Microscopy

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.

Figure 6 shows a green pepper growing on a pepper plant.

The cells of the green pepper contain water.

Water cannot enter the cells through the waxy waterproof coating on the outside of the pepper fruit.

Describe how water reaches the green pepper cells.

A pepper cell was viewed using a microscope.

The image of a pepper cell had a width of 32 mm.

The magnification of the image was × 400

Calculate the real width of the cell in micrometres.

Real width = __________________ micrometres

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.

8. Calculate the mean percentage change in mass at each concentration of sugar solution.

Before the investigation, the pepper was kept at 5 °C.

Suggest why.

Describe why calculating the percentage change in mass is more valid than only calculating the change in mass.

Figure 7 shows the results.

Figure 7

Mean

Concentration

–10

–20

Determine the concentration of the solution inside the pepper cells before the investigation.

_ Concentration = __________________ mol/dm³

Explain the mean percentage change in mass of pepper when the concentration of sugar solution was 0.5 mol/dm³.

As peppers develop, the vacuoles of the cells increase in volume.

Figure 8 shows the shape of a pepper cell before it is fully developed.

Suggest two reasons why the cell walls of pepper cells are wrinkled.

Figure 4 shows a light microscope.

The eyepiece lens has a magnification of ×10

The high power objective lens has a magnification of × 40

Which calculation shows the total magnification?

Tick (✓) one box.

Write down the equation which links magnification, size of image and size of real object.

A student used a different microscope to view a cell.

The cell was viewed with a magnification of × 250

The size of the image of the cell was 1.5 cm.

Calculate the real size of the cell.

Give your answer in mm.

The student focused the image for the low power objective lens and then changed to the high power objective lens.

The high power objective lens should not be moved towards the stage to focus the image.

Give one reason why.

Viruses are approximately 100 times smaller than animal cells.

What type of microscope is used to view viruses?

Chilli plants can be infected with tobacco mosaic virus (TMV).

Farmers grow chilli plants and sell chilli fruits.

Figure 5 shows chilli fruits growing on a chilli plant.

Figure 6 shows how infection with TMV affects the number of chilli fruits produced on chilli plants.

Determine the decrease in the mean number of chilli fruits produced when plants are infected with TMV.

_ Decrease = _______________________ fruits

Suggest one reason why farmers remove and destroy plants that are infected with TMV.

Figure 5 shows a light microscope.

A student was given a prepared slide of cells.

Describe how the microscope in Figure 5 could be used to view the cells with the high power objective lens.

Light microscopes are not used to view viruses.

What are two reasons why electron microscopes are used to view viruses?

Tick (✓) two boxes.

Electron microscopes are expensive to maintain

Electron microscopes can have a magnification of ×1 000 000

Electron microscopes have a high resolving power

Viruses are not living organisms

Viruses are found and are replicated inside living cells

Plant species Q is not resistant to one type of virus.

Explain how the process of natural selection could result in all plants of species Q having resistance to the virus.

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

Pollutants in the atmosphere can be harmful to the environment and to human health.

Four pollutants in the atmosphere are:

Describe how carbon monoxide is produced from hydrocarbon fuels.

Describe one harmful effect of oxides of nitrogen.

Figure 7 shows the emissions of three atmospheric pollutants from 1970 to 2019.

Determine the percentage change in emission of oxides of nitrogen from 1970 to 2019.

Give your answer to 2 significant figures.

Compare the changes in the emission of atmospheric pollutants from 1970 to 2019.

You should refer to:

Use Figure 7.

Suggest one reason for the change in the emission of atmospheric pollutants shown in Figure 7.

Particulates are classified into different groups depending on diameter of the particulate.

Table 4 shows information about the different groups.

A soot particle was viewed using a microscope.

The magnification used was × 5000.

The diameter of the image of the soot particle was 7.5 mm.

Determine the particulate group of the soot particle.

1 mm = 1000 micrometres

Use Table 4.

Real diameter of soot particle = ____________________ micrometres

Particulate group.

Tick (✓) one box.

PM PM PM 10 2.5 0.1

Particulates in the air can be breathed in.

The body’s defences prevent particulates larger than 10 micrometres getting into the lungs.

Describe how the body prevents the particulates reaching the lungs and removes the particulates from the airways.

Students investigated the effect of different concentrations of salt solution on the mass of pieces of potato.

This is the method used.

1. Cut three pieces of potato, each with a mass of 2.00 g.

2. Place the pieces of potato into a salt solution with a concentration of 0.2 mol/dm³

3. After 30 minutes, measure the mass of each piece of potato.

4. Calculate the change in mass.

5. Repeat steps 1 to 4 for five other concentrations of salt solution.

Table 3 shows the results.

Give two control variables the students should have used in the investigation.

Do not refer to mass or time in your answer.

Calculate value X in Table 3.

Figure 14 shows a potato cell.

Explain why the mass of the pieces of potato increased in the 0.2 mol/dm³ salt solution.

You should refer to the cell parts labelled in Figure 14.

The image in Figure 14 was made using an electron microscope and not a light microscope.

Give one piece of evidence to support this.

Starch is digested in the gut.

Why is digestion of starch needed?

Tick (✓) one box.

Starch is a carbohydrate.

Starch molecules are insoluble.

Starch molecules are small.

Describe the process of starch digestion.

Students investigated the effect of different concentrations of salt solution on the mass of pieces of potato.

This is the method used.

1. Cut three pieces of potato, each with a mass of 2.00 g.

2. Place the pieces of potato into a salt solution with a concentration of 0.2 mol/dm³

3. After 30 minutes, measure the mass of each piece of potato.

4. Calculate the change in mass.

5. Repeat steps 1 to 4 for five other concentrations of salt solution.

Table 1 shows the results.

Give two control variables the students should have used in the investigation.

Do not refer to mass or time in your answer.

Calculate value X in Table 1.

Figure 2 shows a potato cell.

Explain why the mass of the pieces of potato increased in the 0.2 mol/dm³ salt solution.

You should refer to the cell parts labelled in Figure 2.

The image in Figure 2 was made using an electron microscope and not a light microscope.

Give one piece of evidence to support this.

Starch is digested in the gut.

Why is digestion of starch needed?

Tick (✓) one box.

Starch is a carbohydrate.

Starch molecules are insoluble.

Starch molecules are small.

Describe the process of starch digestion.

The endocrine system releases hormones into the blood.

Figure 10 shows some endocrine glands and some target organs.

Which structure is the pituitary gland?

Tick (✓) one box.

W X Y Z

Which is the main target organ of the hormone insulin?

Tick (✓) one box.

Kidney Liver Pancreas

The endocrine system sends hormones to target organs.

The nervous system sends impulses to target organs.

How does the speed of movement of hormones compare with the speed of transmission of impulses?

Tick (✓) one box.

Hormones travel more slowly than impulses.

Hormones travel at the same speed as impulses.

Hormones travel more quickly than impulses.

The pituitary gland releases hormones, which results in widespread effects on the body.

Explain why the pituitary gland is sometimes called the ‘master gland’.

Figure 11 shows human blood viewed through a light microscope.

Name cell A and cell B.

The image of a cell has a diameter of 3.5 millimetres.

The magnification of the image is ×500.

Calculate the diameter of the real cell.

Give your answer in micrometres.

Use the equation:

1 millimetre = 1000 micrometres

Diameter of the real cell = __________________ micrometres

The endocrine system releases hormones into the blood.

Figure 1 shows some endocrine glands and some target organs.

Which structure is the pituitary gland?

Tick (✓) one box.

W X Y Z

Which is the main target organ of the hormone insulin?

Tick (✓) one box.

Kidney Liver Pancreas

The endocrine system sends hormones to target organs.

The nervous system sends impulses to target organs.

How does the speed of movement of hormones compare with the speed of transmission of impulses?

Tick (✓) one box.

Hormones travel more slowly than impulses.

Hormones travel at the same speed as impulses.

Hormones travel more quickly than impulses.

The pituitary gland releases hormones, which results in widespread effects on the body.

Explain why the pituitary gland is sometimes called the ‘master gland’.

Figure 2 shows human blood viewed through a light microscope.

Name cell A and cell B.

The image of a cell has a diameter of 3.5 millimetres.

The magnification of the image is ×500.

Calculate the diameter of the real cell.

Give your answer in micrometres.

Use the equation:

1 millimetre = 1000 micrometres

Diameter of the real cell = __________________ micrometres

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.

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.