- 1. Evolution and the environment 11 February 2011
2. Adaption in animals
- All living things have adaptations which allow them to survive
in the conditions in which they live.
- Animals living in cold environments have thick layers of fat
and thick insulating fur. They also have a small surface to volume
ratio.
- Animals living in hot, dry climates have thin fur, little body
fat and large surface to volume ratios.
- Some animals change colour in different seasons to get year
round camouflage.
1 3. Adaptation in plants
- Plants must adapt in order to preserve their water supply which
is lost by evaporation through the stomata in their leaves.
- Some plants have small, wax coated leaves (like succulents
cacti)
- Plants in water rich areas have board leaves.
- Some plants have thorns to prevent them being eaten by
animals.
2 4. Competition in animals
- Animals compete for food, territory and mates.
- Competition can be with members of the same species or between
different species competition between same species is often the
most intense.
- Animals have adaptations that make them good competitors and
more able to survive.
3 5. Competition in plants
- Plants compete for light, water, nutrients (minerals) and
space.
- Plants are adapted to make them able to compete with other
plants in their environment.Examples are: types of root (wide
spreading), leaves (fast growing) and seeds (wide spreading).
- The best adapted plants survive and produce a crop the next
year.
4 6. Inheritance
- Young animals and plants have similar characteristics to their
parents. This is because they inherit genetic information passed
down in the sex cells (gametes) of their parents.
- The nucleus of the sex cells contains chromosomes that control
the characteristics of an organism.
- Half the genes come from each parent.
5 7. Types of reproduction
- Asexual reproduction all the offspring are exact clones of the
original parent. There is no genetic variety.
- Sexual reproduction male and female gametes are equally shared.
There is genetic variety. Different versions of a particular gene
are called alleles. The offspring get a random mix of alleles.
6 8. Cloning
- A clone is an exact match of its one parent.
- Tissue cloning is taking cells from a plant as cuttings and
growing a new plant.
- Animal cloning involved removing a ova from the mother, taking
out its nucleus and replacing it with a complete nucleus of the
cloned parent. The embryo then grow in the normal way.
7 9. Genetic engineering
- Genes from chromosomes of an organism are cut out using enzymes
and transferred in bacteria cells. These grow and can be harvested
later.
- Healthy DNA can be put into cells to prevent genetic
diseases.
- There are growing concerns about the wisdom of using genetic
engineering and its long term affect on the world.
8 10. Origins of life on Earth
- Evidence of the past life on Earth is found in fossils.
- Fossils were formed when harder parts of animals and plants
where covered by mud the prevent decay and they turned into
minerals or the animal or plant was frozen in ice.
- Scientist track changes in plant and animals to get an idea of
how things evolved.
9 11. Theories of evolution
- The theory states that all life on Earth evolved from simple
life forms that existed millions of years ago and which are now
extinct.
- Darwins theory suggests that the fittest survive in a process
of natural selection.
- The fossil record now allows us to trace some developments in
plants and animals over millions of years.
10 12. Natural selection
- New life forms result from small changes (mutations) in
organisms.
- Different organisms show variation due to different genes.
- The organisms that survive are the ones most suited to their
environment.
- These organisms breed successfully and pass on their mutated
genes to their offspring.
11 13. Extinction
- Extinction is the permanent loss of all the organisms of a
species.
- Extinction is caused by one or more of these environmental
changes:
- (d) major climate changes
12 14. Effects of population explosion.
- The human population is growing very rapidly due to improved
food harvesting, control of diseases and no natural predators.
- Population growth is reducing the amount of land available for
other species and future growth.
- There is a huge rise is waste being produced causing major
pollution.
- Raw materials are being rapidly used up.
13 15. Acid rain
- Burning fossil fuels result in the release of carbon dioxide,
sulphur dioxide and nitrogen dioxide gases into the
atmosphere.
- These gases dissolve in water to produce dilute acids which
fall as rain.
- The acid rain may destroy trees and make lakes and rivers too
acidic for plants and animals to survive in them.
14 16. Global warming
- Increased levels of carbon dioxide and methane are thought to
be causing global warming as these gases prevent heat escaping from
the Earth.
- Large scale deforestation and increased burning fossil fuels
are causing carbon dioxide levels to rise.
- More cattle and rice fields are leading to the release of more
methane gas.
15 17. Sustainable development
- This means looking after the environment so there areresources
from future generations.
- Conservation of existing resources is essential if the future
is to be secure.
- This involves both using less of existing raw materials, using
renewable materials and recyclingwaste as much as possible.
- Careful planning is essential.
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