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POPULATIONS
Population size
•A population is the number of a species living in a particular area
What factors could change a population?
• Competition
• Predation
• Migration
• Disease
• Natural disasters
• War
• For food, water and space
• Predators will eat prey and reduce the population (including the number of offspring)
• Members of the population may leave the area
• A disease could kill some of the population
• Drought, fire, floods, volcanic eruptions etc could alter the habitat and affect the population
• Wars can result in the death of many members of a population
What else can affect the numbers and the distribution of a population?
• How well are individuals adapted?
• This will affect their survival in a habitat.
• What else lives there? This may mean competition for food.
• There may be predators.
What is adaptation?
• Adaptation describes how a plant of animal is able to survive in various environments
• Well adapted organisms can cope with the different aspects of their environment, for example, the temperature
It is always a struggle for plants and animals to
surviveANIMALS STRUGGLE :
• For food• For water• For protection
against weather• Against being
eaten by predators• Against disease• Against accidents
PLANTS STRUGGLE:• For water• For light• For minerals in the
soil• Against weather• Against disease• Against being
eaten
How does adaptation help organisms?
• Well adapted organisms are better at coping with extremes of weather
• They are better at competing for food• They are better at escaping from
predators• They are more likely to survive in
their habitat and produce offspring
An arctic habitat
• This sort of habitat can have extremely low temperatures
• The ground is covered with white snow for most of the year
How are animals adapted to survive in
the Arctic?• Animals like polar bears will have a thick insulating coat
• They usually have a large amount of body fat
• They have a large body size to surface area ratio
• They have a camouflaged coat
How do these adaptations help?
A thick fur coat
Large body size to surface area ratio
A large amount of body fat
Camouflage
Traps heat to keep warm
Reduces heat loss by radiation
Acts as a food store and to keep warm
White fur is good camouflage to hide from prey
A desert environment• A desert can have
very little rainfall• There is a lot of
sunshine during the day
• There is very little shade
• The temperatures can get very hot
• At night it can become very cold
How is a camel adapted to survive in the desert?
• Camels can store large amounts of water in the fat in their humps
• They have feet with a large surface area to allow them to walk on sand
• They also have long eye-lashes to stop sand blowing into their eyes
How do reptiles survive in the desert?
• Most reptiles will find some shade under a rock during the hottest part of the day
• When walking on hot sand a lizard will try to touch the ground with only a small area
• This lizard keeps swopping feet, and only stands on two feet at a time
• This snake keeps a loop of itself off the ground as it moves across the sand sideways
How do plants survive the desert?
• A cactus has a long tap root to reach water deep under the ground
• It has a thick, fleshy stem to store water
• It has needle-shaped leaves to prevent water loss through the stomata
• The needles help to stop animals from eating it
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http://www.worldofteaching.com is home to over a thousand powerpoints submitted by teachers. This is a completely free site and requires no registration. Please visit and I hope it will help in your teaching.
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