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Biology Unit 1
Organelle
Function
Nucleus
An organelle found in many living cells
containing the genetic info
...
GLUCOSE + OXYGEN -> CARBON DIOXIDE + WATER
Specialised cells are cells that have been adapted or created so that they suit a particular job the
best
...
Substances that diffuse into and out of the cell:
Oxygen
Carbon Dioxide
Glucose
Water
-
Factors that affect the rate of diffusion:
Concentration
Gas or liquid
Temperature
Concentration Gradient
Viscosity
Thickness
-
Diet and Exercise
Malnutrition occurs when you don’t have enough nutrition in your diet or you have too much
...
A healthy diet contains the right balance of different foods, including carbohydrates, proteins, fats
which are used by the body as energy and to build cells
Mineral ions and vitamins are needed in small doses to keep the functioning of cells in the body
normal
BMI = mass
(height)2
Cholesterol:
-> Decreases all membrane permeability and floridity
-> Important component in the myelin sheath of neurones
Processor to:
- Steroid Hormones
- Vitamin D
- Bile acid
-> Cholesterol is produced by the liver and can be found in everyday diets
-> Liver produces 1g/day of cholesterol
-> Dietary cholesterol is absorbed normally into the large intestine
Statins:
-> Statins are a chemical originally found in fungi
-> They are used to reduce someones cholesterol diet
-> They block an irreversible step in the manufacturing of cholesterol in the body
Metabolism:
Metabolism - the chemical reactions that happen in your body
- Chemical reactions can be faster or slower and this speed is called the metabolic rate
- The metabolic rate varies from person to person
- Someone with a higher metabolic rate will therefore need more energy hence more food will
be used in respiration to generate this energy
Factors affecting the metabolic rate:
1
...
2
...
3
...
4
...
During exercise your
metabolic rate increases and stays fast for some time after you finish
...
5
...
6
...
Disease
Infectious disease - a disease you can catch and spread
Microorganism - a really small organism that can only be seen through a special machine
Pathogen - a microbe all around us that carries and cause disease
Toxin - a poison made by a bacterium or virus
Pathogens (bacteria and viruses) can cause disease either by directly damaging your cells or by
producing toxins (poisons) which affect your body
...
Saliva contains a chemical which kills bacteria
Wax is a physical barrier; it traps microbes and
has some antiseptic qualities
The stomach contains HCL, the acidic pH kills
microbes ingested with our food
The eyes blink to remove dirt
...
Once there, they come into contact with
the white blood cells of your immune
system
...
Lymphocytes
Lymphocytes recognise specific antigens on the surface of a pathogen
...
The lymphocyte also produces memory cells which remain in the blood, they can recognise the
same pathogen if it invades again and produces antibodies quickly
...
1
...
They produce a unique ‘specific’ antibody to destroy the disease causing pathogen
3
...
4
...
5
...
6
...
This is why you usually only suffer from the chicken pox virus once
...
Immunity is when you cannot catch a certain disease
We usually do not suffer from the same particular infectious disease more than once because our
white blood cells detect antigens on the surface of an invading pathogen
...
Some white blood cell retain a
‘memory’ of these pathogens, these are called memory cells
...
This makes you immune to a disease
...
Bacteria mutate and sometimes mutations cause them to be resistance to an antibiotic
2
...
This will kill the nonresistant strains of bacteria
...
3
...
4
...
The resistant bacteria reproduce and the population of antibiotic resistant bacteria increases
...
There is an increased likelihood that the resistant bacteria will infect someone else who
becomes ill
7
...
An antibiotic is a medicine that kill disease casing bacteria inside the body
...
Painkillers help to reduce the symptoms of infectious diseases but don't actually kill the pathogen
that is causing the illness
Antibiotics, including penicillin, are used to help cure bacterial diseases by killing the infectious
disease in the body - however antibiotics cannot be used to kill viral pathogens as the cannot kill
things that live and reproduce inside the cell
...
Vaccination
- Vaccinations involve injecting a small amount of the dead or inactive pathogen which causes a
particular illness
- These carry antigens which causes your body to produce antibodies which attack them
- The memory cells remember the particular antibody which is used to fight this disease
- This means that if you were to develop this particular illness your body would be able to fight
and get rid of it a lot quicker - reducing the risk of the illness affecting you
- The MMR vaccine protects children against measles, mumps and rubella
...
g
...
✓ Epidemics (large out breaks) can be prevented if a large percentage of the population is
vaccinated
✓ Disease cannot spread as quickly
X Vaccines don’t always work and sometimes don’t give you complete immunity
X Sometimes people have bad allergic reactions to a particular vaccine
Drugs
Drug Testing
Animal Testing -> Testing the experimental drug on a ‘whole’ organism
...
B
...
Safe -> The experimental drug is non-toxic and causes unacceptable side-effects
...
Stable -> The medicine can be stored for some time and used under normal conditions
Clinical Trail -> Collects information on the effectiveness of a treatment
...
Incorporated -> The drug reaches the target inside the body
...
Reliable -> Evidence from extensive trials involving many patients and volunteers
...
Placebo -> An inert substance given to the control group
...
Blind Trail -> The patients/ volunteers do not know if they have been given the experimental drug
or placebo
...
Bias -> This will distort the collection or analysis of the data e
...
an external influence with a
vested interest such as a drug company wanting a drug trail to go well
...
g
...
- Alcohol is extremely addictive and alcoholics
experience a constant drunkness so require more
to feel a buzz
Being addicted to drugs is extremely hard to get rid of because the addict experiences extremely
painful and bad withdrawal symptoms, these can include:
- Anxiety
- Insomnia
- Sweating
- Vomiting
- Nausea
Performance Enhancing Drugs
- Some athletes take those to make them stronger, fitter, faster and overall better at sport
- These can include anabolic steroids (increase muscle size) and stimulants (increase heart rate)
- Steroids can cause high blood pressure
- These are all banned for athletes
- Bodybuilders use steroids to build muscle
For
Against
Athletes have the right to make their own decisions It is unfair to give people an advantage by taking
about whther taking drugs is worth the risk or not drugs
Drug-free sport isn't really fair, different athletes
have access to different training facilities, coaches,
equipment etc
...
g
...
This builds up in the summer months so that they can
live off their body fat through the winter
Hair, thick fur
This traps air and insulates therefore reducing heat loss
White fur
Provides camouflage so they cannot be seen easily by prey
Advantages of Hibernation
✓ Food source in Winter
✓ A mammal would need to eat more food in the winter - more respiration to maintain the body
temperature
Disadvantages of Hibernation
X Got to be careful of predators
X Food reserves may run out before the end of the winter
X Habitat may be destroyed/ damaged - unable to escape
Animals often compete with each other for territory, food, water and mates
Extremophiles
Extremophiles are organisms that can live in extremely harsh conditions like super hot volcano
vents, very salty lakes or at an extremely high pressure on the sea bed
Adaptions in Plants
Dessert Plants have Adapted to little Water
Small Surface Area to Volume Ratio - Plants lose water vapour from the surface of their leaves,
Cacti have spines instead of leaves: to reduce surface area and
therefore water loss
- Small surface area compared to their size which reduces
water loss
Water Storage Tissue - For example, cactus store water in their stems
Maximising Water Absorption - Some cacti have shallow but extensive roots to absorb water
quickly over a large area
- Others have deep roots to absorb underground water
Plants compete for each other for light, space, water and nutrients from the soil
To Deter Predators:
- Some plants have armour, like roses have thorns and cacti have spines
- Some plants produce poisons to prevent predators from attacking them
- Some plants have warning colours to warn off predators
Competition
Change in environmental factors can affect the distribution of species (living organisms)
The environment is changing all the time, these changes are caused by living and non - living factors,
these include:
Living - A change in the occurrence of infectious diseases
- A change in the number of predators
- A change in the number of prey or the availability of food sources
- A change in the number of types of competitors
Non - Living - A change in average temperature
- A change in average rainfall
- A change in the level of air or water pollution
Some environmental changes can be measured by using living indicators:Some organisms are sensitive to changes in the environment - these are called indicator
species
Lichen are sensitive to the concentration of sulfur dioxide in the atmosphere, the number and
type of lichen can indicate how clean the air is (lots of lichen means clean air)
If raw sewage leaks into the river then there will be a lot of bacterial population in the water this uses up the oxygen in the water
Invertebrate (e
...
mayfly larvae) are good indicators because they are very sensitive to
dissolved oxygen (lots of mayfly larvae means clean oxygen rich water)
Some environmental changes can be measured by using non-living indicators:Satellites can measure the temperature of the sea surface and the amount of snow and ice
cover
Automatic weather stations tells us the atmospheric temperature at various locations
...
Population Size Increase
E
...
if the number of prey increase, then theres more food available for predators, so more survive
and reproduce leading to an increase in number for them aswell
2
...
g
...
S
...
Population Distribution Changes
This means where an organism lives
E
...
Distribution of birds in Germany changes due to a rise in temperature
Energy and Biomass in Food Chains
- Energy (radiation) from the sun is the source of energy for most living organisms
- Green plants and algae use a small percentage of the light energy from the Sun to make food
-
during photosynthesis
This energy is stored in substances which make up the cells of plants and algae and then works
its way through the food chain as animals eat them and each other
The mass of living material (biomass) is less and less at each trophic level and previous level
As a food chain progresses the amount of energy that is passed on decreases as the energy is used
by each organism (e
...
in movement, respiration, the waste of that animal and transferred to the
surroundings by heat loss, sweat etc
...
Carbon Dioxide in the Atmosphere
Carbon Dioxide from
Volcanoes
Photosynthesis
Animal
Respiration
Plant
Respiration
Plants
Oceans
Dead plants and
Animal form coal
and oil
Carbon Dioxide becomes part
of the plants and animals
(especially shells) which die and
collect at the bottom of the
ocean
...
- Carbon is removed from the environment by green plants and algae for photosynthesis
- The carbon is also used to make carbohydrates, fats and proteins which make up the body of
plants and algae
- When green plants and algae respire, some of this carbon becomes carbon dioxide and is
released back into the atmosphere
- When green plants and algae are eaten by animals these animals are eaten by other animals, so
some of the carbon becomes part of the fats and proteins of these animals
- When the animals respire some of this carbon dioxide is released back into the atmosphere
- When green plants, algae and animals die, some animals and microorganisms feed on their
bodies
- Carbon is released into the atmosphere when these organisms respire
- By the time the microorganisms and detritus feeders have broken down the waste products and
dead bodies of organisms in the ecosystem and cycled the material as plant nutrients, all the
energy originally absorbed by green plants and algae has been transferred
- Combustion of wood and fossil fuels fuels releases carbon dioxide into the atmosphere
Detritus Feeders - They break down matter into smaller pieces with a larger surface area so the
bacteria and fungi can decompose them quicker
Decomposition - The process by which dead organisms are broken down
Syphsrotic Feeders - Bacteria and Fungi release enzymes externally to break down the food to
simple nutrients
When things decay elements like carbon, oxygen, hydrogen and nitrogen are released back into the
soil to be used by plants to form complex compounds (carbohydrates, proteins and fats)
Microorganisms
Microorganisms break down materials (called decay), they work best in warm, moist aerobic
conditions (lots of oxygen)
Conditions
]]]]]]]]
Reason
Warmth
If it is too hot, then the microorganisms (bacteria and fungi) enzymes denature so they
can’t break down the decomposed vegetation
Moisture
The fungi and bacteria are unable to decompose the leafs because they cannot digest the
food, it also stops the microorganisms from drying out
Oxygen
Without oxygen the leafs couldn't be decomposed - the microbes need oxygen to
survive and respire
Decomposition is important because the important nutrients in the body of a dead animal can be
very useful
...
The dead bodies are first broken up by detrivors, third include earthworms, woodlice, mites and
springtails
...
Proteins ——> amino acids
Fats ——> Fatty Acids and Glycerol
Carbohydrates ——> Sugars
By respiring they release Carbon Dioxide into the air which can be used by plants in
photosynthesis
...
The Flow of Energy and the Recycling of Nutrients
SUN
PRODUCER
Consumer
Pool of
Nutrients
Decomposer
= Energy
= Nutrients (They are recycled)
Dead Animals
and Plants
Detrivors
(Detritus
Feeders)
Smaller Pieces
Larger
Surface Area
Enzymes in
Bacteria
and Fungi
Molecules/ Atoms
Composting - 6 Golden Rules
1
...
Add layers of soil between the layers of plant materials
(Gives te micro organisms the nutrients they need)
3
...
Turn the compost every 4-6 weeks
(Aids air and therefore oxygen to the pile)
5
...
Do not add meat or fish waste
(This stops the vermin from going into the compost)
Advantages of Composting:
✓ Saves on wastefully
✓ Cheaper than recycling it
✓ The compost can be good to use on other flowers
✓ Better for the environment than land fill sites
On some landfill sites other decay microorganisms called methanogens can grow, the produce a
lot of methane which is extremely bad for the environment as they produce a lot of methane
Type of Composting
Advantage
Disadvantage
Windrow Composting
Cheap
Cannot treat meat waste
In - Vessel Composting
- Cannot monitor conditions to
ensure fast decay
- Can include meat waste
Costs a lot to buy all of the
equipment
Anaerobic Digestion
- Treats all but wood waste
- Produces methane which can
generate heat and electricity
Costs a lot to buy all of the
equipment
Food Webs
A food web is a diagram that shows all the food chains in an ecosystem and how they react/
interact with each other
Oak tree
Leaf roller moth
Mice
Owl
Bushes
Herbs
Winter Moth
Insects
Voles
Rove Beetles
Shrews
Oak tree, bushes and herbs are all producers because they all make their own foods and dont have
to rely on others for their food
The mass of living material, often measured as the dry mass
...
A Stimulus is a change in your environment which you may need to react to
-> You have 5 different sense organs - eyes, ears, nose, tongue and skin
-> They all contain different receptors - receptors are groups of cells which are sensitive to a
stimulus
...
g
...
The eye is a sense organ and contains light receptors (sensitive to light)
The ear is a sense organ and contains sound receptors (sensitive to sound)
Receptors in the ears that are sensitive to changes in position allow us to keep our balance
Receptors on the tongue and in the nose are sensitive to chemicals and enable us to taste and
to smell
Receptors in the skin are sensitive to touch, pain and change in temperature
Light receptor cells like most animal cells, have a nucleus, cytoplasm, and cell membrane
...
Relay Neurone
The nerve cells that carry signals from sensory neurones to motor neurones
...
Effector
Muscles and glands are known as effectors - they respond in different ways
...
Synapses
- This is the connection between two neurones
- The nerve signal is transferred by chemicals which
diffuse across the synapse (or gap)
- These chemicals then set off a new electrical signal in
the next neurone
Synapses
The CNS (Central Nervous System)
1
...
2
...
3
...
4
...
The connection between neurones is called a synapse, the nerve signal is transferred by chemicals
which diffuse (move) across the gap
...
The stimulus is detected and changed into electrical impulses by the receptor
2
...
At the synapse between a sensory neurone and a relay neurone in the CNS, the impulse is
transferred by chemicals which diffuse across the synapse and then set off a new electrical
impulse into the relay neurone
4
...
This impulse is sent to the effector (muscle or glands)
6
...
- Your organs, tissues and cells cannot function properly if these conditions keep on changing
...
This balancing in the body is called Homeostatic
...
Things we need to keep constant in the body:
Ion Content
- Ions (e
...
Sodium) are taken into the body in food, then absorbed into the blood
- If the food contains too much of any kind of ions then the excess ions need to be removed; e
...
a salt meal will contain to much salt (Na+)
- Some ions are lost in sweat (which tastes salty)
- The kidneys will remove the excess from the blood, this is got rid of in the urine
Water Content
- Water is taken into the body by food and drink
- It is lost through the skin as sweat
- It is lost via the lungs when we breathe out (water vapour)
- Excess water is lost from the kidneys via urine
Body Temperature
- In the body the optimum temperature for enzymes and cells to operate is 37oC
- The brain controls body temperature
Blood Sugar Content
- Eating foods containing carbohydrates puts glucose into the blood from the gut
- Insulin controls the level of glucose in your blood
- This means that our cells can get a constant supply of energy
The balancing act is known as homeostatic
...
Nervous System
-> Acts quickly
-> Information carried as nerve impulses
-> Nerve Impulses travel along nerve fibres
-> Effects last for a short time
-> Effects are isolated to a specific gland or muscle
Endocrine (Hormonal)
-> Acts slowly
-> Information carried as chemicals
-> Chemicals travel in blood
-> Effects last for a long time
-> Effects are wide spread
Hormones control the function of many of your bodies organs, they also control the activities of
you individual cells
...
A woman menstrual cycle is a good example of how this control works
The aim of the menstrual cycle is to prepare the body for pregnancy, it normally lasts for 28 days
In ovaries <- fallide (egg matures)
-> Follicle Stimulating Hormone
-> Luteinising Hormone
-> Progesterone
-> Oestrogen
Main 3 Hormones:
Produced in the Pituitary Gland
Produced in the ovaries
1
...
Oestrogen
- Produced in the Ovaries
- Causes Pituitary to produce LH
- Inhibits the further release of FSH
3
...
The pituitary gland releases FSH which circulates in the blood to the ovaries (how hormones
travel)
2
...
3
...
4
...
Oestrogen also inhibits the secretion of FSH (hence preventing multiple follicles from
developing eggs) and the high levels of oestrogen stimulate the pituitary gland to secrete LH
...
The surge in LH around day 14 brings about OVULATION
...
7
...
8
...
9
...
10
...
11
...
12
...
Girls are born with around 400,000 follicles in the two ovaries
...
In the menstrual cycle one follicle matures and it contains a mature egg
...
The Use of Hormones for Controlling Fertility:
- Giving oral contraceptives that contain hormones to inhibit the production of FSH so that no
eggs mature
- Giving oral contraceptives that contain oestrogen and progesterone to inhibit egg maturation
- Progesterone makes the cervical muscles produce a thick mucus preventing sperm passing and
reaching an egg
The Use of Hormones to Improve Fertility:
- FSH and LH in a ‘fertility drug’ are given to women who's FSH levels are too low to stimulate
egg maturity (e
...
in IVF)
- IVF involves giving the women FSH and LH to stimulate egg maturity, the eggs are taken and
fertilised by the fathers sperm
- They then develop into embryos
- They are then inserted back into the womens womb
- This however can have bad ethical problems
The Pill:
Advantages
Disadvantages
The pill is over 99% effective at preventing
pregnancy
It isn't 100% effective - theres still a chance you could get
pregnant
It reduces the risk of getting some cancers Doesn't work when people are on certain medication
Some hormones if consumed too much can have irreversible
health risks
Doesn't protect against STI and STD’s
It can cause side effects like headaches, nausea, irregular
menstrual bleeding and fluid retention
Control in Plants
Auxin
- Auxin is a plant hormone that controls growth near the tips of shoots and roots
...
- It is produced in the tips and moves backwards to stimulate the cell elongation (enlargement)
process which occurs in the cell just behind the tips
...
- Extra auxin promotes growth in the shoot but inhibits in the roots
...
When a shoot tip is exposed to light, more auxin
accumulates on the side thats in the shade than the side in
the light
...
This means the side in the shade elongates quicker than the
side in the light, so the shoot bends towards the light
...
When a shoot is growing sideways, gravity produces
an unequal distribution of auxin at the tip, with more
auxin on the lower side
...
This means the lower side grows quicker, bending the
shoot upwards
Roots Grow Towards Gravity
1
...
2
...
An uneven amount of moisture either side of a
root produces more auxin on the side with more
moisture
...
This inhibits growth on that side, meaning the root
bends in that direction, towards the moisture
...
Plant Hormones and Agriculture
- Most weeds in crop fields are broad - leaved, unlike grasses and cereals which have very narrow
leaves
...
- They disrupt their normal growth patterns, which soon kills them but leaves the crops
untouched
...
- This helps growers produce lot’s of clones of a really good plant quickly
...
Genes make up chromosomes
Chromosomes carry genes
Genes are made up of DNA
Genes control inherited characteristics through carrying the code leading to the synthesis of
protein in the cell
DNA
The genetic material; found in the nucleus of a cell
...
Cell
The basic building block of a living organism
...
Each one contains the code for a
particular inherited characteristic, that is, to make a particular protein
...
They are found
colour, eye colour, height etc
...
Nucleus
The large, membrane bound organelle inside a cell that contains genetic material
...
g
...
The joining or fusion of male an female gametes is
called sexual reproduction
- A zygote is the joint sperm and egg
- The mixture of both the male and female genetic information can lead to a variety of offspring
- Sexual Reproduction occurs inside the body
The nucleus in each cell
contains half the genes
needed to form the baby
An egg cell from the
mother
The sperm cell enters
the egg when fertilisation
takes place
The two nuclei start to
fuse together
Asexual Reproduction
- This occurs outside of the body
The cell formed is called a
zygote, the nucleus contains the
genes needed to form a baby
-
This only needs one parent
The organism produced is always an exact clone of the original genes it was produced from
This is used by farmers to produce identical crops
There is no mixing of genetic information so there can be no genetic variation
New plants are produced quicker by taking cuttings from the older parent plant and are exactly
identical
Cloning
Plants
- Tissue Culture
This is where a few plant cells are put in a growth medium with hormones, and they grow into
new plants - clones of the parents
These plants can be made very quickly, in very little space, and be grown all year
- Cuttings
Gardeners can take cuttings from good parent plants, and then plant them to produce genetically
identical copies (clones) of the parent
These plants can be produced quickly and cheaply
Animals
- Embryo transplant
1
...
The sperm is then used to artificially fertilise an egg cell
3
...
The cloned embryos can then be implanted into lots of other cows where they grow into baby
calves (which will all be genetically identical to each other)
5
...
Taking an unfertilised egg cell and removing its genetic material (the nucleus)
2
...
g
...
The egg cell is then stimulated by an electric shock - this makes it divide, just like a normal
embryo
4
...
This technique was used to create Dolly - the famous cloned sheep
Adult
Body Cell
Egg
Cell
Nucleus
Removed
+
Nucleus
removed
Electric shock
Cloning
Embryo
Implanted into
surrogate
mother
Live
animal
Advantages
Disadvantages
Gets you lots of ideal offspring
Reduced gene pool, fewer different alleles in population
...
A useful gene is ‘cut’ from one organism’s chromosome using enzymes
2
...
Scientist use this method to do all sorts of things - for example, the human insulin gene can be
inserted into bacteria to produce human insulin
Genes can be transferred into Animal and Plant cells:This method can be used to transfer useful genes into animals and plants at the very early stages of
their development (i
...
shortly after fertilisation)
This means they'll develop useful characteristics:
- Genetically modified crops have had their genes modified e
...
to make them resistant to viruses,
insects or herbicides (chemicals used to kill weeds)
- Sheep have been genetically engineered to produce substances, like drugs, in their milk that can
be used to treat human disease
- Genetic disorders like cystic fibrosis are caused by faulty genes
...
Genetically Modified Crops
Genetically Modified Crops - Plants can be modified by inserting the required gene into the cells of
an early embryo - these plants are called GM Crops
...
> Crops can also be modified so that they are ‘resistant’ to herbicide, this means that the farmer
can spray the plant with a herbicide that would normally kill it, in order to kill the weed without
damaging the crop
...
Evolution
This is the theory that all living things today evolved from the first simple life forms
...
Space - chemicals arrive on earth in meteorites
...
The sun
- Darwin's theory was only gradually accepted because he had no true evidence for the theory
...
- He couldn't give a good explanation as he didn’t know anything about genes or mutations
...
Eventually a new species may be produced
...
Natural Selection: The process by which evolution takes place
...
Giraffes with longer necks can reach more food and therefore have more offspring than less well
adapted individuals - they survive better because they can reach the most food
...
Organisms produce many more offspring than their environment can support
...
Despite the overproduction the number of individuals of a species remain fairly constant
...
) or
the effects of disease and predators
...
There is a variation within a population due to the different genes they inherit
...
4
...
5
...
This is survival of the fittest
...
Why does the rate of change in organisms change when the environment changes?
When the environment changes, the speed of change can be rapid as more of the random
mutations may be beneficial under the new conditions
...
- As each new ‘type’ of organism evolved, the older less well adapted ones became extinct
...
Large Seed Eating Finch
- Bigger beak to eat bigger
seeds
The Peppered
Insect eating finch
- Thinner beak for catching
insects from under bark and
stones
...
- Before the industrial revolution the light moth was more common but after the industrial
-
revolution the dark moth was more common because everything was covered in soot and smog,
and the moth needed to adapt and mutate to blend into the darkened walls
...
The Moth then produces offspring with the dark winged genes - this is evolution
...
He believed in the inheritance of acquired characteristics (as opposed to the
inheritance through genes
...
• Example - if a giraffe stretched its neck for leaves the neck would inherit the longer neck, and
continued stretching would make it longer still over several generations
...
Alleles -> Two different types of genes
Studying the similarities and differences between organisms allows us to classify living organisms
into animals, plants and microorganisms and it helps us to understand evolutionary and ecological
relationships
...
Mutations
- A mutation is a change an organisms DNA
- Most of the time they have no effect but sometimes they can be beneficial and produce a useful
characteristic - it may give the organism a better chance of survival and reproduction
...