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SCIENCE: YEAR 8 REVISION GUIDE—BIOLOGY SECTION

Science Department

This Revision Guide will be generated as the year progresses. Each topic is

covered with both ‘key fact’ sheets, a question sheet and a suggested revision

method.

The question sheet is designed to test your revision of the key facts and see if

the information has sunk in. Just answering the questions is not an effective

revision method.

You will be given a set of sheets for each topic as you cover them in lessons.

The revision sheets will help you to revise for the end of unit test and your

school entrance exams at the end of year 8.

You will be given one hard copy to store in this folder but replacements can

be found online in the Student and Parent Portal section of the school

website. You are allowed to print as many copies as you like for your own

use.

We hope that they will be useful.

Good Luck

The Science Department

Photosynthesis

The process by which plants make their own food (glucose) using light energy.

Word Equation =

Necessary Conditions = Light and Chlorophyll (Chemical used to convert light energy)

Leaves are main area in which photosynthesis happens. Why?

Proving Photosynthesis has occurred

Test for starch – Plants store glucose as starch because it is insoluble. If a plant has been

photosynthesising it will have produced starch.

Proving Light is necessary for Photosynthesis

Destarch plant by placing in dark for 24 hours. Expose half of a leaf to light and cover half with pa-

per. Test for starch 24 hours later and observe that area exposed to light turns black (starch present)

and area covered remains brown (starch not present).

Proving Carbon Dioxide is necessary for Photosynthesis

Destarch plant by placing in dark for 24 hours. Cover one leaf in plastic

bag containing soda-lime (absorbs Carbon Dioxide from atmosphere).

Test for starch after 24 hours. Brown colour should indicate lack of

photosynthesis.

Carbon Dioxide + Water Glucose + Oxygen

Test for starch:

1. Boil leaf in water to remove waxy cuticle

(to allow Iodine Solution to penetrate leaf)

2. Place leaf in boiling ethanol

(To dissolve chlorophyll so that stain shows up)

3. Drop Iodine Solution on leaf

(If turns from brown to black, starch is present).

Photosynthesis, Respiration and Balance Between the Two

Respiration

Respiration is the release of energy from glucose in living cells to enable life processes.

Word Equation =

Respiration occurs in every living cell

Sometimes called Aerobic Respiration which means it uses Oxygen from the air.

Proving that Carbon Dioxide is produced during Respiration

Testing carbon dioxide is present involves bubbling the gas through lime water. If it turns

milky white then carbon dioxide is present.

Proving that Water is produced during Respiration

Exhale onto cold surface to collect condensation. Add anhydrous copper sulphate to

liquid collected. If it turns from white blue water is present. Or use anhydrous cobalt chloride paper, if water is present turns from blue pink.

Balance Between the Two

Plants photosynthesise and respire.

Plants respire 24 hours a day (steadily because they do not move about)

Plants photosynthesise during the day or when light is present

Think of these different scenarios with an indicator (hydrogencarbonate) which shows the levels of CO2 .

What changes will occur?

Photosynthesis removes Carbon Dioxide from the surroundings.

Respiration adds Carbon Dioxide to the surroundings.

Respiration is NOT breathing. Think of it as burning glucose to release its energy.

(Remember burning needs oxygen to happen)

Glucose + Oxygen Carbon Dioxide + Water + Energy

Possible Revision Method—The Model Room

Draw a picture of a room below. Decide on a logical order for each memory trigger.

Then associate it with a fact to be learned on the process of photosynthesis.

Can be adapted, and you can walk around a room, to help you with your associations

(good for kinaesthetic learners)

For example:

Plant in photo—name of

process photosynthesis

Sunlight in picture—hits

plants and starts reaction

CO2 Clock—Carbon dioxide and water needed for photosynthesis.

Green in picture—

represents the chlorophyll.

Sofa—represents the oxygen and

glucose that is produced.

Possible Revision Method—Flow charts

Write down the steps of a process (procedure) as keywords or short phrases the show

the connections by using arrows.

A good technique to learn the method for testing for starch.

STEP 1:____________________

___________________________

___________________________

STEP 2:____________________

___________________________

___________________________

STEP 3:____________________

___________________________

___________________________

STEP 4:____________________

___________________________

___________________________

STEP 5:____________________

___________________________

___________________________

STEP 6:____________________

___________________________

___________________________

Questions

If you have revised the previous sheets effectively you should be able to answer the following

questions without difficulty.

1. Complete the following word equation.

2. Name two necessary conditions for photosynthesis to occur.

3. When testing for starch why do you boil the leaf in water first?

4. What colour change do you witness in Iodine Solution when starch is present?

5. How can you prove that light is necessary for Photosynthesis?

6. Why do you need to destarch a plant before testing to see if photosynthesis has occurred?

7. What substance removes Carbon Dioxide from the surroundings?

8. What fuel does respiration require in order to produce energy?

9. Where does respiration occur?

10. What gas is given off during respiration and how can you prove this?

11. What gas would be detected by a probe if placed near a plant at midnight? Why?

12. Why do levels of photosynthesis fluctuate during a 24 hour period?

13. Why do levels of respiration stay constant in plants during a 24 hour period?

Carbon Dioxide + ______________ _________________ + Oxygen

For extra info or help with revision use the following pages in the KS3 CGP The Study Guide

Photosynthesis pg. 19

Respiration pg. 4

Microscopes and Cells

The Microscope

Used to view things too

small for the naked eye.

Consists of lenses of

different magnification to

make things appear bigger in

the viewfinder.

Eye Piece x10 magnification

Objective Lenses x10, x20

and x40.

Magnification and Estimation

It is often necessary to estimate the size of an organism

from an image produced by a microscope.

You need to know the magnification of the image and

use a ruler to measure the image carefully.

Magnification x 500

Making a temporary slide

Specimens viewed down a microscope are usually placed and possibly stained (to

enable parts of the cell to be seen) on a glass slide to help isolate the specimen.

Revise the process of producing the slide

If an eye piece with magnification x20 is used and an objective lens with a magnification of x40 the total

magnification is x800 (20 x 40).

1. Place specimen on slide.

2. Place a drop of stain over

specimen.

3. Lower a cover slip over stain

and specimen edge first, using a

mounted needle.

Cells

The building blocks of all living organisms. They combine to form tissue which

combines to form organs.

Tissues are lots of cells with the same job.

Organs are tissues cooperating to perform a function.

Organ Systems are organs with cooperate to perform a life function.

Organelles and their functions.

Found in both Animal and Plant

Cell Membrane – Controls what enters and exits the cell

Cytoplasm – Where chemical reactions take place within the cell

Nucleus – Contains DNA which controls the functions taking place in the cell.

Mitochondria – the site of respiration in cells.

Found only in Plants

Cell Wall – Provides structure and support to the cell. Rigidity. Made of Cellulose.

Chloroplast – Contains Chlorophyll which helps photosynthesis take place.

Vacuole – Contains cell sap which helps maintain the shape of the cell.

Specialised Cells

Sperm Cell

Small cell which contains half

the genetic information in

the nucleus in its head. Has

a tail for swimming to make

its way to fertilise the ovum.

Root Hair Cell

Cell within the roots of a

plant with projections which

help increase surface area to

help absorb lots of water.

Red Blood Cell

Carries oxygen around the

body. Has a dimple to in-

crease the surface area for

oxygen to bind to the cell.

Possible Revision Method—Mind Map

Mind maps can be used to represent key information. When designing a mind map you

should look to connect ideas, using keywords and including diagrams to help you

visualise a concept.

CELLS

PLANT

ANIMAL

SPECIALISED

Questions



1. What do microscopes enable scientists to do?

2. Which part of the microscope is responsible for magnifying the image?

3. Estimate the length of the head of the creature in the picture on the first page.

4. Why do you sometimes need to stain specimens?

5. Why do you think a cover slip is placed over the specimen?

6. What is a cell?

7. What do cells combine to form?

8. Name three organelles not present in an animal cell?

9. What does the chloroplast do?

10. What is the nucleus for?

11. What is the job of the cell membrane?

12. What is the cell wall made from?

13. What is the main specialised feature of a sperm cell?

14. Why do root hair cells have small projections coming out of them?

15. Why does a red blood cell have a dimple?


The Microscope pg. 1

Cells & Cell Organisation pg. 2 & 3

Health, Nutrition and Digestion

Health

Microbes and Disease

Microorganisms come in different

varieties and sizes.

From largest to smallest

Protozoan

Bacteria

Virus

They cause disease in living

organisms e.g. Smallpox or influenza.

Pathogen = Disease causing microorganism

Host = Organism affected by pathogen

Protection form disease: Good levels of hygiene. Washing hands

Prevention of entry of microorganisms into body – Forming of scabs, wearing of plasters

White blood cells kill bacteria and viruses if unwanted in body Vaccination – prevention of infection

Nutrition

Good for Health Bad for health

Regular exercise Excessive eating

Balanced diet Poor diet

Vitamins Lack of exercise

Hydration Drug abuse

Excessive Alcohol intake

Part of diet Foods rich in substance Reason for needing it

Fats Meat, Dairy Source of energy, helps insulate body

Proteins Meat, Poultry, Nuts Cell repair and growth

Simple Carbohydrates Sweets, Chocolate Quick energy release

Complex Carbohydrates Bread, Pasta, Rice Slow energy release

Vitamins Vegetables and Fruit Improved cell function

Fibre Wholemeal bread, Fruit Aid food moving through digestive system.

Food Tests:

Starch: Adding Iodine solution to food. If starch is

present the colour change is from

red/brown blue/black

Sugar: Add Benedicts Reagent. If sugar is present a

Brick Red precipitate is formed in the reagent. Traces

of sugar cause green/yellow/orange colour.

Fats: Add one or two droplets of ethanol. Add this

ethanol to water. If a white suspension forms fats are present.

Digestion

The mechanical and chemical breakdown of large food molecules into smaller molecules which

can be easily absorbed into the blood.

Not to be confused with:

Ingestion – consumption of a substance

Egestion – removal of undigested food or faeces from gut (make sure to know the difference

between egestion and excretion)

Enzymes:

Produced in the various glands including the pancreas. They are mostly secreted into

the duodenum to be mixed with food and to chemically breakdown the food.

Different enzymes are produced for different substances (lock and key model).

e.g. Amylase in saliva is used to breakdown starches.

Can be denatured (stopped from working) if the pH or temperature is too high.

Benedicts Reagent

Possible Revision Method—Mind Map

Mind maps can be used to represent key information. When designing a mind map you

should look to connect ideas, using keywords and including diagrams to help you

visualise a concept.

Create a mind map on the different type of nutrients include food tests

Possible Revision Method—Flow charts

Write down the steps of a process (procedure) as keywords or short phrases the show

the connections by using arrows.

Use a blank piece of paper.

Create a flow chart on the digestive process

Attempt below.

Questions



1. When does alcohol consumption become dangerous?

2. Name one factor that aids a healthy lifestyle.

3. Name three types of microorganism.

4. Which is the smallest in size?

5. Name two forms of defence against infection?

6. What is the difference between pathogen and host?

7. What is the role of fat in our diet?

8. Name a foodstuff that contains high levels of complex carbohydrates?

9. What is the difference between complex and simple carbohydrates?

10. What are proteins used for in our diet?

11. What is the test for starch in foods? Describe colour change.

12. What is the test for sugars in our diet? Describe colour change.

13. What is digestion?

14. Where is the first site of mechanical breakdown of food in the digestion process?

15. What is mixed with food in the duodenum?

16. Name one source of enzymes in the human body.

17. What can denature enzymes and stop them from working effectively?


Nutrition pg. 6 & 7

Digestion pg. 8 & 9

Health and Drugs pg. 17

Sexual Reproduction and Growth: Plants & Humans

Plants

Flowers are produced by a plant for reproduc-

tion

Petals – Attract insects for pollination

Sepal – protected flower when a bud.

Stamen – Male part of flower

Anther – produces pollen cells

Pollen – Male Gamete

Stigma – a female part that receives

pollen

Ovule – female gamete

Pollination and Fertilisation in plants

Pollination is when pollen travels from anther to

stigma.

Wind pollinated plants are different to Insect

pollinated plants (less colourful etc.)

Insect vs.

Pollinated

Fertilisation is when pollen grows a pollen tube,

and the male gamete from inside the pollen enters

the ovary and fuses with the ovule. Fertilisation results in a fruit being produced which

contains seeds.

Wind

Pollinated

Seeds

Seeds contain an embryo and a food store protected by a seed coat.

Seeds can be dispersed in a number of ways.

Seeds need to be dispersed to find resources not being used by the

parent plant e.g. sunlight, nitrates etc.

Seed Dispersal

Methods include:

Wind Dispersal

Animal Dispersal (eating & carrying)

Water Dispersal

Explosion (self)

Germination

Seeds need specific conditions to

germinate and begin to grow into a plant.

Water

Oxygen

Warmth

Humans

Reproductive Organs

The Menstrual Cycle

Process by which the female reproductive organ readies

itself for fertilization of the ova. It may also result in bleed-

ing from the uterus which is the lining of the uterus and

unfertilized ova being ejected from the body. This process

is known as a period and occurs roughly once a month.

The Gametes

A Gamete is a reproductive cell. It only contains

half of the genetic information (referred to as a

haploid cell).

Male Gametes are called Sperm – Millions produced, very small cells.

Female Gametes are called Ova (Eggs) – One or two produced each month, very

large cells.

Both are examples of specialised cells.

Ovary – Where the ova are produced

Fallopian Tubes – Where fertilization occurs

Uterus – Where the fertilized ova embeds and the foe-

tus develops. Where Placenta develops too.

Cervix – Area between Vagina and Uterus

Vagina – Where Penis is inserted during intercourse

Placenta – The organ which develops within the womb

to help allow nutrients and waste to pass between

mother and foetus.

Testes – Where the sperm are produced

Scrotum – Area which contains testes and helps to

regulate their temperature.

Urethra – Tube down which semen and urine pass

Vas Deferens – Tube along which sperm travel

from testes to Seminal Vesicle

Seminal Vesicle – Produces semen to which sperm

cells are added before ejaculation. Semen is needed

to nourish the sperm cells and give them a medium to

survive in.

Ejaculation – The ejection of semen from the penis.

FEMALE REPRODUCTIVE SYSTEM MALE REPRODUCTIVE SYSTEM

Reproduction Terms to Remember

Fertilisation – The fusing of the male and female gamete.

Gamete – The reproductive cell containing half of the genetic information of the parent.

Zygote – The name for the fertilised ovum

Embryo – The name given to the organism when it is between zygote and foetus stage (9 weeks).

Foetus – Developing organism after the embryo stage (from 9 weeks after implantation to birth).

Gestation Period – Period between fertilization and birth (9 months in humans).

The Placenta

An organ which develops as the foetus develops.

Connects the foetus to the wall of the uterus

Helps nutrients from mother’s blood transfer to the foetus for growth.

Helps remove waste products from the foetus and transfer to mother’s blood for excretion.

Helps Oxygen transfer from mother’s blood to foetus.

Helps remove Carbon Dioxide from foetus and transfer to mother’s blood for

excretion.

Can transfer disease and harmful substances from mother to foetus e.g. HIV or

alcohol.

Questions



1. Why do plants produce flowers?

2. What is the function of the anthers?

3. What is Pollination?

4. Name four methods by which seeds are dispersed.

5. Is the fruit produced before or after fertilization?

6. What three conditions are needed for germination?

7. What are the male and female gametes called in plants?

8. Where are the ova produced in a human?

9. Where does fertilization occur in humans?

10. What are the male and female gametes called in humans?

11. What is the main difference between the two gametes?

12. Why does the human body produce semen for the sperm cells to be mixed with?

13. What is a zygote?

14. What is a foetus?

15. What is the job of the placenta?

16. Why shouldn’t pregnant women drink alcohol?


Human Reproductive System pg. 15

Having a Baby pg. 16

Plant Reproduction pg. 20

Fertilisation and Seed Formation pg. 21

Possible Revision Method—Review Cards (Flash Cards)

Review Cards pose questions with long answers or facts on the back.

Flash Cards can be used to learn key words or definitions

Create flash cards—questions on human reproduction and plant reproduction key words

Using templates provided earlier.

Interdependence and Variation

Variation and Classification

Continuous Variation

Variation with many different possibilities e.g. height or weight

Discontinuous Variation

Variation with a few small possible groups e.g. eye colour or blood group.

Vertebrate – has a backbone

Mammals – have fur, produce milk, and give birth to live young

Birds – have feathers, produce eggs, and can fly

Fish – have scales, can breathe underwater, produce eggs

Reptiles – Cold blooded, produce eggs, scaly skin

Amphibians – produce eggs, porous skin, live in and out of water

Invertebrate – has no backbone

Insects have 3 body parts and 6 legs

Arachnids (spiders) have 2 body parts and 8 legs

Adaptation

Animals have evolved and become adapted to their environments. See example below

Clear eyelid that closes in

sandstorm.

Fur to keep warm at night in

extreme cold.

Wide feet to distribute weight on

sand.

Large fat stores in humps

for long periods without

food or water.

http://www.google.co.uk/imgres?q=frog+clipart&num=10&hl=en&biw=1440&bih=782&tbm=isch&tbnid=bye5CsJet2qiGM:&imgrefurl=http://www.frog-life-cycle.com/10-frog-clip-art.html&docid=Cxdiu97iz3p5NM&imgurl=http://www.frog-life-cycle.com/graphics/frog10.jpg&w=500&h=41

Feeding Relationships

Food Chains

Shows a flow of energy through various organisms.

ALWAYS start with a producer (plant). Only organisms

that can ‘produce’ usable energy for the rest of the food

chain.

Food Webs

Give a better indication of all of the food chains in a par-

ticular habitat or ecosystem.

Help to show which organisms would be affected should

another die out or increase in numbers.

Keys and Identification

Branching or Listing keys can be used to help identify organisms. Read them carefully.

e.g. Should all herbivorous insects be

killed by pesticide in this food web then

all predaceous insects and spiders

would begin to die out.

Possible Revision Method—Summary Cards

Summary Cards contain the most important details of a topic. You should try to create

a summary of the information, including key words, concepts and diagrams.

Su

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nim

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ingd

om

Mam

mals:

Bird

s: Fish

:

Rep

tiles: Am

phib

ians:

Insects:

Ara

chnid

s:

Questions



1. Give an example of discontinuous variation

2. What characteristics are commonplace in mammals?

3. What characteristics are commonplace in reptiles?

4. What is the difference between and insect and an arachnid?

5. Name an organism and describe how it is adapted to its environment

6. Name two adaptations of a giraffe?

7. Name two adaptations of humans?

8. What is a food chain?

9. What do the arrows in a food chain represent?

10. Write a food chain that begins with grass as the producer

11. What is a producer?

12. What would happen to the number of mice if all rabbits and squirrels were killed in the

food web on the previous page?

13. Draw an identification key for the following characters from the Simpsons. Marge, Homer,

Bart, Maggie, Lisa, Mr Burns, Smithers, Selma, Patty, Grandpa Abe, Moe, Lenny and Karl.


Dependence on Other Organisms pg. 23

Food Chains and Food Webs pg. 24

Variation pg. 27

Breathing & Heart, Blood and Circulation

Breathing

Breathing is the process by which the body gets Oxygen into the lungs (inhalation/ventilation) and

Carbon Dioxide and Water Vapour out of the lungs (Exhalation)

Breathing is NOT Respiration

Model of a Thorax

Oxygen levels decrease in the alveoli because

oxygen is absorbed into the blood.

Carbon Dioxide levels increase in the alveoli as

carbon dioxide is removed from the blood (as waste

product).

Gas Exchange

Occurs in the alveoli

Alveoli are specially adapted for the job.

Diffusion

The movement of particles from an area of high concentration to an area of low concentration.

Gas

% in Air

when

inhaled

% in Air

when

exhaled

Oxygen 21 16

Carbon Dioxide 0.03 1

Nitrogen 78 78

Alveoli Adaptation How and Why?

Large Surface Area ‘Bunch of Grapes’ shape (allows more oxygen to enter the

blood)

Thin walls One cell thick (allows gases to diffuse easily)

Moist Allows gases to diffuse better (moisture dissolves gases well)

Rich Blood Supply Allows gases to diffuse faster into the bloodstream

Trachea

Bronchi

Bronchioles

Alveoli

Diaphragm

Ribs

Smoking Smoking seriously damages health. It affects your lungs, hindering breathing as well as potentially

causing cancer (a carcinogen, tar, can cause this). It reduces surface area in lungs by depositing tar in the alveoli.

It damages cilia in the trachea which help prevent dirt entering the lung.

Heart, Blood and Circulation

The Heart is necessary to pump blood to the body (to deliver oxygen) and to the lungs

(to collect oxygen.

Blood Vessels

There are three types of blood vessel. They do

different jobs.

1. Arteries – Carry blood away from the heart

under high pressure.

2. Veins – Carry blood back to the heart under

low pressure. They have valves to help blood

get back to the heart when fighting gravity.

3. Capillaries – Allow Oxygen to leave the blood and Carbon Dioxide enter the blood. They are

one cell thick and slow blood down to allow gas

exchange.

Blood

Blood consists of four different components, each having their own job.

1. Red Blood Cells – Carry Oxygen around the body.

2. White Blood Cells – Help to fight infection in the body.

3. Platelets – Help to form scabs and heal open wounds in the skin.

4. Plasma – The majority of blood. The medium holding glucose,

Carbon Dioxide and other components.

Effect of Exercise on Heart Rate

When you exercise your muscles need more oxygen to work (respire).

Oxygen carried in the blood needs to be pumped more regularly to muscles.

The heart beats faster to get blood around the body quicker.

This can be observed by checking someone’s pulse.

The Heart Chambers and

Valve names will not be

examine at CE

Red Blood Cells have the ‘dimple’

shape to help increase surface area.

Questions



1. How is breathing different to respiration?

2. What is the process of getting air into one’s lungs called?

3. What is the name of the first airway that air travels into?

4. What is the name given to the structures of the lung in which gas exchange with the blood oc-

curs?

5. What is the difference in composition of air when it is inhaled as opposed to when it is exhaled?

6. How are the alveoli adapted for their purpose?

7. Where does the right side of the heart pump its blood to?

8. Which vessels carry blood away from the heart?

9. What is the job of the capillaries?

10. What adaptation do Veins have to help fight the effects of gravity and low pressure?

11. What are the four components of blood called?

12. What is the job of White Blood Cells?

13. What advantage is it for Red Blood Cells to have the doughnut/dimple shape?

14. How can you prove that Heart Rate increases as a person exercises?

15. Why does heart rate increase when a person exercises?


Gas Exchange pg. 11

Breathing pg. 12

Exercise, Asthma and Smoking pg. 13

Skeleton & Movement

Skeleton

Skeleton important for:

Protection Support Movement

Joints

Place where two or more bones meet.

Joints held together by ligaments

Types of joint:

Hinge e.g. Elbow

Ball & Socket e.g. Shoulder

Gliding e.g. Fingers

Fixed e.g. Cranium

Movement

Movement is brought about by muscles.

Muscles are attached to bones with tendons (figure 6.)and they pull on the bones to create

movement.

Muscles work in antagonistic pairs. This is because muscles only pull and don’t push.

Muscles contract to pull and relax to allow other muscles to pull.

Questions



1. Name the three main jobs of the skeleton

2. What is a place where two bones meet referred to as?

3. What is the scientific name for the skull?

4. What is the scientific name for the spine?

5. What is the name given to the bones in your fingers and toes?

6. What is the name of the tissue which attaches muscle to bone?

7. What is the name of the tissue which holds bone to bone?

8. Do muscles ever push?

9. Describe how you can bend your arm towards your face and then away again.

Use names of muscles to help.

10. What is an antagonistic pair?

11. Why do we have antagonistic muscle pairs?


The Skeleton and Muscles pg. 9

How Muscles Work pg. 10

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