Name

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Cambridge Secondary 1 Science Topic Book: B7c Part 2 Cells and organisms CIE Topic code: B7c

Essential Science workbook: Chapter 2 Micro-organisms (Pages 10 to 17)

Biology Bc Cells and organisms (UK KS3: 7A, 8C) • 7Bc2 Know about the role of micro-organisms in the breakdown of organic matter, food production and

disease, including the work of Louis Pasteur.

Contents CIE Topic code: B7c ............................................................................................................................ 1

Biology Bc Cells and organisms (UK KS3: 7A, 8C) ........................................................................... 1

What you should have done if you wanted the highest grade in this course for this topic: ................. 2

Sec1 Sci B7c Part 2 WL Micro-organisms and disease 24Core words .................................................... 3

Fill in the missing meaning ...................................................................................................................... 5

Essential information -What is a microorganism? ................................................................................... 6

Extension information: ............................................................................................................................. 6

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Microorganism .................................................................................................................................. 6

Free-living microorganisms ..................................................................................................... 6

Parasitic microbes ........................................................................................................................ 7

Commensalism .............................................................................................................................. 7

References ....................................................................................................................................... 7

Bacteria ................................................................................................................................................. 7

Reproduction and gene transfer ............................................................................................ 8

Shape ................................................................................................................................................. 8

Pathogens ......................................................................................................................................... 8

Extremophiles ................................................................................................................................ 8

References ....................................................................................................................................... 8

Germ theory of disease ................................................................................................................... 8

Decomposer ...................................................................................................................................... 10

Examples of decomposers ....................................................................................................... 10

Other pages ................................................................................................................................... 11

References ..................................................................................................................................... 11

Fermentation .................................................................................................................................... 11

Types of fermentation ............................................................................................................... 11

Other websites ............................................................................................................................. 11

Extension task: Expanding your mind using the C7s States of matter topic .......................................... 12

Notebook points

Effort score for word list activities Word list test score

Effort score for mind map Multiple Choice test result

Effort score for past exam questions End of topic test

Overall effort score for

this topic

Overall grade for

topic

What you should have done if you wanted the highest grade in this course for this topic:

1. Complete notes taken from class, which clear headings underlined with a ruler and the date for each

piece of work. All single sheets should be neatly stuck in your book, ideally with clear tape and with

the edges cut off so that they don’t stick our of your book

2. Cornell notes along the side with translations of new English words you don’t understand and a

summary at the bottom of the page that explains in just one sentence what you. Only the very best

students will probably be able to do this properly, but everyone should at least try.

3. Complete the exercises for the word list test you will have in the second week. Remember, when I

take these topic books in, I will check and give you and effort score

4. Compete the mind map based on the review sheets inside this topic book. This will help you to learn

for the multiple choice question test

5. Completed the past exam questions as the back of this topic book to help you prepare for the end of

topic test, which is the most important of the assessed activities you will do.

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6. EXTENSION ACTIVITIES: The ablest students will also have completed all of the questions in the

workbook, and in the back of their exercise book, also completed the questions given in the textbook

sections that have been handed out.

7. FOR THE VERY ABLEST STUDENTS: They will also have explored one part of this topic that they find

fascinating and will have either made a poster, or a presentation, e.g. on power point and explained

what they know during a chemistry gifted and talented session, which are open to all students across

grades 6 and 7, and run every Wednesday during prep time 3:45 to 4:30pm in Mr Brannac’s

classroom.

Sec1 Sci B7c Part 2 WL Micro-organisms and disease 24Core words # Difficulty English Chinese Meaning in English Meaning in Chinese

1 Core Bacterium 细菌 A type of microbe bigger than viruses.

(plural = bacteria)

一种比病毒更大的微生物。 （复数=

细菌）

2 Core Fungus 菌

Organisms which are different from animals, plants and bacteria. Examples

include mushrooms and yeasts. (plural = fungi)

与动物，植物和细菌不同的生物。例

子包括蘑菇和酵母。 （复数=真菌）

3 Core Microbe 微生物 Short for micro-organism. 微生物的简称。

4 Core Micro-

organism 微生物 A very small living thing. 一个非常小的生物。

5 Core Virus 病毒

The smallest type of microbe. Many people think that they are not living

because they do not carry out the seven life processes for themselves.

最小的微生物类型。许多人认为他们

没有生活，因为他们没有为自己实施

七个生命过程。

6 Core Yeast 酵母 A type of fungus with only one cell and

therefore a microbe. They are bigger than bacteria.

一种真菌只有一个细胞，因此是一种

微生物。它们比细菌更大。

7 Core Ethanol 乙醇 Often just called ‘alcohol’. Produced by

yeast when they ferment sugar.

通常被称为'酒精'。酵母在发酵糖时产

生。

8 Core Disease 疾病 When some processes that happen in the body do not work in the way they should.

当身体中发生的某些过程不能按照它

们应该的方式工作时。

9 Core Fever 发热 A high body temperature. 体温很高。

10 Core Infect 感染 When a microbe gets into your body you

are ‘infected’ by it. 当微生物进入你的身体时，你会被它“

感染”。

11 Core Infectious 传染病 A disease that can be spread from person

to person or from animal to person is infectious.

可以在人与人之间或从动物传播到人

的疾病具有传染性。

12 Core Symptoms 症状 The effects that a disease has on your

body. 疾病对你身体的影响。

13 Core Cell 细胞 wave to move mucus up to the gullet to

be swallowed. 挥动将粘液移到吞食的食道上。

14 Core Disinfectant 消毒剂 Strong chemical used to kill microbes. 用于杀死微生物的强化学品。

15 Core Mucus 粘液 Sticky substance used to trap microbes and dust. Found in nose and trachea.

用于捕获微生物和灰尘的粘性物质。

发现于鼻子和气管。

16 Core Natural

defences 自然防御

Your body’s way of trying to keep microbes out (e.g. skin) or killing them if

they get inside you (eg stomach acid).

你的身体试图保持微生物（例如皮肤

）或杀死它们（如胃酸）的方法。

17 Core White blood

cell 白细胞

A type of blood cell which helps to destroy microbes. They either engulf microbes or

make antibodies.

一种有助于破坏微生物的血细胞。他

们要么吞噬微生物，要么制造抗体。

18 Core Antibiotic 抗生素 Medicine that can kill bacteria but not

viruses. 可以杀死细菌而不是病毒的药物。

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# Difficulty English Chinese Meaning in English Meaning in Chinese

19 Core Immune 免疫的 If you cannot get a disease you are said to

be ‘immune’ to it.

如果你不能患上疾病，你会说它对它

有“免疫力”。

20 Core Immunisation 免疫接种 Making people immune to diseases. 让人们免疫疾病。

21 Core Infect 感染 When a microbe gets into your body you

are ‘infected’ by it. 当微生物进入你的身体时，你会被它“

感染”。

22 Core Medicine 医学 A drug that helps the body to ease the

symptoms of a disease or cure the disease.

一种帮助身体缓解疾病症状或治愈疾

病的药物。

23 Core Resistant 耐 Bacteria that are not affected by an

antibiotic are said to be resistant to it.

据说不受抗生素影响的细菌对其具有

抗性。

24 Core Vaccine 疫苗

A mixture containing microbes which normally cause disease, which have been treated so that they don’t. Injected into

people to make them immune.

含有通常会引起疾病的微生物的混合

物，经过处理后不再使用。注入人，

使他们免疫。

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Fill in the missing meaning English Meaning in English

Microbe Short for micro-organism. Disinfectant Strong chemical used to kill microbes.

Mucus Sticky substance used to trap microbes and dust. Found in

nose and trachea. Immunisation Making people immune to diseases.

Antibiotic Medicine that can kill bacteria but not viruses.

Vaccine

A mixture containing microbes which normally cause disease, which have been treated so that they don’t. Injected into

people to make them immune.

Infectious A disease that can be spread from person to person or from

animal to person is infectious. Infect When a microbe gets into your body you are ‘infected’ by it.

Ethanol Often just called ‘alcohol’. Produced by yeast when they

ferment sugar.

Resistant Bacteria that are not affected by an antibiotic are said to be

resistant to it. Cell wave to move mucus up to the gullet to be swallowed.

Natural defences Your body’s way of trying to keep microbes out (e.g. skin) or

killing them if they get inside you (eg stomach acid). Fever A high body temperature.

White blood cell A type of blood cell which helps to destroy microbes. They

either engulf microbes or make antibodies.

Virus The smallest type of microbe. Many people think that they are not

living because they do not carry out the seven life processes for themselves.

Infect When a microbe gets into your body you are ‘infected’ by it.

Fungus

Organisms which are different from animals, plants and bacteria. Examples include mushrooms and yeasts. (plural =

fungi) Bacterium A type of microbe bigger than viruses. (plural = bacteria)

Medicine A drug that helps the body to ease the symptoms of a

disease or cure the disease. Symptoms The effects that a disease has on your body.

Disease When some processes that happen in the body do not work

in the way they should. Immune If you cannot get a disease you are said to be ‘immune’ to it.

Yeast A type of fungus with only one cell and therefore a microbe.

They are bigger than bacteria. Micro-organism A very small living thing.

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Essential information -What is a microorganism? From: https://www.bbc.com/bitesize/articles/zsgtrwx

For more information follow the link above and the links below, but some content may not be available in every country

Microorganisms are tiny. They are so small they can only be seen with a microscope. Yeast is a helpful microorganism which makes bread rise. Bacteria is a microorganism which breaks down plants into nutrients. Microorganisms are also known as 'germs'. Harmful germs can make us unwell. Good hygiene will avoid spreading these germs. Use soap and hot water to wash your hands after preparing food or using the toilet. This will kill bacteria. Part of Science Microorganisms

Extension information: Further information can is available from the websites that this information is taken from

Microorganism From: https://wiki.kidzsearch.com/wiki/Microorganism KidzSearch Safe Wikipedia for Kids.

A cluster of Escherichia coli bacteriamagnified 10,000 times.

A microorganism or microbe is an organism (living thing) which is too small to be seen by the unaided human eye. They are microscopic. The study of microorganisms is called microbiology.

Microorganisms include bacteria, fungi, archaea or protists and viruses. The first four types of microorganisms may be either free-living or parasitic. Viruses, however, always reproduce inside other living things.[1][2][3]

Most micro-organisms are single-celled, or unicellularorganisms, but there are unicellular protists that are visible to the human eye, and some multicellular species are microscopic.

Microorganisms live almost everywhere on earth where there is liquid water, including hot springson the ocean floor and deep inside rocks within the earth's crust. Such habitats are lived in by extremophiles.

Microorganisms are critical to nutrient recycling in ecosystems, because they act as decomposers. Because some microorganisms can also take nitrogen out of the air, they are an important part of the nitrogen cycle. Pathogenic, or harmful, microbes can invade other organisms and cause disease.

Free-living microorganisms

Free-living microbes get their energy in many different ways. Some use photosynthesis, like plants do. Some break down natural chemicals in their environment. Others feed on things that were once living,

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such as fallen leaves and dead animals, causing them to breakdown or decay. Some fungi and bacteria cause food to decay. Moldy bread or fruit, sour milk, and rotten meat are examples of decayed food. In nature, decayed materials mix with soil, providing essential nutrients for plants to use. Without this process, the nutrients in the soil would run out. These types of organisms are called decomposers. They are the natural recyclers of living things on our planet.

Microbes also help us make some of our foods, such as bread, cheese, yogurt, beer, and wine. They feed on the sugar in grain, fruit, or milk, giving these foods a special texture and taste. [4]

Parasitic microbes

Some microbes, often called germs, cause illness or disease. They are parasites which live by invading living things. Chickenpox, mumps, and measles are all caused by viruses.[4] They are infectious diseases. Certain bacteria cause tooth decay.[4] It is possible to protect humans against some harmful microbes by storing and preparing food properly, cleaning the teeth, washing hands, and by avoiding close contact with ill people.

Commensalism

All animals seem to have bacteria and protozoa living in or on them without doing much harm. Sometimes, as with herbivores, the microorganisms are vital to the digestion of food. The human gut has more organisms living inside it than there are cells in the human body.[5]

References

1. Jump up↑ Rybicki E.P. 1990. The classification of organisms at the edge of life, or problems with virus systematics. S African J Sci 86: 182–6.

2. Jump up↑ Lwoff A. 1957. The concept of virus. J. Gen. Microbiol. 17 (2): 239–53. PMID 13481308 .

3. Jump up↑ Forterre P. 2010. Defining life: the virus viewpoint. Orig Life Evol Biosph. 40(2):151-60. [1]

4. ↑ Jump up to:4.0 4.1 4.2 Blue Planet. McGrawHill. 2003.

5. Jump up↑ Sears C.L. 2005. A dynamic partnership: celebrating our gut flora. Anaerobe 11 (5): 247–51. doi:10.1016/j.anaerobe.2005.05.001 . PMID 16701579 .

Bacteria From: https://wiki.kidzsearch.com/wiki/bacteria KidzSearch Safe Wikipedia for Kids.

Bacteria (one of them is a bacterium) are very small organisms. They are prokaryotic microorganisms. Bacterial cells do not have a nucleus, and most have no organelles with membranes round them. However, they do have DNA, and their biochemistry is basically the same as other living things.

Almost all bacteria are so tiny they can only be seen through a microscope. Bacteria are made up of one cell, so they are a kind of unicellular organism. They are among the simplest single-celled organisms on Earth, and were one of the earliest forms of life. They include a number of extremophiles which live in extreme habitats.

There are probably more individual bacteria than any other sort of organism on the planet.[1] Most bacteria live in the ground or in water, but many live inside or on the skin of other organisms, including humans. There are about ten times as many bacterial cells as human cells in each of our bodies. Some bacteria can cause diseases, but others help us in everyday activities like digesting food (gut flora). Some even work for us in factories, producing cheese and yogurt.

The founder of bacteriology was a German biologist called Ferdinand Cohn (1828–1898). He published the first classification of bacteria, based on their appearance.[2]

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Reproduction and gene transfer

A bacterium reproduces (creates more bacteria) by dividing in half and creating two "daughter" cells. Each daughter is identical in shape to the parent, but smaller. It is this which permits them to pass resistance to antibiotics from one strain to another. The complete DNA sequence is known for many bacterial strains.

Shape

Bacteria vary widely in size and shape, but in general are at least ten times larger than viruses. A typical bacterium is about 1 µm (one micrometer) in diameter, so a thousand bacteria lined up would be one millimeter long. There are about five nonillion (5×1030) bacteria on Earth.[1]

Bacteria are identified and grouped by their shapes. Bacilli are rod-shaped, cocci are ball-shaped, spirilla are spiral-shaped and vibrio are shaped like a comma or a boomerang.

Pathogens

Pathogenic bacteria, the harmful kind, enter the human body from the air, water or food. Once inside, these bacteria attach themselves to or invade specific cells in our respiratory system, digestive tract or any open wound. There they begin to reproduce and spread while using the human body as a source of their own nutrients and energy.

Extremophiles

researchers reported related studies that microbes thrive inside rocks up to 580 metres below the sea floor under 2.6 kilometres of ocean off the coast of the northwestern United States.[3][4]According to one of the researchers,"You can find microbes everywhere — they're extremely adaptable to conditions, and survive wherever they are."[3]

References

1. ↑ Jump up to:1.0 1.1 Whitman W, Coleman D, Wiebe W (1998). "Prokaryotes: the unseen majority". Proc Natl Acad Sci USA 95 (12): 6578–83. doi:10.1073/pnas.95.12.6578 . PMID 9618454 .

2. Jump up↑ Encyclopedia Britanniaca: Bacteriology. [1]

3. ↑ Jump up to:3.0 3.1 Choi, Charles Q. (2013). "Microbes thrive in deepest spot on Earth". LiveScience. Retrieved 17 March 2013.

4. Jump up↑ Oskin, Becky (2013). "Intraterrestrials: Life thrives in ocean floor". LiveScience. Retrieved 17 March 2013.

5. Jump up↑ Woese C.R. 1987. Bacterial evolution. Microbiological reviews 51 (2): 221–71. [2]

6. Jump up↑ Holland L. (1990). "Woese, Carl in the forefront of bacterial evolution revolution". Scientist 3 (10).

Germ theory of disease From: https://wiki.kidzsearch.com/wiki/Germ_theory_of_disease KidzSearch Safe Wikipedia for Kids.

The Germ theory of disease is a theory in biology. It says that small organisms (called germs), also known as microbes, cause diseases. Most, but not all diseases are infectious. The germ theory states that small organisms cause a reaction in the body of those who are infected. The body's reaction to infection is called a disease.

Main page: Medical microbiology

Bacteria

Temporal range: Archaean – Recent

Escherichia coli image is

8 micrometres wide.

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Scanning electron microscope image of the bacteria that causes the disease cholera.

Many scientists and doctors in history figured out that diseases are caused by microscopic organisms. Even after the microscope was invented, people still didn't know that germs caused diseases. People long believed that "bad air" from stinky trash dumps and from rotting meat was the cause of diseases. So people thought that covering their mouth and nose with a cloth would help filter out the "bad air." Back in the olden days, scientists and doctors would use garlic and perfumes to ward off the bad air. But people still got sick and even died, so this theory was wrong. "Bad air" is not the cause of disease.

One problem with the old theories of disease was that people believed that things spontaneously generated. Spontaneous generation is when something like a fly grows from a small speck of smelly meat. That old theory is called abiogenesis. In the seventeenth century, Francesco Redi(February 18, 1626 – March 1, 1697) discovered that flies lay eggs called maggots. Prior to this, people thought that maggots came from rotting meat. He discovered this by sealing some meat in a jar and watching it. No maggots were found on the sealed meat. He also put some meat in a jar and covered it with gauze. Maggots were found on the gauze but not inside the jar. But when he placed meat in an open jar, maggots were found on the meat and inside the jar. Experiments like this proved that maggots come from flies who lay eggs, not from rotting meat. Later scientists would prove that diseases did not come from the air. Diseases are spread by infection.

Also in the eighteenth century, Antonie van Leeuwenhoek discovered the first microscopic organisms with a microscope. He was the first microbiologist. He saw some of the microscopic organisms that cause diseases, but he didn't know what they were. In 1700, Nicolas Andrythought that some of these microscopic organisms caused smallpox and other diseases. Over 100 years later, Agostino Bassi figured out what caused disease in silkworms. Ignaz Semmelweis was a doctor who figured out that if doctors washed their hands after touching dead people, that other patients wouldn't get sick. That was in 1847. It was about this time that sanitation and hand washing became popular with some, but not all doctors. Doctors began to use chemicals to cleanse wounds and clean their tools between each patient.

Original map by John Snow showing where people lived that got sick from cholera during the London 1854

epidemic.

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One of the most famous experiments of the nineteenth century was when John Snowdiscovered the source of a cholera outbreak. It turns out that cholera is transmitted when human waste contaminates water that people drink. Snow found out that there was a large number of sick people in Soho in London. After talking to many people in the area and mapping where each sick person lived, he realized that the sick people were almost all getting their drinking water from the same public water pump. He solved the epidemicby having the water pump's handle removed so that the people would get water from some other place. It worked, and the epidemic was soon over.

Louis Pasteur showed that the germ theory of disease was true. In 1862, he invented a process that heats up a liquid to a high temperature to keep it from spoiling. This process is known as pasturization, named after Pasteur. Pasteurization is used to kill microscopic organisms in liquids like milk, wine, and beer. Liquids that are pasteurized will last much longer before they spoil.

Later, he did an experiment with fermentation. In one case he made a broth that he put inside a jar with a very long winding tube, so that no particles could pass to it from outside. Air could get inside the tube, but almost no dust. The broth he made did not change, and no fermentation took place.

He then took a similar broth, but this time he allowed air and dust to go inside the jar. This time, fermentation took place. The thing that caused fermentation therefore needed to come from outside (the environment). And it wasn't just air that caused fermentation, it must be something floating in the air which was very small. We now know that small particles called yeast cause fermentation.

In the latter part of the nineteenth century, Robert Koch and Joseph Lister would go on and help establish the germ theory of disease as an important part of science and medicine. Koch's theories are called "postulates" and helped medical researchers know what causes diseases. Lister's ideas would help establish sanitation as a major defense against disease. Koch's postulates and Lister's sanitation discoveries are still very important today.

We now know that small things cause diseases. Each one of these things can cause infection: fungus, bacteria, virus, prion, yeast, protist.

Decomposer From: https://wiki.kidzsearch.com/wiki/Decomposer KidzSearch Safe Wikipedia for Kids.

A decomposer means an organism that breaks down large molecules from dead organisms into small molecules and returns important materials to the environment. Sooner or later, all living things die. When a plant or an animal dies, its body begins to break down into small pieces. Special living things called decomposers break down the body. A decomposer makes dead things into chemicals and then the chemicals go into the air, ground or water and is used again.

Examples of decomposers

A mushroom, an example of a decomposer

Some types of decomposers are Bacteria and Fungi. Others are worms, and mushrooms. [1]The worms live in the ground. They eat their way through bits of dead plants and animals. Some mushrooms and fungi grow out of dead plants and animals to help break them down. [1]But most decomposers are too small for us to see. They are all around us in the air and in the ground.[1]

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Other pages

• Mushrooms

• Microbes

• Ecosystems

• Producers

• Consumers

References

1. ↑ Jump up to:1.0 1.1 1.2 Focus on Science. Austin, Texas: Harcourt Achieve. 2004. pp. 62.

Fermentation KidzSearch Safe Wikipedia for Kids.

Fermentation of cheese

Fermentation is when a cell uses sugar for energy without using oxygen at the same time.

Yeast is an organism that ferments. When yeast ferments sugar, the yeast eats sugar and produces alcohol. Other cells make vinegar or lactic acid when they ferment sugar. This is used to make beer, some types of fuel and to make bread rise.

Types of fermentation

When yeast ferments, it breaks down the glucose (C6H12O6) into ethanol (CH3CH2OH) and carbon dioxide (CO2).

• Ethanol fermentation always produces ethanol and carbon dioxide. It is important in bread-making, brewing, and wine-making.

• Lactic acid fermentation produces lactic acid. It happens in muscles of animals when they need lots of energy fast.

Other websites

• The chemistry behind fermentation and respiration

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Mind map TASK Using your notes, the information contained in the word lists, the past exam questions and in this topic

book (and any extra information you may have discovered in your own research along the way) create

a mind map in the space below

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Sec1 Sci B7c Part 2 EXAM QUESTIONS 31marks Q1

(a) The graphs show the number of deaths from lung cancer and from tuberculosis of the lungs, in England and Wales, between 1920 and 1960.

(i) Between which two dates on the graph did the number of deaths from lung cancer rise fastest?

........................................... and ........................................... 1 mark

(b) The number of deaths from tuberculosis of the lungs went down because of better medical treatment and preventive medicine.

What type of treatment is given to young people nowadays to prevent them from getting tuberculosis?

...................................................................................................................... 1 mark

Q2 (a) In 1967 a national immunisation programme against measles began. Children were injected with a measles vaccine to make them immune to the disease.

The graph shows how the number of people with measles varied between 1950 and 1980.

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(i) What does ‘immune’ mean?

............................................................................................................. [1mark]

(ii) Complete the following sentence.

When a person is vaccinated, white blood cells produce

.................................................................. which kill micro-organisms. 1 mark

(iii) What is present in a vaccine to cause white blood cells to respond in this way?

............................................................................................................. [1mark]

(b) Explain how a new born baby can have immunity to measles for a short time without being vaccinated.

............................................................................................................. [1mark]

(c) The national immunisation programme worked well.

Explain how the graph shows this.

............................................................................................................. [1mark]

(d) An increasing number of children are not being immunised.

Predict what is likely to happen to the number of cases of measles as a result of this.

............................................................................................................. [1mark]

Q3. Michael cut his knee while he was playing football.

A first-aider put a bandage over the cut.

(a) A bandage helps to stop a cut getting dirty or infected.

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Give the name of one type of micro-organism which can infect a cut.

............................................................................................................. [1mark]

(b) While he was cleaning Michael’s knee, the first-aider wore rubber gloves.

(i) Give one reason why wearing rubber gloves is important for the

first-aider’s health.

............................................................................................................. [1mark]

(ii) Give one reason why it is important for Michael’s health that the

first-aider wears rubber gloves.

............................................................................................................. [1mark]

Q4. Spots may be caused by bacteria in the skin. A researcher investigated the effect of spot-lotion on bacteria.

(a) He grew bacteria on the surface of jelly in a Petri dish.

At what temperature would the bacteria reproduce quickly?

Tick the correct box.

100°C 4°C

37°C –15°C 1 mark

(b) The researcher placed two small paper discs onto the surface of the jelly.

One disc had been soaked in spot-lotion. The other disc had been soaked in water.

The diagrams below show the jelly at the beginning of the experiment and two days later.

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Suggest what had happened to the bacteria in the clear area around the paper disc soaked in spot-lotion.

............................................................................................................. [1mark]

(d) Give two safety precautions the researcher should take to avoid contact

with the bacteria.

1. ……………………………………………………………………………………

2. ……………………………………………………………………………………. 2 marks

Q5. One evening Jenny and Leah ate chicken sandwiches which had been in their school bags all day. There were harmful bacteria in the food. The next day both girls became very ill. Their doctor gave them antibiotics to take for eight days.

The graph represents how antibiotics affect the number of bacteria in the body.

(a) Use the graph to explain why the girls did not become ill until the day after

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eating the sandwiches.

............................................................................................................. [1mark]

(b) After taking the antibiotics for eight days Jenny was completely better. Explain why she got better.

............................................................................................................. [1mark]

(c) Leah should have taken the antibiotics for eight days. She felt much better after five days and stopped taking the antibiotics. Two days later she felt very ill again.

Use the graph to help you explain why Leah became ill again.

.....................................................................................................................

..................................................................................................................... 2 marks

(d) Food will keep longer if it is placed in a refrigerator at 2°C.

Refrigeration does not kill bacteria.

What effect does the low temperature have on bacteria?

............................................................................................................. [1mark]

Q6. Cholera is a disease caused by bacteria. These bacteria produce a poison.

The poison prevents the large intestine from absorbing water from the food passing through it.

People with cholera can lose more than a litre of water per hour.

(a) Give one function of water in the body.

............................................................................................................. [1mark]

(b) People can be injected with a vaccine against cholera. The vaccine contains a tiny amount of the cholera poison and not the cholera bacteria. As a result, people become immune to cholera.

Describe how vaccination makes a person immune to cholera.

.....................................................................................................................

..................................................................................................................... 2 marks

(c) The cholera poison makes the skin permeable. A new method of vaccinating against cholera is to put a small amount of the poison, mixed with other vaccines, on a plaster. The plaster is left on the skin for a day. The vaccines

Patrick Brannac www.SmashingScience.org Page 18 of 24

pass through the skin and the person becomes immune to cholera and to other diseases.

(i) Why should only a tiny amount of the poison be used?

............................................................................................................. [1mark]

(ii) Suggest one advantage of vaccinating people in this way.

............................................................................................................. [1mark]

Q7. (c) Rahma cut his foot on a piece of glass. A scab formed over the cut.

Give one way a scab protects the body.

............................................................................................................. [1mark]

Q8. The thermometer drawn below can be used to measure the temperature of the human

body.

(a) (i) What is the lowest temperature this thermometer can measure?

..............°C 1 mark

(ii) What is the normal temperature of the human body?

Tick the correct box.

37°C 39°C 41°C

1 mark

(iii) When we are ill our temperature may go up.

A nurse can measure a child’s temperature with two different thermometers

as shown below.

Patrick Brannac www.SmashingScience.org Page 19 of 24

Give one reason why it is safer to use a plastic strip thermometer than a

glass thermometer.

............................................................................................................. [1mark]

(b) Viruses are micro-organisms that can make us ill.

Give the name of one other type of micro-organism that can make us ill.

............................................................................................................. [1mark]

(c) Alcohol and mercury are two liquids that can be used in glass thermometers.

The table gives information about these liquids.

liquid boiling point (ºC) colour

alcohol 78 colourless

mercury 357 shiny grey

(i) A red dye is added to the colourless alcohol used in thermometers.

Suggest a reason for this.

............................................................................................................. [1mark]

(ii) Choose words from the list below to fill the gaps in the sentences.

gas liquid solid

When alcohol and mercury boil they both change from a liquid to

a ............................................................................................................. [1mark]

A thermometer containing mercury can be used to measure the

temperature of an oven at 150°C because mercury is a

....................................... at 150°C. 1 mark

Patrick Brannac www.SmashingScience.org Page 20 of 24

Mark Scheme

M1. (a) (i) 1950 and 1955

both dates are required for the mark

accept the dates in reverse order

accept ‘1945 and 1955’

do not accept ‘1945 and 1950’ 1 (L6)

(ii) tar

accept a named recognised carcinogen

accept ‘carbon particles’

do not accept ‘nicotine’ or ‘carbon monoxide’

if both tar and nicotine are given award no mark

1 (L6)

(b) any one from

• immunisation

accept ‘inoculation’

• vaccination

do not accept ‘injection’

• BCG

accept ‘TB jab’

• BCG injection

do not accept ‘jab’

• BCG jab

do not accept ‘shot’

• BCG shot

do not accept ‘medicine 1 (L6)

[3]

M2. (a) (i) any one from

• resistant to disease

accept ‘having antibodies against the disease’

• will not catch the disease

do not accept ‘able to fight the disease’ 1 (L7)

(ii) antibodies

accept ‘antitoxins’ 1 (L7)

(iii) any one from

• dead bacteria or virus or micro-organism

• weakened bacteria or virus or micro-organism

• non-virulent strain of bacteria

• mild strain of virus

• antigens 1 (L7)

(b) any one from

• antibodies pass to baby via placenta

• antibodies pass to baby via breast milk

accept ‘through the placenta’

accept ‘through mother’s milk’

do not accept ‘antibodies passed to baby through milk’

1 (L7)

(c) any one from

• it goes down and stays down

accept ‘it goes down’

• continues downwards

• fewer people got measles after 1967 1 (L6)

(d) it will increase or return to the pre-1967 levels

1 (L6)

[6]

M3. (a) any one from

• bacteria

do not accept ‘germs’ or ‘microbes’

• viruses

• fungi 1 (L4)

(b) (i) to stop micro-organisms passing from Michael to the first-aider

accept ‘bacteria’ or ‘viruses’ or ‘fungi’

Patrick Brannac www.SmashingScience.org Page 21 of 24

or ’microbes’ or ‘germs’ for micro-organisms

accept ‘to stop blood getting on the first-aider’

1 (L3)

(ii) to stop micro-organisms passing from the first-aider’s hands

to the cut or to Michael

accept ‘bacteria’ or ‘viruses’ or ‘fungi’ or ‘microbes’

or ‘germs’ for micro- organisms accept ‘rubber gloves

are sterile or cleaner than hands’

accept ‘to prevent the spread of infection or HIV

or AIDS’ as an alternative to one of the answers only

1 (L3)

[3]

M4. (a) 37°C

if more than one box is ticked, award no mark

1 (L5)

(b) the lotion killed the bacteria

accept ‘they died’ or ‘they were killed or destroyed’

1 (L5)

(c) the paper disc soaked in water

accept ‘the other disc’ 1 (L5)

(d) any two from

• keep the lid on the dish

• seal or secure the dish

• wear gloves

• wear a mask or goggles

• use tweezers to add the paper disc

do not accept ‘do the experiment in a fume cupboard’

2 (L5)

[5]

M5. (a) any one from

• there were not enough bacteria in the

food or body

accept ‘the bacteria had to grow first’

• the bacteria multiplied by the next day 1 (L6)

(b) the antibiotic or medicine killed all the bacteria

accept ‘the antibiotics got rid of all the bacteria’

or ‘there were no bacteria left’ 1 (L5)

(c) any one from

• antibiotic or medicine had not killed all the bacteria

accept ‘not all the bacteria had gone’

• there were still bacteria left alive 1 (L6)

• the bacteria multiplied

accept ‘the population rose again’

accept ‘they could grow again’

accept ‘they reproduced again’ 1 (L6)

(d) any one from

• it slows down reproduction

accept ‘it stops them reproducing’

or ‘it stops them breeding’ or ‘it stops them multiplying’

• it is too cold for the bacteria to divide or reproduce

accept ‘it stops them growing’

accept ‘slows down growth’

do not accept ‘they are dormant’

do not accept ‘it freezes them’ 1 (L6)

[5]

M6. (a) any one from

• for transport or for blood or plasma

accept ‘it stops cells becoming dehydrated’

‘it stops the body becoming dehydrated’

or ‘it keeps us hydrated’ are insufficient

• it is needed for sweat or for cooling

• for tears

Patrick Brannac www.SmashingScience.org Page 22 of 24

• it is a solvent

• for getting rid of waste

• it is needed for gas exchange

• it is a lubricant

• it is part of the cytoplasm

accept ‘allows chemical reactions to take place’

accept ‘for digestion’ 1 (L7)

(b) any two from

• white blood cells

• (produce) antibodies or antitoxins

• prevent further infections or destroy the toxin or poison

accept ‘destroy or kill the bacteria’ 2 (L7)

(c) (i) any one from

• so that the patient does not get cholera

accept ‘the person might die’

• so the poison does not prevent the large intestine from

absorbing water

accept ‘intestine’ for large intestine

do not accept ‘small intestine’ 1 (L7)

(ii) any one from

• no need for injections

• some people are afraid of needles

accept ‘it does not hurt’

• less or no risk of infection

do not accept ‘so they can be vaccinated against several diseases’

1 (L7)

[5]

M7. (a) (i) oxygen

accept ‘O2’

do not accept ‘air’ 1 (L3)

(ii) any one from

• glucose

accept ‘sugar’

• digested food

accept ‘amino acids’ or ‘fatty acids’ or ‘glycerol’

accept ‘food’ or ‘nutrients’

• vitamins

accept a named vitamin

• minerals

accept a named mineral

• water 1 (L4)

(b) any one from

• it prevents oxygen getting to the organ

accept ‘it stops oxygen’

• it prevents food getting to the organ

• it stops blood getting to the organ

accept ‘it blocks the blood vessel’

accept ‘it causes a heart attack’ or ‘a stroke’

or ‘thrombosis’ accept ‘it stops the flow of blood’

or ‘it stops blood flowing around the body’

‘you would die’ is insufficient 1 (L4)

(c) any one from

• it stops bleeding

• it prevents bacteria or viruses from entering

accept ‘microbes’ or ‘germs’ for bacteria

these less precise terms are accepted if the answer

indicates that the scab acts as a barrier

‘to keep it clean’ is insufficient

accept ‘it stops dirt getting in’

accept ‘it stops infection’

accept ‘it stops disease’

‘it stops diseases getting in’ is insufficient 1 (L3)

[4]

M8. (a) (i) 35

Patrick Brannac www.SmashingScience.org Page 23 of 24

1 (L3)

(ii) 37°C 1 (L4)

(iii) any one from

• less chance of micro-organisms being passed on or spread

• glass could break

accept ‘less chance of germs being passed on’

accept ‘might pass on disease’

accept ‘a child might bite or swallow the thermometer’

if more than one box is ticked, award no mark

• mercury or alcohol or liquid could spill

(if the glass thermometer broke)

• mercury is poisonous

• you could choke 1 (L3)

(b) any one from

• bacteria

• fungi

• protozoa

accept a named non-viral pathogenic

micro-organism such as ‘salmonella’

do not accept names of diseases

do not accept ‘germs’ 1 (L4)

(c) (i) any one from

• so that alcohol can be seen

accept ‘so you can see it’

• alcohol is difficult to see

• you cannot easily see a colourless liquid

accept ‘you cannot see a colourless liquid’

• to make it easier to read the thermometer

accept ‘so you can read it’ 1 (L4)

(ii) • gas 1 (L3)

• liquid 1 (L4)

answers must be in the correct order [7]

Patrick Brannac www.SmashingScience.org Page 24 of 24

Extension task: Expanding your mind using the B7c Part 2 Cells and Micro-organisms topic

Use the information below to

create a 2 to 5 minute power

point presentation, or poster, to

explain something that really

interests you about this topic.

There will be a special extra

session in the last week or this

topic, or the first week of the

next topic when you can explain

to others your idea.

• Only students who are really

interested in becoming the best at

science need to try this, it is up to you if you want to give it a go. All students in any teaching group are

welcome to try though.

• Try to include colorful pictures,

especially ones you have drawn

yourself, they will make your

project much better than simply

copying and pasting from the

internet.

• Include lots of details.

• Explaining one thing clearly is

much better than just stating many

facts.

• Ask a science teacher for help if

you want more information about

how to do a great presentation, or

about the idea you are interested in. Mr Brannac especially is most interested in any question you

have that he cannot answer!

Extra information to help you get ideas is available here: Extension links, activities and simulations

For this interesting model of how genes work in bacteria click below:

https://phet.colorado.edu/en/simulation/legacy/gene-machine-lac-operon

Simple Wikipedia This uses simpler English words in its articles. It is still run by the same non-profit foundation as

Wikipedia, but you might find it easier to read

Homepage is: https://simple.wikipedia.org/wiki/Main_Page

For up to date news on science in general For interested but less able students: https://www.dogonews.com/category/science

For more able students: https://www.sciencenewsforstudents.org/

ONLY for the most interested and ablest students: For interested but less able students: https://www.dogonews.com/category/science

For more able students: https://www.sciencenewsforstudents.org/

BBC Bitesize - you may not be able to access all of the content in some parts of the world, but the

notes here about space are at the iGCSE level and are excellent:

https://www.bbc.com/bitesize/levels/z4kw2hv

Figure 1 A bacterial cell being infected by virus particles