AQA GCSE Trilogy Biology Paper 1 Higher June 2019 question paper 8464/B/1H

Figure 1 shows a human heart.

Which blood vessel carries deoxygenated blood away from the heart to the lungs? Tick (✓) one box.

The natural resting heart rate is controlled by a group of cells that act as a pacemaker. Where in the heart are ‘pacemaker cells’ found?

Tick (✓) one box.

Some people may be treated with a drug to slow their heart rate.

Digitalis is a drug that slows the heart rate. Where does the drug digitalis originate from?

Tick (✓) one box.

Beta blockers are another type of drug that slows the heart rate. Table 1 shows information for people who do not take beta blockers and for people who do take beta blockers.

• Stroke volume is the volume of blood pumped out of the heart each time it beats.

• Cardiac output is the total volume of blood pumped out of the heart each minute.

Calculate stroke volume X in Table 1. Use the equation: cardiac output = stroke volume × heart rate Give your answer to 2 significant figures.

Some people who take beta blockers get out of breath when they exercise. Explain why beta blockers can have this effect during exercise. You should refer to information given in Table 1.

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 2 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 2 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.

A student used a potometer to investigate the rate of water uptake in a plant shoot. Figure 3 shows a potometer.

As the shoot takes in water the air bubble moves. The rate of water uptake is the distance the air bubble moves in a given time. This is the method used.

1. Place the potometer in moist air at 25 °C

2. Position the air bubble at 0 mm in the capillary tube.

3. Record the position of the air bubble in the capillary tube every minute for 5 minutes.

4. Repeat steps 2 and 3 with the potometer in different conditions.

Table 3 shows the conditions used.

After investigation A the air bubble had moved part way along the capillary tube. Suggest how the student moved the air bubble back to 0 mm for the start of investigation B.

Capillary tubing is very narrow. Explain why narrow tubing was used.

Figure 4 shows the results for investigation A.

The cross-sectional area of the capillary tube was 0.8 mm² Calculate the rate of water uptake for investigation A in mm³/min

Table 4 shows the results from investigation B.

Plot the data from Table 4 on Figure 4. You should:

• draw a line of best fit

• label the line B.

Investigation C was carried out in dry air at 25 °C Draw a line on Figure 4 to show the results you would expect for investigation C. Label the line C.

The investigations were carried out in daylight. The air bubble would not move if the investigations were done in the dark. Explain why.

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.

Figure 8 shows a root hair viewed using a microscope.

The root hair was viewed at a magnification of ×50 The image length of the root hair X – Y is 43 mm Calculate the real length of the root hair in micrometres (µm).

A microscope has a ×5 eyepiece lens. Describe how to use this microscope to observe a prepared slide of root hair cells at a magnification of ×50

Root hair cells absorb water and mineral ions from the soil. A scientist investigated the rate of nitrate ion uptake by two seedlings. Figure 9 shows how the investigation was set up.

The scientist determined the mass of nitrate ions absorbed by each seedling every 30 minutes for 4 hours. Table 5 shows the results.

Describe the changes in the rate of absorption of nitrate ions for the seedling with no oxygen added. Use information from Table 5.

Explain what the results in Table 5 show about how nitrate ions are absorbed.

Nitrate ions are essential for plants to grow. Describe how nitrate ions are used in a plant to help the plant grow.