explaining water movement: worksheet 3 · why do nitrogen fertilisers help the cereal plants to...

Chapter 3: Moving and changing materials

AQA GCSE Biology: Teacher Pack © HarperCollinsPublishers Limited 2016

Explaining water movement: Worksheet 3.1

1 Demonstrating osmosis Look at the demonstration. It has been set up for a few days.

1. The level of the sugar solution has risen. Explain what has caused this.

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2. The left-hand diagram below shows the concentrations of water and sugar molecules inside and outside the Visking sac at the start of the demonstration.

Complete the second diagram to show what has happened by the end of the demonstration.



3. The membrane is a partially permeable membrane.

Explain what is meant by a partially permeable membrane.

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4. Which cells in a plant are adapted to take in water from the soil by osmosis?

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2 Osmosis and animal cells The diagram shows blood cells that have been placed into three different liquids.

1. Match A, B and C to the following three types of liquid.

distilled water .........................

concentrated salt solution .............................

solution with the same salt concentration as the cytoplasm of the cells .............................

2. Explain the effect of each liquid on the cells.

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3 Extend osmosis The diagram shows the pathway of water in a root.

1. Which cells will have the more dilute solutions – the root hair or the cells inside the root?

Explain your answer.

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2. Describe and explain how water moves from the soil to the xylem vessel.

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Learning about plants and minerals: Worksheet 3.11

1 Root hairs Look at the diagram of a root hair. Annotate the diagram by adding these labels to the boxes above.

• large surface area for absorption of water • thin wall to reduce the distance for osmosis • large permanent vacuole to absorb as much water as possible • mitochondria provide energy for active transport.



2 Looking at fertilisers Look at the information on fertilisers in the table below.

Material Nitrogen (%)

Phosphorus (%)

Potassium (%)

Comments

cow manure 0.4 0.1 0.4 slow acting, amounts vary

wood ash 0.0 0.5 10.0 alkaline

bonemeal fertiliser 4.0 20.0 0.0 slow acting, alkaline

superphosphate fertiliser

0.0 18.0 0.0 lasts for 2–3 months

ammonium sulfate fertiliser

20.5 0.0 0.0 quick acting, acidic.

pig manure 0.4 0.1 0.5 slow acting, amounts vary

horse manure 0.6 0.1 0.5 slow acting, amounts vary

fishmeal fertiliser 9.0 12.0 3.0 slow acting, amounts vary

ammonium phosphate fertiliser

11.0 48.0 0.0 quick acting, needs to be diluted

1. Write down the names of three natural fertilisers in the table.

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2. Write down the names of three artificial fertilisers in the table.

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3. A farmer grows a crop that needs a high amount of potassium. Which fertiliser would they use?

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4. Using information from the comments in the table, write down one general difference between natural and artificial fertilisers.

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5. Suggest why ammonium phosphate fertiliser needs to be diluted.

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3 Nitrogen fertiliser and growth A research team investigated how much nitrogen fertiliser was needed to get a good crop of cereal.

Amount of nitrogen fertiliser used in kg/hectare

Mass of cereal produced in tonnes/hectare

0 2.5

50 7.0

100 8.4

150 9.0

200 9.1

Plot this information on the grid below. Complete the graph by drawing a curve.



1. If the amount of fertiliser is doubled from 100 to 200 kg/hectare, how much extra cereal is produced?

.......................................tonnes/hectare

2. How much nitrogen fertiliser would you recommend a farmer to use on his cereal crop? Remember that fertilisers are expensive! Explain why you chose your answer.

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3. Why do nitrogen fertilisers help the cereal plants to grow?

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4 The Rothamsted experiment In 1843, a long-term experiment was set up on the Rothamsted Estate to investigate the use of fertilisers. The experiments are still continuing, which makes it the longest running experiment in the world. Fertilisers containing nitrogen, phosphorus and potassium were used on wheat and potato crops in the same fields for more than 160 years.

Results

Field Fertiliser added in kg/hectare Crop yields in tonnes/hectare

nitrogen phosphorus potassium wheat potatoes

1 0 0 0 1.69 9.47

2 96 0 0 3.68 8.30

3 0 77 107 2.04 16.63

4 96 77 107 6.60 38.57



1. Explain why, in this experiment, field 1 had no fertiliser added.

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2. Suggest why fields 1 and 2 produced almost the same crops of potatoes, but different crops of wheat.

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3. Which field produced the best crop of both wheat and potatoes? Suggest why this treatment may not be used by a farmer.

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4. Which substances do plants make using the three minerals?

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Learning about plants and minerals: Worksheet 3.11

1 Root hairs Look at the diagram of a root hair. Annotate the diagram by adding these labels to the boxes above.

• large surface area for absorption of water • thin wall to reduce the distance for osmosis • large permanent vacuole to absorb as much water as possible • mitochondria provide energy for active transport.



2 Looking at fertilisers Look at the information on fertilisers in the table below.

Material Nitrogen (%)

Phosphorus (%)

Potassium (%)

Comments

cow manure 0.4 0.1 0.4 slow acting, amounts vary

wood ash 0.0 0.5 10.0 alkaline

bonemeal fertiliser 4.0 20.0 0.0 slow acting, alkaline

superphosphate fertiliser

0.0 18.0 0.0 lasts for 2–3 months

ammonium sulfate fertiliser

20.5 0.0 0.0 quick acting, acidic.

pig manure 0.4 0.1 0.5 slow acting, amounts vary

horse manure 0.6 0.1 0.5 slow acting, amounts vary

fishmeal fertiliser 9.0 12.0 3.0 slow acting, amounts vary

ammonium phosphate fertiliser

11.0 48.0 0.0 quick acting, needs to be diluted

1. Write down the names of three natural fertilisers in the table.

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2. Write down the names of three artificial fertilisers in the table.

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3. A farmer grows a crop that needs a high amount of potassium. Which fertiliser would they use?

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4. Using information from the comments in the table, write down one general difference between natural and artificial fertilisers.

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5. Suggest why ammonium phosphate fertiliser needs to be diluted.

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3 Nitrogen fertiliser and growth A research team investigated how much nitrogen fertiliser was needed to get a good crop of cereal.

Amount of nitrogen fertiliser used in kg/hectare

Mass of cereal produced in tonnes/hectare

0 2.5

50 7.0

100 8.4

150 9.0

200 9.1

Plot this information on the grid below. Complete the graph by drawing a curve.



1. If the amount of fertiliser is doubled from 100 to 200 kg/hectare, how much extra cereal is produced?

.......................................tonnes/hectare

2. How much nitrogen fertiliser would you recommend a farmer to use on his cereal crop? Remember that fertilisers are expensive! Explain why you chose your answer.

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3. Why do nitrogen fertilisers help the cereal plants to grow?

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4 The Rothamsted experiment In 1843, a long-term experiment was set up on the Rothamsted Estate to investigate the use of fertilisers. The experiments are still continuing, which makes it the longest running experiment in the world. Fertilisers containing nitrogen, phosphorus and potassium were used on wheat and potato crops in the same fields for more than 160 years.

Results

Field Fertiliser added in kg/hectare Crop yields in tonnes/hectare

nitrogen phosphorus potassium wheat potatoes

1 0 0 0 1.69 9.47

2 96 0 0 3.68 8.30

3 0 77 107 2.04 16.63

4 96 77 107 6.60 38.57



1. Explain why, in this experiment, field 1 had no fertiliser added.

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2. Suggest why fields 1 and 2 produced almost the same crops of potatoes, but different crops of wheat.

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3. Which field produced the best crop of both wheat and potatoes? Suggest why this treatment may not be used by a farmer.

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4. Which substances do plants make using the three minerals?

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Learning about the circulatory system: Worksheet 3.13.1

1 Different circulatory systems This question is about the blood system of different animals. Look at these examples.

Choose your answers from these examples. 1. Which animal does not have a blood system?

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2. Which animal has an open blood system?

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3. Which animals have closed circulatory systems?

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4. Finish the flow diagram to show the circulation of blood in a closed circulatory system.




Circulation The diagram shows a plan of the circulation of a fish and a mammal.

1. Explain how the circulation of a fish is different from the circulation of a mammal.

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2. The graph shows the change in pressure of blood as it passes through different blood vessels.

The aorta is the artery leaving the heart and the vena cava the vein taking blood back to the heart.

a) Write down the name of the type of blood vessel labelled X on the graph.

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b) The graph shows that the blood flow in an artery is different to the blood flow in the vena cava.

Describe how the blood flow is different.

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Exploring the heart: Worksheet 3.14

1 The function of the heart Complete the sentences.

The function of the heart is to pump ........................................... around the body.

The right side of the heart pumps blood to the ........................................ .

The left side of the heart pumps blood to the rest of the ...................................... .

Blood in the arteries is under higher ...................................... than blood in veins.

Blood flows from areas of ................................... pressure to areas of ………..………… pressure.

2 My journey as a red blood cell Choose from the following words to complete the sentences below.

aorta atrium atrium away lungs

oxygen pressure pulmonary artery pulmonary vein valves

vein vein vena cava ventricle ventricle

I am a red blood cell. I carry ............................................. to all the cells in the body.

I like travelling in arteries – I get pushed around so fast. This is because the blood in arteries goes

..................................................... from the heart, so it is under high ………………………………..

I return to the heart in a ........................................ .

I have to get through ............................................ , which are like a one-way door.

I return in a large ............................................................. called the ………………………………...

I enter the right ........................................................ of the heart.

Muscles contract and squeeze me into the right ......................................... .

This chamber then contracts, forcing me out of the heart through the ........................................... .

This takes me to the ........................................ , where I pick up oxygen. I go bright red!

I return to the heart in the ............................................. and go to the left …………………………...

This then forces me into the left .................................................. .

This chamber is the most powerful part of the heart.

I am then forced out in the main artery called the ......................................... .



3 The heart 1. Label the diagram of the heart. Use the words in the box to help you.

aorta bicuspid valve left atrium left ventricle

pulmonary artery pulmonary vein right atrium right ventricle

semi-lunar valve tricuspid valve vena cava

2. Name the part of the heart that pumps blood to the lungs.

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3. Name the part of the heart that pumps blood to the body.

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4. Name the part of the heart that receives blood from the body.

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5. Name the part of the heart that receives blood from the lungs.

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6. What is the function of the tricuspid valve?

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7. Explain why the left ventricle has a thicker wall than the right ventricle.

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4 The cardiac cycle The diagram shows a section through a human heart.

1. Describe the stage of the cardiac cycle that is shown by the arrows in the diagram.

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The diagram shows a section through a fish heart.

2. Describe how and why the structure of the fish heart is different from the human heart.

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Investigating gas exchange: Worksheet 3.16

1 The human respiratory system 1. Use the following words to label the diagram below.

air sac bronchus diaphragm intercostal muscles lung trachea pleural membrane rib

2. List the parts of the respiratory system that:

a) a molecule of oxygen passes through before entering the blood, starting with the trachea.

Trachea ...........................................................................................................................

b) a molecule of carbon dioxide passes through after leaving the blood, starting with an air sac.

Air sac .............................................................................................................................



2 Ventilation of the lungs Look at the bell jar with a rubber sheet. It is a model of our lungs, chest and diaphragm.

1. If you pull and push on the rubber sheet you can see how the lungs are filled and then emptied of air.

a) If the rubber sheet is pushed downwards, this increases the volume inside the chest. What happens to the balloons?

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b) If the rubber sheet is pushed upwards, this decreases the volume inside the chest. What happens to the balloons?

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2. Write down one way that the respiratory system of the lungs is similar to the demonstration.

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3. Write down one way that the respiratory system of the lungs is different from the demonstration.

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4. The diagram below shows inhalation and exhalation.

a) Complete the following sentences to explain how we breathe in.

The intercostal muscles between the ........................... contract.

This moves the ribs ............................... and …………………..

At the same time, the diaphragm muscle .................... and moves …………………..

The volume of air inside the chest .......................... .

This decreases the pressure inside the chest. The air pressure outside the chest is higher so air enters the lungs.

b) Complete the following sentences to explain how we breathe out.

The intercostal muscles ................................... .

The ribs are moved .......................................... and …………………..

At the same time, the diaphragm muscle .......................... and moves …………………..

The volume of air inside the chest ................................... .

This increases the pressure inside the chest. The air pressure outside the chest is now lower so air leaves the lungs.



3 Alveoli The diagram shows an alveolus and a blood vessel.

Explain how the structure of the lungs enables maximum gaseous exchange to take place.

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4 Breathing rate A spirometer can be used to investigate the depth and rate of breathing. The graph shows spirometer traces for a person before and after exercise. Tidal volume is the volume of air taken in each time a person inhales. The tidal volume is represented on the spirometer as the height of each wave.

1. What was the rate of breathing at rest? .....................per minute

2. What was the tidal volume at rest? ..................... litres

3. The volume of air exchanged per minute can be worked out by multiplying the rate of breathing by the tidal volume. What was the volume of air exchanged per minute at rest? Show your working.

………….............. litres

4. What was the volume of air exchanged per minute after exercise?

Show your working.

................. litres

5. Suggest reasons for the difference in the volume of air exchanged.

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Learning about coronary heart disease: Worksheet 3.17.1

1 Heart disease 1. Complete these sentences about coronary heart disease.

Heart disease is caused by blockages in the ................................... that supplies the heart

………………………. with blood. If there is a shortage of blood the cells run out of

………………………. and glucose. This means they cannot gain enough energy from

………………………. and so the heart cannot …………………….. blood around the body.

2. What is a stent and how can it be used to help somebody with coronary heart disease?

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3. What is the job of the valves inside the heart?

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4. State two faults that occur with heart valves.

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5. Why might a faulty valve cause problems for a person?

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6. People with faulty valves can have them replaced with biological or artificial valve replacements.

Explain the difference between biological and artificial valve replacements.

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7. Some people are fitted with artificial pacemakers.

Artificial pacemakers take over the job of the natural pacemaker of the heart.

a) What is the natural pacemaker and what does it do?

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b) How does the artificial pacemaker work?

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2 Transplants Read this information about artificial heart transplants.

1. What are the main difficulties to overcome when doing a donor heart transplant?

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2. What are the advantages and disadvantages of an artificial heart over a donor heart transplant?

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As well as it being possible to replace some parts of the heart, a whole heart can be transplanted from a suitable donor. The operation is very complicated, but it is done relatively routinely in well-equipped hospitals. To prevent rejection, the tissue type of the donor heart must be a similar match to the patient. Artificial hearts can replace the human heart. They are normally used to keep somebody alive while they wait for a replacement heart. The heart needs batteries to keep it working. These are usually carried outside the body in a pack carried around the waist. After being fitted with an artificial heart, a patient is closely monitored for risk of his body rejecting the device and the risk of infection. The device gives the patient more time to find a suitable heart donor, but a transplant must still be performed.




1 Heart disease leaflet You are going to carry out an Internet search about heart disease, then produce a leaflet that explains to somebody the causes and treatment of heart disease.

Start by carrying out an Internet search and place any useful information into a word-processing document. Then start your leaflet presentation. Make it colourful and include diagrams and pictures.

To find information on the Internet, type the bullet points below into the search engine.

You can also find information in the Student Book.

Your leaflet should include these ideas:

• What is coronary heart disease? • What causes coronary heart disease? • Who is at risk of developing coronary heart disease? • Why are statins used to treat coronary heart disease? • Why are stents used to treat coronary heart disease? • What is heart valve disease? • What might cause heart valve disease? • What is the treatment for heart valve disease? • What is the difference between biological and artificial valve replacements? • Why do people have pacemakers fitted?



2 Transplants Read this information about artificial heart transplants.

1. What are the main difficulties to overcome when doing a donor heart transplant?

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2. What are the advantages and disadvantages of an artificial heart over a donor heart transplant?

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Heart disease leaflet You are going to carry out an Internet search about heart disease, then produce a leaflet that explains to somebody the causes and treatment of heart disease.

Start by carrying out an Internet search and place any useful information into a word-processing document. Then start your leaflet presentation. Make it colourful and include diagrams and pictures.

To find information on the Internet, type the bullet points below into the search engine.

You can also find information in the Student Book.

Your leaflet should include these ideas:

• What is coronary heart disease?

• What causes coronary heart disease?

• Who is at risk of developing coronary heart disease?

• Why are statins used to treat coronary heart disease?

• Why are stents used to treat coronary heart disease?

• What is heart valve disease?

• What might cause heart valve disease?

• What is the treatment for heart valve disease?

• What is the difference between biological and artificial valve replacements?

• Why do people have pacemakers fitted?

• The advantages and disadvantages of treating heart diseases by drugs (e.g. statins) or mechanical devices (e.g. stents).




Maths skills: Extracting and interpreting information: Worksheet 3.18.1

1 Catalase investigation Catalase is an enzyme found in liver. It breaks down hydrogen peroxide to form oxygen and water. A student investigated this reaction using 3 g of liver. They added the liver to hydrogen peroxide solution and collected the oxygen in a gas syringe. Every 30 seconds they recorded the total amount of oxygen in the syringe. The diagram shows their apparatus. The student recorded the results in their note book. 1. Complete the results table below to show the student’s results.

Time

Total volume of oxygen in the gas syringe

0 0

2. Plot the results on a graph. Include a line of best fit.

3. Describe the pattern in the graph.

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0 seconds = 0 cm3 30 seconds = 6 cm3

60 seconds = 8 cm3 90 seconds = 10 cm3 120 seconds = 12 cm3 150 seconds = 12 cm3




1 Catalase investigation Catalase is an enzyme found in liver. It breaks down hydrogen peroxide to form oxygen and water. A student investigated this reaction using 3 g of liver. They added the liver to hydrogen peroxide solution and collected the oxygen in a gas syringe. Every 30 seconds they recorded the total amount of oxygen in the syringe. They then repeated the investigation with different amounts of liver but the same volume and concentration of hydrogen peroxide. The diagram shows their apparatus. The student recorded the results in their note book. 1. Complete the results table below to show the student’s results.

Time Total volume of oxygen in the gas

syringe

3 g liver 0 seconds = 0 cm3

30 seconds = 6 cm3

60 seconds = 8 cm3 90 seconds = 10 cm3 120 seconds = 12 cm3 150 seconds = 12cm3


30 seconds = 10 cm3




2. Plot the results on one graph. Include a line of best fit for each set of results.

3. Describe the patterns in the graph.

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4. Suggest reasons why 9 g of liver made more oxygen than 3 g.

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1 Catalase investigation Catalase is an enzyme found in liver. It breaks down hydrogen peroxide to form oxygen and water. A student investigated this reaction using 3 g of liver. They added the liver to hydrogen peroxide solution and collected the oxygen in a gas syringe. Every 30 seconds they recorded the total amount of oxygen in the syringe. They then repeated the investigation with different amounts of liver but the same volume and concentration of hydrogen peroxide. The diagram shows their apparatus. The student recorded the results in their note book. 1. Complete a results table to show all of the student’s results.

2. Plot the results on one graph. Include a line of best fit for each set of results.

3. Describe the patterns in the graph.

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30 seconds = 6 cm3



30 seconds = 10 cm3



30 seconds = 10 cm3




4. Use the slope of each graph to calculate the rate of reaction for the first 50 seconds.

Rate for 3 g ...........................................................................................................................

Rate for 9 g ...........................................................................................................................

Rate for 15 g .........................................................................................................................

5. Use ideas about enzymes to explain the different rates.

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Required practical: Investigate the effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue: Worksheet 3.2

1 Investigating osmosis Answer these questions while your potato chips are in solution.

1. Which variable are you changing in your investigation?

2. Which variables are you controlling in your investigation?

3. Explain why the measurements you are making may not be accurate?

4. Explain why it is important to use potato chips of the same size.

5. Identify any hazards and suggest how to reduce the risk of harm.

2 Evaluating the investigation Answer these questions after you have completed your conclusion.

1. Do you have enough results to decide if your measurements are precise or not? Explain

your answer.

2. Identify any anomalies. Suggest reasons for the anomalies.

3. Suggest ways you could improve your investigation.



Learning about active transport: Worksheet 3.3

1 Active transport You are going to research examples of active transport in living organisms.

To find information on the Internet, type each bullet point from the list below into a search engine.

Your Student Book may also help you.

• active transport and villi

• active transport and mineral ions

• active transport and gills

• active transport and the kidney

• active transport and crocodiles.

Set out your poster in a similar way to this:

Active transport

write a definition of active transport

active transport and villi

active transport and the kidney

active transport and crocodiles

active transport and mineral ions

active transport and gills



2 Uptake of minerals Two similar groups of barley seedlings were grown in culture solutions.

The sulfate ions in the solution contained a radioactive isotope of sulfur.

Oxygen was bubbled through one container and nitrogen through the other container. Nitrogen gas is very inert.

The amount of radioactive sulfate ions remaining in the culture solution was measured at the start of the experiment and then after every 30 minutes.

The difference between the results was assumed to be the amount of sulfate ions absorbed by the plant.

Time in minutes

Amount of sulfate ions absorbed

With oxygen In nitrogen (without oxygen)

0 0 0

30 220 120

60 290 180

90 360 200

120 390 230

150 440 260

180 500 270

210 510 280

240 540 290

1. Using graph paper, plot a graph of these results using time as the horizontal axis. Draw the two curves in different colours.

What pattern is there between the oxygen available and the amount of sulfate ions absorbed?

2. Which process in plants uses oxygen?

3. Suggest why giving roots plenty of oxygen affects the uptake of sulfate ions.

4. Draw a series of diagrams to illustrate the movement of sulfate ions into the root hair cells.



Key concept: Investigating the need for transport systems: Worksheet 3.4

1 Specialised gas exchange surfaces The diagrams represent gas exchange surfaces in different organisms.

1. Match each picture to one of the following descriptions. • Two gills on the inside of the body which are open to the outside. ................................

• Two lungs; each lung connected to the outside by a single tube. ................................

• Gills on the outside of the body. ................................

• Tiny tubes run from holes on the outside of the body. ................................

2. All the gas exchange surfaces have the same adaptation for efficient gas exchange. What is this adaptation?

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3. Explain why larger organisms need specialised systems for gas exchange.

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2 Diffusion equation The rate of diffusion across a membrane is related to the surface area of the membrane and thickness of the membrane.

This relationship can be shown by the following equation.

rate of diffusion = surface area × difference in concentration thickness of membrane

1. For maximum rate of diffusion, which factors in the equation should be as large as possible?

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2. For maximum rate of diffusion, which factors in the equation should be as small as possible?

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3. Use the equation to explain how lungs are adapted for efficient gas exchange.

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4. In high mountain areas the concentration of oxygen is much lower than at sea level. Toads use their skin and their lungs for gas exchange.

A species of toad that lives in a high mountain area has loose folds of skin.

Use the equation to explain this adaptation.

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Explaining enzymes: Worksheet 3.5

1 Enzymes and chemical reactions Watch the demonstration and then finish the sentences. Choose words from this list.

enzyme fats hydrogen oxygen protein

Liver contains an .............................................. . The enzyme speeds up the breakdown of

hydrogen peroxide into water and ............................................................... .

Enzymes are ................................................... molecules that speed up chemical reaction.

Finish labelling the diagram of the enzymes and substrate.

2 Optimum conditions The graph shows the effect of temperature on the activity of an enzyme.



1. What is the optimum temperature for the enzyme? .................................

2. Explain why the enzyme stops working at high temperatures?

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3. Explain the complete pattern shown in the graph.

Use ideas about collisions, kinetic energy and denaturing in your answer.

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Required practical: Investigate the effect of pH on the rate of reaction of amylase enzyme: Worksheet 3.6.1

1 Enzymes experiment 1. Record your results in the table. You should write in the pH value of the buffer you use each time.

Time in seconds

Colour of iodine solution

pH....... pH....... pH....... pH....... pH....... pH....... pH....... pH.......

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30

60

90

120

150

180

210

240

270

300 2.

a) At which pH did the amylase digest the starch the fastest?

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b) Did any pH fail to work? If so, which ones?

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c) Use your results to describe the effect of pH on the action of amylase.

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2 Evaluating your experiment 1. Identify any anomalies in your results.

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2. Suggest reasons for the anomalies.

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3. Suggest how you could improve your method to reduce the effect of random error.

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Time in seconds



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300 2.

a) At which pH did the amylase digest the starch the fastest?

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b) Did any pH fail to work? If so, which ones?

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c) Use your results to describe the effect of pH on the action of amylase.

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3. Use the lock-and-key mechanism to explain why amylase could not break down starch at low pH values. Include a diagram in your answer.

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4. The pH of the small intestine of the digestive system is about pH 7. The stomach is about pH 2. In which of these two areas will amylase work? Explain your answer.

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2 Evaluating your experiment. 1. Identify any anomalies in your results.

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Time in seconds



0

30

60

90

120

150

180

210

240

270

300 2.

a. At which pH did the amylase digest the starch the fastest?

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b. Did any pH fail to work? If so, which ones?

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c. Use your results to describe the effect of pH on the action of amylase.

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3. Use the lock-and-key mechanism to explain why amylase could not break down starch at low pH values. Include a diagram in your answer.

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4. The pH of the small intestine of the digestive system is about pH 7. The stomach is about pH 2. In which of these two areas will amylase work? Explain your answer.

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2 Evaluating your experiment 1. Identify any anomalies in your results.

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3 Calculating Q10 The temperature coefficient Q10 is the effect of temperature on the rate of a chemical reaction.

It is calculated using the formula:

Q10 = rate at higher temperature

rate at lower temperature

Most enzymes have a Q10 of around 2.

A student investigated the effect of temperature on amylase activity. They used a similar method to your investigation, but changed the temperature of the water bath each time and kept the pH the same. At 20 °C, the rate was 0.005 s–1 and at 30 °C, the rate was 0.017 s–1.

1. Calculate Q10 for their reaction between 20 °C and 30 °C.

Is the value close to what you would have expected? If not, suggest reasons why.

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Learning about the digestive system: Worksheet 3.7

1 Digestive system The diagram shows some organs in the human body.

1. Label the four organs that have label lines.

2. Finish the sentences about digestion.

Choose words from this list.

Digestion means to break the food down into smaller ............................ molecules.

Chemicals in the body that speed up digestion are called ..............................................

Bile from the liver helps with the digestion of .................................................................

Digested food is absorbed into the blood in the ................................................ intestine.

enzymes fat insoluble large protein small soluble sugar



2 Small intestine The diagram shows a part of the small intestine.

1. The small intestine is adapted for the absorption of food molecules.

Write about how it is specialised for absorption. You can add labels to the diagram to help you.

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2. Coeliac disease affects several million people in the world.

For these people eating a protein called gluten can lead to the destruction of villi. If the villi are destroyed, people with coeliac disease may not grow properly. Suggest why.

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3 Absorbing fat Some people want to be able to eat foods with fats without gaining weight.

One way to do this is for manufacturers to replace fats with a substance called olestra.

This makes the food taste similar but olestra has different properties to fats.

The diagram shows an olestra molecule.

1. Write down one way that an olestra molecule is different from a normal fat molecule.

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2. Explain why olestra is not digested in the body.

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3. Explain why olestra can be eaten and does not cause the person to put on weight.

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Explaining digestion: Worksheet 3.8

1 Digestion 1. Complete the following sentences using the words below.

stomach physical broken swallow

Food is ................................................... down by your teeth.

This action is called ................................................... digestion.

This makes it easier to ............................................. and for enzymes to act on it.

It is then followed by chemical digestion in your ........................................... and intestines.

2. Complete the table to show the action of enzymes in the digestive system.

Food type Enzyme Products of digestion Part of digestive system

where digestion takes place.

starch mouth and small intestine

protein protease

fat fatty acids and glycerol



2 Digesting a beef burger Beef burgers contain all the main food types. You must produce a PowerPoint presentation to show how a burger is digested. You can use Student Book pages 200–201, the table below and the Internet to help you. Your PowerPoint presentation should include the following slides:

• Digestion in the mouth – include the name of the enzyme found in saliva and its function; describe the difference between physical and chemical digestion.

• Peristalsis – describe how food is moved through the digestive system. • Digestion in the stomach – include the action of protease enzymes, acid and churning the

food. List what food types the enzymes work on and what the products of digestion are for each food. You must use the terms ‘chemical digestion’ and ‘mechanical digestion’.

• Bile – include what bile does and why it is important • Digestion in the small intestine – state which enzymes are present, what food types they

work on and the products of digestion. • Absorption in the small intestine – explain how the products of digestion move into the

blood; include the term active transport. Describe how the small intestine is adapted for efficient absorption. Also say what happens to the products of digestion in the body.

• What happens in the large intestine – reabsorption of water.

Part of beef burger

Main food type it contains

Part of digestive system where it is digested

Enzyme used Product(s) of digestion

What product(s) is used for in the body

bread bun carbohydrate (starch)

mouth, small intestine

carbohydrase sugar energy / respiration

meat protein stomach, small intestine

protease amino acids making new proteins, growth

fat small intestine

lipase fatty acids and glycerol

energy store

lettuce fibre not digested

lost as faeces



3 Digestion poster You will need to produce a poster about the digestive system. Your poster should include:

• A diagram of the digestive system with all the parts labelled. (You can cut out the diagram on Worksheet 3.7 and glue it onto A3 paper.)

• You must label the mouth, oesophagus, stomach, small intestine, large intestine, pancreas and liver.

• Write down which enzymes are used in the different parts, what type of food the enzymes work on and what the food is broken down into.

• Describe the function of bile in the digestion of fat. • Describe features of the small intestine that help with the absorption of the products of

digestion. • What happens to the digested food in the body? • Use Student Book pages 200–201 to help you.

Try to set your poster out in a similar way to this:



Looking at more exchange surfaces: Worksheet 3.10.1

1 Exchange surfaces 1. Draw lines to link each organism with the type of respiratory surface.

One has been done for you.

amoeba moist external body surface

earthworm lungs

frog cell membrane of single cell

human gills

shark body surface and lungs

2. Some frogs, when sitting still, can absorb all the oxygen they need through the skin. Only when they move do they start to breathe. Explain these observations.

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2 Exchange surfaces presentation You will need to produce a poster or PowerPoint presentation about different exchange surfaces. You should include the following ideas:

• The main features of all respiratory exchange surfaces • A description of how the gills of fish are adapted for efficient gas exchange • A diagram showing how fish gills are adapted for efficient gas exchange.

Use Student Book pages 101, 106 and 107 to help you.



Looking at more exchange surfaces: Worksheet 3.10.3

Exchange surfaces presentation You will need to produce a poster or PowerPoint presentation about different exchange surfaces. You should include the following ideas:

• The main features of all respiratory exchange surfaces • A description of how the gills of fish are adapted for efficient gas exchange • A diagram showing how fish gills are adapted for efficient gas exchange • A comparison of fish gills and lungs • A diagram of the gas exchange surface in lungs • A description of how the tracheal system of insects is adapted for efficient gas exchange,

including a diagram • A comparison of all three exchange surfaces • Explanation of how and why gas exchange surfaces are kept moist

Use Student Book pages 101, 106 and 107 to help you.

Fish gills Each gill in a fish has a large number of filaments. Each filament in turn has many gill plates. The diagram shows the direction of water flowing over and the direction of blood flowing through the gill plates. The data in the table refers to the gills of different species of fish. Species Gill surface area per mass

(mm2/g) Thickness of gill plate (mm)

Mackerel

1158 0.54

Bonito

595 0.22

Dab 188 No data available

Skate No data available 1.32

1. Suggest why the blood in the gills flows in the opposite direction to the flow of water.

Use ideas about diffusion gradients in your answer.

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2. Explain why the units for gill area are per gram of fish.

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3. Mackerel and bonito are more active fish than dab and skate. How does the data support this fact?

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explaining water movement: worksheet 3 · why do nitrogen fertilisers help the cereal plants to...

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