Transport in and out of cells

Figure 17 shows a beaker containing a potato cylinder in distilled water.

Explain why the mass of this potato cylinder will change when it is placed in distilled water.

A scientist investigated the rate of diffusion using three agar cubes of different sizes.

Each cube contained a pH indicator that changed from pink to colourless when placed in acid.

The cubes were placed in a beaker containing an acid.

Figure 18 shows some information about each cube.

Calculate the volume of cube C.

Explain the difference in the times taken for cubes A and B to become colourless.

* (c) Liquid agar was poured into a Petri dish and allowed to set.

A well was cut in the centre of the set agar.

Kiwi fruit juice was poured into the well.

Kiwi fruit juice contains an enzyme that causes set agar to break down into a liquid.

Figure 19 shows the results after 30 minutes.

Devise a plan to investigate the effect of different concentrations of kiwi fruit juice on the breakdown of set agar, using the equipment shown in Figure 19.

Your plan should include:

• measurements that need to be taken

• variables that need to be controlled.

Figure 3 shows a beaker containing a potato cylinder in distilled water.

Explain why the mass of this potato cylinder will change when it is placed in distilled water.

A scientist investigated the rate of diffusion using three agar cubes of different sizes.

Each cube contained a pH indicator that changed from pink to colourless when placed in acid.

The cubes were placed in a beaker containing an acid.

Figure 4 shows some information about each cube.

Calculate the volume of cube C.

Explain the difference in the times taken for cubes A and B to become colourless.

In 2018, all the plants were removed from the soil in a 1000 m² area.

A wall was built around this area to keep people out.

In 2019, three species of plants were recorded growing in this area.

Two of these species were indigenous.

State what is meant by the term ’indigenous’.

Name one piece of equipment that could be used to sample the number of indigenous plants in this area.

The area was surveyed every year and the number of plants of each species (A to H) was estimated.

Figure 6 shows the results.

State the trend shown by the data in Figure 6 for plant species C from 2019 to 2023.

A scientist suggested that the decrease in the number of plants of species B in 2021 was caused by competition from one of the other species of plant.

Which species is most likely to have out-competed species B in 2021?

Explain one way that this species could have out‑competed species B.

Give one way that species H could have moved into the area.

Plants also need water to grow.

Explain how water is absorbed into the plant.

A teacher was demonstrating a process to students.

The teacher had a beaker of water and added five drops of food colouring to the beaker.

State the process being demonstrated.

A student asked if different food colourings spread evenly in the same amount of time.

Give two variables that would need to be controlled if the investigation was repeated with different food colourings.

The teacher repeated this process with water at different temperatures. Figure 11 shows the results of this experiment.

Draw a line graph to show the results in Figure 11.

Explain why the time taken decreased.

Figure 13 shows a root hair cell from a plant.

Name the part labelled X.

State one way that the structure of the root hair cell increases the volume of substances it absorbs.

Explain why root hair cells do not contain chloroplasts.

*(c) The arrows in Figure 15 show the direction of water movement through a tree.

Explain how water is moved from the soil, through the plant and into the air.

3 (a) Figure 2 shows a root hair cell from a plant.

(i) Name the part labelled X.

(ii) State one way that the structure of the root hair cell increases the volume of substances it absorbs.

(iii) Explain why root hair cells do not contain chloroplasts.

from the Elodea cells in tap water.

(ii) Explain why placing the Elodea cells in the 10% salt solution causes the changes seen in Figure 3.

A student investigated the movement of water in potatoes.

The student used three identical cubes of potato.

The size of a cube is shown in Figure 12.

Calculate the volume of this cube.

Include the units in your answer.

One cube was placed in water and each of the other two cubes were placed in solutions with different concentrations of salt.

The cubes were left for 20 minutes.

Figure 13 shows the student’s results.

Give one way the student could ensure the measurement of the mass of the cubes is accurate.

Explain the mass change in the cube in the concentrated salt solution.

The student wanted to find the concentration of salt solution where the potato cube did not change mass.

Describe how the student could modify this investigation to find this concentration.

Explain why potato cells do not burst when placed in water.

8 People with diabetes cannot always control the concentration of glucose in their blood.

(a) Two people eat identical meals. One person has diabetes, the other person does not have diabetes. Figure 15 shows the concentration of glucose in the blood of these two people after eating the meals.

time after eating the meal in hours

Figure 15

(i) Describe two differences in the concentration of glucose in the blood of the two people shown in Figure 15.

(ii) Calculate the maximum increase in the concentration of glucose in the blood of the person with diabetes.

(iii) Water moved out of the red blood cells of the person with diabetes when the concentration of glucose in the blood was above 15 mmol per dm³. Explain why water moved out of the red blood cells of the person with diabetes.

(b) The pancreas produces a hormone that causes the concentration of glucose in the blood to decrease.

(i) Name this hormone.

(ii) State how this hormone is transported from the pancreas to its target organs.

(iii) Which is the target organ for the hormone that controls the concentration of glucose in the blood?

(c) Explain how type 2 diabetes can be controlled.

People with diabetes cannot always control the concentration of glucose in their blood.

Two people eat identical meals.

One person has diabetes, the other person does not have diabetes.

Figure 4 shows the concentration of glucose in the blood of these two people after eating the meals.

Figure 4

Calculate the maximum increase in the concentration of glucose in the blood of the person with diabetes.

Water moved out of the red blood cells of the person with diabetes when the concentration of glucose in the blood was above 15 mmol per dm³.

Explain why water moved out of the red blood cells of the person with diabetes.

The pancreas produces a hormone that causes the concentration of glucose in the blood to decrease.

Name this hormone.

State how this hormone is transported from the pancreas to its target organs.

Which is the target organ for the hormone that controls the concentration of glucose in the blood?

Explain how type 2 diabetes can be controlled.

Alcohol is broken down by liver cells.

Which process moves alcohol from the blood into the liver cells?

If a person drinks too much alcohol, liver cells die and the person can develop cirrhosis of the liver.

The relative risk of developing cirrhosis of the liver is affected by two factors.

1. The volume of alcohol a person drinks in one week.

2. Whether the person drinks the alcohol on its own or with a meal.

Figure 7 shows how these two factors affect the relative risk of people developing cirrhosis of the liver.

Number of units of alcohol consumed per week

Figure 7

Person A drinks alcohol on its own.

Person B drinks alcohol with their meals.

Calculate the difference in risk for these two people when each one drinks 28 units of alcohol per week.

Using evidence from Figure 7, state two pieces of health advice for people about drinking alcohol.

Cystic fibrosis is a genetic condition that can also cause liver disease.

State where genes are found in cells.

Figure 8 shows the inheritance of cystic fibrosis in a family.

F represents the dominant allele that does not cause cystic fibrosis.

f represents the recessive allele that causes cystic fibrosis.

person C person D
person E (ff)

A scientist states that the genotype of person B is Ff.

Explain why the scientist is correct.

State the genotype of person C.

4 (a) Figure 5 shows some onion cells that have been soaked in a concentrated salt solution.

(Source: © Rattiya Thongdumhyu/Shutterstock)

Figure 5

(i) The cells in Figure 5 have been stained. Give one reason why the cells have been stained.

(ii) Which is the name of the structure labelled V?

(iii) The salt solution outside the cell has a higher concentration than the solution inside the cell. Explain why the cytoplasm shrinks away from the sides of the cell when the cells are in salt solution.

(b) Figure 6 shows the equipment used to prepare a microscope slide of onion cells.

Describe how this equipment could be used to prepare a slide of onion cells to view under a microscope.

(c) A student investigated the percentage change in mass of potato cylinders placed in sucrose solutions of different concentrations. Figure 7 shows the results of the student’s investigation.

concentration of sucrose solution in mol/dm³

Figure 7

State two conclusions that can be made from these results.

5 (a) Carrots have different physical characteristics such as colour. Which genetic term describes the physical characteristics of a carrot?

(b) Figure 10 shows some carrot sticks.

(Source: © rukxstockphoto/Shutterstock)

Figure 10

A student chose three carrot sticks and weighed each one. The carrot sticks were placed in 50 cm³ of distilled water. After two hours the student weighed each carrot stick again. Figure 11 shows the results for these carrot sticks P, Q and R.

Figure 11

(i) Give one reason why the student used three carrot sticks instead of just one carrot stick.

(ii) Give two ways that this method could be improved.

(iii) Calculate the percentage change in mass of carrot stick Q.

Use the equation

Give your answer to 2 significant figures.

percentage change =_{..............................................................}

(iv) Explain the change in mass of the carrot sticks.

9 (a) Figure 13 shows a sperm cell.

Figure 13

Describe how structure A and structure B enable fertilisation.

structure A

structure B

(b) Figure 14 shows a human egg cell, magnified ×700.

(Source: © Pascal Goetgheluck / Science Photo Library)

Figure 14

Calculate the actual width of the region indicated by the line on Figure 14. Give your answer in millimetres, in standard form.

* (c) A student investigated the movement of water. Hens’ eggs were placed in vinegar for two days to dissolve the shell. This makes the eggs permeable to water. The eggs were then weighed and placed in different solutions. After 24 hours the eggs were weighed again. Figure 15 shows the results.

Figure 15

Evaluate the results of this investigation. You should include calculations using the data in Figure 15.

Figure 10 shows a single-celled pond organism (Amoeba proteus).

Which row of the table allows the net diffusion of oxygen into Amoeba proteus ?

Amoeba proteus uses oxygen for aerobic respiration.

Complete the equation for aerobic respiration.

glucose + oxygen _........ +_........ (+ energy is released)

Humans breathe faster when they exercise.

Which two changes allow the rate of respiration in the muscle to increase?

Figure 11 shows breathing data for a human at rest and when running at 5 metres per second on a running machine.

Calculate the mean volume of air breathed per minute when running at 5 metres per second.

Give your answer to one decimal place.

_........ dm³ per minute

Devise an investigation to compare the mean number of breaths per minute for men, with the mean number of breaths per minute for women, when running at 5 metres per second on a running machine.

Whilst running, the leg muscles of an athlete tightened up, causing cramp.

Name the product of anaerobic respiration that can cause cramp.

Figure 21 shows the human urinary system.

Urine is made by removing water, urea and salts from the blood.

Use the letter X to label where urine is made.

Which substance is converted to urea in the liver?

A patient cannot remove enough urea from the blood when making urine.

Figure 22 shows a dialysis machine attached to the arm of this patient.

Their blood is pumped out of their arm, passed through the dialysis machine, and then put back into the patient.

Describe what happens to urea as the blood passes through the dialysis machine.

Two patients need to have dialysis treatment.

Patient A needs this treatment three times a week.

Patient B needs this treatment once a week.

Give one reason why patient B needs dialysis treatment less often than patient A.

Describe how to test for glucose in the dialysis fluid.

Urease is an enzyme that breaks down urea into smaller molecules.

Explain why urease will not break down starch into smaller molecules.

Figure 7 shows the human urinary system.

Urine is made by removing water, urea and salts from the blood.

Use the letter X to label where urine is made.

Which substance is converted to urea in the liver?

A patient cannot remove enough urea from the blood when making urine.

Figure 8 shows a dialysis machine attached to the arm of this patient.

Their blood is pumped out of their arm, passed through the dialysis machine, and then put back into the patient.

Describe what happens to urea as the blood passes through the dialysis machine.

Two patients need to have dialysis treatment.

Patient A needs this treatment three times a week.

Patient B needs this treatment once a week.

Give one reason why patient B needs dialysis treatment less often than patient A.

Describe how to test for glucose in the dialysis fluid.

Urease is an enzyme that breaks down urea into smaller molecules.

Explain why urease will not break down starch into smaller molecules.

Figure 9 shows the structure and actual size of red blood cells (erythrocytes).

red blood cells side view of red blood cell (cut)

(Source: © N.Vinoth Narasingam/Shutterstock)

Figure 9

Calculate the image size of the top view of this red blood cell if this cell is

Give your answer in mm.

Explain how the shape of a red blood cell is related to its function.

State the role of haemoglobin inside the red blood cell.

Some blood transfusions contain red blood cells.

Red blood cells are stored in a solution containing 5.0% glucose and 0.9% salt.

Explain why red blood cells cannot be stored in pure water.

Figure 4 shows three cells.

What is structure X ?

The bacterial cell in Figure 4 has a flagellum.

State the function of a flagellum.

Give one other difference between the bacterial cell and the animal cell shown in Figure 4.

Substances move into and out of cells.

How does oxygen move into and out of cells?

A plant leaf cell is 0.04 mm long.

Calculate the length of the image after this cell has been magnified 500 times.

A student placed three different sized cubes of agar jelly into separate beakers containing the same concentration of hydrochloric acid.

The cubes contained a pink indicator.

This indicator becomes clear when in contact with an acid.

Figure 7 shows the results of the investigation after the cubes had been in the acid for 120 seconds.

The distance from the outside of cube B to the pink area was 3 mm.

Calculate the distance diffused by hydrochloric acid in one second.

The student wanted to confirm their results.

Give one improvement the student should make to this investigation to confirm their results.

Devise a method, using cubes of agar jelly, to investigate how temperature affects the rate of diffusion.

Some substances move into and out of cells by active transport.

Which is the correct description of the movement of a substance by active transport?

Some drugs used to treat cancer are taken into cells by active transport.

Figure 8 shows some causes of preventable cases of cancer in 2015.

What is the percentage of preventable cases of cancer that are caused by tobacco?

In 2015, data from Cancer Research UK suggested that 163 440 cases of cancer could have been prevented.

Calculate the number of preventable cases of cancer caused by alcohol.

Give your answer to the nearest whole number.

number of preventable cases of cancer caused by alcohol_........

Figure 6 shows a root hair cell from a strawberry plant.

Label the cell vacuole in Figure 6.

Explain how the structure of root hair cells increases water absorption from the soil.

Figure 7 shows fungus growing on strawberries.

The fungus is decomposing the strawberries.

A scientist investigated the effect of temperature on the decomposition of strawberries.

The scientist spread fresh strawberries on six trays.

Each tray was kept at a different temperature.

After five days the scientist measured the area of fungus that had grown on each tray of strawberries.

The results are shown in Figure 8.

The mean rate of growth of fungus at 25C was 12 cm² per day.

Calculate the mean rate of growth of fungus at 30C.

_........ cm² per day

State the effect of temperature on the growth of fungus on strawberries from 5C to 30C.

Decomposition of strawberries can be prevented by boiling the strawberries with sugar to make jam.

Enzymes in the fungus caused decomposition.

Explain how boiling stops the enzymes from working.

Cells from a fungus can land on jam.

The sugar solution inside the jam is more concentrated than the sugar solution inside the fungus cells.

State how osmosis causes the fungus cells to die.

A person with kidney disease may need kidney dialysis treatment.

Figure 15 shows an experiment to show how a dialysis membrane works.

Describe the method that would be used to find out what is present in the solution in the beaker, after one hour.

Explain how this experiment represents a simple model of kidney dialysis treatment.

*(b) The nephrons in the kidney remove unwanted substances from the blood.

Figure 16 shows the structure of a nephron.

Explain how substances are exchanged between the blood entering the nephron and the filtrate leaving the collecting duct.

Include reference to named structures of the nephron in your answer.

Figure 10 shows a plant cell as seen under a light microscope.

(Source: © HERVE CONGE, ISM/SCIENCE PHOTO LIBRARY)

Figure 10

Draw this plant cell in the box below.

Label three parts of this cell.

Mitochondria cannot be seen with a light microscope.

What is the function of mitochondria in a plant cell?

A student wanted to investigate the movement of water into and out of cells in potatoes.

The student had the equipment shown in Figure 11.

The test tubes in the rack contain different concentrations of sodium chloride solution.

The solutions were 0.1 M, 0.2 M, 0.3 M, 0.4 M and 0.5 M sodium chloride solution.

The test tube in the beaker contains distilled water.

There are three potato chips in each of the six test tubes.

State why the test tube in the beaker only contains distilled water and three potato chips.

State two variables that need to be controlled in this investigation.

Explain why the chips in the 0.5 M sodium chloride solution lost mass.

(a) Figure 10 shows alveoli from a lung.

Figure 10

Explain why these alveoli have the internal structure shown in Figure 10.

How does oxygen move across the alveolar membrane into the capillary?

Figure 11 shows the movement of molecules across a membrane.

at start
after 2 seconds
after 4 seconds

Figure 11

Describe how Figure 11 illustrates movement of molecules across a membrane.

*(c) Explain, using Fick’s law, the factors that affect the diffusion rate of molecules into and out of cells.

Figure 11 shows two potato chips.

Figure 12 shows some information about each potato chip.

Calculate the total surface area of potato chip B using the formula,

Total surface area = 2XY + 2XZ + 2YZ

The potato chips were placed in distilled water for 20 minutes.

Figure 13 shows the increase in mass of each potato chip.

Explain why potato chip B has a greater increase in mass than potato chip A.

Potato chip A is transferred from the distilled water into a concentrated salt solution.

Explain what will happen to the cells in potato chip A.

*(b) Figure 14 shows two varieties of potato plant.

• large potatoes • small potatoes

• few potatoes • many potatoes

• slow growing plant • fast growing plant

Figure 14

New varieties of potato plant can be produced by selective breeding.

Explain how selective breeding of the two varieties of potato plants can produce new potato plants that are all faster growing and produce many, large potatoes.

(a) Figure 5 shows two potato chips.

Figure 6 shows some information about each potato chip.

Calculate the total surface area of potato chip B using the formula,

Total surface area = 2XY + 2XZ + 2YZ

The potato chips were placed in distilled water for 20 minutes.

Figure 7 shows the increase in mass of each potato chip.

Explain why potato chip B has a greater increase in mass than potato chip A.

Potato chip A is transferred from the distilled water into a concentrated salt solution.

Explain what will happen to the cells in potato chip A.

The potatoes of a potato plant develop underground.

Explain one difference in the sub-cellular structures in a cell in the potato and those in a cell in the leaf of the potato plant.

Figure 16 shows the urinary system of a human.

Name the structures labelled P and Q.

The kidney contains nephrons.

Figure 17 shows the concentration of glucose and protein found in the blood plasma and in the filtrate inside a nephron.

Explain the difference in the concentration of protein in the blood plasma and in the filtrate in the nephron.

Explain how glucose moves from the blood plasma into the nephron.

*(c) Figure 18 shows a patient undergoing kidney dialysis.

Describe how dialysis removes unwanted substances from the blood.

Include examples of unwanted substances in your answer.

(a) A student investigated the effect of nitrate ion concentration on plant growth. She placed barley seedlings in three test tubes containing different concentrations of nitrate fertiliser.

Test tube 1 contained distilled water with 1 pellet of nitrate fertiliser. Test tube 2 contained distilled water with 2 pellets of nitrate fertiliser. Test tube 3 contained distilled water with 3 pellets of nitrate fertiliser.

After 7 days, the lengths of the seedlings were measured.

Figure 13 shows an example of the apparatus used.

Describe a control for this investigation.

The nitrate fertiliser contains the chemical compound potassium nitrate. The hazard symbol on the bag of potassium nitrate fertiliser is shown in Figure 14.

Which hazard does this symbol represent?

Give a method, other than measuring the change in length, that would show the growth of the seedlings.

Figure 15 shows the results of this investigation.

Explain why there are differences in the change in the lengths of the seedlings.

Explain how nitrate ions were absorbed by the seedling in test tube 3.

Farmers use crop rotation to reduce the need to add nitrate fertilisers to the soil.

Plants such as peas and beans have a mutualistic relationship with nitrogen-fixing bacteria.

Explain why farmers use these plants in their crop rotation cycle.