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Science GCSE Your complete teaching and learning solution for the new specification Aim high – for the top grades! LONGMAN
ScienceGCSE
Your complete teaching and learning solution for the new specification
Aim high – for the top grades!
L O N G M A N
Encourage your students to achieve their best in AQA GCSE Biology, Chemistry, Physics, Science and Additional Science!In this exciting new series, we’ve provided you with the tools to help them, and make your teaching, planning and homework setting for AQA GCSE Science that little bit easier.
We worked with a panel of top UK schools to understand what makes a resource absolutely right for the higher tier, resulting in Longman AQA GCSE Science - written by experienced examiners and authors for complete coverage of the new specification.
Inside, you’ll find details of resources for teachers and for students, and information on the many ways to get in touch with us to learn more. Plus, if you visit us online you’ll find top tips and free resources!
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Print and digital resources to inspire your students on their route to A*
for Students
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Student BooksWe know your high achievers enjoy the satisfaction of doing well. That’s why our Student Books contain challenging content and examiner support to help them understand how to move up the grade scale. l Packed with all types of questions, including those that
require longer-text answers, students get plenty of practice to help them feel confident tackling their exams.
l GradeStudio question pages contain vital examiner commentary so students know how to improve their answers.
l End of unit exam-style questions offer thorough exam preparation.
l With online ActiveLearn students can annotate the Student Book on-screen – the perfect tool for helping them revise!
l Each book is written to incorporate higher-order thinking skills.
l The ISA-style pages prepare students for the new controlled assessment.
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Making salts 161
Many metal oxides are insoluble. When they react with acids, you know that the reaction is complete when there is some metal oxide left over.
The diagrams show how copper sulfate is made by reacting copper oxide with sulfuric acid. Here is the equation for the reaction:
copper oxide sulfuric acid copper sulfate waterCuO(s) H2SO4(aq) CuSO4(aq) H2O(l)
Practical
1 Add copper oxide powder to warm sulfuric acid, and stir until it all disappears.
2 Add more copper oxide, a little at a time with stirring, until an excess is left over.
3 Filter to remove the excess copper oxide. Evaporate the water from the solution, leaving blue copper sulfate crystals behind. The more slowly this is done, the larger the crystals will be.
copper oxideundissolved
copper oxide
sulfuric acidcopper sulfate
solution
coppersulfate
solution
evaporating dish
Figure 2 Making copper sulfate from copper oxide and sulfuric acid.
It is important that scientists can
communicate their ideas and discoveries to each other easily and clearly. The French chemist Antoine Lavoisier invented a system, published in 1787, to name chemicals. It led directly to the systems used today. Before Lavoisier’s work, it was very diffi cult to work out what a substance was, or what it contained, from its name.
For example, copper sulfate had several names including ‘Roman vitriol’, ‘blue stone’ and ‘super-vitriolated copper’. Sulfuric acid had even more names. ‘Acid of sulphur’ was probably easy enough to understand, but other names were not. Chemistry would be much more diffi cult to understand if you still had to remember names like vitriolic acid, oil of vitriol and spirit of vitriol.
Science skills
Copper sulfate is white when anhydrous, but blue when hydrated. This is because a copper ion forms a ‘complex ion’ in solution. Each copper ion becomes chemically bonded to water molecules by ‘coordinate bonds’, a type of covalent bond.
Taking it further
Transition metals, such as copper and iron, often form more than one ion. The diff erence is shown using Roman numbers in brackets: Cu+ is copper(I) and Cu2+ is copper(II). The numbers are not used where a metal commonly forms just one ion.
Transition metals, such as copper
A*Route to A*
1 Name two soluble salts and give one use of each.2 Name the salts formed when nitric acid reacts with: (a) magnesium
(b) copper oxide.3 Explain why you should make potassium chloride using potassium
hydroxide, not potassium.4 Explain why you could make silver nitrate using silver oxide, but not
using silver.5 Describe how you could make copper sulfate using copper oxide and
sulfuric acid.6 Calcium chloride can be made from hydrochloric acid by reaction
either with calcium or with calcium oxide. (a) Write a word equation for each reaction. (b) Describe what you would expect to observe in each reaction. (c) Give a reason, other than the reactivity of calcium, why using calcium oxide may be safer.
7 Zinc nitrate (Zn(NO3)2) can be made by reacting nitric acid (HNO3) with zinc, or with insoluble zinc oxide (ZnO). Write balanced chemical equations for the two reactions involved.
8 Magnesium oxide, MgO, is only sparingly soluble in water. Magnesium sulfate, MgSO4, is also known as Epsom salts. It is used in bath water to ease aches and pains. Describe how you could prepare dry magnesium sulfate from magnesium oxide. Include a balanced chemical equation in your answer.
8 Magnesium oxide, MgO, is only sparingly soluble in water. Magnesium sulfate, MgSO4, is also known as Epsom salts. It is used in bath water to ease aches and pains. Describe how you could prepare dry magnesium sulfate from magnesium oxide. Include a balanced chemical equation in your answer. A*
Questions
M21_ASCH_SB_GCSE_3793_U21.indd 161 28/2/11 11:20:50
GradeStudioAIM HIGH FOR THE TOP GRADES
119
Grade answer
Examiner comment
Student 3
The injuries caused to the driver during a head-on crash with another car or vehicle are most severe when the acceleration of the driver is high. The designers work to reduce the acceleration of the driver during the impact. One method is to use a crumple zone. The engine compartment and bonnet area are designed to crumple during a collision. This spreads the time of the collision over a longer time than if the car bonnet region was rigid. The passenger compartment is made very rigid and the seatbelt holds the driver in place so that they slow down with the car as the crumple zone crushes. Because the change in speed happens over a longer time the acceleration of the driver is less. This produces less force on the driver’s chest so reducing external injuries and also reduces the acceleration of the internal organs so reducing internal injuries too.
This candidate has covered all the main points. It is the effect of acceleration on the internal organs that causes most injury, rather than the force itself, which causes external injuries. The way that the crumple zone and the seatbelt work together is
clear. The contrast with the ability of the front area of the car to crumple as well as the rigidity of the passenger compartment is clearly made. The candidate clearly understands the link between force and acceleration.
Good identifi cation of what causes the injury.
Good link between speed change, time and acceleration.
Grade answerA*
Good extension of what the injuries are.
Grade answer
Examiner comment
The designers understand that the thing that causes injury to the driver is the force on their chest when the car slows down. The amount of force depends on the mass of the driver and the acceleration of their body. If the car has a crumple zone, the time it takes to slow down is also bigger, so the acceleration is less. This means that the force on the driver is less. The seatbelt also helps by reducing the impact on the driver during the collision.The link between the crumple zone
and acceleration is well made but the seatbelt explanation is too superfi cial.
It would be better to say that the force on the chest also causes high acceleration of the internal organs, and that it is the high acceleration that causes internal injuries.
Like student 1, this candidate has shown a good understanding of the way that the crumple zone works and has made clear links between the injuries caused through force and how these are reduced by extending the time of the impact.
However, the explanation of the role of the seatbelt is underdeveloped and they should have explained how the crumple zone and the seatbelt work together.
Student 2
Grade answerA
M15_ASPH_SB_GCSE_3830_U15.indd 119 28/2/11 12:00:41
Three student answers are given at three different grades, enabling students to see clearly how each answer is improved.
Examiner feedback helps students to understand what they need to do to produce an A* answer.
Highlighted questions on each spread require extended-writing answers, helping to prepare students for their exams.
‘Route to A*’ boxes provide the right level of challenge for the higher tier.
‘Taking it further’ sections cover content that extends students’ learning from GCSE to A Level.
Lots of questions displayed in order of increasing difficulty provide plenty of practice on all types of exam questions.
Student Book
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AIM HIGH FOR THE TOP GRADES
119
Grade answer
Examiner comment
Student 3
The injuries caused to the driver during a head-on crash with another car or vehicle are most severe when the acceleration of the driver is high. The designers work to reduce the acceleration of the driver during the impact. One method is to use a crumple zone. The engine compartment and bonnet area are designed to crumple during a collision. This spreads the time of the collision over a longer time than if the car bonnet region was rigid. The passenger compartment is made very rigid and the seatbelt holds the driver in place so that they slow down with the car as the crumple zone crushes. Because the change in speed happens over a longer time the acceleration of the driver is less. This produces less force on the driver’s chest so reducing external injuries and also reduces the acceleration of the internal organs so reducing internal injuries too.
This candidate has covered all the main points. It is the effect of acceleration on the internal organs that causes most injury, rather than the force itself, which causes external injuries. The way that the crumple zone and the seatbelt work together is
clear. The contrast with the ability of the front area of the car to crumple as well as the rigidity of the passenger compartment is clearly made. The candidate clearly understands the link between force and acceleration.
Good identifi cation of what causes the injury.
Good link between speed change, time and acceleration.
Grade answerA*
Good extension of what the injuries are.
Grade answer
Examiner comment
The designers understand that the thing that causes injury to the driver is the force on their chest when the car slows down. The amount of force depends on the mass of the driver and the acceleration of their body. If the car has a crumple zone, the time it takes to slow down is also bigger, so the acceleration is less. This means that the force on the driver is less. The seatbelt also helps by reducing the impact on the driver during the collision.The link between the crumple zone
and acceleration is well made but the seatbelt explanation is too superfi cial.
It would be better to say that the force on the chest also causes high acceleration of the internal organs, and that it is the high acceleration that causes internal injuries.
Like student 1, this candidate has shown a good understanding of the way that the crumple zone works and has made clear links between the injuries caused through force and how these are reduced by extending the time of the impact.
However, the explanation of the role of the seatbelt is underdeveloped and they should have explained how the crumple zone and the seatbelt work together.
Student 2
Grade answerA
M15_ASPH_SB_GCSE_3830_U15.indd 119 28/2/11 12:00:41
ActiveLearn
Online homework and revision for AQA GCSE Science
A new approach to online student learning! ActiveLearn provides online homework and revision practice and support for higher tier students.
l A variety of guided-practice activities at B-A*, so students can practice both short answer and the new extended writing exam questions.
l Gives teachers the option to assign grade-specific work to individuals or classes, or allow students to work independently.
l Includes a bank of exam-style questions with access to learning support.
l Highly motivational, with features that recognise success and make students want to progress.
l Links directly to the Longman AQA Student Books.
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Students will learn by the process of answering the questions, from highlighting command words to structuring their answer, ensuring they are fully engaged with the subject.
Students are guided through self marking step-by-step; the marks are then fed straight through to the teacher.
Sample A* answers will provide a comparison so they can see exactly what they need to do to reach the top grades.
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A range of print and digital resources to help you deliver a varied, integrated and engaging course.
for Teachers
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Teacher BooksMapped to the Student Books, in full-colour and with an at-a-glance overview of the lesson! You can save valuable planning time and be guided by experts on the new specifications.
l Thumbnails of the Student Book pages are included for easy reference.
l Plenty of ideas for activities and suggestions on how to stretch and challenge the higher tier.
l Specifically designed for skim-reading, so you can get the ideas you want for the lesson – fast!
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Teacher Book
Plenty of ideas for activities and suggestions on how to stretch and challenge the higher tier.
Images of the Student Book pages are included for easy reference.
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110 111111Digestive enzymes Amylase bile digested extracellular gall bladder lipase liver mouth pancreas protease small intestine stomach
Digestive enzymesB2 4.3
Link to the specifi cationB2.5.2c Some enzymes work outside the body cells. The digestive enzymes are produced by specialised cells in glands and in the lining of the gut. The enzymes then pass out of the cells into the gut where they come into contact with food molecules. They catalyse the breakdown of large molecules into smaller molecules.B2.5.2d The enzyme amylase is produced in the salivary glands, the pancreas and the small intestine. This enzyme catalyses the breakdown of starch into sugars in the mouth and small intestine.B2.5.2e Protease enzymes are produced by the stomach, the pancreas and the small intestine. These enzymes catalyse the breakdown of proteins into amino acids in the stomach and the small intestineB2.5.2f Lipase enzymes are produced by the pancreas and small intestine.
These enzymes catalyse the breakdown of lipids (fats and oils) into fatty acids and glycerol in the small intestine.B2.5.2g The stomach also produces hydrochloric acid. The enzymes in the stomach work most eff ectively in these acid conditions.B2.5.2h The liver produces bile, which is stored in the gall bladder before being released into the small intestine. Bile neutralises the acid that was added to food in the stomach. This provides alkaline conditions in which enzymes in the small intestine work most eff ectively.
Ideas for practical workUsing small pieces of cooked sausage, use 2% pepsin and 0.01 M HCl in water baths at diff erent temperatures to estimate the rate of digestion. This can also be carried out with 2% trypsin and 0.1 M NaOH. The concentration of both enzymes can be varied.
Most students should be able to:• relate digestive enzymes to their function and where they work in the
digestive system• describe the breakdown of products after catalysis by digestive enzymes• describe the conditions that diff erent digestive enzymes work in• explain how digestive enzymes work outside body cells • describe the function of the liver in digestion as a producer of bile, and what
the function of bile is.
Learning objectives
1 Give each student a small piece of bread or a plain, unsweetened biscuit and ask them to chew on it until it completely breaks down in the mouth. Note that the food must be prepared hygienically as in a food technology lesson. Also, be sensitive to any students with food allergies. Ask students what they notice about the taste as they chew. They should fi nd that the food starts to taste sweeter as the
starch (which doesn’t taste sweet) in the food is digested to glucose (which does taste sweet). Use this to introduce the idea of digestive enzymes. These are enzymes that are secreted and act outside the cells in which they were made.
2 Issue diagrams of the digestive system and discuss the sites of production of the diff erent enzymes. Students annotate the diagrams as the discussion takes place.
Lesson activitiesStarter
1 B2 4.3a Eff ect of pepsin concentration on digestion In this practical activity, students weigh cubes of sausage before and after the experiment. (~30 mins)
2 B2 4.3b Digestion of fat A practical investigation into the digestion of olive oil by lipase, in the presence of bile salts. It
makes use of an indicator, bromothymol blue. (~35 mins)
3 Worksheet B2 4.3c Investigating digestion looks at the enzymes involved in digesting diff erent types of foods. ActiveTeach has a matching activity relating to the enzymes used in digestion. [AT]
Main
1 Give students 5 minutes to think of a plus, a minus and an interesting response to the statement ‘The human body does not need enzymes to digest food.’ Take examples of answers from the class, and discuss any misconceptions that may have arisen.
2 Divide the class into four groups. One group names an enzyme, the second group says where it is produced, the third group says what is digested and the fourth group gives the product(s) of digestion.
Plenaries
1 Worksheet B2 4.3d is an opportunity for students to revise enzyme action in the digestive system.
2 Students use textbooks and the Internet to fi nd out about the cells in the lining of the small intestine that manufacture and release enzymes.
Homework
Points to note• Bile salts are a constituent of bile and cause emulsifi cation.
• The breakdown of starch, protein and fat into smaller molecules are all hydrolysis reactions, involving the addition of a molecule of water.
• Digestive enzymes are continuously removed from the gut as food passes through it.
Route to A*1 Ask higher achievers to research the structure of the
stomach lining and to diff erentiate between glands that produce hydrochloric acid and those that produce enzymes, in a PowerPoint presentation.
2 Ask students to research precisely where and how gastric bands are fi tted, as a surgical aid to weight loss. The risks and benefi ts of the procedure can be evaluated.
Digestive enzymes pass out of specialised cells into the gut where they catalyse the breakdown of large food molecules.
The three types of digestive enzymes are proteases, amylases and lipases.
The pH in diff erent regions of the gut is controlled so that enzymes work most eff ectively.
Key points
140 Proteins and their functions 141
Using the food you eatYour food contains proteins, starches and sugars, and fats and oils. The molecules of proteins, starch and fats are huge – much too large for you to absorb into your body. This means they have to be digested, broken into smaller molecules, in your gut. These digestion reactions need to be quick so that you can absorb what you need from your small intestine, before the remains pass out of your body. All of these digestive reactions are catalysed by enzymes to speed them up.
Enzymes work outside cells that produce themYour gut is simply a hollow tube of diff erent diameters and wall types. Digestive enzymes are produced by specialised cells in glands and tissues lining the gut. They are made inside cells, but they move out of the cells into the gut where they work as they come in contact with food molecules. Some mix with the food in the gut, others remain attached to the outside of cells in the gut wall. They are extracellular enzymes.
The right tools for the job Each type of food needs a particular enzyme to break it down into products that are useful to the body. Diff erent enzymes work on diff erent substances.
Amylase enzymes catalyse the breakdown of starch to sugars.
Protease enzymes catalyse the breakdown of protein into amino acids.
Lipase enzymes catalyse the breakdown of lipids (fats and oils) into fatty acids and glycerol.
Where are these digestive enzymes produced and where do they work?
Controlling gut pHIn each region of the gut other substances are released to control the pH. For example, the stomach produces hydrochloric acid because the protease enzymes there work best in an acid solution. The liver produces bile, which is stored in the gall bladder before being released into the small intestine. Bile neutralises the acid that was added to food in the stomach and provides alkaline conditions for enzymes in the small intestine. These are other protease, lipase and amylase enzymes.
Digestive enzymesB2 4.3
relate digestive enzymes to their function and where they work in the digestive systemdescribe the breakdown products after catalysis by digestive enzymesdescribe the conditions that diff erent digestive enzymes work in.
Soon to be catalysed by enzymes.
Type of food Enzyme Products
A protein molecule is made upof many different amino acids.
A starch molecule is made upof many glucose molecules.
protease
amino acids
amylase
glucose
A fat molecule is made upof fatty acid and glycerol molecules.
lipase
fatty acids
glycerol
Figure 1 Specifi c enzymes break food down into products useful for your body.
The pancreas produces protease, amylase and lipase enzymes.
The small intestine produces protease, amylase and lipase enzymes. Enzymes in the small intestine work best in alkaline conditions.
Salivary glands in the mouth produce amylase enzymes.
The stomach produces protease enzymes. Hydrochloric acid is also produced. The enzymes in the stomach work best in acid conditions.
The liver produces bile, which is stored in the gall bladder. Bile neutralises the acid produced by the stomach and provides alkaline conditions.
gall bladder
Figure 2 Enzymes, hydrochloric acid and bile are released into the gut for digestion.
Pancreatic cells produce digestive enzymes.
cells that produce digestive enzymes
Learning objectives
Science skillsRead the information below about food transit time in the gut.
After a meal the time taken for food to travel through your gut depends on many factors. Roughly, it takes 2.5–3 hours
for 50% of stomach contents to empty into the intestines. Total emptying of the stomach takes 5–6 hours. Then 50% emptying of the small intestine takes 2.5–3 hours. Total emptying of the small intestine takes 5–6 hours. Finally, transit through the large intestine takes 30–40 hours.
a Tabulate the data in the paragraph above and include total transit time for each region of the gut. Then graphically display the data for total transit time.
Table 1 Each part of the digestive system releases diff erent enzymes to digest food.
Type of enzyme Where is it produced?
pH conditions for enzymes
Where does it work?
protease enzymes stomach acid stomach
pancreassmall intestine
alkaline small intestine
amylase enzymes salivary glands slightly alkaline mouth
pancreassmall intestine
alkaline small intestine
lipase enzymes pancreassmall intestine
alkaline small intestine
Protease, amylase and lipase enzymes are all produced in the pancreas and small intestine.
Bile is not an enzyme: it is a pH regulator.
Examiner feedback
A*
QuestionsThere are many kinds of enzyme in your gut. Explain why.
What would happen if you didn’t have enzymes in your gut?
Look at Figure 2. (a) In which two parts of the gut is amylase made? (b) Protease enzymes are made in the small intestine wall. Where else are they made? (c) In which part of the gut does lipid digestion take place?
Look at Figure 2. The stomach makes a chemical that is not an enzyme. What is the chemical?
Suggest the conditions that enzymes in the stomach work best in.
You eat a cheese sandwich. Write down the stages of digestion of the starch and fat as they pass through your gut.
What kind of tissue produces enzymes in general and what organs in the gut produce enzymes? Why are digestive enzymes described as extracellular?
Describe how bile reaches the small intestine.
What is one role of bile in digestion?
What is meant by digestion and why is it necessary in humans?
ActiveTeach Resource: Digestive enzymes – Matching activity
Science skillsa Region of gut Time to pass through (hours)
50% 100%
stomach 2.5–3 5–6
small intestine 2.5–3 5–6
large intestine 30–40
Displayed as a bar chart, with x-axis showing region of gut and y-axis showing total transit time in hours.
Answers1 There are diff erent substances in food that need to be digested.
2 You wouldn’t digest food and wouldn’t be able to absorb it.
3 (a) Any two from mouth, pancreas and small intestine. (b) Pancreas and stomach. (c) Small intestine.
4 (a) Hydrochloric acid. (b) Acidic conditions.
5 The starch in the bread starts to be broken down by salivary amylase in the mouth. It continues to be broken down to glucose by amylase – produced in the pancreas and small intestine – in the small intestine. Fat is broken down to fatty acids and glycerol by lipase – produced in the pancreas and small intestine – in the small intestine.
6 (a) Glandular tissue produces enzymes. The gut, salivary glands, pancreas and small intestine are organs that produce enzymes. (b) Digestive enzymes work outside the cells that produce them, either mixed with the food or on the outside of the cells in the gut wall.
7 (a) It is made in the liver and passes to the gall bladder where it is stored until needed, when it passes into the small intestine. (b) To neutralise the acid from the stomach. The enzymes in the small intestine work better in an alkaline liquid.
8 Our food contains proteins, starches and sugars, and fats and oils. The molecules of proteins, starch and fats are much too large for us to absorb into our body as they are. This means they have to be digested, broken into smaller molecules, in our gut. These digestion reactions need to be quick so that we can absorb what we need from our small intestine, before the remains pass out of the body.
Answers to Student Book questions
8 Our food contains proteins, starches and sugars, and fats and oils. The molecules of proteins, starch and fats are much too large for us to absorb into our body as they are. This means they have to be digested, broken into smaller molecules, in our gut. These digestion reactions need to be quick so that we can absorb what we need from our small intestine, before the remains pass out of the body.
M11_BIOL_TB_GCSE_3755_U11.indd 110-111 8/10/11 8:08:27 PM
Teacher and Technician Planning PacksMake learning personal! Containing original and imaginative activity ideas and lesson guides, these packs make planning and teaching of the new specification simple.
l Pedagogical guidance is provided for non-specialist teachers.
l Available on CD-ROM – so you can load them on to your ActiveTeach and access them at a click of a button!
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140 © Pearson Education Ltd 2011. Copying permitted for purchasing institution only. This material is not copyright free.
BTEC First <series>
B2 2.1b – Teacher and technician sheet
Using leaf discs to investigate the need for chlorophyll in photosynthesis Aim To investigate leaf discs from green and white/cream parts of variegated leaves to see if both types photosynthesise.
Specification • B2.3.1a,b
Equipment For groups of 2–3 students:
● beaker ● bench light ● 2×boiling tube ● Bunsen burner ● cork borer 5 mm diameter ● destarched variegated leaves
● 20 cm3 distilled water ● dropper ● ethanol (IDA) ● gauze ● marker pen ● heatproof mat
● hot water bath ● iodine/KI solution ● measuring cylinder ● 2×Petri dishes ● tweezers ● eye protection
Other resources Worksheet B2 2.1b; Skills sheet 9, Skills sheet 13
Safety notes ● Ensure an appropriate risk assessment is carried out for this practical activity. ● Students should wear eye protection. ● Ethanol is highly flammable and harmful. Make sure all Bunsen burners are turned off when
ethanol is in use. ● Do not allow students to pour used ethanol down the sink. They must hand it to you. ● Iodine/KI solution is an irritant and stains skin and clothes. ● Using electric water baths instead of Bunsen burners reduces the fire risk.
Running the activity 1 Soft leaves with large white/cream areas are needed, e.g. some varieties of Pelargonium,
Hosta, Ivy or any the florist has in stock. 2 The plants need to be completely destarched by keeping them in a warm, dark cupboard or
putting them in a black bag for 48 hours before use. 3 Wide diameter drinking straws can be used to cut discs in leaves in addition to cork borers. 4 Remind the students to label the boiling tube contents clearly as all the discs will look the same
after decolouration. 5 The leaf discs can be left photosynthesising in the Petri dishes for 3 days but they may need
topping up with distilled water.
Expected outcomes Students learn that: ● chlorophyll must be present in plant tissues if it is to photosynthesise ● non-green parts of leaves are kept alive by sugar from green parts being transferred to them ● glucose is quickly converted to starch during photosynthesis ● it is valid to use leaf discs to assess the process of photosynthesis.
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BTEC First <series>
B2 5.3 – Lesson guide
Anaerobic respiration This lesson helps students to explain the contribution of anaerobic respiration to releasing energy for activity in the body.
Resources available Student Book lesson B2 5.3
Sheet number Title Type Specification reference
B2 5.3a Muscle fatigue and muscle size Student practical sheet B2.6.2d B2 5.3a Muscle fatigue and muscle size Teacher and technician
sheet B2.6.2d
B2 5.3b What causes muscle cramps? Classwork B2.6.2a,b,c,d B2 5.3c Endurance sports Homework B2.6.2a,b,c,d B2 5.3d Diving animals Homework B2.6.2a,b,c,d
Specification B2.6.2a During exercise, if insufficient oxygen is reaching the muscles they use anaerobic respiration to obtain energy.
B2.6.2b Anaerobic respiration is the incomplete breakdown of glucose and produces lactic acid.
B2.6.2c As the breakdown of glucose is incomplete, much less energy is released than during aerobic respiration. Anaerobic respiration results in an oxygen debt that has to be repaid in order to oxidise lactic acid to carbon dioxide and water.
B2.6.2d If muscles are subjected to long periods of vigorous activity they become fatigued, i.e. they stop contracting efficiently. One cause of muscle fatigue is the build up of lactic acid in the muscles. Blood flowing through the muscles removes the lactic acid.
Ideas for practical work Investigating holding masses at arm’s length and timing how long it takes the muscles to fatigue.
Investigating the effect of exercise on pulse rate, either physically or using pulse sensors and data loggers.
Designing an investigation using force meters and data loggers to find the relationship between the amount of force exerted by a muscle and muscle fatigue.
How Science Works Skills, Knowledge and Understanding: B2.6 bullet point 1: Interpret data relating to the effects of exercise on the human body.
Controlled Assessment: B4.5.4d Evaluating methods of data collection; B4.6.1b Developing scientific ideas as a result of observations and measurements.
Lesson objectives Most students should be able to:
● explain how anaerobic respiration supplies energy to muscle cells when insufficient oxygen is available
● describe anaerobic respiration as the incomplete breakdown of glucose
● explain why anaerobic respiration results in an oxygen debt that has to be repaid
● explain why muscles become fatigued after long periods of activity.
Some students should also be able to:
● evaluate claims that lactic acid causes pain after anaerobic activity. [Ext]
Keywords Anaerobic respiration, fatigue, lactic acid, oxygen debt.
Points to note This topic provides some interesting opportunities for comparing results that are apparently based on scientific evidence with those based on true scientific investigation. The role of lactic acid in causing pain and cramps is one example. During vigorous activity, many changes happen in the muscles and the common assumption is that, since acids are generally 'bad things', they must be the cause. The evidence is more
Learning objectives and clear references to the new specification make planning and teaching of the new specifications simple.
Pedagogical guidance is provided for non-specialist teachers.
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Sheet 1 of 2
196 © Pearson Education Ltd 2011. Copying permitted for purchasing institution only. This material is not copyright free.
BTEC First <series>
B2 5.3 – Lesson guide
Anaerobic respiration This lesson helps students to explain the contribution of anaerobic respiration to releasing energy for activity in the body.
Resources available Student Book lesson B2 5.3
Sheet number Title Type Specification reference
B2 5.3a Muscle fatigue and muscle size Student practical sheet B2.6.2d B2 5.3a Muscle fatigue and muscle size Teacher and technician
sheet B2.6.2d
B2 5.3b What causes muscle cramps? Classwork B2.6.2a,b,c,d B2 5.3c Endurance sports Homework B2.6.2a,b,c,d B2 5.3d Diving animals Homework B2.6.2a,b,c,d
Specification B2.6.2a During exercise, if insufficient oxygen is reaching the muscles they use anaerobic respiration to obtain energy.
B2.6.2b Anaerobic respiration is the incomplete breakdown of glucose and produces lactic acid.
B2.6.2c As the breakdown of glucose is incomplete, much less energy is released than during aerobic respiration. Anaerobic respiration results in an oxygen debt that has to be repaid in order to oxidise lactic acid to carbon dioxide and water.
B2.6.2d If muscles are subjected to long periods of vigorous activity they become fatigued, i.e. they stop contracting efficiently. One cause of muscle fatigue is the build up of lactic acid in the muscles. Blood flowing through the muscles removes the lactic acid.
Ideas for practical work Investigating holding masses at arm’s length and timing how long it takes the muscles to fatigue.
Investigating the effect of exercise on pulse rate, either physically or using pulse sensors and data loggers.
Designing an investigation using force meters and data loggers to find the relationship between the amount of force exerted by a muscle and muscle fatigue.
How Science Works Skills, Knowledge and Understanding: B2.6 bullet point 1: Interpret data relating to the effects of exercise on the human body.
Controlled Assessment: B4.5.4d Evaluating methods of data collection; B4.6.1b Developing scientific ideas as a result of observations and measurements.
Lesson objectives Most students should be able to:
● explain how anaerobic respiration supplies energy to muscle cells when insufficient oxygen is available
● describe anaerobic respiration as the incomplete breakdown of glucose
● explain why anaerobic respiration results in an oxygen debt that has to be repaid
● explain why muscles become fatigued after long periods of activity.
Some students should also be able to:
● evaluate claims that lactic acid causes pain after anaerobic activity. [Ext]
Keywords Anaerobic respiration, fatigue, lactic acid, oxygen debt.
Points to note This topic provides some interesting opportunities for comparing results that are apparently based on scientific evidence with those based on true scientific investigation. The role of lactic acid in causing pain and cramps is one example. During vigorous activity, many changes happen in the muscles and the common assumption is that, since acids are generally 'bad things', they must be the cause. The evidence is more
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BTEC First <series>
B2 2.1b – Teacher and technician sheet
Using leaf discs to investigate the need for chlorophyll in photosynthesis Aim To investigate leaf discs from green and white/cream parts of variegated leaves to see if both types photosynthesise.
Specification • B2.3.1a,b
Equipment For groups of 2–3 students:
● beaker ● bench light ● 2×boiling tube ● Bunsen burner ● cork borer 5 mm diameter ● destarched variegated leaves
● 20 cm3 distilled water ● dropper ● ethanol (IDA) ● gauze ● marker pen ● heatproof mat
● hot water bath ● iodine/KI solution ● measuring cylinder ● 2×Petri dishes ● tweezers ● eye protection
Other resources Worksheet B2 2.1b; Skills sheet 9, Skills sheet 13
Safety notes ● Ensure an appropriate risk assessment is carried out for this practical activity. ● Students should wear eye protection. ● Ethanol is highly flammable and harmful. Make sure all Bunsen burners are turned off when
ethanol is in use. ● Do not allow students to pour used ethanol down the sink. They must hand it to you. ● Iodine/KI solution is an irritant and stains skin and clothes. ● Using electric water baths instead of Bunsen burners reduces the fire risk.
Running the activity 1 Soft leaves with large white/cream areas are needed, e.g. some varieties of Pelargonium,
Hosta, Ivy or any the florist has in stock. 2 The plants need to be completely destarched by keeping them in a warm, dark cupboard or
putting them in a black bag for 48 hours before use. 3 Wide diameter drinking straws can be used to cut discs in leaves in addition to cork borers. 4 Remind the students to label the boiling tube contents clearly as all the discs will look the same
after decolouration. 5 The leaf discs can be left photosynthesising in the Petri dishes for 3 days but they may need
topping up with distilled water.
Expected outcomes Students learn that: ● chlorophyll must be present in plant tissues if it is to photosynthesise ● non-green parts of leaves are kept alive by sugar from green parts being transferred to them ● glucose is quickly converted to starch during photosynthesis ● it is valid to use leaf discs to assess the process of photosynthesis.
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