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:

(a) new predators

(b) new competitors

(c) new diseases

(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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