involves the movement of gases  
Requires energy from respiration  
Movement occurs through a partially permeable membrane  
Particles move down a concentration gradient  

 

2b1 mark

Draw an arrow on the diagram in Figure 2 to show the overall direction that the water particles will move in (net water movement).

Figure 2

osmosis-1

2c3 marks

Describe an example of where diffusion of gasses is important in multicellular organisms.

2d1 mark

Identify one feature of a gas exchange surface which maximises the rate of diffusion.

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3a2 marks

Describe how the root hair cell in Figure 3 is adapted for absorption of water by osmosis.

Figure 3

root-hair-cell-1

3b2 marks

Figure 4 shows two cells after the effects of osmosis.

Figure 4
osmosis-in-plant-cells-1

Draw a line from each cell to the correct description.

3c2 marks

A student carried out an experiment into osmosis in plant tissue. They set up their investigation as shown in Figure 5.

Figure 5

potatos-and-sucrose-1

Each beaker contained potato discs in a solution of sugar or distilled water.
The student found that the potato discs in Beaker 5 decreased in mass.

Explain why this is with reference to osmosis.

3d1 mark

Which of the following is a suitable control variable for the investigation carried out by the student in part (c)?

  • Maintain the same sugar concentration in each beaker

  • Repeat the experiment 3 times

  • Use the same size potato pieces in each beaker

  • Calculate an average of the results

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4a
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2 marks

Pre-cut potato chips can be stored in salt solution before being cooked in restaurants. To avoid the chips becoming too salty, it is important to make sure that water does not move in or out of the chips as they are stored.

A scientist wanted to collect some data about the salt content of potato chips to inform the restaurants of the best storage concentration.

The steps in Table 2 refer to the method that the scientist used to collect his results.

Table 2

1 Measure out 100ml of each salt solution into 5 different test tubes
  Remove the chips, pat dry and reweigh
  Cut 5 potato chips of similar size and dimensions
  Place 1 chip into each concentration of salt solution and leave for 1 hour
  Record the mass of the potato chips

Place the steps in the correct order by adding numbers 2 to 5 into the left hand column of Table 2. The first stage has been labelled for you.

 
4b
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1 mark

Figure shows the results obtained by the scientist when completing the investigation from part (a).

Figure 6
osmosis-and-salt-1

In which salt solution did the mass of the chip increase after one hour?

4c1 mark

Explain what led to this increase in mass of the chip identified in part (b).

  • Water moved out of the chip by osmosis

  • Salt moved into the chip by diffusion

  • Water moved into the chip by osmosis

  • The chip reacted with the salt in the solution

4d
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1 mark

The scientist concluded that the best solution for storing chips in would be 0.5 mol dm-3 salt solution because there would be no net (overall) movement of water into or out of the potato chips.

Suggest how the scientist can tell this from the results in Figure 6.

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5a2 marks

Figure 7 shows two cells.

Figure 7
adapted-for-diffusion-1

Suggest which cell (X or Y) is better adapted to carry out diffusion and give a reason for your choice.

5b1 mark

The cells in Figure 7 from part (a) also contain a high number of mitochondria.

Identify which transport process requires mitochondria to move particles across the cell membrane.

5c3 marks

Complete the three sentences below by entering the appropriate transport process into the space provided.

_____(i)_____ is the movement of particles from a low concentration to a high concentration with the help of energy in the form of ATP.

_____(ii)_____ is the movement of particles from a high concentration to a low concentration.

_____(iii)_____ is the movement of water particles from a high water concentration to a low water concentration through a partially permeable membrane.

5d1 mark

Which substance is absorbed by plants during active transport?

  • Magnesium ions

  • Glucose

  • Water

  • Oxygen

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1a6 marks

The statements in Table 1 refer to processes occurring in an organism.

Table 1

Process Transport mechanism
Absorption of oxygen into the blood from the alveoli  
Movement of mineral ions into the root hair cell of a plant  
Movement of water from the kidney tubules into the blood  
Absorption of glucose into respiring cells  
Movement of urea from liver cells into the blood  
Movement of water from the cell vacuole into the xylem of a plant  

Complete Table 1 to show which transport mechanism is being used for each of the processes described.

1b4 marks

During digestion, glucose is absorbed from the partially-digested food in the lumen of the small intestine, across the cells lining the small intestine (the epithelial cells) and into the bloodstream.

It is a two-stage process, shown in Figure 1.

Figure 1

glucose-absorption-hard-1

Process A - glucose moves from the partially digested food in the small intestine into the epithelial cell (lining the small intestine) using energy from ATP.

Process - glucose moves passively from the epithelial cell into the the bloodstream.

Use the information in Figure 1 and your knowledge of transport across cell membranes to describe the mechanisms used in process and process B for the absorption of glucose into the bloodstream.

1c2 marks

Process B (in Figure 1) relies on the presence of a concentration gradient.

Explain how a steep concentration gradient is maintained in order to continually support Process B.

1d2 marks

Absorption of glucose may not always occur through the transport mechanism shown in Process A in Figure 1.

Suggest a situation when glucose may be absorbed into the epithelial cell through an alternative transport mechanism different to that shown in Figure 1.

You should refer to concentration gradients in your answer.

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2a3 marks

Particulate matter (PM) refers to the small particles in air pollution which can irritate the airways and caused damage to the alveoli.

If concentrations of PM are high, the epithelium cells of the alveoli may be killed and replaced with unspecialised cells resulting in:

  • Fewer functioning alveoli
  • Thickening of alveolar walls

Explain how particulate matter could lead to reduced gas exchange in the lungs of humans.

2b
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3 marks

Figure 2 shows the results of an investigation into the concentration of particulate matter and the percentage of dead alveolar epithelium cells after 48 of exposure.

Figure 2

particlate-matter-1

Scientists studied 31 080 alveolar epithelium cells in this study.

Calculate how many more cells died after 48 hours of exposure to 1 000 µg cm-3 of particulate matter than after 48 hours of exposure to 50 µg cm-3 of particulate matter.

2c6 marks

Compare, with examples, the different transport processes involved in moving substances across the cell membrane.

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3a
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3 marks

Monoglycerides are molecules made up of glycerol and one fatty acid tail. They are absorbed into the epithelial cells of the small intestine by diffusion across the cell membrane.

A scientist measured the uptake of monoglycerides in the epithelial cells of mice. In the investigation, the scientist provided the mice with different concentrations of monoglycerides and measured the uptake into the epithelial cells of the small intestine.

Complete Table 1 to show which variables the scientist used in this investigation.

Table 1

Independent Variable  
Dependent Variable  
Control Variable  

3b
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3 marks

The graph in Figure 3 shows the results of the investigation from part (a).

Figure 3

monoglycerides-1

Describe and explain what the graph shows.

3c3 marks

Human body temperature is approximately 37 °C, which provides the optimum temperature for activity of protein molecules such as enzymes.

Suggest why a temperature of 37 °C helps to maximise the rate of transport of substances across the cell membrane.

3d
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1 mark

Figure 4 shows the concentration of sugars in three different cells. X, Y and Z.

Figure 4

osmosis-from-cell-to-cell-1

Which of the following statements is correct?

  • More water will move by osmosis from cell Z to cell X than from X to Z.

  • More water will move by osmosis from cell X to cell Z than from Z to X

  • More water will move by osmosis from cell X to cell Y than from Y to X

  • More water will move by osmosis from cell Z to cell Y than from Y to Z.

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4a2 marks

A student wanted to investigate the transport of water across a partially permeable membrane. Figure 5 shows how the student prepared the beaker at the start of the investigation.

Figure 5

osmosis-and-partially-permeable-membraneosmosis-and-partially-permeable-membrane-2

 

Complete Figure 5 to show what the student would observe after 15 minutes.

4b2 marks

Explain your answer to part (a).

4c
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5 marks

The student carried out a further investigation into the effect of osmosis on plant tissue. 

They cut a potato into cubes and recorded the change in mass over a 30 minute period.

Figure 6 shows the results the student obtained from one cube of potato.

Figure 6
osmosis-and-potatos-1

Describe and explain the trend shown on the graph.

4d
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2 marks

The potato cube from Figure 6 had an initial mass of 2.3g.

Calculate the percentage increase that the potato cube had shown after 10 minutes.

4e2 marks

The student repeated the investigation but with the beaker placed in a water bath at 30°C.

Draw a second line on the graph to show the trend expected from these results.

4f4 marks

Explain your line drawn for part (e)

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5a6 marks

Glucose is a soluble sugar molecule. It can be stored in cells once it has been converted to an insoluble form.

In plants, glucose is stored as starch grains and in animals, glucose is stored as glycogen.

Cells in the roots of a clover plant contain the following specialised adaptations

  • Large quantities of mitochondria
  • Many stored starch grains
  • Nodules on the roots which contain bacteria

Explain how these adaptations assist with the absorption of mineral ions and water from the soil into to cells of the clover root.

5b4 marks

A student places an animal cell and a plant cell into distilled water and examines both under a microscope.

Explain the differences in observations that the student would have made of the animal cell and plant cell.

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1a4 marks

Sugar molecules are moved from the gut to the blood by active transport.

What is involved in active transport?

1b2 marks

Outline two ways in which the intestine is specialised for exchanging materials.

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2a1 mark

Figure 1 shows two plant cells.

Figure 1

plant-cells_hypertonic

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

2b4 marks

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

2c3 marks

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

Figure 2 below shows a red blood cell.

Figure 2

red-blood-cell

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.

2d3 marks

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

Figure 3red-blood-cell_spherocytosis

Suggest the possible impact of this condition on a sufferer.

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3a4 marks

All living organisms exchange substances with the environment. Plant roots use two different methods to absorb water and ions from the soil.

Explain why roots have two different methods to absorb water and ions.

3b2 marks

Table 1 shows the concentrations of three mineral ions in the roots of a plant and in the surrounding soil.

All three mineral ions are essential to the healthy functioning of a plant.

Table 1

56d754e1-4695-4476-8fc5-f6fcf0611237

Explain why the plant roots can not absorb these mineral ions by diffusion.

3c2 marks

Waterlogged soil has a lower oxygen concentration than non-waterlogged soil.

Suggest the impact of waterlogged soil on the activity of root cells.

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4a2 marks

A student decided to investigate the effect of different salt solutions on the mass of chicken eggs.

They used the following method:

  1. 5 eggs were placed in acid for 24 hours to dissolve the eggshell.
  2. The mass of each egg was measured and recorded.
  3. Five beakers were set up; four with 200 cm3 of salt solution of a particular concentration and one with water (0.0 mol dm-3).
  4. An egg was placed in each of the beakers.
  5. After 1 hour, the eggs were removed and dried with a paper towel.
  6. The mass of each egg was measured and recorded.

Their results are shown in the table in Table 2 below:

Table 2

Concentration of salt solution (mol dm-3) Mass of egg without shell in grams Mass of egg after 1 hour in solution in grams
0.0 74.5 79.2
0.2 73.0 75.8
0.4 74.2 75.5
0.6 73.6 72.0
0.8 75.8 71.5

Calculate the percentage change of the egg placed in the 0.4 mol dm-3 salt solution.

Show your working.

Give your answer to two significant figures.

4b3 marks

Explain why in some of the solutions the mass of the eggs decreased.

4c3 marks

Explain what the student would need to do to determine an estimate of the concentration of the solution inside an egg.

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5a1 mark

A group of scientists investigated the rates of absorption of different sugars using two pieces of the intestine.

One piece of the intestine was poisoned with cyanide which stops cellular respiration.

The results are shown in Table 3 below.

Table 3 7906e547-6287-4609-842a-9e625c7ed8c5

Which of the sugars in Table 3 are absorbed by active transport?

5b3 marks

Explain why you chose these sugars, using evidence from Table 3.

5c2 marks

One of the scientists states ‘All four of the sugars we investigated can be absorbed by diffusion.

Is this statement correct or incorrect? Justify your answer.

5d1 mark

One of the sugars absorbed by active transport is glucose.

Xylose is a sugar that is the same size as glucose, but it is not absorbed by active transport.

Suggest a reason why.

5e3 marks

The wall of the small intestine contains smooth muscle cells.

Muscle cells convert soluble glucose into glycogen which is insoluble in water.

Suggest an explanation as to why it is essential that muscle cells store glucose as glycogen.

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