Biology, Unit 1 Environment

brief notes on each part in the section 'environment' 

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  • Created on: 16-06-11 17:24
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A food chain shows relationships between the living organisms. It also shows how energy and biomass
are transferred. Biomass refers to the total mass of the organic material at each stage.
Pyramid of biomass shows the amount of energy and biomass being loss at each stage as faeces,
movement energy and heat energy.
Food chains can also affect us.
Wheat for example, would cost less than sheep because sheep require lots of grass. Wheat itself is a
producer therefore it gains 100% energy from the sun. Sheep however, is an herbivore and it loses
energy through movements and droppings. This is why sheep need more grass to feed on in order to
ensure they contain enough energy for the humans to eat.
Living organisms fight for space, food and water in an ecosystem. Interspecies competition is when
different types of species fight against each other and intraspecies competition is when the same type of
species fight against each other. The strongest, healthiest and best adapted one ends up winning.
Predators kill and eat preys. Predator and prey have a relationship of interdependence between them.
When the rate of the predators increase, then the rate of the preys decreases and when there are few
preys, predators end up dying because they have no food to eat therefore the rate of the predators
decrease. Because there are few predators, the preys are able to breed and increase without being
eaten therefore the rate of the preys increases. It's a cycle!
Human activities can affect the population size of the food chains. Burning fossil fuels releases
greenhouse gasses are harmful for the ecosystem. Sulfur dioxide is a greenhouse gas and it can kill crops
such as lichens. Herbivores who eat lichens will decrease, and due to that the carnivores would also
decrease as there's a low rate of herbivores.
Computer models are able to predict the following:
life expectancy of the organism
reproductive rate
food availability
size of habitat

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The advantages of computer models are:
they take less time to estimate
no human errors are made
predictions can be made when there's diseases going around
The disadvantages are:
lots of factors must be programmed into the computer
high values can be estimated
Method Description How it happens
Natural selection According to Darwin's Theory, individuals It's natural
with better adapted characteristics are able
to reproduce with each other.
Selective breeding When desired characteristics are found Human intervention
within two individuals then they are bred.…read more

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Charles Darwin believes that organisms that survive can pass on their best survival skills to their
offspring. This gets involved with natural selection. Darwin had difficulties explaining his theory.
(Variation, competition, better adapted, pass on their genes, successful generation.…read more



A concise set of notes on environment that could be used by many students studying ecology. It would be useful to download these and add some key diagrams to help illustrate the points.

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