Upper Fourth Revision
2014
This revision booklet provides students with notes and diagrams that
are to be used to support their revision for their summer exam 2014.
Topics covered that will be present on the exam paper are all included:
1. Seed Dispersal and Germination
2. Microbes
3. Teeth, Bones
4. Designing Investigations and Drawing Graph
Equipment needed for exam: Pen, sharp pencil, ruler, rubber and CALCULATOR
1
Topic 1 Seed Dispersal and Germination
Types of seed dispersal
Appreciate the importance of seed dispersal
 Avoid competition
 Increase chance of survival
Factors needed for Germination




The structure of a seed.




Cotyledon: Energy store for germination
Plumule: grows to become shoot
Radical: grows to form room
Testa: waterproof protection whilst seed
is dormant
2
Water (to activate ENZYMES)
Suitable temperature
Light
Oxygen
Topic 2 Micro-Organisms
Different types of microbes:
Appreciate experiments carried out by various scientists to disprove spontaneous
generation and support biogenesis.
3
•
Biogenesis: The theory claims living things could only arise from living things.
•
The opposite of this theory is the spontaneous generation theory, which states that living things arise from
nonliving things.
Redi’s Investigation:
•
Louis Pasteur’s Investigation:
•
Micro-organisms can be harmful and cause disease (PATHOGEN).
4
5
6
7
Natural Defences of the body
Use of Antibiotics
8
Use of Microbes in the Food and Drink Industry
Cheese Making




Fermenting Microbes are added to Pastuerised milk
Bacteria produce an acid which causes milk to coagulate into curds (soid) and Whey (liquid)
Curds serperated and treated with salt and flavouring
Place in moulds and left to mature
Making Yogurt


Bacteria culture lactobacillus is added to milk
Respiring bacteria produce lactic acid which causes milk to become sour
9
Brewing Industry
Beer and wine are alcoholic drinks made by fermentation reactions that use yeast to convert
sugars into ethanol. There are harmful effects and social problems because of ethanol in
drinks.
Sugar from plant material is converted into ethanol and carbon dioxide by fermentation. The enzymes
found in single-celled fungi - yeast - are the natural catalysts that can make this process happen. Here
are the word and balanced formulae equations:
sugar → ethanol + carbon dioxide
C6H12O6
2C2H5OH + 2CO2
10
Fermentation usually works best at around 37ºC. It is a slow process and several weeks or more are
usually needed to produce an acceptable alcoholic drink.
Beer
The sugars for beer-making come from boiling barley in water. Hops are added to adjust the flavour of
the beer.
Wine
The sugars for wine-making come from grape juice. Different varieties of grapes are used to produce
wines with different flavours. Wine contains a higher proportion of ethanol than beer does, because
grape juice contains a higher concentration of sugars than barley in water.
Methods of Food preservation
Method
Advantages
Disadvantages
Drying (e.g. freeze-drying, spraydrying, sun-drying)
Produces concentrated form of
food.
Can cause loss of some nutrients,
particularly thiamin & vitamin C.
Inhibits microbial growth &
autolytic enzymes.
Retains most nutrients.
Sulphur dioxide is sometimes
added to dried fruits to retain
vitamin C, but some individuals
are sensitive to this substance.
Smoking
Preserve partly by drying, partly
by incorporation of substances
from smoke.
Eating a lot of smoked foods has
been linked with some cancers in
some parts of the world.
Refrigeration
Slows microbial multiplication.
Slow loss of some nutrients with
time
Slows autolysis by enzymes
Freezing
Adding salt or sugar
Prevents microbial growth by low
temperature & unavailability of
water.
Blanching of vegetables prior to
freezing causes loss of some BGroup vitamins and vitamin C.
Generally good retention of
nutrients.
Unintended thawing can reduce
product quality.
Makes water unavailable for
microbial growth.
Increases salt and sugar content
of food.
Process does not destroy
nutrients.
High heat processing (e.g.
pasteurisation)
Inactivates autolytic enzymes
Loss of heat-sensitive nutrients.
Destroys microorganisms.
Canning (involves high heat
processing)
Destroys microorganisms &
autolytic enzymes.
11
Water-soluble nutrients can be
lost into liquid in can.
Topic 3 Teeth. Bones and Joints
Tooth Decay (Cavities)
Tooth decay can happen to anyone who has their own natural
teeth in their mouths—no matter what age!
Tooth decay is caused by bacteria that normally live in the mouth. These
bacteria cling to teeth and form a sticky, colourless film called dental plaque.
The bacteria in plaque live on sugars and produce decay-causing acids that
12
dissolve minerals on tooth surfaces. Tooth decay can also develop on the
exposed roots of the teeth if you have gum disease or receding gums (Receding
gums are gums that are pulling away from the teeth so that you can see the
roots.
Just as with children, fluoride is also important for adult teeth. Adding
fluoride to the water can reduce tooth decay for all ages. Fluoride can also be
added to mouth rinses and some toothpastes so it is wise to read labels
carefully and buy mouthwashes and toothpastes that have added fluoride.
Periodontal (Gum) Disease
A common cause of tooth loss after age 35 is periodontal disease. These are
infections of the gum and bone that hold the teeth in place. Gum diseases are
also caused by dental plaque. The bacteria in plaque causes gums to become
inflamed and bleed easily. If left untreated, the disease gets worse as pockets
of infection form between the teeth and gums. This causes receding gums and
loss of supporting bone. You may lose enough bone to cause your teeth to
become loose and fall out.
You can prevent gum disease by removing plaque. Thoroughly brush and floss
your teeth each day. Carefully check your mouth for early signs of disease such
as red, swollen or bleeding gums. See a dentist regularly—every 6 to 12 months
or immediately you see any signs of gum disease!
Tartar
If plaque stays on the teeth for a while it forms a hard layer called tarter.
Tartar has to be scraped off teeth by a dentist. Tartar build-up increases the
risk of dental cavities.
13
The Skeleton
14
15
16
Designing Investigations and Drawing Graph
Designing Investigations: C ORMS
C
Change
O
Organism
R
Repeats
M
Measurements
S
Same
What are you changing in your
investigation? Independent
variable
Are you using any organisms?
What ethical consideration do
you need to think of? Be nice to
them!
HOW many repeats are you
going to do? Appreciate that
repeats are necessary to ensure
the results we are obtaining are
reliable. You can calculate a
mean/average result if you carry
out repeats
What measurements are you
taking (time, length, mass etc)
make sure you consider what
units you are measuring in (i.e
cm or mm?). Dependant variable
What Variables are you keeping
the same in your investigation.
HOW and WHY?
Graph Skills









Always use a SHARP PENCIL
Use suitable SCALE to your graph (use over a quarter of your graph paper)
Your independent variable goes on your X AXIS
You dependant variable goes on your Y AXIS
Include UNITS used when labelling x/y axis
Plot points using sharp PENCIL not pen
Always provide suitable TITLE that incorporates both your x/y axis
When drawing line graph you can use ruler to draw line between points unless you are asked to
draw a line of best fit.
SPLATUK
17
18