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Past Papers
Monday, December 12, 2016

6:15 PM

http://qualifications
...
com/content/dam/pdf/GCSE/Science/2011/Exam%
20materials/5BI1F_01_que_20121105
...
pearson
...
pdf
http://qualifications
...
com/content/dam/pdf/GCSE/Science/2011/Exam%
20materials/5BI2F_01_que_20121105
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• Artificial lighting when sun goes down to increase hours of photosynthesis
...
are at optimum temperature
...

Fertilizers:
Can be added to soil to replace those used up by previous crop, or those missing
...
Manure must be broken down in decomposition by fungi and bacteria to release
minerals such as magnesium, nitrates and phosphates
...

Pest control:
Insect pests consume leaves, reducing phs, weed pests compete with crop for light, minerals space
and water
...

Pesticide chemicals include insecticides, herbicides (kills weeds), and fungicides
...
The pesticide may affect organisms in the food chain, ie "non specific" leading to
disruption of the food chain for example bees
...
Biological control of the pests; involves introducing a predator to
the pest
...
Biological control can have a longer lasting effect than
chemicals, and less harmful to other organisms
...

• Fish move less so more of their food is used for growth
...

• Intraspecific (within the same species) predation and competition for food is reduced by
keeping young, female and males separate
...
Bacteria would decompose/feed on the food pellets,
overgrow and respire all the dissolved oxygen
...
Wrasse can be
added, which eat lice on farmed fish (biological control) or chemical pesticides added
...
Ensure faeces and waste food is removed from underneath cage/bottom of
tank
...

• Selective breeding of fish which are less aggressive and faster growing
...
Oxygen can be obtained by aerating
the water
...
However, it might be toxic to other
Biology Page 2

intraspecific (same
species)/interspecif
ic (different
species) predation

predators using nets/tanks etc
...
Interspecific predation can also be prevented by
allocating one species per tank
...
A
suspended net (over the top) protects the fish from aerial predators
...
Antibiotics are used
...
Also, there is a chance that the pathogen might
mutate and a new antibiotic will be needed
...
Large buildups of waste can
cause eutrophication
...

breeding

Biology Page 3

Features of the 5 kingdoms and Viruses
Saturday, December 17, 2016

3:11 PM

Plants:
Multicellular, have chloroplasts, can photosynthesize to make organic molecules such as proteins,
lipids, carbs and DNA
...


Animals:
Multicellular, do not have chloroplasts, so they must consume organic molecules made by producers
such as plants and algae
...


Fungi:
Some are multicellular, others are single (eg yeast)
...
They have cell walls made of chitin, and store carbs and
glycogen
...


Biology Page 4

Protoctists:
Single celled
...
Include algae and seaweeds
...
They do not have a nucleus and their chromosone is circular DNA
...

Many bacteria act as decomposers
...
They are smaller than bacteria, and can only reproduce inside living
cells, so are parasitic
...


Outside wall is protein coat
...

1
...
They're carried in the blood plasma
to other parts of the body, but only affect particular cell, (target cells) in particular places
...

2
...
They travel quite slowly and tent to have relatively
long-lasting effects
...

Hormone Source
ADH

Role

Effects

Pituitary gland Controls water content
(In the brain)

Increases the permeability of the kidney
tubules to water
...

muscles and blood sugar level
...


Testoster Testes
one

Main male sex hormone

Promotes male secondary sexual
characteristics e
...
facial hair
...


Oestroge Ovaries
n

Main female sex hormone

Controls the menstrual cycle and
promotes female secondary sexual
characteristics, e
...
widening of the hips
...

1
...
Very fast message
...
Act for a very short time
...
Act on a very precise area
...
Hormones:
a
...

b
...

c
...

3
...

4
...

5
...

6
...

7
...
(hypes you up)
8
...


Biology Page 7

Homeostasis
15 December 2016

11:22

Homeostasis - it's all about balance
1
...
This
involves balancing inputs (stuff that goes into your body) and outputs (stuff leaving)
...

2
...

3
...

Homeostasis is the maintenance of a constant internal environment
...

1
...
Through the skin as sweat
b
...
Via the kidneys in urine
...
The balance between sweat and urine can depend on what you are doing, or what the
weather is like
...
On a hot day, or when you are exercising, you sweat a lot
...
You will also lose more water
through your breath when you exercise because you breathe faster
...
On a cold day, or when you're not exercising, you don’t sweat much
...


Body temperature is kept at about 37C
1
...
The enzymes in the human body
work best at about 37C - and so this is the temperature your body tries to maintain
...
A part of the brain acts as your own personal thermostat
...

3
...


Biology Page 8

Homeostasis (Cont
...

1
...
Lots of sweat is produced - when it evaporates it transfers heat from you to the
environment, cooling you down
...
Blood vessels close to the surface of the skin widen - this is called vasodilation
...

c
...

2
...
Very little sweat is produced
...
Blood vessels near the surface constrict (vasoconstriction) so that less heat can be
transferred from the blood to the surroundings
...
You shiver, and the movement generates heat in the muscles
...

d
...

Smaller organisms can cool down quicker
...
Smaller organisms have bigger surface area to volume ratios
...
Organisms with bigger surface area to volume ratios can gain (or lose) heat faster because
there is more area for heat to transfer across
...
This allows small organisms to lose body heat more easily in hot climates and reduces the
chance of them overheating
...

4
...

5
...


Biology Page 9

Responses in plants
15 December 2016

11:41

Plants need to respond to stimuli too
...
Plants, like animals, increase their chances of survival by responding to changes in their
environment, e
...

a
...

b
...

c
...

2
...
g
...
White clover is a plant that can produce substances that are toxic to cattle
...

3
...
e
...
some plants respond to extreme cold by producing
their own form of antifreeze
...
Carrots produce antifreeze proteins at low temperatures - the proteins bind to ice
crystals and lower the temperature that water freezes at, stopping more ice crystals
from growing
...

1
...
They move
through the plant in solution (dissolved in water)
...
Auxin is produced in the tips and diffuses backwards to stimulate the cell elongation process
which occurs in the cells just behind the tips
...
Auxin promotes growth in the shoot, but actually inhibits growth in the root
...
Auxins are involved in the growth responses of plants to light (phototropism) and gravity
(geotropism)
...

1
...
When a shoot tip is exposed to light, it accumulates more auxin on the side that’s in the shade
than the side that’s in the light
...
This makes the cells grow (elongate) faster on the shaded side, so the shoot bends towards the
light
...
Shoots are negatively geotropic
...
When a shoot is growing sideways, gravity produces an unequal distribution of auxin in the tip,
with more auxin on the lower side
...
This causes the lower side to grow faster, bending the shoot upwards
...
Roots are positively geotropic
...
A root growing sideways will also have more auxin on its lower side
...
But in a root the extra auxin inhibits growth
...


Biology Page 10

DNA, Genes and Chromosomes
15 December 2016

21:04

Human body cells are diploid - this means that they have two copies of each chromosome, arranged
in pairs
...

Genes are chemical instructions
...
DNA is a long list of instructions on how to put an organism together and make it work
...
Each separate gene in a DNA molecule is a chemical instruction that goes for a particular
protein
...
Proteins are important because they control most processes in the body
...

4
...

5
...
The different versions of the same gene are called
alleles
...

1
...
The two strands are held together by chemicals called bases
...

a
...
Cytosine (C)
c
...
Thymine (T)
3
...
This is called
complementary base pairing
...
DNA is a type of nucleic acid
...
You can only see them when using a powerful
microscope
...
Here are some of the organelles found in a typical animal cell
...
Nucleus: an organelle which contains the genetic material that controls the cell's
activities
...

b
...

c
...
It
contains enzymes (see enzyme page) which control these reactions
...
Plant cells usually have all the organelles that animal cells have, plus a few extra:
a
...
Chrloplasts contain a green substance called chlorophyll, which is used in
photosynthesis
...
Cell wall: a rigid structure made of cellulose, which surrounded the cell membrane
...

c
...
It
helps to support the cell
...
Most cells don’t look exactly like the ones shown above
...

2
...

Similar cells are organised into tissues
1
...

2
...

3
...

Tissues are organised into organs
1
...

2
...

Organs make up organ systems
1
...
Each system does a different job
...
For example, in mammals, the digestive system is made up of organs including the stomach,
intestines, pancreas and liver
...

Respiratory system
...

Excretory system
...

Nervous system
...

Reproduction system
...
Plants are multicellular
...
They have chloroplasts which means they can photosynthesise
...
Their cells have cell walls, which are made of cellulose
...
Plants store carbohydrates as sucrose or starch
...


Animals

1
...

2
...

3
...

4
...
This means they can
respond rapidly to changes in their environment
...
They can usually move around from one place to another
...
They often store carbohydrates in the form of glycogen
...
Some are single-celled
...
Others have a body called a mycelium, which is made up of hyphae
...

3
...

4
...

5
...

6
...


Yeast - this is a
single celled
fungus
...


Biology Page 14

Nutrition
17 December 2016

18:26

Nutrition
Carbohydrate molecules are made up of small sub-units called sugars
...
Examples include glucose
C6H12O6
...
Carbs provide the main source of energy for respiration in living
organisms
...
Like carbohydrates, fats are also a source of
energy
...

Proteins are made up of long chains of amino acids linked together
...
Examples include glycine, alanine, valine and cysteine
...
It takes part in the many chemical reactions happening
inside the cytoplasm
...

Carbohydrates

Provides quick energy
...
They make up 5% of our body
mass
...
25% of our diet should be
fat
...


Oils, dairy products, nuts and
fish

Protein

Builds and repairs muscle
...
Makes up 18% of the mass
in our body
...
Fills you up and keeps you
'regular'

Fresh fruit, vegetables and
wholegrain cereals

Minerals

Calcium – Making teeth and bones

Found in dairy products, fish,
bread, vegetables, red meat
e
...


Phosphorus – making teeth and bones; part of
many chemicals such as DNA
Magnesium – Making bones, found inside cells
Iron – Part of haemoglobin in red blood cells,
helps carry oxygen
Water

Maintains fluid levels

The tap

Vitamin Use

Effect of Deficiency

Where you get it

A

Making a chemical in the retina;
also protects the surface of the
eye

Night blindness, damaged
cornea

Fish liver oils, liver,
butter, margarine,
carrots

B1

Helps with cell respiration

Beri-Beri

Yeast extract, cereals

B2

Helps with cell respiration

Poor growth, dry skin

Green vegetables, eggs,
fish

B3

Helps with cell respiration

Pellagra (dry red skin, poor
growth, and digestive

Liver, meat, fish

Biology Page 15

growth, and digestive
disorders)
C

Sticks together cells lining
surfaces such as the mouth

Scurvy

Fresh fruit and
vegetables

D

Helps bones absorb calcium and
phosphate

Rickets, poor teeth

Fish liver oils; also made
in skin in sunlight

Biology Page 16

Food Tests
17 December 2016

18:52

Food Tests
Test for Starch
Dilute iodine solution reacts with starch, forming a very dark blue colour
...

Test for Glucose

Glucose is called a reducing sugar
...


Biology Page 17

The test for glucose is called the Benedict’s test
...
Add enough to turn the mixture blue
...
The clear blue solution will gradually change colour,
forming a cloudy orange or brick red precipitate of copper(I) oxide
...

Test for Proteins
The test for protein is called the Biuret test
...
Then, dilute potassium hydroxide solution is added to the mixture
...
A mauve colour develops
...
The test is done by dissolving a lipid
in ethanol
...
A white cloudy layer forms on top of the
water
...


Biology Page 18

Enzymes
17 December 2016

19:37

Enzymes
Enzymes are biological catalysts - catalysts are substances that increase the rate of chemical
reactions without being used up
...
The place where these substrate molecules fit is called the
active site
...
The slots where substrate molecules
fit into is the active site
...


This enzyme is only capable to working on this particular substrate
...

Lock and Key Theory
Let's use some analogies
...
Only one specific key can open one specific lock
...
Now if the lock changed shape, it wouldn’t be able to fit into the key anymore
...
Key Point: Low temperatures DO
NOT denature enzymes
...

Temperature and enzymes

As the temperature increases, so does the rate of reaction
...

The graph shows the typical change in an enzyme's activity with increasing temperature
...
Then,
as the temperature continues to rise, the rate of reaction falls rapidly, as heat energy denatures the
enzyme
...
Different enzymes work best at different pH values
...
For example, intestinal enzymes
have an optimum pH of about 7
...
Enzymes in the stomach have an optimum pH of about 2
...
Other
enzymes are produced by specialised cells and released from them; the digestive enzymes are like
this
...

Different enzymes catalyse different digestion reactions
...
Protease refers to all the
enzymes that break down proteins
...

Enzyme What it Does

Where Produced

amylase salivary glands, pancreas,
small intestine

Amylase catalyses the breakdown of starch into sugars in the
mouth and small intestine
...


lipase

Lipases catalyse the breakdown of fats and oils into fatty
acids and glycerol in the small intestine
...
It converts
large insoluble molecules into small soluble molecules, which can be absorbed into the blood
...
Food is taken into the mouth to our body
...
A slippery liquid called saliva helps moisten the food and contains the enzyme amylase,
which starts the breakdown of starch
...
The food is also chewed, cutting the food down into smaller
pieces to increase surface area, so enzymes can act on the food more quickly
...

In the Stomach

The lump of food, mixed with saliva, then passes along the oesophagus, to the stomach
...
The stomach
wall secretes hydrochloric acid, so the stomach contents are strongly acidic
...
The protease enzyme that is made in the stomach, called pepsin, has to be able to work
in these acidic conditions, and has an optimum pH of 2
...
When this
relaxes, it releases the food into the first part of the small intestine, called the duodenum
...
The wall of the
intestine contains two layers of muscles
...
This is
the circular muscle layer
...
Together, the two layers push food along
...
Waves of muscle contraction like this is what helps push food along
...
It means that the movement of food in the gut doesn’t depend on gravity – we can eat
while standing on our heads!

Several digestive enzymes are added to the food in the duodenum
...
As well as this, the liver makes a digestive juice called bile,
which is stored in the gall bladder
...
Its function is to turn any large
lipid globules in the food into an emulsion of tiny droplets
...
Bile and pancreatic juice are both alkaline
...

As food continues along the intestine, more enzymes are added, until the parts of the food that can
be digested have been fully broken down into soluble end products, which can be absorbed
...

The Ileum

Biology Page 23

The ileum is highly adapted to absorb digested food
...
The length of the intestine helps provide a large surface area, and this is aided by the
folds in its lining, but the greatest increase in area is due to the tiny projections from the lining,
known as the villi
...
This provides a massive area in contact with the digested food
...

Each villus has a wall made of single cells and a network of blood capillaries
...

The lacteal is part of the body’s lymphatic system, which transports liquid called lymph
...
Tiny food molecules enter the blood stream by a
process known as diffusion (high concentration to low concentration)
...

The blood vessels from the ileum join up to form a large blood vessel called the hepatic portal vein,
which leads to the liver
...

The digested food molecules are distributed around the body by the bloodstream
...

This is called assimilation
...
Excretion is the removal of the
waste products of cells of the body
...
The remaining water is absorbed by the first
part of the intestine known as the colon, leaving a semi-solid waste material called faeces
...


Biology Page 25

Measuring The Energy Content of Food
17 December 2016

19:41

Measuring Energy Content in Food – Such as a Peanut
If a sample of food will burn well in air, you can measure its energy content using a simplified version
of the food calorimeter
...

2
...

4
...

Measure temperature of water
...

Hold the lit peanut underneath boiling tube
...

5
...

Some facts:
-4
...
2)/mass of
food (g)

Biology Page 26

Structure of the Body
17 December 2016

19:48

Structure
The lungs are located at the chest, or the thorax
...
They aren’t labeled on the diagram but it’s those bumps on the outside of the
lungs
...
The
diaphragm separates the contents of the thorax from the abdomen
...


The trachea is where air enters when we breathe in
...
They divide into even smaller tubes called bronchioles
...
It is here that gas exchange takes place
...
These help keep the airways open when we
breathe in
...
The inside of the
thorax is separated from the lungs by two thin, moist membranes called pleural layers
...
Between them is a space called the pleural cavity, which is filled
with pleural fluid
...
They secrete a
liquid known as mucus, which traps particles of dirt or bacteria that we breathe in
...


Biology Page 27

Ventilation – The Gruesome Details

Ventilation requires a difference in air pressure
...
The external ones contract, pulling the ribs up
...
These movements increase the
volume of the thorax
...
This causes air to enter the lungs
...
The external intercostal muscles relax, and the internal
intercostal muscles contract, pulling the ribs down and in
...
This causes volume of thorax to decrease, making the
pressure inside the thorax greater than outside
...


Biology Page 28

The Alveoli
17 December 2016

19:57

The Alveoli

Oxygen enters the blood through the alveoli – bumpy air sacs
...
It also provides a concentration gradient for
diffusion as oxygen will move from higher to lower concentration
...

Gas

Atmospheric Air (%) Exhaled Air (%)

Nitrogen

78

79

Oxygen

21

16

Carbon Dioxide 0
...
The blood has come from respiring tissues of the body, where it has given up some of the
oxygen to the cells, and gained carbon dioxide
...
It is thin so
oxygen can easily diffuse to capillaries and carbon dioxide, from the capillaries
...
At the same time,
there is more carbon dioxide in blood than there is in the air so it diffuses out of the blood and into
the alveolus
...
When air is exhaled, lungs get drier as water
escapes
...
Finally, moisture is
useful as it speeds diffusion
...
They are also a major
contributing factor to other problems such as coronary heart diseases, stomach and duodenum
ulcers
...

Tar in cigarettes destroys the cilia in airways
...
This is made worse by the fact that the smoke irritates
the lining of airways, stimulating cells to secrete more mucus
...

Emphysema is another lung disease
...
This greatly reduces the surface area for gas exchange
...
There is no cure
...
Smoking
increases the chance of this; however, giving up the habit can soon improve your chances of survival
...
It also
contains at least 17 chemicals that are known to cause cancer
...


Apart from tar, carbon monoxide is another harmful and poisonous gas found in cigarettes
...

When combined with carbon monoxide, it forms carboxyhaemoglobin
...
Carbon monoxide from smoking is a major cause of heart
disease
...
Nicotine is actually harmless, and the
brain secretes it to ease stress
...
Gradually, the nicotine dose reduces until the smoker is weaned off the
habit
...


Biology Page 31

The Circulatory System
17 December 2016

20:02

Blood is pumped around the body
...
Hormones, antibodies and many other substances are also transported by blood
...

Unicellular organisms don’t need this function as they can obtain oxygen from the surface
membrane of the cell
...

Ratio of supply to demand = surface area/volume

One of the main functions of a circulatory system in animals is to transport oxygen
...
It is then pumped to other parts of the body where the
oxygen can be used
...

 Double Circulatory Systems: Blood is pumped from the heart to the gas exchange organ, back to the
heart and then to the rest of the body
...
You not included
...

 Systemic Circulation: Blood is circulated through other parts of the body
...
The blood travels more quickly to organs
...

 Blood vessels – These carry blood around the body; arteries carry blood away from the heart and
towards other organs
...

 Blood – The transport medium
...
In
girls, it comes out automatically every month
...
It can do this because the wall of the heart is made from cardiac
muscle
...


2
...

4
...


Blood enters the atria
...

The walls of the atria contract, raising the pressure of the blood
...

When the ventricles are full, the contract, increasing blood pressure in the two chambers and closing
the valves
...
The pulmonary artery carries blood to the lungs
...

As the ventricles empty, the higher pressure in the aorta and pulmonary artery closes the valves
...

Adaptations of the Heart
When a chamber of the heart is contracting, it is systole
...
The structure
of the heart is adapted to its functions in several ways:

 The septum divides the right and left side of the heart
...
The right ventricle pumps blood only to the
lungs, whereas, the left ventricle pumps blood to other parts of the body
...

 Valves prevent backflow of blood
...
They can be stretched to receive blood and can contract to push
blood through the tricuspid and mitral valves
...

 It also has its own blood supply
...
Blood is returned to the right atrium via the
coronary veins
...
The pulmonary artery carries blood to the lungs where it gets oxygenated
...

2
...

3
...


Biology Page 35

Blood Vessels and Composition Of Blood
17 December 2016

20:06

Blood Vessels
Blood
vessel

Function

Adaptations

Artery

carry oxygenated blood away
from heart at high pressure

Thick, elastic, muscular walls to withstand pressure
and to exert force (pulse)
...


Capillary

allow exchange of materials
between blood and tissues

Thin permeable walls

Vein

return low pressure
deoxygenated blood to heart

Large diameter (lumen) to offer least flow resistance
...


Composition of Blood
Compone Description
nt

Function

Plasma

Straw coloured clear liquid
...

Makes up approx
...


Red
Blood
Cells

Biconcave, no nucleus to fit Packed with red haemogloblin which combines with
more haemogloblin, makes oxygen to give oxyhaemogloblin – a reversible reaction so
up 45% of the blood, made oxygen can be dropped off
...


Produces antibodies/antitoxins
...

They may cause bacteria to stick together, act as a ‘label’
on the pathogen, cause bacterial cells to burst open,
neutralise poisons produced by the pathogen, or develop
into memory cells
...
Also made
es
cells with a large spherical in bone marrow
...
It’s like an egg with
a C-shaped yolk
...


Memory cells make you immune to a disease
...


Biology Page 36

Osmosis
17 December 2016

20:07

Osmosis is the process that takes place when water moves in and out of cell membranes
...
It can only happen if the membrane is permeable to water –
or a partially permeable membrane
...


An experiment to show osmosis can be done by attaching a glass tube to a Visking tube filled with
sugar solution
...
What happens? The sugar solution in the
Visking tube would rise up the glass tube
...
As a result, the water outside the tube would
move into the Visking tube, pushing the sugar solution up the glass tube
...
The food is then left for a while
...

Factors That Affect Rate of Movement of Substances In and Out of Cells
 Concentration Gradient – the steeper the faster
...

 Surface area to volume ration – the bigger, the faster
...
It is the state at which the cells are turgid
...
This makes the
cytoplasm push against the cell wall, giving the cell and internal pressure
...

Back to the point
...
This
supports the non-woody parts of the plant, such as young stems and leaves, and holds stems upright
so the leaves can carry out photosynthesis properly
...
If a plant loses too much water from its cells because there is more water potential
outside the cell, it would become flaccid – making the plant wilt
...
It cuts down water loss by reducing the exposed surface area of the leaves and closing the
stomata
...


Biology Page 37

Active Transport
17 December 2016

20:12

Active Transport
Sometimes, a cell needs to take in a substance when there is very little of it outside the cell
...
These pumps are large protein molecules located in the cell
membrane
...
It happens in the small intestine, where some glucose in
the gut is absorbed into the cells
...


Biology Page 38

Excretion
17 December 2016

20:13

Excretion
Excretion is the process by which waste products of metabolism are removed from the body
...
Another one is carbon dioxide, excreted
by the lungs
...
When plants
respire, they excrete carbon dioxide
...


Skin

Takes out urea water and other useless salts in the form of sweat
...

The Kidneys – Homeostasis and Osmoregulation
Inside our bodies, conditions are kept relatively constant
...
If you were to
drink a litre of water, your body would respond to this change by producing the same amount of
urine
...
Keeping the
water and salt content of the internal environment (inside the body) is known as Osmoregulation
...
Other examples include the level of carbon
dioxide in blood, the pH of the blood, the body temperature…etc
...


Biology Page 39

The Nervous System
17 December 2016

20:22

The Central Nervous System
The nervous system consists of the brain and spinal cord
...
Motor neurons transmit impulses to the
muscles and glands
...
Dendrons are cytoplasmic
extensions which form further extensions called dendrites
...
The axon terminals carry impulses to the effector organ
...


Sensory Neurones
A sensory neurone has a similar structure to the motor neurone, but the cell body is located on the
side branch of the fibre, just outside the CNS
...


Synapses
Synapses are gaps between nerve cells
...
The gap is not crossed by electrical impulses, but by
chemicals
...
This starts off impulses in the second cell
...


Reflex Arc
The stimulus is detected by pain receptors in the skin, generating impulses in the sensory neurones
...
In the spinal cord, the sensory neurons are
connected by synapses to relay neurones (interneuron), which in turn, connect to the motor
neurones
...
These muscles contract, pulling the finger away from the painful stimulus
...
Anyways cut that bullshit
...

Sclera

White part of the eye
...


Iris

Coloured ring of tissue
...


Choroid

Located underneath the sclera, it is a dark layer
to stop light being reflected inside the eye
...

Rod Cells

Work well in dim light, cannot
distinguish colours
...
Three types
that respond to red, blue and greed
...


Fovea

Centre of the retina where cones are
particularly concentrated at
...
Refraction takes place when light passes
Biology Page 42

To form an image on the retina, light needs to be refracted
...
In the eye, this happens first at the cornea, and
again at the lens, where fine focusing is done
...
The brain interprets the image right way
up
...
It contains two types of muscles
...
In bright light, the pupil is made smaller, or constricted
...

Photosynthesis is the process of making glucose in plants
...
It is when plants use simple inorganic molecules carbon dioxide and water, in the presence of
chlorophyll and light, to make glucose and oxygen
...


Limiting Factors That Affect Photosynthesis
Limiting factors are factors that are in shortest supply and will limit the rate of photosynthesis
...
When increased, the rate of photosynthesis will increase
steadily, but only to a certain point because temperature/carbon dioxide
will become the limiting factor
...
The concentration in air is about 0
...


Temperat Affects the enzymes involved in photosynthesis
...
Anything higher than 350C, and the enzymes denature
...


Biology Page 44

The Leaf
17 December 2016

20:37

Anatomy of the Leaf

Adaptation

Use

Large Surface
Area

To absorb more light
...


Chlorophyll

Contained in chloroplasts, it absorbs sunlight to transfer energy into chemicals
...


Waxy
Cuticle

Reduces water loss and acts as a barrier to pathogens such as bacteria and fungi
...

Biology Page 45

Outer
Epidermis

Is transparent and thin to allow light to reach the palisade cells
...


Spongy
Layer

The main gas exchange surface of the leaf
...


Lower
Epidermis

Contains many pores called stomata
...
Each stoma is controlled by two guard cells, which can
alter their shape to open or close the stoma
...
They get these minerals from
soil
...

Mineral
Ion

Use

Deficiency Symptoms

Nitrates

 Contains nitrogen for making amino acids, proteins,
chlorophyll, DNA etc
...


 Stunted growth
...


Phosphate  Contains phosphorus for DNA and cell membranes
...


 Poor root growth
...


Potassium  Needed for enzymes that control respiration and
photosynthesis
...


Magnesiu  Needed for making chlorophyll as it is part of the
m
chlorophyll molecule
...


Biology Page 47

Photosynthesis Experiment
17 December 2016

20:39

Photosynthesis Experiment

You can measure the rate of photosynthesis by:
 Counting the number of bubbles per min
...

Controlled variables:





Species of plant
Amount of sodium hydrogen carbonate solution
...

Reminder: Diffusion is the movement of particles from a higher to lower concentration
...
The opposite happens during respiration
...

Plants respire all the time
...
When light intensity is high, plants photosynthesize at a much
higher rate than when they respire
...
In dim
light however, a plant produces more carbon dioxide as it is respiring more than it photosynthesis
...
This is shown by the
extremely ugly graph(s) below
...
They have walls made of cellulose
...

The tubes transport products of photosynthesis from leaves to other parts of the plant
...
Despite being living cells, the
phloem sieve tubes have no nucleus and are controlled by the companion cells
...


Biology Page 51

Xylem

Xylem vessels are made of dead cells
...
The walls contain a woody material called lignin
...
Their role is to carry water and minerals from the roots up the shoot to the
leaves in the transpiration stream
...
I also think this might be
in the test so yeah
...
Plants
produce carbohydrates (sugars) in their leaves by photosynthesis, but nonphotosynthetic parts of
the plant also require carbohydrates and other organic and nonorganic materials
...

There is a pressure gradient between the source and sink, which allows the movement of foods
through the phloem
...
Each hair is a single, specialized cell of the root epidermis
...

Water uptake is done by osmosis
...
This increases the water potential in
Biology Page 53

causes water to move into the very first of the root hair cells
...
However, the cells behind the first ones have a lower water potential, which causes
water to move from the first cells to the second ones
...


Biology Page 54

Transpiration in Plants
18 December 2016

12:00

Transpiration in Plants
Transpiration is the loss of water vapour from the leaves
...

The loss of water causes a suction – or low pressure in the stem, which pulls the water up the xylem
in a continuous flow known as the transpiration stream
...

Role of Stomata in Transpiration
The reason why stomata is found usually on the lower surface of the leaves, is because it would lose
too much water if exposed to direct sunlight
...
This is where the stomata come to help! When the guard cells are turgid from
water, they bend outwards, opening the stomata, to let water diffuse out of the plant
...


Measuring the Rate of Transpiration
Potometers are used to measure the rate of transpiration
...

Everything must be placed in a sink whilst setting up to prevent formation of air bubbles
...
Vaseline can be used to seal joints
...
Time taken for the bubble to move along the scale is
recorded
...
In experiments like this, we assume that they’re equal
...


 Keeping the same
distance from the lamp
...


Temperat High temperatures increase the rate of transpiration, by
ure
increasing the rate of evaporation of water as water
particles gain more energy
...

 Using a heat filter/a glass
container filled with

container filled with
water
...

 Using a humidifier???

Humidity

If the air is humid, this reduces the diffusion gradient
...


Wind
Speed

Increases rate of transpiration with faster air movements  Conducting experiments
across the surface of the leaf
...

near the stomata
...


Biology Page 56

Feeding Relationships
18 December 2016

12:03

Feeding Relationships

Food chains show the feeding relationships within an ecosystem
...
10% of total energy is passed down each food chain
...

In a food chain, there are stages, called trophic levels
...
e
...
They produce the food with the energy from the Sun
...

 Primary consumers are herbivores
...

 Secondary consumers eat the primary consumer and are also carnivores or herbivores, predators or
scavengers
...
These can be carnivores, herbivores or omnivores,
predators or scavengers
...
These are bacteria, fungi or detrivores
(worms…etc
...
In other words, food webs show the feeding relationships and energy flow between food
chains
...
The amount of energy available
decreases down the food chain, reducing by 90%
...

Pyramids of biomass show the total mass of the organisms in each trophic level
...
Just remember that energy can never
be created or destroyed, so make sure the useful/waste energy is equal to the total energy input
...
It is extremely important, even though
carbon monoxide can kill us all
...

 Respiration releases energy from food, releasing carbon as carbon dioxide into the air
...

 Combustion/Burning of fossil fuels releases carbon dioxide into the air
...

 Transpiration from plants also rise into the atmosphere as water vapour
...

 This precipitate, either water or ice (as in snow, hail…) falls back onto the Earth where it is taken up
by animals or plants, or enters rivers and flows to the seat to start the cycle all over again
...
It is present in proteins, amino acids, most
vitamins, DNA, RNA…etc
...

 Decomposition – produces ammonia from the nitrogen in compounds like proteins, DNA and
vitamins
...
This overall process is
called nitrification
...

Bacteria
 Denitrifying bacteria – uses nitrates as energy source and converts them into nitrogen gas
...

 Free-living nitrogen-fixing bacteria – converts nitrogen gas into ammonia in the soil
...
When the bacteria die, their proteins decompose,
releasing ammonia back into the soil
...
Death and decomposition of the plant returns
the nitrogen to the soil as ammonia
...
Nitrogen gas in the atmosphere cannot be used directly by plants and animals due to its unreactivity
...
Nitrogen-fixing bacteria in root nodules convert nitrogen gas to ammonia (N2 – NH3)
...
This is converted to proteins and amino acids by plants (feeding and assimilation) OR free-living
nitrogen-fixing bacteria in soil convert nitrogen gas to ammonia and use it as proteins for
themselves
...
Both plants (or animals that ate the plants) and bacteria die and their proteins and amino acids
become this detritus (dead matter)
...
Decomposers turn these into ammonia
...
Nitrifying bacteria converts NH3 to NO2 (nitrite) and then NO3 (nitrate)
...

Biology Page 61

6
...
This is called nitrification
...
Denitrifying bacteria convert NO3 back to N2 gas in the soil OR plants absorb nitrates and use them
for proteins
...
The male gamete is then
transferred to the female gamete (i
...
sexual
intercourse in humans
...
Meiosis
...


Uses more
energy as one
needs to find a
mate who is
interested
...
These means that the new
cells produced are exact copies of the original
cell, and therefore, the same genes as the cells
of the adult
...


Does not need to find
a mate and is useful if
an organism is well
adapted to a stable
environment
...


Note: Fertilisation involves the fusion of a male and female gamete to produce a zygote that
undergoes cell division and develops into an embryo
...


Female Gamete Ova

Produced in ovules in the ovaries
...
In other words, the pollen
grains are transferred from the anthers to the stigma
...
Fertilisation then takes place and the zygote that’s formed develops into a seed and
becomes enclosed in a fruit
...
Crosspollination is when pollen grains are transferred to the stigma of a different flower
...

Stigma is sticky so pollen grains attach from insects
...

Nectaries are present, containing nectar which serves as a ‘reward’ for insects
...


Biology Page 64

Wind-Pollinated Plant






Stamens are exposed so the wind can easily blow the pollen away
...

Petals are small and not brightly coloured – usually green
...

Pollen grains are smaller, smooth inflated grains to carry in the wind (???)
...
To transfer the nucleus of the pollen grain to the ovum, the pollen grain grows a tube which digests
its way through the tissue of the style and into the ovary
...
It then grows around, and to the opening of the ovule
...
The tip of the tube dissolves and allows the pollen grain nucleus to move out of the tube and into
the ovule
...
It then fertilises the ovum nucleus
...
The zygote develops into an embryonic plant with a small root (radicle) and a shoot (plumule)
...
The other contents of the ovule develop into cotyledons which will be a food store for the young
plant when the seed germinates
...
The ovule wall becomes a seed coat or testa
...
The ovary wall becomes the fruit coat
...

Type of
Dispersal

Structure of Seed

Example(s)

Wind

Very small and light – or their fruits have ‘wings’ or a ‘parachute’ to Dandelions,
catch the wind
...


Coconuts

Animals

Seeds have hairs or hooks that catch in the animal’s fur
...


Strawberries,
clover fruit

Explosion

Capsules of the seed ‘explodes’ and shoots the seed further away
from the mother plant
...


Biology Page 66

Asexual Reproduction In Plants
18 December 2016

17:07

Asexual Reproduction in Plants
Asexual reproduction in plants usually involves some part of the plant growing, then breaking away
from the parent before growing into a new plant
...
When the runner touches the ground, a new plant is produced
...

c) Some plants form bulbs, bases of leaves which have become swollen in food
...


Artificial methods of reproducing plants asexually include cutting a piece of a plant’s stem, with a
few leaves attached
...


Biology Page 67

Germination
18 December 2016

12:31

Germination

A seed contains a plant embryo, consisting of a radicle, plumule (shoot) and one or two seed leaves
called cotyledons
...
Monocotyledonous plants or monocots have one, examples being orchids and irises
...
Once the seedling is able to photosynthesise, germination is over
...
The food store in dicots is present in the cotyledons
...
Dispersed seeds contain only about 10% water
...


Biology Page 68

Sexual Reproduction In Humans
18 December 2016

17:12

Sexual Reproduction in Humans

Males have a penis, in which they use to pass urine out, and to deposit sperm in females
...
During sexual intercourse, when the male experiences an orgasm, the
sperm passes along the sperm duct and are mixed with a fluid made from the seminal vesicles (labeled
‘glands’)
...


Biology Page 69

One ovum is released from the ovaries into the Fallopian tube each month
...
The zygote formed will begin to develop into an embryo and
implant itself into the lining of the uterus
...
The placenta also secrets progesterone to maintain pregnancy and prevent the embryo
from aborting
...
When it becomes recognizably human, the embryo is called a
fetus
...
This is called ‘going
into labour’
...
Dilation of the cervix – cervix gets wider to allow the baby to pass through
...

2
...

3
...


Biology Page 70

Puberty and The Menstrual Cycle
18 December 2016

17:14

Puberty
When children become teens, they experience changes that lead to sexual maturity
...
During this period, gametes are produced and the bodies of both sexes are
changed to allow reproduction to occur
...


Male

Female

FSH stimulates sperm production, while LH
instructs testes to secrete testosterone

FSH and LH control the release of oestrogen from
the ovaries

Testosterone controls the development of the Oestrogen controls the development of the female
male secondary sexual characteristics
secondary sexual characteristics
Growth of penis and testes, growth of pubic
hair, muscle development, breaking of the
voice, increase in body mass…etc
...


Menstruation

Biology Page 71

A function of the menstrual cycle is to control the development of the uterus lining so if the egg
(ovum) is fertilised; the lining will be ready to receive it
...

The cycle is continuous, but day 1 is usually referred to as the first day of menstruation
...
The pituitary gland releases FSH into the bloodstream, stimulating the growth of an ovum in
one of the ovaries
...

2
...
This causes a
decrease in FSH so no more ova will develop, and thickens the lining of the uterus so it’ll be
ready for a fertilised ovum
...
Eventually, the increasing amounts of oestrogen triggers a release of LH
...

Meanwhile in the ovary, the follicle begins to develop into a ‘yellow body’ (corpus luteum)
...
The corpus luteum makes progesterone, which completes the development of the uterus
lining and prevents the release of FSH and LH, stopping ovulation
...
If the egg is not fertilised, the corpus luteum breaks down and stops making progesterone
...
If the egg is fertilised, then
sooner or later, the placenta takes over the secretion of progesterone
...

When a parent cell divides it produces daughter cells
...
The stages of mitosis are as follows:

Chromosomes are copied as the DNA replicates and more histones (proteins the DNA coils around)
are made
...

1
...

2
...

3
...

4
...


Biology Page 73

Meiosis
18 December 2016

17:19

Meiosis
Meiosis produces four cells, each with the haploid number of chromosomes, resulting genetic
variation in the cells
...
Each chromosome copies itself and results in having a sister chromatid
...
The parent cell then splits, and results in two daughter cells
...
The resulting daughter cells split once again and one chromatid from each chromosome ends up in
each daughter cell
...


*Note: The ‘metaphase plate’ are spindle fibres; and forget about the names of the steps in meiosis
...
Using a ‘low’ estimate of about 8
...
5 million types of sperm and ova
...
5 million types of sperm and ova
...
5 million x 8
...

Identical twins are formed from the same zygote
...
Nonidentical twins develop from different zygotes
...


Biology Page 75

Natural Selection
18 December 2016

17:21

Natural Selection – Survival of the Fittest
Evolution – the gradual change in the range of organisms on Earth
...

Natural Selection – the mechanism by which new species arise
...
Over time these different forms become increasingly different
and may eventually become different species
...
This means that the weaker offspring will die or reproduce in smaller numbers and
the stronger offspring will pass on their ‘stronger characteristics’ to the next generation
...
Any evidence for natural selection must show that:
a) There is variation within the species
b) Changing conditions in the environment (a selection pressure) which favours one particular form of
the species (one with a selective advantage)
c) Frequency of the favoured form increases and the frequency of the less adapted form decreases
d) Changes are not due to any other factor
An Example – Antibiotic – Resistant Bacteria
The use of antibiotics has increased dramatically and can lead to the development of bacterial
resistance to an antibiotic
...
This happens because ‘bacteria generations’ are a lot
shorter than human generations, and a mutation in a bacteria can give it resistance to an antibiotic
...
Many mutations are
harmful, but some can be beneficial to the organism, such as becoming antibiotic-resistant
...
If not, the cell may not die
...

When an organism dies, the mutation is lost
...


The rate at which gene mutations occur can be increased by mutagens including:
 Exposure to ionising radiation (such as gamma rays, X-rays and ultraviolet rays)
 Chemicals in tobacco such as nitrous oxide and chemicals formed from burnt food
When DNA is replicating, mistakes can be made, resulting a gene mutation that can alter the
sequence of bases in a gene
...
Some ways include:
Original
A

T

T

T

C

C

G

T

T

T

T

T

T

C

C

G

T

Becom
es
A

Duplication – the nucleotide is inserted twice (the ‘T’ is duplicated and pushes everything to the
right, altering each of the triplet code and resulting in different proteins being made
...

Original
A

T

T

T

C

C

G

T

T

T

G

T

C

C

G

T

T

Becom
es
A

Substitution – A different nucleotide is used
...
If it does, then
there would be an alteration in the functioning of the protein
...

Original
A

T

T

T

C

C

G

T

T

T

T

C

C

T

G

T

T

Becom
es
A

Inversion – The sequence of bases in a triplet is reversed
...


Biology Page 78

Selective Breeding
18 December 2016

17:31

Selective Breeding
Plants and animals with desired characteristics can be developed by selective breeding
...
The Brassica plant for example, has
been selectively bred to form cabbage, cauliflower, broccoli and other things
...

Selective breeding can produce plants and animals with characteristics such as…:
Plants

Animals

• Give higher yields
• Are resistant to certain diseases
• Are resistant to certain pest damage
• Are hardier (they survive harsher climates)
• Have a better balance of nutrients – e
...
plants that contain
more of the types of amino acids needed by humans

• Produce more meat, milk or
eggs
• Produce more fur or better
quality fur
• Produce more offspring
• Show increased resistance to
diseases and parasites

Biology Page 79

Cloning and Cloning Animals
18 December 2016

17:32

Cloning
Cloning describes any procedure that produces genetically identical offspring
...
The tips of the stems and side shoots are removed from the plant to be cloned
...

2
...
5 – 1mm and placed in an agar medium containing
nutrients and plant hormones to encourage growth
...
More explants can be taken from the new shoots that form on the original ones
...

4
...

5
...
They are then gradually acclimatised to normal growing conditions
...
The atmosphere in the greenhouse is kept very moist to reduce water loss from young plants
...
In vitro means made to occur in
a laboratory vessel or other controlled experimental environment rather than in a natural setting
...

Species that are difficult to grow from seed or from cuttings can be propagated this way
...

Large numbers of plants can be stored easily
...

Cloning Animals – Dolly the Sheep

Biology Page 80

1
...

2
...
However, an ordinary diploid cell is too specialized
...
It is usually
easier to transfer a small whole cell such as an udder cell, rather than just the nucleus as the nucleus
alone can be too easily damaged)
...
The udder cell containing the nucleus is transferred into the enucleated egg cell
...
The cell develops into an embryo
...
The embryo is transferred into a foster mother, who gives birth to Dolly
...
Dolly contains the genes of her biological mother (the foster mother’s only there to provide the
womb)
...

• Producing individual organs for transplantation (they may also need to be genetically modified again
so they don’t get rejected by the human immune system) – produced by pigs!
• Producing commercial quantities of human antibodies
...
This new DNA is called recombinant DNA
...
The organism now has an added
capability and will manufacture the protein its new gene codes for
...

Restriction enzymes cut DNA molecules at specific points, whilst ligase enzymes join cut ends of DNA
molecules
...
Others make ‘sticky
ends’, which are more easily joined by ligase enzymes
...
The plasmid is called a vector because it is the
means of transferring the gene
...

Another vector that could be used is a virus that attacks a bacterium
...
This DNA becomes
incorporated into the DNA of the host cell, and eventually causes the production of many virus
particles
...
Once they’ve
been modified, they are cultured in fermenters to produce large amounts of the product such as:
 Human Insulin: For people suffering from diabetes
...

 Human Growth Hormone: For children with pituitary gland problems
...
This involves cutting a plasmid from a bacterium such as Agrobacterium and joining the desired gene
to the plasmid using ligase enzymes
...
This plasmid is then introduced to some leaf discs from the plant to be modified using a liquid
solution
...
They are then cultivated on a nutrient medium (micropropagation)
...
The plantlets will then grow into whole plants, containing the foreign gene
...

Disadvantages of Modifying Plants:

•
•
•
•
•

Transgenic products may be harmful to some – new proteins may cause allergies
...

It may cause the emergence of pest, insect, or microbial resistance due to natural variation
...

The gene may be taken up by non-target organisms and grant them resistance to things
...
The transparent
material allows natural light in for photosynthesis; however, additional light can help especially
during the winter
...
Short wave radiation
entering the greenhouse becomes longer wave radiation
...
Some features controlled in the greenhouse is
summarised below:
Feature
How and Why?
Controlle
d
Soil pH

Adding lime to acidic soils
...
It can also denature enzymes in the plant
...
These increase the rate of
photosynthesis so plants have more food and therefore, fewer plants die, increasing
yield of crops
...
Any hotter and it’d be a waste of money as there
would be no further increase in yield due to the denaturing of enzymes and other
factors
...


Light

For photosynthesis – light can enter the glass or transparent material
...

 Inorganic fertilisers – carefully formulated to yield a specific amount of nitrate or some other ion
...

Also, when crops are sold, the nitrogen in the proteins in plants goes with them and is lost from the
farm ecosystem
...


Biology Page 86

However, fertilisers can also cause problems
...

This increases the level of nitrates and other ion and causes eutrophication
...

 This prevents light from penetrating further in the water
...

 The algae also die as they run out of nitrates
...

As they reproduce more and more due to the large amount of dead matter, their respiration uses up
more and more oxygen
...


Biology Page 87

Pests
18 December 2016

17:40

Pest Control
Pests reduce the yield of crops or stock animals and can cause economic damage to the farmer
...
Pesticides can be used to kill pests and so,
improve the yield from the crop
...
Through mutation and natural selection, the pest can
develop a resistance to the pesticide, rendering it useless
...


Another option for the farmer is biological control
...
Biological controls never
eradicate the pest, because if it kills off all the pests, it will die too due to lack of food
...

Introducing a pathogenic microorganism
...

Using pheromones – these animal sex hormones attract the males or females, which are then
destroyed, reducing the reproductive potential of the population
...


When carbon is burned in a limited supply of oxygen, carbon monoxide (CO) is formed
...
Exhaust gases contain significant amounts of carbon
monoxide
...
It binds more
strongly to haemoglobin than oxygen, and prevents it from carrying oxygen around the body
...


Sulphur dioxide (SO2) is released in by many factories that burn fossil fuels
...
As a result, acid rain is formed
...
It can also damage stone works and trees
...
It can also damage stone works and trees
...
Lichens are used to indicate levels of sulphur dioxide
...
They have no waxy cuticle, meaning they will readily absorb acid rain
...
They would also be
whiter/yellower
...
They
would be greener and bushier
...
Its effects:
 Leaching
 Soil Erosion – because the soil lacks a protective canopy provided by trees, and because it is not held
together by tree roots
...
Deforestation means that fewer trees can transpire (because the rest would be dead
and chopped down) and may disrupt the water cycle
...

 Disturbance of the Balance in Atmospheric Oxygen and Carbon Dioxide – Less carbon dioxide is
absorbed by trees to produce oxygen because of deforestation
...
It is the
increase in concentration of a pollutant from the environment to the first organism in a food chain
...

This can be magnified as a pesticide is passed along a food chain
...
The effects of bioaccumulation are
therefore magnified at each stage in the food chain
...


Biology Page 90

Revision Questions and Answers
17 February 2017

14:35

Biology Page 91

Questions on Structures and Functions in Living organisms
31 December 2016

13:38

1
...
Name three organelles that are found in both animal and plant cells
...
Name two organelles that are only found in plant cells
...

Vacuole - Contains a sugary solution which contains cell sap - and this keeps the cells' shape
...

4
...

5
...

An organ system is a group of similar organs working together to create a system, such as the
digestive system
...
What are plant cell walls made of?
Cellulose
7
...
Give two examples of fungi
...
Explain what is meant by the term "saprotrophic nutrition"
...

10
...


Biology Page 92

Algae and Seaweed
11
...

Their cells have cell walls made of chitin
...

They store carbohydrates in the form of glycogen
...
What are pathogens? Name two pathogens
...
For example bacteria, or fungi
...
What name is given to a biological catalyst?
Enzymes
14
...

15
...
Suggest what will happen
to it
...
It has to
remain at 37C in order to retain the ability to catalyse reactions
...
Briefly describe an experiment to show how temperature can effect enzyme activity
...
The enzyme amylase catalyses the breakdown of starch and maltose
...
It is easy to detect starch using iodine solution - if starch is present, the iodine solution
will change from browny-orange to blue-black
...
You can time how long it takes for the starch to disappear by regularly sampling the
starch solution, and use the times to compare rates with different tests
...
By adjusting the water bath temperature, you can see how temperature affects the
activity of amylase
...
What is diffusion?
The net movement of particles from an area of higher concentration to an area of lower
concentration
...
What is osmosis?
The net movement of water molecules across a partially permeable membrane from a region of
higher water c0oncentration to a region of lower water concentration
...
A solution of pure water is separated from a concentrated sugar solution by a partially
permeable membrane
...


20
...
This is
Biology Page 93

Turgid cells cause the cell to push against the cell wall - this is called turgid pressure
...

21
...
Then, do
the same for osmosis
...
Make up some agar jelly with phenolphthalein and dilute sodium hydroxide
...
Then fill a beaker with some dilute hydrochloric acid
...

c
...

22
...
Active transport uses energy released during respiration to travel against
the concentration gradient
...
Describe how surface area to volume ratio affects the movement of substances in and out of
cells
...

If the surface area is small and the volume is large, solutions will move very slowly into these
cells
...


Biology Page 94

Questions on Human Nutrition
31 December 2016

13:50

1
...

Carbon, Hydrogen, and Oxygen
...
What type of biological molecules are made up of: a) fatty acids and glycerol? b) amino acids
...
Proteins
3
...
Make sure that the solution doesn't
boil
...

4
...


5
...
The body needs proteins to be able to repair broken cells and grow new
cells
...
What nutrients does the body get energy from?

Carbohydrates and fats
7
...
He has been told that he needs to increase the amount of
vitamin D in his diet
...
He needs it for calcium absorption
...
Explain fully what is meant by the term "a balanced diet"
...

9
...
b) a
woman who is pregnant and one who isn't
...
Children need more energy than older people because they are growing and are generally
more active
...
A woman who is pregnant needs more energy than other woman because they have to
provide energy for their babies as well as themselves
...
Describe a simple experiment to measure the amount of energy in a food
...

Get a food that burns well, then weigh it
...

Then get 25cm3 of water, and measure the temperature
...
keep
doing it until it won't set alight again
...

Then measure the temperature of water again
...
What is the main role of digestive enzymes?
They break down big molecules into smaller ones
...
Name the enzymes that convert starch into glucose
...

13
...

14
...
Where in the body is bile produced, stored, and used? (3 different places)
Bile is produced in the liver
...

It is used in the small intestine
...
What are the two functions of bile
...

Bile also emulsifies fats - breaks them int0o tiny droplets
...
Describe the functions of a) the mouth b) the oesophagus c) the small intestine d) the
pancreas
...
The mouths salivary glands produce amylase in the saliva
...

b
...

c
...
This is
also where nutrients get absorbed out of the alimentary canal into the bloodstream
...
The pancreas produces protease, amylase and lipase enzymes and releases them into the
small intestine
...
Describe the process of peristalsis
...
Its job is to squeeze balls of
food (boluses) through your gut - to stop it getting clogged up
...


19
...

Egestion is excreting faeces through the anus
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Put the following digestive processes in the order that they occur: absorption, assimilation,
and digestion
...
Explain how villi help with absorption in the small intestine
...
Each cell on the surface of a villus contain its own microvilli, which are little
projections which increase the surface area even more
...
Write down the word and balanced symbol equations for photosynthesis
...
How does being broad help a leaf to photosynthesise?
A larger surface area is created meaning more cells can capture sunlight and absorb CO2 and
rainwater needed for photosynthesis
...
Describe one other way that leaves are adapted for efficient photosynthesis
...

4
...

Take a variegated leaf from a plant that has been exposed to light for a bit
...

Test the leaf for starch - only the bits that are green will turn blue black
...

5
...

To show that light is needed for photosynthesis you need a plant that has grown without any
light - e
...
in a cupboard
...
Name the three main mineral ions plants need for healthy growth
...
How can you tell by looking at a plant that it isn't getting enough magnesium?
Its leaves are yellow
...
which mineral ion is needed by plants to make chlorophyll?

Magnesium
...
Explain why plants and animals need transport systems to move substances around their
bodies but unicellular organisms don’t
...
The diffusion rate is quick because of the short distances substances have to
travel
...
That’s why they have a transport system
...
What is the function of xylem vessels in plants?

Biology Page 98

The Xylem carry water and mineral salts from the roots up the shoot to the leaves in the
transpiration stream
...
What is the function of phloem vessels in plants?
The phloem transport sugars, like sucrose and amino acids from where they are made in the
leaves to the other parts of the plant
...

12
...

13
...

14
...
The warmer it is, the faster transpiration happens
...
The drier the air around a leaf, the faster transpiration happens
...


Biology Page 99

Questions on Respiration and Gas Exchange
31 December 2016

15:58

1
...

Respiration is the process of releasing energy from glucose
...
What is aerobic respiration? Give the word and symbol equations for it
...
What is anaerobic respiration?

Respiration which doesn't use oxygen at all
...
What are the main disadvantages of anaerobic respiration compared to aerobic respiration?
It is not as efficient - produces less energy than aerobic respiration
...


5
...

Glucose --> Lactic acid + (less energy)
Glucose --> Ethanol + Carbon Dioxide + (Energy)
6
...
Describe an experiment to detect carbon dioxide production from respiration
...
If it turns yellow, then
it is producing carbon dioxide
...

8
...

Diffusion
9
...
At night, there is a lot of oxygen inside a leaf and not a lot of carbon dioxide
...

Explain your answer
...
Therefore, plants are releasing co2 and gaining oxygen - so this true
...
Explain how leaves are adapted for efficient gas exchange
...
Leaves are broad, so there is a large area for diffusion
...
They are also thin, which means gases only have to travel a short distance to reach the
cell where they are needed
...
There are air spaces inside the leaf
...
There are air spaces inside the leaf
...
It also increases the surface area for gas exchange
...
The lower surface is full of little holes called stomata
...
They also allow water to escape - which is known as transpiration
...
Describe an experiment you could use to show the effect of light on gas exchange in leaves
...

a
...

b
...
Trap the leaf stem with the bung to stop it falling down into the solution if you
need to
...
Completely wrap one tube in aluminium foil, and a second tube in gauze
...
Place all the tubes in bright light
...
No light will get to the leaf covered in foil
...
Leave the tubes for an hour, then check the colour of the indicator
...
You would leave the fourth test tube with nothing in but indicator - as a control
13
...
Name the key structures of the respiratory system
...

b
...

d
...

f
...
What happens to the intercostal muscles and diagram when you breathe in?
Intercostal muscles and diaphragm contact
...
What happens to the intercostal muscles and diagram when you breathe out?
Intercostal muscles and diaphragm relax
...
Explain why exercise increases your breathing rate
...

18
...

This is because muscles respire more during exercise - they require more oxygen and carbon
dioxide, hence increasing your heart rate
...
Give four ways that the alveoli's structure is ideal for gas exchange
...
The huge number of microscopic alveoli gives the lungs an enormous surface area
...
There is a moist lining for gases to dissolve in
...
They have very thin cell walls - only one cell thick for efficient gas exchange as the cells
don’t have very far to diffuse
...
They have a great blood supply to maintain a high concentration gradient
20
...
To make up
for this, heart rate increases - which leads to an increase in blood pressure
...
Therefore increasing
the risk of coronary heart disease
...
Name two other diseases linked the smoking tobacco
...
Chronic bronchitis
...
Emphysema
...
What are the four main components of blood?
Plasma
Platelets
Red blood cells
White blood cells (lymphocytes and phagocytes)
2
...

Red and white blood cells and platelets
...

Carbon dioxide
...

Hormones
...

3
...

4
...

They contain haemoglobin which reacts with oxygen to become oxyhaemoglobin, which
enables them to carry oxygen around the body through the blood stream
...

5
...

6
...
These
are specific to the type of pathogen - they won't lock on to any others
...
Explain the role of memory cells in the immune system's response against pathogens
...

8
...

This injects the body with a dead form of the pathogen of the disease so that the body will
know how to cope with the proper version of the pathogen if it comes
...
Why do arteries need very muscular, elastic walls?
To be able to pump the blood at a very high pressure
...

10
...

They are really small
...

They are only one cell thick to be able to diffuse substances easily
...

11
...

12
...
Where does it take the
blood?
Pulmonary vein takes deoxygenated blood to the lungs
...
Why does the left ventricle have a thicker wall than the right ventricle?
This is because it needs more muscle to be able to pump blood around the whole body,
whereas the right ventricle only has to pump blood to the lungs
...
How does heart rate change during exercise?
You need more energy during exercise, so you respire more, hence why your heart rate
increases as your cells need more oxygen from the blood
...
What hormone cases heart rate to rise?
Adrenaline
16
...

17
...
What are the names of the two main blood vessels associated with the lungs
...

19
...

20
...

Blood from the renal artery flows through the glomerulus - a bundle of capillaries at the start of
the nephron
...

The membranes between the blood vessels in the glomerulus and the Bowman's capsule act
like filters, so big molecules like proteins and blood cells are not squeezed out
...
The filtered liquid in the bowman's capsule is known as the glomerular filtrate
...
What happens in the collecting duct of a nephron?
All the glucose is reabsorbed from the proximal convoluted tubule
...
This involves the process of
active transport against the concentration gradient
...
Describe the path taken by urine once it leaves the nephron
...

23
...
Why do organisms respond to changes in their environment?
It helps organisms survive e
...
avoiding places that are too hot or too cold
...

2
...
These are detected by receptors
...
g
...
Gives two types of effector
...
What does the central nervous system do? What does it consist of?
Its job is to coordinate the response to stimuli
...

5
...

6
...

a
...

c
...

e
...


A stimulus causes something to change (e
...
pain)
Stimulation of the pain receptor
...

Impulses are passed along a relay neurone, via a synapse
...

When impulses reach muscle, it contracts automatically, pulling itself away from cause of pain (e
...
candle burning
finger)
...
Draw a labelled diagram of the human eye
...
Explain the roles of the following parts of the eye: a) cornea b) iris c) lens
...
The cornea refracts light into the eye
...

b
...
If it is dark, the pupil will expand, and if it is very bright, the pupil will contract
...
The lens focuses the light onto the retina - (the light-sensitive part - it is covered in light receptors called rods and
cones)
...
Describe the iris reflex
...


10
...
This makes the len s
go thin
...
The lens becomes fat
...
Define the term "hormone"
...

12
...
It increases heart rate, blood flow to muscles and blood sugar level
...
Where is insulin made? Describe inulin's role in the body
...
Its job is to maintain and control the blood sugar level
...
List three differences between nervous and hormonal responses
...

Hormones have a slower message, act for a long time, and act in a very general way
...
Define homeostasis
...

16
...

Water content
Body temperature
17
...


Through the skin as sweat
Via the lungs in breath
...

18
...

On a hot day or when you are exercising, you sweat a lot
...

On a cold day, or when you are not exercising, you don’t sweat much
...

19
...
Describe how body temperature is reduced when you are too hot
...

When you are cold, very little sweat is produced, blood vessels near the surface constrict (vasoconstriction), you shiver so
the movement generates heat in your muscles, and hairs stand on end to trap an insulating layer of air between your hairs
and the skin
...
Do larger animals tend to have small or large surface area to volume ratios? How does this affect their temperature
control?

Yes and this affects their temperature control because they can gain and loose heat faster because there is more area for
the heat to transfer across
...
Give two ways in which plants respond to stimuli
...

They can sense gravity, so their shoots an roots grow in the right direction
...
What are auxins?
Auxins are plant growth hormones
...


24
...
Positive geotropism is the act of growing towards gravity
...
Shoots are negatively geotropic
...
The extra auxin inhibits growth, so the cells on
the top of the root elongate faster, and so the root bends downwards
...
What is a gene?
Genes are chemical instructions on how to put an organism together and make it work
...
What does diploid mean? What is the diploid number for a human body cell?
Diploid means each cell contains two copies of each chromosome
...
Name the four different bases found in DNA
...
A and T go together, G and C go together
...
Name the type of cell division used in asexual reproduction
...
This type of cell division is also used for growing and repairing plants damaged tissue
...
Explain why sexual reproduction results in offspring that are genetically different from either parent
...

6
...
Where does it take place in humans?
Gametes are produced by meiosis
...

7
...

By planting cuttings of the good plants, they grow into genetically identical copies of the parent plant
...
Where are sperm made? Where are ova made?
Sperm are made in the testes
...

9
...

10
...
Label the four stages of the cycle and show when
the ovum is released
...
What roles do oestrogen and progesterone play in the menstrual cycle?
Oestrogen: causes lining of uterus to thicken and grow and stimulates the release of an ovum at day
14
...

12
...


13
...
g
...
What are codominant alleles?
When you get two dominant alleles in the same gene, e
...
CC
15
...
Draw a genetic diagram showing that there's an equal chance of a baby being a boy or girl
...
List four features of animals which aren't at all affected by the environment, and three which are
...

Eye colour,
Hair colour,
Inherited disorders,
Blood group
...

18
...

Life began as simple organisms from which more complex organisms evolved
...
Explain what is meant by natural selection
...

20
...

21
...

a) It could stop the production of protein, could multiply in an uncontrolled way and invade other
parts of the body (cancer)
b) Could lead to survival in certain conditions where others cant
...
What is a superbug?
A strain of bacteria that is resistant to antibiotics
...
Define the following: a) a habitat b) a population c) an ecosystem
...
g
...

Population - all the organisms of one species in a habitat
...
g
...
How could you estimate a population size in a habitat using a quadrat? Give two reasons why your results might not be 100% accurate
...

Count all the organisms within the quadrat
...

You can do this again in a different area and compare population sizes
...
e
...

The sample size affects the accuracy of the estimate - the bigger your sample, the more accurate your estimate of the total population is likely to be
...

3
...

Then collect data along the line using quadrats placed next to each other
...
What is a producer? What is a secondary consumer?
A producer is an organism that creates its own food using energy from the sun
...

5
...

Fungi
...
Explain why pyramids of number are not always pyramid-shaped
...

7
...
Approximately how much energy is passed on to the next trophic level?
10%
9
...

Some parts of food aren't eaten by organisms so the energy isn't taken in
...
What does a food web show?
A food web shows how food chains are linked
...
Draw a sketch of the water cycle
...
What do all those words mean?
12
...
Give two ways that carbon can enter the air from dead animals and plants
...

14
...

15
...

16
...
How is it produced?
Sulfur dioxide is produced by burning fossil fuels
...
This then mixes with rain clouds to form acid rain
...
How does acid rain affect lakes and trees?
Acid rain can cause a lake to become more acidic
...
Many organisms are sensitive to changes in pH and can't survive
in more acidic conditions
...

18
...
If this didn’t happen, no heat would
be trapped and we would become very cold
...
What is the effect of increasing the contraption of greenhouse gases in the atmosphere?
Global warming - we would increase the worlds average temperature, which would melt ice caps in the north and south poles, causing many areas to flood
...

20
...
How are they produced?
Carbon dioxide - burning fossil fuels
...

Nitrous oxide - released by bacteria in soils and the ocean, or from vehicle engines
...

21
...

Nitrates and phosphates are put onto fields as mineral fertilisers
...

The extra nutrients cause algae to grow fast and block out the light
...

With more food available, microorganisms that feed on dead plants increase in number and deplete all the oxygen in the water
...

22
...


Biology Page 112

Questions on the Use of Biological Resources
31 December 2016

16:55

1
...
Why do farmers use artificial fertilisers?
3
...

4
...

5
...
Don’t forget to name the bacterial involved
...
Draw and label a diagram of a fermenter
...
List the conditions that have to be controlled in a fermenter
...
Describe the main stages in brewing beer
...
Describe an experiment to measure carbon dioxide production by yeast during anaerobic
respiration
...
What is selective breeding?
11
...

12
...

13
...
Describe the function of: a) a restriction enzyme b) a ligase
...
What is a vector?
16
...

17
...
Describe one way plants can be genetically modified to help improve food production
...
Give an advantage of producing cloned plants
...
Describe the process of micropropagation
...
Describe the process of cloning an animal from an adult cell
...
Describe the advantages and disadvantages of cloning transgenic animals

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