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B2
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 Contains genes and chromosomes, that carry instucitons to make new cells
Cytoplasm:



Liquids gel
Where chemical reactions take place

Cell membrane:



Controls passage of substances in and out of the cells
Holds cell together

Mitochondria:



Where oxygen is used
Where energy is used in respiration

Ribosomes:


Protein synthesis (where proteins are made from DNA)

Only in plant and algae:

Cell wall:



Made of cellulose
Strengths cell and gives support

Chloroplasts:



Contains chlorophyll
Absorbs light energy for photosynthesis

Permanent vacuole:



Contains cell sap
Keeps cells rigid for support

Bacteria and Yeast

Bacteria



Single- celled organisms, no nucleus
Lots of bacteria= bacteria colony

Genetic material:



Long strand of DNA
Unlike plant and animal cells the DNA
isn’t in the nucleus

Plasmids:


Circular bits of extra DNA

Flagella:


Protein strand that help the bacteria move

Yeast

When yeast is without oxygen they use anaerobic respiration, and
when their sugar is broken down they produce CO2 and ethanol
...
It needs energy to change back
Packed full of mitochondria to get this energy to change the
visual pigment , letting you see colour continually
The synapses connects to the optic nerve that, when the visual
pigment changes an impulse sis triggered and crosses the
synapse and travels along the optic nerve to the brain

Root hair cell:

Adapted to take up water more efficiently
Adaptions:



The root hairs increase the SA for water to move into
the cell
Large permanent vacuole that speed up the movement of
water by osmosis form the soil to the cell

Sperm cells:
Released a long way from the egg they are going to fertilize
Then they have to break into the egg
Adaptions:





Long tail- helps them move to the egg
Full of mitochondria- provides energy for the tail to work
The acrosome- stores digestive enzymes to break down the
outer layer of the egg
Large nucleus- contains DNA to be passed on

RBC
Carry oxygen around the body with haemoglobin
Adaptations:




Concave shape creates a big SA to absorb oxygen, and
pass smoothly through capillaries
Packed with haemoglobin that absorbs oxygen
No nucleus- to leave more room for haemoglobin

Diffusion

Dissolved substances and gases move in and out of cells across the cell membrane by
diffusion

Diffusion is the spreading out of particles of gas or a liquid from an area of high
concentration to low till evenly spread
Overall movement of particles= a net movement
This is a random movement:

Rates of diffusion
Difference in concentration between 2 areas= concentration gradient (CG)
The bigger CG the faster diffusion happens



Many particles will move towards the low C
Only a few will move to the high C, as it a a random movement

But if the CG is low then diffusion will be slower


The particles moving to the low C will only be slightly bigger than the ones
moving to the high C

Diffusion occurs down the CG
NOTE- the net movement= particles moving in – particles moving out
SUMMARY- the greater the C the faster diffusion happens

The movement of particles across membrane
It is important to note that the very last image although looks like nothing is moving, but
in fact all the particles are moving
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Temp also affects the rate



Increase- particles move faster
Diffusion occurs faster as the random movement of articles speeds up

Diffusion in living organisms:

NOTE: in all of these the solution/gas move along the CG from high C (where they are)
to low C (inside the cell) by diffusion




Water and glucose move into the cells by diffusion
The amino acids from the breakdown of proteins in the gut
Oxygen from the air gets into the RBC through the cell membranes

To make diffusion easier the SA of the cell membrane is bigger in some cells



This is because there is more room for diffusion to take place, and more of a
substance moves in a given time
To can be done by folding the cell/tissue

Tissues and organs

Tissue- a group of cells with a similar structure and function, working together
Animal:



Muscular tissue: contract to bring about movement
Glandular tissue: secretory cells produce substances like enzymes and hormones

Plant:



Epidermal tissue: cover the surface and protect plants
Mesophyll tissue: contain chloroplasts to carry out photosynthesis



Xylem and phloem are transport tissues

Organs- made up of tissues, sometimes several different types, all working together to
carry out important functions in the body
The stomach contains:




Muscular tissue to churn up food and digestive juices
Glandular tissue, to produce digestive juices to break down food
Epithelial, which covers the inside and outside of the stomach

Different organs combined- an organ system:






Digestive
Circulatory
Nervous
Reproductive
Endocrine (control hormone glands)

Adaptions for exchange:
Organs adapted for the exchange of materials to take place



Exchange of gases in the lungs
Digested food moves form the small intestine to the blood

Many adaptations in these areas include:



Increasing the SA, to increase the rate of diffusion
Increase the CG across membranes, to increase the rate of diffusion- organs do
this by having a good blood supply to bring and take away substances, to
maintain a steep CG

Organ Systems

= group of organs that all work together to do a particular function
The digestive system
Food is insoluble and your body cannot absorb this, so it needs to be broken down into
soluble molecules to be absorbed by the cells
This takes place in the digestive syste

The digestive system is a muscular tube that squeezes food through
There are glands that produce enzymes to break the food down
The soluble food is absorbed in the small intestine into the blood, to get transported
around the body
The small intestine has a large SA to increase diffusion
Insoluble foods are passed into the large intestine where water is absorbed, and the
foods are passed out the anus as faeces

Plant organs
Tissues- Mesophyll, xylem, phloem
Organs- leaves, stem, roots

B2
...

Plant use light energy to convert CO2 and water into glucose, and oxygen being
produced as the by-product
Some glucose is used immediately, but a lot is stored as the insoluble starch
The iodine test turns starch blue black, which shows if a plant has photosynthesise

Plant adaptations:





Plant organelle- parts of a plant (cell wall, cytoplasm
Plant organ- root system, leaves, stem
Plant cell- root hair cell, palisade mesophyll cell

Leaves are adapted so photosynthesis can take place as efficiently as possible





Broad leaves- big SA for light
In algae (aquatic) they absorb CO2 dissolved in the water around them
Thin leaves- allows easy diffusion of gases, as the distance is shorter
Mesophyll layer (spongy + palisade) is where most photosynthesis happens

Vein

Waxy cuticle:



Reduces water loss
Waterproofing- important in dry/ hot conditions

Upper epidermis:



No chloroplasts to allow light to pass through
Protects and reduces water loss

Palisade layer:



Palisade mesophyll cells are near the top, near the light and packed with
chloroplasts to increase photosynthesis
They are thin to pack more in

Vein:



Xylem- transports water to leaves
Phloem- transports dissolves food from the leaf to the rest of the plant

Spongy layer:



Contains spongy mesophyll cells with a big SA for gas exchange
Air spaces for rapid diffusion of gases (O2 out CO2 in)

Stomata:



Allows gases to move in and out by diffusion
Controlled by guard cells

Guard cells:





Adapted for gas exchange and control water loss by regulated the size of the
stomata
In low light/night the guard cell lose water and become flaccid, closing the
stomata, no photosynthesis is happening (no CO2 is needed) to reduce water
loss
When these water they become turgid so the stomata opens for gas exchange

Limiting factors

Temperature, light, CO2


LF= if in short supply, limits the rate of photosynthesis

Water:



Plants also need water
But if a plant is short of water the stomata close to prevent further loss of water,
and photosynthesis can’t take place

1
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Temperature

1- the LF= temp

2- At 45* the enzymes denature and stop working
In winter temp is ususally the LF
3
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Respiration
 Glucose provides energy for cell function- growth, reproduction
 Glucose is broken down using O2, releasing CO2 and water as a by-product
...
Cell Walls
 Some glucose is converted into more complex carbs like cellulose to strength cell
walls
3
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Seeds
 Glucose is turned into lipids (fats and oils) in seeds to provide energy when it
germinates
 This is where plant oils come from
5
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(Important ones- nitrates, magnesium)

MINERALS

USES

DEFICIENCY

Nitrates

To keep the plant healthy
For making amino acids in
proteins

Stunted growth
Yellow older leaves

Magnesium

Makes chlorophyll

Yellow leaves

Potassium

Yellow leaves
Dead spots

Phosphates

Stunted root growth
Purple younger leaves

B2
...
Temperature:
At first the higher the temo the higher the
acitvity
But at 40-45* the enzymes denature
 When the chains of amino acids
unravel, so the active site changes and doesn’t
work
 This is why a fever can be harmful

2
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So
they can be broken down by enzymes into soluble ones
...


Speeding up Digestion:

Different enzymes work best at different PHs in different parts of the body:




Protease- stomach- acidic
Protease- small intestine- alkaline
The body makes chemicals to make ideal conditions

Changing the PH:
In the stomach:


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Produces HCL as well as pepsin
Works best in acidic conditions
Also kills bacteria

In the small intestine:

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Bile changes the acidic partially digested food into alkaline
Bile- made by liver released by gall bladder
Protease works best here in alkaline conditions

Altering the SA




Because fats don’t mix with watery liquids (emulsion) in the stomach they stay in
large globules, which are difficult for lipase to break down
So bile emulsifies fat droplets to increase the SA which increase the rate of fat
digested by the lipase
The larger the SA helps the lipase chemically break down the fates into fatty
acids and glycerol

Making use of enzymes

Biological detergents:



Contain protease and lipase to break down the protein and fat in stains
Work better in lower temps- less energy is used

Baby food



Contains protease that ‘predigest’ the protein in foods
Make it easier for a baby’s digestive system to cope, and get the amino acids they
need

Sugar syrup




Carbohydras is used to convert start into sugar
Starch is cheap and easy to make from plants
Provides a cheap souse of sweetness for food manufacturers

Slimming foods




Isomerase is used to chains glucose into fructose
Fructose has the same amount of energy, but is sweeter
So smaller amounts are needed, less calories

Pros and cons of using enzymes
PROS

CONS

Used at low temps

Denature 40-45*

Used at low
pressures

PH needs to be controlled to conditions that suit enzyme, which
costs

Fairly cheap to run

Microorganisms that make enzymes are cheap, but need to be
supplied with food and oxygen, and waste products need to be
removed
Pure enzymes use the substrate more efficiently, but expensive

Pros and cons of using biological detergents:
PROS

CONS

The problems with allergies has been
solved

Used to cause allergies, which people still
remember

Lower temps means:
 less electricity is used
 good for environment
 cheaper to use

At low temps not all pathogens are killed,
but at higher temps, they denature

Break down stains effectively
Enzymes and medicine

To diagnose disease:
If your liver is damaged the enzymes may leak out into the blood
A blood test will show this and diagnose liver damage/disease

To diagnose and control disease:
People with diabetes have too much glucose in the blood, which can be detected with a
urine test
The test contains a chemical indicator and an enzyme on a strips, which breaks down
any glucose found, and the strip will change colour if the products of this reaction are
present

To cure disease:
If the pancreas is damage it cannot make enzymes, so you have to take extra to digest
foods
If you have a heart attack streptokinase is infected, which dissolves clots in the arteries
of the heat wall, reducing the damage done to the heart muscle
An enzyme is being used to treat a type of blood cancer that cannot make a particular
amino acid, so take from your body fluids, Enzymes can breakdown this stopping the
cancer from getting nay and they die
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4- Energy from Respiration
Respiration= the release of energy from the breakdown of glucose in every cells

Aerobic respiration (AR)

During this glucose reacts with oxygen to release energy for cells from food
CO2 and water are released as waste products of the reaction
Glucose + Oxygen = CO2 + Water (+ Energy)
Aerobic= oxygen
AR involves lots of chemical reactions catalysed/controlled by enzymes

Mitochondria
AR takes place in the mitochondria
Mitochondria have a folded inner membrane to increase SA for the enzymes involved in
the reaction
The number of mitochondria shows how active the cell is

Reasons of respiration






Cells need energy to carry out functions of life:
o Make new cells
o Building large molecules from small (amino acids- proteins)
o Synthesis reactions (building activities)
Mammals- muscle contractions that need energy
...

This needs energy

The effect of exercise in the body

Muscles need a lot of energy
Muscle tissue is made up of protein/muscle fibres:




Contract when supplied with energy from respiration
Contain many mitochondria to carry out aerobic respiration
In groups are muscles that contract to cause movement

Muscles also store glucose as the carb glycogen that can be converted rapidly back to
glucose during exercise for respiration to supplies energy to make the muscles contact

The response to exercise

Muscles use up oxygen and glucose, and when you exercise they contract and need
more oxygen and glucose to get energy
During exercise muscles also produce CO2 that needs to be removed to work effectively

Response:




Increasing blood flow- due to increase heart rate and dilated arteries supplying
blood to the muscles
o To increase the supply of glucose and oxygen to the muscles
o Also increase the rate CO2 is removed
More oxygen is brought in- due to increase in breathing rate and you breath in
more deeply
o So more oxygen is picked up by the RBC and carried to the exercising
muscles
o Also so that more CO2 is removed from the blood in the lungs and
breathed out

The benefits of exercise
The heart and lungs get larger, and develop a bigger and more efficient blood supply
Meaning that they function as effectively as possible, exercising or not

Anaerobic respiration

When you exercise hard the muscle cells may become short of oxygen, as the blood
cannot supply fast enough
So the cells use anaerobic respiration to get energy
Glucose = Lactic Acid (+ Energy)
Anaerobic= shortage of oxygen
Glucose is incompletely broken down to form lactic acid instead of CO2 and water
Releases less energy that aerobic- glucose isn’t broken down completely
If you are fit the heart and lungs can keep a good supply, but if unfit you will run short
sooner
But anaerobic respiration means that you can keep the muscles going for longer

Muscle fatigue
Using the muscles fibres vigorously can make them fatigued- meaning they stop
contracting efficiently
One cause of this is the build-up of lactic acid
Blood flowing through the muscles removes lactic acid

Oxygen dept
...
,
like with CO2





Lactic acid has to be broken down to form CO2 and water which need oxygen
The amount of oxygen need= oxygen dept
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5- ENERGY IN BIOMASS

Pyramid of Biomass

Biomass- the dry mass of living material in a plant/ animal




Built up using energy from the sun
Plants absorb this energy to be used photosynthesis for food, which is stored as
chemical energy, in plants/algae= this is biomass
Biomass is passed through the food chain, when animals/plants eat each other
Each bar is the mass of a living thing
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Where energy is lost:

1
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Only a small amount of energy is in the cells, so only a little is passed on
3
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Movement:
 Energy is used in respiration to supply energy to the body




Energy is used when muscles contract
More movement, more biomass from food is lost

5
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Energy is lost through waste
 Not all energy consumed by animals is used up
 Herbivores- cannot digest all plant material, so is passed out
 Carnivores- meat is easier to digest, so is eaten less often, but still some is
passed out
 Some material is inedible, such as bones, so isn’t passed to the nest stage of
the food chain
 An excess amount of protein od broken down and passed out as urine

Decay Process

-

Decay releases minerals and nutrients

Decay cycle

Living things are made of materials they take from the world:






Plants take C, O2, H2, and nitrogen, and turn them into complex carbohydrates
which make them up, which are passed up the food chain
This elements then return in waste products and death
Detritus feeders- break waste down, and then produce waste Eg: worms
Bacteria and fungi then breakdown everything into CO2, H2O, and nutrients
The elements are now returned to the environment, and can be used again

Conditions for microorganisms, and decay:




Warm- they can work faster, but at 45+ they denature
...

Compost- vegetables and weeds are allowed to decompose and are used as
fertilizers

Compost:
Warm- improve rate of reaction
and optimum temperature for
enzymes
Holes in compost containerintroduce oxygen into the
mixture to allow enzymes to
respire and break down
material

Carbon Cycle:

All the main molecules that make up our bodies (carbohydrates, proteins, fats and DNA)
are based on C atoms combined with other elements
Carbon cycle- constant cycling of carbon in nature:
1
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Respiration
 CO2 is produced as waste, so C is returned to the atmosphere
 When plants and animals die they are broken down by decomposers an
detritus feeders
3
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6- Old and New Species

The origins of life on Earth

Life began on earth 3-4 billion years ago
Fossils



Remains of organisms from many 1000s/ millions of years ago
Animals and plants are preserved on rocks, ice and other places

Fossils form in 1 of 3 ways:
1
...
Casts and impressions
 Fossils can be formed when they are buried in soft material like clay
 The clay hardens around the organism as its decaying, leaving a cast
 Roots, burrows and footprints are also formed, building a picture of what life
was like on earth
3
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New predators
 Predators may evolve, or existing species may move to an area- this can be
due to human intervention
 The prey don’t have adaptations to avoid them, and nor do they have usually
time to develop them against a new predator
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Successful competitors
 New mutations can give one type of organisms an advantage over another
 Or another species in introduces that is a more successful competitor, and
takes over from other organisms



They can make a species extinct by eating all its food, water or territory, or in
the case of plants, light
4

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