PEARSON EDEXCEL INTERNATIONAL GCSE (9–1) HUMAN …

PEARSON EDEXCEL INTERNATIONAL GCSE (9–1)

HUMAN BIOLOGYLAB BOOK

PEARSON EDEXCEL INTERNATIONAL GCSE (9–1)HUMAN BIOLOGY LAB BOOK

SAMPLE

PEARSON EDEXCEL INTERNATIONAL GCSE (9–1)

HUMAN BIOLOGYLab Book

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Published by Pearson Education Limited, 80 Strand, London, WC2R 0RL.

www.pearson.com/international-schools

Copies of official specifications for all Pearson Edexcel qualifications may be found on the website: https://qualifications.pearson.com

Text © Pearson Education Limited 2021Edited by Deborah Webb, Penelope Lyons and Judith ShawDesigned by © Pearson Education Limited 2021Typeset by © SPi GlobalOriginal illustrations © Pearson Education Limited 2021Cover design © Pearson Education Limited 2021

The rights of Sue Hocking, Mark Levesley and Sue Kearsey to be identified as authors of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988.

First published 2021

24 23 22 2110 9 8 7 6 5 4 3 2 1

British Library Cataloguing in Publication DataA catalogue record for this book is available from the British Library

ISBN 978 1 292 39493 0

Copyright notice All rights reserved. No part of this publication may be reproduced in any form or by any means (including photocopying or storing it in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright owner, except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency, 5th Floor, Shackleton House, 4 Battle Bridge Lane, London, SE1 2HX (www.cla.co.uk). Applications for the copyright owner’s written permission should be addressed to the publisher.

Printed in the UK by Ashford Digital

AcknowledgementsAll artwork © Pearson Education Limited 2021

A note from the publishers:While the Publishers have made every attempt to ensure that advice on the qualification and its assessment is accurate, the official specification and associated assessment guidance materials are the only authoritative source of information and should always be referred to for definitive guidance. Pearson examiners have not contributed to any sections in this resource relevant to examination papers for which they have responsibility. Examiners will not use this resource as a source of material for any assessment set by Pearson.

Neither Pearson, Edexcel nor the authors take responsibility for the safety of any activity. Before doing any practical activity you are legally required to carry out your own risk assessment. In particular, any local rules issued by your employer must be obeyed, regardless of what is recommended in this resource. Where students are required to write their own risk assessments they must always be checked by the teacher and revised, as necessary, to cover any issues the students may have overlooked. The teacher should always have the final control as to how the practical is conducted.

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1

1 VITAMIN C CONTENT OF FOODS 2

2 ENERGY CONTENT IN FOOD 7

3 TEMPERATURE, pH AND ENZYME ACTIVITY 10

4 IMMOBILISED ENZYMES 17

5 SENSORY RECEPTORS 21

6 HUMAN EAR 25

7 CARBON DIOXIDE CONCENTRATION IN INSPIRED AND EXPIRED AIR 28

8 EXERCISE AND BREATHING RATE, AND LUNG CAPACITY 31

9 EXERCISE AND PULSE RATE 37

10 DIFFUSION 40

PRACTICAL SKILLS TABLE 49

MATHS SKILLS 50

GLOSSARY 53

ANSWERS 55

CONTENTS

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2

CORE PRACTICAL 1: VITAMIN C CONTENT OF FOODSINVESTIGATE THE QUALITATIVE AND QUANTITATIVE CONTENT OF VITAMIN C IN FOODS

SPECIFICATIONREFERENCE

2.4(6.1, 6.2, 6.3, 6.4, 6.10, 9.2)

Introduction

Vitamin C (ascorbic acid) is an antioxidant. It protects cells from damage by free radicals (unstable molecules made during metabolism) by becoming oxidised by the free radicals. Free radicals may promote cancer, heart disease and stroke, so vitamin C is essential for general good health. Vitamin C is also essential for keeping skin, blood vessels and joints healthy by helping to make collagen.

DCPIP (dichlorophenolindophenol) is blue when dissolved in water and in the oxidised state. When reduced, it becomes colourless. In acid conditions DCPIP is red/pink. When DCPIP is reduced by vitamin C, the vitamin C is oxidised.

So, when you add DCPIP solution to a solution of vitamin C, the blue colour of DCPIP disappears. This shows that vitamin C is present. This is a qualitative test; it shows that vitamin C is present but does not measure how much vitamin C there is.

If we use a vitamin C solution of known concentration, we can find out how much vitamin C is needed to decolorise a specific volume of DCPIP solution. We can then find out how much vitamin C is in particular liquids such as fruit juices or vegetable extracts. This is a quantitative test.

If each group of students tests a different juice or extract in the quantitative tests below, you can share your results with each other.

Your teacher may watch to see if you can:

● follow instructions

● work carefully and take readings from equipment accurately

● work safely, reducing the risk of harm from hazards.

Part 1: Qualitative testMethod

1 Use a 1 mL syringe to place 1 mL DCPIP solution into a test tube in a rack.

2 Use another syringe to add fruit juice or vegetable extract to the DCPIP solution until all the blue colour of the DCPIP solution has disappeared.

3 This shows you that the juice or extract you tested contains vitamin C. However, it does not tell you how much vitamin C is in that food.

Part 2: Quantitative testMethod

● Wear eye protection.

● Avoid skin contact with the DCPIP and any of the other solutions.

● Do not taste any of the juices or extracts.

● Wash off any chemical splashes immediately.

! Safety notes

● To investigate the qualitative and quantitative vitamin C content of foods

Objectives

Equipment

● eye protection

● syringes – 1 mL and 5 mL

● 0.1% DCPIP solution

● test tubes

● test tube rack

● 0.1% vitamin C solution

● a selection of fruit juices

● a selection of vegetable extracts

test tube

DCPIP solution

fruit juice solution

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2.4(6.1, 6.2, 6.3, 6.4, 6.10, 9.2)

Learning tip

● A 0.1% solution contains 0.1 g (100 mg) of solid in 100 mL water. Therefore, in 1 mL of the solution there is 1 mg of solid.

● Vitamin C and DCPIP react together in a 1 : 1 ratio. This means that when 1 mL 0.1% DCPIP solution (containing 1 mg solid DCPIP) is decolorised, 1 mg vitamin C has been added.

1 Using the 1 mL syringe, take up 1 mL of the 0.1% DCPIP solution. Gently shake the syringe to get rid of any air bubbles.

2 Add this 1 mL DCPIP solution to a test tube and place the test tube in a rack.

3 Using a 5 mL syringe, take up 5 mL of 0.1% vitamin C solution. Carefully, add the vitamin C solution to the DCPIP in the test tube. Start by adding a few drops at a time then, when the blue colour begins to fade, add the vitamin C just one drop at a time. You may need to gently move the test tube but do not shake it vigorously because that will introduce air to the test tube. The oxygen in the air will bring the blue colour back again. Also, make sure that the drops of liquid fall into the DCPIP and do not stick to the sides of the test tube. Note the volume of vitamin C solution needed to decolorise the 1 mL DCPIP solution.

4 Repeat steps 1–3 twice more and find the mean value for the volume of solution used.

5 Repeat steps 1–4 using one of the fruit juices or vegetable extracts. Note: If the fruit juice is acidic, the DCPIP turns pink/magenta, so the end point is when there is no blue colour (the DCPIP remains pink). Similarly, if the juice or extract has some colour, the end point is when there is no blue colour and only the colour of the extract remains.

6 If you have time, repeat steps 1–5 with a different juice or extract.

7 Obtain the results from others in your class for different juices or extracts.

Results

1 Record your results in a table.

Learning tip

● Note that the mean is the arithmetic average of the numbers in a set of data.

● The mode is the number seen most often in a set of data.

● The median is the number that is halfway in the range of the numbers in the set of data. Here you are calculating the mean.

Juice or extractVolume of juice or extract needed to decolorise

1 mL 0.1% DCPIP solution (mL)Concentration of vitamin C

in juice or extract (mg 100 mL–1)1 2 3 mean

0.1% vitamin C solution

1.0 1.0

(6.1, 6.2, 6.3, 6.4, 6.10, 9.2)

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2.4(6.1, 6.2, 6.3, 6.4, 6.10, 9.2)

Learning tip

● You should find that 1 mL 0.1% vitamin C solution decolorises 1 mL 0.1% DCPIP solution, because there is 100 mg solid vitamin C (ascorbic acid) in 100 mL of 0.1% solution of vitamin C. Therefore, there is 1 mg vitamin C per 1 mL of the 0.1% solution.

Analysis

The 0.1% vitamin C solution contains 1 mg vitamin C per mL.

The 0.1 % DCPIP solution contains 1 mg DCPIP per mL.

DCPIP and vitamin C react together in a 1 : 1 ratio.

Therefore 1 mL 0.1% vitamin C solution decolorises 1 mg DCPIP.

Therefore, the volume of fruit juice that decolorises 1 mL 0.1% DCPIP solution contains 1 mg vitamin C.

Examples

a If 1 mL vitamin C solution decolorises 1 mL 0.1% DCPIP solution, then 1 mL vitamin C solution contains 1 mg vitamin C. So, 100 mL vitamin C solution contains 100 mg vitamin C.

b If 5 mL fruit juice is needed to decolorise 1 mL 0.1% DCPIP solution, then there is 1 mg vitamin C in 5 mL of that fruit juice. So, the concentration of vitamin C in that fruit juice is 1 mg in 5 mL. which is (1 ÷ 5) = 0.2 mg in 1 mL which is (0.2 × 100) = 20 mg in 100 mL.

1 Calculate the concentration of vitamin C, in mg per 100 mL (mg 100 mL–1), for each of the juices or extracts tested and complete the last column of the data table.

Use the formula:

concentration of vitamin C in juice = q1

r × 100 mg 100 mL–1

volume of juice needed to decolorise 1 mL DCPIP

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2.4(6.1, 6.2, 6.3, 6.4, 6.10, 9.2)

2 Plot a graph of your data showing vitamin C content in the juices/extracts.

Learning tip

● As these data are discrete, a bar graph is the most suitable.

Evaluation

1 State the independent and dependent variables in this investigation.

a IV..........................................................

b DV........................................................

2 Explain why the test was repeated three times for each type of juice or extract.

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2.4(6.1, 6.2, 6.3, 6.4, 6.10, 9.2)

3 Discuss the sources of errors in this investigation.

Extension

1 Describe how you could use this method to test the following hypothesis: The vitamin C content of fruit juice is reduced when the juice is heated.

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7

CORE PRACTICAL 2: ENERGY CONTENT IN FOODINVESTIGATE THE ENERGY CONTENT IN A FOOD SAMPLE


2.5(2.1, 2.2, 4.5, 6.1, 6.2, 6.3, 6.11, 7.1, 9.2)

Introduction

All foods contain stored energy. The energy is in the carbohydrates (sugars and starches), fats and proteins. Plants make those foods originally, using energy from sunlight. Animals eat the plants or eat other animals that have eaten the plants, and so the energy passes up the food chain.

Carbohydrates and proteins contain less energy per gram than fats contain.

You can estimate how much energy is in a food sample by burning the food and releasing the energy from it in the form of heat energy. The heat energy can be used to heat up a certain volume of water. In this way, you can calculate how much energy is in 1 g of the food. You can try carbohydrate foods, such as cereal or dried bread, and fats, such as cooking oil.

Your teacher may watch to see if you can:

● work carefully and safely

● make accurate measurements

● record data accurately.

Learning tip

● Remember that energy cannot be made or destroyed but one form can be changed to another form. In this investigation, the stored chemical energy in food is changed to heat energy.

Method

● To investigate the energy content in a food sample/food samples

Objectives

Equipment

● eye protection

● 50 mL measuring cylinder

● water

● boiling tubes

● boss, clamp and stand

● thermometer

● access to a selection of foods to test (e.g. dried bread, pasta, crisps, pasta, 0.5 g cooking oil) in crucibles/watch glasses/very small beakers

● accurate balance

● Bunsen burner

● heat-resistant mat

● mounted needle

● forceps

● mineral wool

● metal forceps

● paper to insulate the forceps handles

● Wear eye protection.

● Take care with the Bunsen burner.

● Take care with glassware.

● Take care with sharp needle.

● Do not eat any of the food samples.

● Do not use nuts if anyone in the class has a nut allergy.

● Keep bottle/beaker/crucible/watch glass of cooking oil away from any naked flames.

! Safety notes

1 Use a measuring cylinder to add 20 mL water to a boiling tube.

2 Set up the tube of water in a clamp on a stand, as shown in the diagram.

3 Use the thermometer to read the temperature of the water. Make sure that the bulb of the thermometer is not too near the bottom of the boiling tube when you read the temperature. Write down this temperature.

4 Cut a piece of dried bread about 1 cm3.

5 Use the accurate balance to weigh this piece of bread. Write down the mass of the bread.

6 Light the Bunsen burner and adjust the flame to hot. Keep the Bunsen burner away from the boiling tube.

7 Place the piece of dried bread on the end of a mounted needle. Hold the bread in the Bunsen burner flame until it begins to burn.

boiling tube

heat-resistant mat

wooden handle

needle

burning food

clamp, boss and standwater

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2.5(2.1, 2.2, 4.5, 6.1, 6.2, 6.3, 6.11, 7.1, 9.2)

8 Quickly move the needle and bread so that the burning bread is under the boiling tube of water. Keep the Bunsen burner flame on but away from the boiling tube. Keep it there until the bread stops burning. However, if the food stops burning before it is used up, relight it in the Bunsen burner flame and put it under the boiling tube again. Observe the thermometer and note the highest temperature it reaches.

9 Pour away the hot water from the boiling tube.

10 Repeat the procedure using different food samples.

For cooking oil:

a Using the accurate balance, weigh a small bundle of mineral wool.

b Use forceps to hold this wool and dip it into cooking oil so that all of the oil is absorbed onto the mineral wool.

Learning tip

● 1 mL of water weighs 1 g.

Results

1 Present your data in the table.

Name of food Mass of food (g)Temperature of

20 g water before heating (0 °C)

Temperature of 20 g water after

heating (0 °C)

Temperature change (0 °C)

Analysis

1 In this investigation, identify:

a the independent variable (IV) ...................................................................

b the dependent variable (DV) .....................................................................

2 For an investigation to be valid, the variables (other than IV and DV) must be kept the same. These are called the control variables. One control variable is the mass of water in the boiling tube. State two other control variables for this investigation and describe how you tried to keep each one the same.

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2.5(2.1, 2.2, 4.5, 6.1, 6.2, 6.3, 6.11, 7.1, 9.2)

3 a Which food contains the most energy?

b Explain how you reached that conclusion.

Evaluation

1 Describe any problems that you identified while doing this experiment.

2 Using a larger volume of water may improve the accuracy of the investigation. Explain why.

3 Explain two other ways that the investigation could be improved.

4 The amount of energy that raises the temperature of 1 g water by 1 °C is 4.2 joules. 1 kilojoule (kJ) = 1000 Joules (J) Calculate the energy content of the food(s) you tested in kilojoules per gram (kJ g–1). Use the equation:

energy transferred from 1 g food =mass of water (g) × 4.2 (kJ g–1 °C–1) × temperature increase (°C)

kJ g–1

mass of food (in grams) × 1000

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PEARSON EDEXCEL INTERNATIONAL GCSE (9–1) HUMAN …