Old and new species
- Created by: emews
- Created on: 01-12-17 12:33
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- Old and new species
- A fossil is the preserved remains or traces of a dead organism. Fossils are found in rocks and can be formed from:
- Hard body parts, such as bones and shells
- Parts of organisms that have not decayed.
- Casts or impressions, such as footprints or burrows.
- A species becomes extinct when the last individual of that species dies.
- Several factors can cause a species to become extinct. They include:
- new diseases
- new predators
- new, more successful competitors
- changes to the environment over geological time, such as climate change
- a single catastrophic event,
- Several factors can cause a species to become extinct. They include:
- New species can arise as a result of:
- genetic variation
- natural selection
- speciation - where the populations become so different that successful interbreeding cannot happen anymore
- New species can also arise as a result of isolation.
- Polar bears are well adapted for survival in the Arctic. Their adaptations include:
- a white appearance - as camouflage
- thick layers of fat and fur - for insulation
- a small surface area to volume ratio - to minimise heat loss
- a greasy coat that sheds water after swimming
- large feet - to distribute their load and increase grip on the ice
- Camels are well adapted for survival in the desert. Their adaptations include:
- large, flat feet - to spread their weight on the sand
- thick fur on the top of the body for shade
- a large surface area to volume ratio - to maximise heat loss
- the ability to go for a long time without water
- the ability to tolerate body temperatures up to 42°C
- slit-like nostrils and two rows of eyelashes - to help keep out sand
- Cacti are also well adapted for survival in the desert. Their adaptations include:
- stems that can store water
- widespread root systems that can collect water from a large area
- In addition, cacti have spines instead of leaves. These minimise the surface area and so reduce water loss by transpiration.
- An endangered species is at risk of becoming extinct.
- There are several reasons why a species can become endangered.
- A species may even be at risk of becoming extinct if there is not enough genetic variation in the population.
- The number of available habitats may fall below a critical level
- There are moral and cultural reasons for conserving endangered species. Conservation also:
- maintains the possibility that plant species might be identified for medicines
- keeps damage to food chains and food webs to a minimum
- protects our future food supply
- Some species in the UK are endangered, for example the water vole, red squirrel and osprey (bird of prey).
- These three species, along with other endangered species, can be helped by conservation measures such as:
- education programmes
- captive breeding programmes
- legal protection and protection of their habitats
- making artificial ecosystems for them to live in
- These three species, along with other endangered species, can be helped by conservation measures such as:
- There are several reasons why a species can become endangered.
- A fossil is the preserved remains or traces of a dead organism. Fossils are found in rocks and can be formed from:
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