Evolution and the enviroment

Biology notes on evolution and the enviroment

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Adaptions in Animals

  • All living things have adaptions which help them to survive in the conditions where they live.
  • Animals which are adapted to cold enviroments are oftern large, with a small surface area: volume ratio.
  • They have think layers of fat and fur; reduces heat lost, and also provides a food supply, blubber is built up in the summer to keep for the winter.
  • Changing coat colour in the different seasons = all year round camouflage.
  • Adaptions for hot, dry enviroments include:
    LARGE surface area : volume ratio
    Thin fur
    Little body fat
    Behaviour patterns to avoid heat, they
    are often more active in the morning.

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Adaptions In Plants

  • Plants take in water constantly, through their roots in the soil. It moves up the plant, and is lost through their leaves in the transporation stream.
  • Plants always lose water throght the stomata and these allow gases in and out for photosynthesis and respiration.
  • Surface area : volume ratio is important to prevent water loss in plants.
    Some plants have curled leaves, reducing the surface area, and traps a layer of moist.
    Few plants have broad leaves with a large surface area, and funnel the water to their shallow roots.
    Some plants have small fleshy leaves with a thick cuticle to keep water loss down.
  • Plants store water in their tissues = helps to cope with dry conditions.
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Competition In animals and plants

  • Animals compete for water, territory and mates.
  • Competition is common among carnivores, for prey.
  • Animals will aim to avoid direct competition with other species.
  • A successful competitor - An animal which is adapted to be better at finding food or a mate and breeds successfully.

  • Plants compete for light, water and nutrients from the soil.
  • Plants are in competition with other species of plants and their own, such as light with bigger and taller trees, so smaller plants.
  • Adaptions with plants help them to avoid competition, such as, having different types of roots, growing taller to get light etc.
  • To compete successfully, shedding seeds is effective in avoiding competition. Wind is used to help them, or special adaptations for flight, such as a dandelion, some use a mini explosion, berries are produced to tempt animals to eat them and spread their seeds.
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Inheritance and types of reproduction

  • Youngs animals and plants have similar characteristics to their parents, this is due to genetic information passed onto them by sex cells. (gametes)
  • This information is carried during reproduction, carried by the nucleus of cells.
  • Chromosomes - Made up of DNA, carries genetic information.
  • DNA - The material of inheritance.
  • Chromosomes are inherited from both mother and father, but half from each.
  • Genes - A section of DNA, carrying genetic information.
  • Chromosomes are organised so that both of the chromosomes in a pair carry genes controlling the same things.
  • Asexual Reproduction - Only involves one parent, producing identical organisms. There is no joining of sex cells and no variety of offspring ( clones ). Common in small animals, plants and bacteria.
  • Sexual Reproduction - The joining of a male and females sex cell from two parents, and form an individual. In this, genetic information is inherited from both parent, and characterisitcs are similar, but not the same.
  • Variation - This occurs in sexual reproduction. Each pair of genes affects different characterisitcs but the genes can come in different forms, they are different versions of the same gene ( alleles ) .
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Cloning and new ways of cloning.

  • Cloning plants : Cuttings, a form of asexual reproduction. A small piece of a plant is removed (stem or leaf) and grow in the correct conditions, a new plant will be grown. This is an old technique.
  • A modern way is called tissue culture, and is more expensive although thousands of new plants can be produced.
  • Cloning Animals : Embryo cloning and double the amount of babies born every year. Top quality cows produce eggs, and fertilize them will sperm, divide each embryo, allow each cells to grow into an identical embyro, transfer the embryos and identical babies are born. This is commonly used in cows.
  • Fusion Cell Cloning : A form of asexual reproduction, taking place constantly in the body, to produce millions of identical cells.
  • Adult Cell Cloning : This is taking a cell from an adult and making an embryo. It is farely rare still.
  • It can be very helpful as GE can produce animals with proteins in their milk, to be used for helping animals.
  • Some disagree because it is creating many identical cells, leading to the population being unable to survive changes in enviroment, as the lack of useful mutations.
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Genetic Enginering

  • Genetic Engineering : Involves changing the genetic material of an organism.
  • Genes from the chromosomes of organisms can be cut out, using enzymes and transfered to bacteria cells.
  • They can also be transferred to the animal or plants dells at early development.
  • As this is a new science, many are concerned that no-one is aware of the long term effects and what dangers there are.
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Origins of Life on Earth and Evolution

  • Fossils provide evidence of how much / little organisms have changed since life developed.
  • They can be formed by the harder parts being replaced by minerals over time.
  • They can be formed by when an animals did not decay when it died, due to the temperature, so it has been preserved in ice. These are much rarer.
  • Evolution - The process of slow change in living organisms over long periods of time as those best fitted to survive breed successfully.
  • Theories : States all species living today, evolved from simple life forms which developed billions of years ago.
  • Darwin believes in the theory of natural selection, organisms producing more offspring that the enviroment can support so only the best will survive. The genes which have proved to to be successful are pased on to the next generation.
  • Extinction : Caused by the changes to the enviroment, new predators, new competitors and possibly new diseases.
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Population explosions

  • The Human populationis growing rapidly, and the standard of living is increasing.
  • This leads to more waste being produced, and if not handled correctly, it can pollute the water, air and land.
  • Humans are reducing the amount of lands available for plants and animals, so population is destroyed for living organisms.
  • Raw materials are being used, including non - renenwables, which are unable to restored, natural gas and metal ores for example.
  • Sustainable Development : Looking after the enviroment, by conserving natural resources, such as trees, being used for wood and paper.
  • Resources must be used wisely, and using what is only needed, and conserving natural resources as much as possible.
  • Recycling waste, saving resources, using land wisely and using less energy.
  • Homes can be made more energy efficiently, as energy is one of the most important resources. The less electricity, gas, oil used in home will help with the pollution of the atmosphere, as CO2 damages it, so the less used tthe better.
  • Transport can be limited, by using cars less, and cycling or walking instead to cut CO2 emissions going into the atmosphere.
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Acid Rain and Global Warming

  • When fossil fuels are burn't, CO2 is released into the atmosphere. ( from cars etc )
  • Sulfur Dioxide and Nitrogen Oxides can be released when fossil fuels are burn't.
  • These gases dissolve in the rain and make it more acidic.
  • Acid make rivers/lakes too acidic so plants and animals are unable to live them.
  • Sulfure Dioxide DOES NOT CAUSE global warming, BUT it causes ACID RAIN.
  • There is large scale deforestation in tropical areas => an increase of CO2 in the atmosphere. It reduces the rate which CO2 is removed by plants.
  • As there is an increase of rice fields and cattle farming to supply the demand for the increase of population, increased levels of methane has gone into the atmosphere.
  • Increased levels of greenhouse gases, may be causing global warming as a result of the greenhouse effect.
  • Green house Effect : The Earth radiates back much of the heat it absorbs from the Sun. This keeps the temperature acceptablte. Carbon dioxide and methane build up, so they are a greenhouse around the earth, making energy trapped and increasing the temperature on the Earth.
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