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Name _______________________
Biodiversity is the term used to describe the range of living organisms that are found on the
planet. Human activities can have negative impact on Biodiversity by decreasing it. Examples
of such activity include:
Many human activities can affect the biodiversity in an area.
1. Habitat destruction
destroying the homes of animals
2. Over-fishing
catching more fish than needed
3. Deforestation
cutting down too many trees
4. An oil spill
oil being released into the sea
All of these would DECREASE biodiversity as the numbers of animals and plants would
An animal that hunts other animals is a predator. What it hunts is its prey. The feeding
relationship can be shown in a food chain.
Food chains are joined together to form food webs.
Food chains and food webs show how energy is transferred from one organism to another.
Each stage is linked by an arrow. Every food chain/food web starts with a producer (green
plant). They make their own food through the process of photosynthesis. Energy from the
sun is used to form a chemical energy, which gets passed to the consumer when it is eaten.
Food chains and food webs describe the interdependence of living things. The removal of
organisms from either a food chain or a food web can have a consequence on the other
organisms in that chain or web.
If one organism is removed from a food web, the other animals and plants in the food web
can also be affected.
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In the food web above, if the slugs were all removed, then the thrush numbers would
DECREASE due to a lack of food.
The numbers of grass could INCREASE as they are no slugs eating it.
Natural hazards
Natural hazards affect all populations. Floods, cyclones, droughts, fire and heat waves
are related to climate change, deforestation and the world’s weather systems. Earthquakes,
volcanoes and tsunamis are all the results of movements in the Earth’s crust. They have the
greatest impact in a areas where the population is high.
Such hazards will have a wide variety on biodiversity. With habitats being destroyed,
animals and plants will lose shelter, food, and reproductive mates. These all affect the
survival rates of the species.
Sampling techniques and abiotic factors
If we want to learn about a particular habitat, we need to carry out an investigation. This
involves collecting and identifying organisms and measuring the physical conditions. It is not
possible to collect all the organisms within a habitat, so we take samples. A quadrat is used
to take plant samples, it is thrown randomly and the number of squares which contain the
plant are counted. A pitfall trap is used to take sample of small organisms that live on the
An abiotic factor is a physical factor such as light, moisture, pH or temperature. Abiotic
factors influence the organisms living in a habitat.
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Abiotic factor
Light intensity
Technique for
Possible source of
Ways of minimising
Use a light meter,
Operator may shadow Stand to one side of
direct the light
the light sensitive
the light meter so
sensitive panel
that there is no
towards the light.
Take a reading
Soil moisture
Use a soil moisture
Moisture from a
Wipe the probe in
meter, push the
previous reading on
between readings.
probe gently into the
the probe.
soil. Take a reading.
Animals and plants are adapted to where they live. This means that they have certain
inherited features that allow them to survive in a habitat. For example, fish are adapted to
living underwater. They have gills to take in oxygen out of the water, fins to swim with and
streamlined bodies to help them move easily through the water.
A CAMEL has broad feet to stop it sinking into the sand
EAGLES have good eyesight to hunt prey
DEER have good hearing to listen out for predators
In birds, the shape and size of their beak is matched to the type of food they eat.
1. Very small beaks will be used to eat small insects or seeds e.g a CHAFFINCH
2. Birds with sharp pointed beaks will often eat other animals e.g a HAWK
3. Birds with very large beaks can eat a lot of fish very easily e.g a PELICAN
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Animal behaviour
Animals can learn behaviour, ranging from being trained to perform extraordinary things
(guide dogs) to animals being trained to entertain us (whales and dolphins).
Hungry snails will follow a trail of flour and water that is painted onto a Perspex sheet. This
is of survival value as the snail will move in the direction of a food source.
An animals learning is influenced by a number of internal and external factors. Animals
exposed to a continual harmless stimulus will eventually stop responding to the stimulus, a
process known as habituation.
Animal behaviour can be studied experimentally by investigating how they respond to the
Importance to animal
Moves towards moisture
Need to keep breathing system
moist to be able to breathe
Blowfly maggot
Moves away from light
Needs to stay in dark places to
obtain food and protection
from predators
day length
Conserves energy when food is
in short supply
Becomes active
Less chance of being caught by
Enables it to obtain food
day length
Micro-organisms and industry
Living cells such as bacteria and yeast can be used to produce a range of useful substances.
Yeast is used to make bread and wine. Yeast can respire without oxygen (anaerobically) and
this process is called fermentation.
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Carbon dioxide makes bread dough rise and alcohol is used to produce wine, beer and all
other alcoholic beverages.
Bacteria is used in the manufacture of both cheese and yoghurt. Bacteria feeds on the
lactose sugar in milk and converts it into lactic acid. This causes the milk to curdle and
change consistency and taste, forming yoghurt. To make cheese an enzyme called rennet is
then added to the yoghurt like substance. Rennet used to be obtained from the lining of
calves stomachs but is now manufactured differently. Rennet causes the milk proteins to
clot forming curds which go on to form cheese when salt is added and the solid is allowed to
Plant reproduction
To reproduce sexually some plants produce flowers. The flowers contain the sex organs.
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Many plants can reproduce in way that only involves one parent and no seed formation. This
is called asexual reproduction and does not involve the formation of sex cells. The parent
plant produces new cells that separate from the parent and become new plants.
Commercial plant growth
When plants are grown commercially growers are always looking for ways to speed up the
growing process. One of the ways in which they do this is through the use of polytunnels and
another is the use of rooting powders.
Germination is the development of a new plant from the embryo plant in a seed. Seeds need
Water, Oxygen and Warmth to germinate. All of these factors can affect the rate of
germination as can competition when many seeds are planted together or too close together.
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Photosynthesis is the process where green plants trap the light energy from the sun using
the green pigment chlorophyll in their leaves and convert it into chemical energy in the form
of glucose.
The glucose that is not required is converted into the storage carbohydrate starch. To
prove a plant is photosynthesising it can be tested for starch.
We can measure the rate of photosynthesis by how much oxygen is produced in a given time.
There are three factors that can limit the rate of photosynthesis, we call them limiting
factors. They are:
Light intensity
Carbon dioxide concentration
This is often shown in a graph.
Nitrogen cycle
The element nitrogen is recycled through all ecosystems. Nitrogen is essential to the
survival and chemistry of all living things because it is found in all proteins. The nitrogen
cycle involves a series of chemical reactions that transfers nitrogen between the non-living
environment and living things.
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Nitrogen can be found present in soil in the form of nitrates. Plants can absorb nitrates
through their roots and use the nitrates for growth. Therefore, an increase in nitrate
concentration in soil can increase the growth of plants.
Nitrates can be found in fertilisers to encourage plant growth. Other minerals are found as
well. Natural fertilisers include manure and growing plants like clover which can then be
ploughed back into the soil.
Importance to plant growth
‘N’ Nitrogen
For leaf growth
‘P’ Phosphorus
For root growth
‘K’ Potassium
For growth of fruit and flowers
Excess nitrates however can cause pollution in an environment, and cause the growth of
unwanted plants, i.e. weeds and algae.
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Farmers make use of fertiliser to increase the growth of their crops,
however, improper
use of them can have a negative effect on the environment.
Fertilisers can be a source of pollution. Excess fertilisers used by farmers are washed off
in to rivers and underground water sources. Eutrophication is the main environmental hazard
associated with fertilisers. Excess fertilisers cause the nitrates levels in rivers to increase
and encourage the growth of algae. When the algae die the bacteria feed on them using up
all the oxygen which means that the other organisms suffer and die from oxygen deprivation.

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