Cell structure

Figure 9 shows a human egg cell viewed using a light microscope.

In Figure 9, the diameter of the image of the egg is 38 mm.

The magnification of Figure 9 is × 400

Calculate the real diameter of the egg cell in micrometres.

Use the equation:

1 millimetre = 1000 micrometres

Real diameter of egg cell = _____________________ micrometres

Draw a simple diagram of the egg cell shown in Figure 9.

On your drawing:

$l~bel two parts of the egg cell that are visible in Figure 9

$do not include other cells.

Some parts of a human egg cell are not visible in Figure 9.

Name one part of a human egg cell that is only visible using an electron microscope.

Name the process of cell division that produces egg cells.

How many chromosomes are in a human egg cell?

Describe how a chromosome in a sperm cell determines whether the offspring that forms is male or female.

Which hormone stimulates the release of an egg?

Tick () one box.

FSH

LH

Oestrogen

Oral contraceptive pills contain hormones that prevent the release of an egg.

Scientists studied the effectiveness of different types of contraception with perfect use and with use in real life.

‘Perfect use’ means following all the instructions.

‘Use in real life’ is what actually happens in the population. The instructions may not always be followed in real life.

Figure 10 shows the results.

Evaluate the effectiveness of the three types of contraception shown in Figure 10.

Use data from Figure 10.

Figure 1 shows a human egg cell viewed using a light microscope.

In Figure 1, the diameter of the image of the egg is 38 mm.

The magnification of Figure 1 is × 400

Calculate the real diameter of the egg cell in micrometres.

Use the equation:

1 millimetre = 1000 micrometres

Real diameter of egg cell = _____________________ micrometres

Draw a simple diagram of the egg cell shown in Figure 1.

On your drawing:

$l~bel two parts of the egg cell that are visible in Figure 1

$do not include other cells.

Some parts of a human egg cell are not visible in Figure 1.

Name one part of a human egg cell that is only visible using an electron microscope.

Name the process of cell division that produces egg cells.

How many chromosomes are in a human egg cell?

Describe how a chromosome in a sperm cell determines whether the offspring that forms is male or female.

Which hormone stimulates the release of an egg?

Tick () one box.

FSH

LH

Oestrogen

Oral contraceptive pills contain hormones that prevent the release of an egg.

Scientists studied the effectiveness of different types of contraception with perfect use and with use in real life.

‘Perfect use’ means following all the instructions.

‘Use in real life’ is what actually happens in the population. The instructions may not always be followed in real life.

Figure 2 shows the results.

Evaluate the effectiveness of the three types of contraception shown in Figure 2.

Use data from Figure 2.

Bacteria can cause disease.

Bacterial cells do not have a nucleus.

Which term describes bacterial cells?

Tick (✓) one box.

Eukaryotic

Fungal

Prokaryotic

Bacterial cells have no nucleus and are smaller than animal cells.

Give one other difference between bacterial cells and animal cells.

Escherichia coli (E. coli) is a type of bacterium.

E. coli causes symptoms of food poisoning.

Water companies sterilise rain water to produce drinking water.

The drinking water is then transported to homes in underground pipes.

Flooding can cause contamination of the drinking water by E. coli.

Suggest how people should treat drinking water at home if there is a risk of E. coli contamination.

Figure 11 shows two graphs:

The rainfall in one town in one month.

The number of cases of E. coli in the town in the same month.

The rainfall on day 12 was greater than on day 10.

Calculate how many times greater.

Symptoms of E. coli infection usually occur 5 days after infection.

A scientist stated:

‘Increased rainfall causes an increase in the number of cases of E. coli.’

Describe one piece of evidence from Figure 11 that supports the scientist’s statement.

Why might the number of cases of E. coli infection increase in the future?

Tick (✓) one box.

Climate change is causing loss of habitats for wildlife.

Climate change is causing more extreme rainfall.

Climate change is causing sea-levels to be lower.

Climate change is caused by an increase in the concentration of greenhouse gases in the atmosphere.

Carbon dioxide is a greenhouse gas.

Name two other greenhouse gases.

Do not refer to carbon dioxide in your answer.

Describe one way the rate of increase in carbon dioxide concentration in the atmosphere could be reduced.

Bacteria can cause disease.

Bacterial cells do not have a nucleus.

Which term describes bacterial cells?

Tick (✓) one box.

Eukaryotic

Fungal

Prokaryotic

Bacterial cells have no nucleus and are smaller than animal cells.

Give one other difference between bacterial cells and animal cells.

Escherichia coli (E. coli) is a type of bacterium.

E. coli causes symptoms of food poisoning.

Water companies sterilise rain water to produce drinking water.

The drinking water is then transported to homes in underground pipes.

Flooding can cause contamination of the drinking water by E. coli.

Suggest how people should treat drinking water at home if there is a risk of E. coli contamination.

Figure 1 shows two graphs:

The rainfall in one town in one month.

The number of cases of E. coli in the town in the same month.

The rainfall on day 12 was greater than on day 10.

Calculate how many times greater.

Symptoms of E. coli infection usually occur 5 days after infection.

A scientist stated:

‘Increased rainfall causes an increase in the number of cases of E. coli.’

Describe one piece of evidence from Figure 1 that supports the scientist’s statement.

Why might the number of cases of E. coli infection increase in the future?

Tick (✓) one box.

Climate change is causing loss of habitats for wildlife.

Climate change is causing more extreme rainfall.

Climate change is causing sea-levels to be lower.

Climate change is caused by an increase in the concentration of greenhouse gases in the atmosphere.

Carbon dioxide is a greenhouse gas.

Name two other greenhouse gases.

Do not refer to carbon dioxide in your answer.

Describe one way the rate of increase in carbon dioxide concentration in the atmosphere could be reduced.

Figure 5 shows a green pepper growing on a pepper plant.

Figure 6 shows a drawing of a cell from a pepper.

Cell part A contains a green pigment.

Label parts A, B and C on Figure 6.

Choose answers from the box.

Water can move into cells and out of cells.

A student investigated how different concentrations of sugar solution affect the mass of pepper tissue.

This is the method used.

1. Cut three pieces of pepper 1 cm wide and 1 cm long.

2. Dry each piece.

3. Record the mass of each piece.

4. Leave each piece in sugar solution for 1 hour.

5. Remove the pieces from the sugar solution and dry each piece.

6. Record the mass of each piece.

7. Repeat steps 1 to 6 using different concentrations of sugar solution.

Before the investigation, the pepper was wrapped in plastic and kept at 5 °C.

Which are two reasons for keeping the pepper wrapped in plastic at 5 °C?

Tick (✓) two boxes.

To change the colour of the pepper

To decrease the size of the pepper

To increase growth of the pepper

To reduce water loss from the pepper

To slow down decay of the pepper

The student calculated the mean percentage change in mass at each concentration of sugar solution.

Figure 7 shows the results.

Figure 7

Concentration

–10

–20

In some concentrations of sugar solution, the mass of the pieces of pepper increased.

The mass increased because water moved into the cells.

What process moved water into the cells?

What concentration of sugar solution would cause a mean percentage change in mass of 0%?

Use Figure 7.

Concentration of sugar solution = __________________ arbitrary units

The cells of the pepper have wrinkled cell walls.

What is the advantage of wrinkled cell walls to the pepper plant?

Tick (✓) one box.

The cells can expand

The cells contain less cellulose

The surface area is smaller

Tobacco mosaic virus (TMV) can infect pepper plants.

Infected plants have yellow patches on the leaves.

Explain why plants with TMV grow slower than plants that do not have TMV.

All living organisms are made of cells.

Figure 15 shows two types of cell.

Calculate how many times longer the liver cell is than the bacterial cell.

Compare the structure of cell A with the structure of cell B.

You should include similarities and differences in your answer.

Do not refer to cell size.

In multicellular organisms, cells are organised into tissues.

What is meant by a ‘tissue’?

A scientist investigated the effect of different concentrations of sugar solution on red blood cells.

Figure 16 shows the effect of placing a red blood cell into a sugar solution.

What conclusion can be made from the result in Figure 16 ?

Tick (✓) one box.

The sugar solution was less concentrated than inside the cell.

The sugar solution was the same concentration as inside the cell.

The sugar solution was more concentrated than inside the cell.

A student investigated the effect of different concentrations of sugar solution on the change in mass of plant tissue.

The student used pieces of potato.

Describe a method the student could use to produce valid results.

The student used a valid method.

The student calculated the percentage change in mass of the pieces of potato.

Table 5 shows the results.

Complete Figure 17.

You should:

plot the data from Table 5

draw a line of best fit.

Some of the results have been plotted for you.

Determine the concentration of sugar solution that would cause no change in the mass of a piece of the potato.

Use Figure 17.

Concentration of sugar solution = _________________________ mol/dm³

All living organisms are made of cells.

Figure 1 shows two types of cell.

Calculate how many times longer the liver cell is than the bacterial cell.

Compare the structure of cell A with the structure of cell B.

You should include similarities and differences in your answer.

Do not refer to cell size.

In multicellular organisms, cells are organised into tissues.

What is meant by a ‘tissue’?

A scientist investigated the effect of different concentrations of sugar solution on red blood cells.

Figure 2 shows the effect of placing a red blood cell into a sugar solution.

What conclusion can be made from the result in Figure 2 ?

Tick (✓) one box.

The sugar solution was less concentrated than inside the cell.

The sugar solution was the same concentration as inside the cell.

The sugar solution was more concentrated than inside the cell.

A student investigated the effect of different concentrations of sugar solution on the change in mass of plant tissue.

The student used pieces of potato.

Describe a method the student could use to produce valid results.

The student used a valid method.

The student calculated the percentage change in mass of the pieces of potato.

Table 1 shows the results.

Complete Figure 3.

You should:

plot the data from Table 1

draw a line of best fit.

Some of the results have been plotted for you.

Determine the concentration of sugar solution that would cause no change in the mass of a piece of the potato.

Use Figure 3.

Concentration of sugar solution = _________________________ mol/dm³

Heart tissue is made of cardiac muscle cells.

Figure 2 shows a cardiac muscle cell.

Cardiac muscle needs to contract and relax continuously.

Cardiac muscle cells contain a large number of the structures labelled A.

Name structure A.

Oxygen moves from the cytoplasm into structure A by the process of diffusion.

Why does the oxygen move by diffusion?

Which change would cause the rate of diffusion of oxygen across an exchange surface to decrease?

Tick (✓) one box.

An increase in the surface area of the exchange surface

An increase in the temperature of the cell

An increase in the thickness of the exchange surface

The cardiac muscle cells in humans can respire aerobically and anaerobically. Aerobic respiration uses oxygen. Anaerobic respiration does not use oxygen.

Compare the processes of aerobic respiration and anaerobic respiration.

Do not refer to oxygen in your answer.

Figure 3 shows a diagram of a human heart.

What is the name of blood vessel X ?

Tick (✓) one box.

Aorta

Pulmonary artery

Pulmonary vein

Vena cava

Give one difference in the composition of the blood in the right ventricle compared with the blood in the left ventricle.

When the walls of the atria and ventricles contract, the pressure increases.

Table 4 shows information about the pressure during one contraction of the heart.

The left ventricle has the highest pressure.

Why does the left ventricle need to have the highest pressure?

What is the most likely maximum pressure in the right atrium?

Use Table 4.

Tick (✓) one box.

< 25 = 25 > 25

Some people have a medical condition called a ‘hole in the heart’.

A ‘hole in the heart’ is a small hole between the right ventricle and the left ventricle.

Some blood flows from the right ventricle to the left ventricle.

Explain why a ‘hole in the heart’ causes a person to feel tired.

Figure 3 shows a human bone cell.

Label the cell structures A, B and C on Figure 3.

Which structure in the cell contains DNA?

Tick (✓) one box.

A student used a microscope to view a cell.

The length of the image of the cell was 40 mm

The real length of the cell was 0.25 mm

Calculate the magnification of the image.

Use the equation:

Magnification = ×

Root hair cells are found on the roots of plants.

Root hair cells do not photosynthesise.

Give one structure found in a leaf cell, but not in a root hair cell.

Which two structures are found in plant cells but not in animal cells?

Tick (✓) two boxes.

Escherichia coli (E. coli) is a species of bacteria that can cause food poisoning.

Which term describes E. coli cells?

Tick (✓) one box.

Antibiotics are used to treat many different bacterial infections.

The government wants scientists to research and develop a new ‘antibiotic test’ that:

• takes less than 30 minutes

• shows doctors if an antibiotic is needed for an infection

• shows doctors which antibiotic to use.

Suggest two reasons why research into antibiotics is needed.

The new test should mean that fewer people take antibiotics.

What are two effects of fewer people taking antibiotics?

Tick (✓) two boxes.

A vaccine against E. coli is being trialled.

Suggest what this vaccine contains to cause immunity to E. coli.

Escherichia coli (E. coli) is a species of bacteria that can cause food poisoning.

Which term describes E. coli cells?

Tick (✓) one box.

Some strains of E. coli are resistant to antibiotics.

Table 1 shows the number of infections caused by antibiotic resistant E. coli.

Calculate the percentage increase in the number of infections caused by antibiotic resistant E. coli between 2014 and 2018.

Use the equation:

Antibiotics are used to treat many different bacterial infections.

The government wants scientists to research and develop a new ‘antibiotic test’ that:

• takes less than 30 minutes

• shows doctors if an antibiotic is needed for an infection

• shows doctors which antibiotic to use.

Suggest two reasons why research into antibiotics is needed.

The new test should mean that fewer people take antibiotics.

What are two effects of fewer people taking antibiotics?

Tick (✓) two boxes.

A vaccine against E. coli is being trialled.

Suggest what this vaccine contains to cause immunity to E. coli.

Figure 3 shows part of one liver cell.

The photograph was taken with an electron microscope.

Name structure X.

Describe the function of mitochondria.

Protein synthesis occurs at ribosomes.

Describe the structure of a protein molecule.

The storage substance in liver cells is a carbohydrate.

Name the carbohydrate storage substance found in liver cells.

Electron microscopes have higher resolving power than light microscopes.

What is the resolving power of a microscope?

Tick (✓) one box.

An electron microscope has a magnification of × 650 000

The length of a cell structure in an image from the electron microscope was 27 mm

Calculate the real length of this cell structure in mm

Give your answer to 2 significant figures.