Diffusion

The human body is made of different types of cell.

Draw one line from each type of cell to the organ system where the cell is found.

Explain one way a sperm cell is adapted for its function.

Figure 1 shows a cell.

Oxygen molecules are shown inside and outside the cell.

Give one way you can tell that the cell in Figure 1 is not a plant cell.

Which part of a cell controls the movement of substances into and out of the cell?

Tick (✓) one box.

What is the name of the process that moves oxygen molecules into the cell in Figure 1 ?

Give the reason for your answer.

Tick (✓) one box.

Name two substances that move into most cells in the body from the blood.

Do not refer to oxygen in your answer.

Figure 2 shows a section through a leaf.

Give one way that the palisade layer is adapted for photosynthesis.

Gases pass into and out of the leaf through small pores in the surface of the leaf.

What are the small pores labelled X called?

Tick (✓) one box.

A student viewed a section of a leaf using a microscope.

The student measured the length of one of the palisade cells.

The cell image measured 28 mm in length when viewed at a magnification of ×400

Calculate the real length of the palisade cell in millimetres (mm).

Use the equation:

Convert the real length of the cell from millimetres to micrometres (µm).

1 mm = 1000 µm

Carbon dioxide can move into and out of cells.

What is the process by which carbon dioxide can move into and out of cells?

Tick (✓) one box.

Figure 3 shows a diagram of four cells.

Each cell is surrounded by carbon dioxide molecules.

Which cell will carbon dioxide move into at the fastest rate?

Give a reason for your answer.

Tick (✓) one box.

A student investigated the effect of different colours of light on the rate of photosynthesis.

Figure 4 shows some of the apparatus the student used.

The student placed the apparatus in blue light, then in green light and then in red light.

The student measured the rate of photosynthesis in each colour of light.

What two measurements should the student make to calculate the rate of photosynthesis?

Give two variables the student should keep the same in this investigation.

Table 2 shows the results.

Complete Figure 5.

You should:

• label the y-axis

• use a suitable scale

• plot the data from Table 2 as a bar chart

• label each bar.

Look at Table 2.

What colour of light should be used to grow plants in a greenhouse?

Tick (✓) one box.

Starch is digested to form sugar molecules in the digestive system.

What is the name of the enzyme that digests starch?

Where are most food molecules absorbed? Tick (✓) one box.

Figure 6 shows two villi. Figure 6 also shows one cell on the surface of a villus as seen using an electron microscope.

Give one advantage of using an electron microscope compared with using a light microscope.

What type of blood vessel is labelled X ? Tick (✓) one box.

The real length of one villus is 0.8 mm Calculate the image length if the villus is viewed at a magnification of ×20 Use the equation:

Figure 7 shows two cells from the surface of a villus. There are sugar molecules inside and next to each cell.

Name the process by which sugar moves into cell A.

Name the process by which sugar moves into cell B.

Give one use of sugar in the body.

Figure 6 is repeated below.

Explain how villi are adapted for efficient absorption of sugar molecules.

Starch is digested to form sugar molecules in the digestive system.

What is the name of the enzyme that digests starch?

Where are most food molecules absorbed? Tick (✓) one box.

Figure 2 shows two villi. Figure 2 also shows one cell on the surface of a villus as seen using an electron microscope.

Give one advantage of using an electron microscope compared with using a light microscope.

What type of blood vessel is labelled X ? Tick (✓) one box.

The real length of one villus is 0.8 mm Calculate the image length if the villus is viewed at a magnification of ×20 Use the equation:

Figure 3 shows two cells from the surface of a villus. There are sugar molecules inside and next to each cell.

Name the process by which sugar moves into cell A.

Name the process by which sugar moves into cell B.

Give one use of sugar in the body.

Figure 2 is repeated below.

Explain how villi are adapted for efficient absorption of sugar molecules.

A single-celled organism has a large surface area to volume ratio.

How does oxygen enter a single-celled organism?

Tick (✓) one box.

Figure 3 shows two cubes.

The surface area to volume ratio for cube A is 6:1

Calculate the surface area to volume ratio of cube B.

Surface area of one face of cube B

Total surface area of cube B

Volume of cube B

Multicellular organisms have exchange surfaces to absorb substances.

Figure 4 shows part of the exchange surface in the lungs.

Oxygen passes from the alveolus into the blood.

Name the part of the blood that carries the most oxygen.

Name the gas that passes out of the blood into the alveolus.

Alveoli provide a large surface area for gas exchange.

Give two other ways the lungs are adapted for efficient gas exchange.

This question is about digestion.

Name the enzyme that digests starch in the human digestive system.

A student set up a model to represent the digestion and absorption of food molecules in the digestive system.

Figure 11 shows the student’s model.

This is the method used.

1. Fill a test tube with water at 37 °C

2. Test the water for starch and for sugar.

3. Mix together starch and enzyme solution and immediately test it for starch and for sugar.

4. Fill some partially permeable tubing with the starch and enzyme mixture.

5. Seal the tubing and place it in the test tube of water.

6. Place the test tube in a water bath at 37 °C

7. After 30 minutes, test the mixture inside the partially permeable tubing and test the water in the test tube for starch and for sugar.

Suggest which parts of the body the partially permeable tubing and the water in the test tube represent.

Partially permeable tubing

Water in the test tube

Table 3 shows the results.

✗ = Not present

Name the reagents used to test for starch and for sugar.

Why was there no sugar present in test 1 ?

Explain the results for test 3.

Explain the results for test 4.

Pathogens are microorganisms that cause infectious diseases.

What type of pathogen causes malaria? Tick (✓) one box.

Give two methods used to prevent people catching malaria. Give a reason why each method works.

Describe two differences between a bacterial cell and a eukaryotic cell.

A scientist investigated the population growth of bacteria in a culture solution. At the start of the investigation the culture solution contained all the nutrients the bacteria needed. The scientist determined the number of living bacterial cells in the solution every hour over two days. Figure 5 shows the apparatus used.

Describe why there are air holes in the cap of the culture bottle.

Figure 6 shows the scientist’s results.

Give one reason for what is happening to the number of bacteria at each of the stages.

Figure 7 shows two cubes. Cube X represents a bacterial cell. Cube Y represents a small multicellular organism.

A bacterial cell can absorb all the nutrients it needs by diffusion through its outer surface. Explain why a multicellular organism cannot absorb all the nutrients it needs by diffusion through its outer surface. You must include calculations in your answer. Use Figure 7.