biology

> young animals and plants have similar characteristics to their parents. That's because of genetic information passed on to them in the sex cells from which they developed

> the nucleus of your cells contains chromosomes. Chromosomes carry the genes that control the characteristics of your body

inheritence

> in asexual reproduction there is no joining of gametes (sex cells) and only one parent. There is no genetic variety in the offsprin they are all clones

> in sexual reproduction male and femal gametes join. The mixture of genetic information from two parents leads to gentic variety

types of reproduction

> the gentically identical offspring produced by asexual reproduction are known as clones

> new plants can be reproduced cheaply and quicly by taking cuttings from older plants. The new plants are genetically identical to the older ones

> there are a number of more modern clongin techniques. These include tissue culture of plants and embryo cloing and transfers in animals

cloning

> fusion cell cloning is a form of asexual reproduction

> in adult cell cloning a whole cloned animal can result. the nucleus from a cell from an adult animal is transferred to an empty egg cell from another animal. A small electric shock fuses the cell and starts embryo development. The embryo os placed in a third animal to develop

new ways of cloning animals

> in genetic engineering, genes from the chromosomes of humans and other organisms can be " cut out" using enzymes and transferred to the cells of bacteria

> genes can also be transferred to the cells of animals and plants at an early stage of their development

> there are many potential advantages and disadvantages to the use of genetic engineering

genetic engineering

> fossils provide us with evidence of how much, or how little, different organisms have changed since life developed on earth

> it is very difficult for scientists to know exactly how life on earth began because ther is no direct evidence

the origins of life

> the theory of evolution states that all the species which are alive today, and many more which are now extinct, evolved from single lifeforms which first developed more than three billion years ago

> darwin's throry is that evolution take splace through natural selection

> studying the similarities and dfifferences between species helps us to understand how they have evolved and how closely related they are to each other

theories of evolution

> new forms of genes result from changes (mutations) in existing genes

> diffferent organisms in a species show a wide range of variation because of differences in their genes

> the individuals with the characteristics most suited to their environment are most likely to survive and breed sucessfully

> the genes which have produced these successful charcteristics are then passed on to the next generation

natural selection

> extinction may be caused by changes to the environment, new predators, new competitiors and possibly new diseases

extinction

> the human population is growing rapidly and the standard of living is increasing

> more waste is being produced. If it is not handled properley it can pollute the water, the air and the land

> humans reduce the amount of land available for other animals andplants

> raw materials, including non-renewable resources, are being used up rapidly

the effects of the population explosion

> when we burn fossil fuels, carbon dioxide is released into the atmosphere

> sulfur dioxide and nitrogen oxides can be released when fossil fuels are burnt. These gases dissolve in the rain and make it more acidic ( acid rain)

>acid rain may damage trees directly. it can make lakes and rivers too acidic so plants and animals cannot live in them

acid rain

> there is a large scale deforestation in tropical areas

> large scale deforestation has led to an increase of carbon dioxide in the atmosphere (from burning and the actions of microorganisms). It has also reduced the rate at which carbon dioxide is removed by plants

> more rice fields and cattle have led to increased levels of methane in he atmosphere

> increased levels of the greenhouse gases carbon dioxide and methane may be causing global warming as a result of the greenhouse effect

global warming

> improving your quality of life without compromising future generations is known as sustainable development

> sustainable development involves using natural resources wisely

> we can help by recycling, making our homes energy efficient and avoiding using our cars when possible

sustainable development

> we can use information gained from field studies to help us make planning decisions about sustainable development. One type of information is to use living organisms as indicators of pollution levels

> brown field sites are thought to be more suitable than green field sites for new buildings

> environmentalists believe it is important not to build on Sites of Special Scientific Interest ( SSSI's)

planning for the future