Classification and biodiversity



Living organisms can vary in size and complexity. They can have different structural and functional features.

scientists classify living organisms into groups which have simular features. 


  • makes it easier to identify organisms
  • helps scientists communicate

For example, you could have groups of animals where some are invertebrates and others are vertebrates. And within this are also cold blooded animals, and also warm blooded animals. scientists will need to classify them and put them into simular groups. 

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So, how can they do this?

Taxonomy is a practice, where, like before, they put different organisms into catagories to classify the different organisms.

Kingdom, Phylum, Class, Order, Family, Genus, Species.

This is hard to remember so use this mnemonic that I made up

Kungfu Panda Cooks Omeletes For Giant Snakes

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Binomial System

The binomial system clear up any confusion over names. This can help scientists that are anywhere in the world to know what organism is being described if its scientific name is given.

For this, it uses the genus and the species of the organism. However, there are some rules when writing it that you have to remember:

  • the genus has to be written with a capital letter
  • the species is all in lower case
  • when writing, you have to underline the whole name, or when typing, you write it in italics

Here are some examples:

Tiger - Panthera tigris

Grey wolf - Canis lupus

Human - Homo sapin


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Closely related species can show differences through evolution. Species become adapted to their environment. Feature development aids survival and these adaptions can occur in two ways:

Morphological - Internal and external structural changes e.g. Fur colour, Petal shape

Behavioural - How an organism reacts within their environment e.g.Nocternal hunting, Movement  towards light


  • can store a lot of water
  • sandy colour good for camourflage
  • large feet to spread its load on the soft sand
  • large surface area which makes it easier to lose body heat
  • very little sweating
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Measuring Biodiversity

Biodiversity is the number of different species in a particular area, at a particular time.

Sampling Requirements

  • unless the environment studies is very small, an entire area cannot be explored to find all living organisms there. The way they to do this is to take a sample then to estimate the total number in the whole environment
  • the sample must be big enough to represent the whole area
  • the sample must be random and free from unconcious bias
  • the sampling method must not affect the results

There are two techniques that are used:

  • Quadrat technique
  • capture - recapture technique
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Alien species and biological control

  • Alien species are species that are found in an area but not native to it.
  • Biological control is when an organism is deliberately introduced to feed on other organisms that are causing a problem

Reasons non native species are introduced:

  • for control
  • may produce food
  • provide less chemical use
  • but they can also be introduced by accident


  • cause disease
  • competition with native species
  • kill and predate natives
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Structure of the nervous system

The brain and spinal cord makes up the central nervous system (CNS) and these two, along with the nerves, make up the peripheral nervous system (PNS)

  • Electrical information passes along newrones as impulses to cause a reaction

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Blood glucose

If blood glucose is too high:

  • brain detects high blood glucose
  • a signal is sent to the pancreas to release insullin
  • insullin travels in blood to the liver
  • this then signals the liver to store glucose as glycogen

If blood glucose is too low:

  • brain detects low glucose levels
  • signal is sent to the pancrease to release glycogon
  • glycogon travels in blood to the liver to store glycogon as glucose and then releases it.

Negative feedback is a control mechanism often used in living organisms to keep a particular factor within an acceptable range. If something is not within the range it sets of a series of events leading to the factor being brought back to normal. 

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Testing medicinal drugs

A drug is a chemical that alters the way the body works in a certain way

Rigorous testing is needed before a drug is safe to sell to the public. Side affects can happen, so a decision has to be made to see if its worth the side affects.

Testing stages

  • the drug is tested on human cells that are grown in a labortary.
  • the drug is then tested on animals
  • clinical trials begin on healthy individuals
  • further clinical tests are done to work out the dose
  • the drug is then tested on people with the disease.
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Resistance bacteria - MRSA

MRSA (Methicillin resistant Staphylococcus aureus) is very hard to treat as its resistant to some antibiotics. It can be spread in hospitals and health care facilites.

MRSA infections start out as small red bumps that can quickly turn into deep, painful abscesses. It can spread to areas such as the lungs, bones and urinary tract. 

you WILL NOT know you have it unless you have a screening test. If MRSA gets deeper into your body it can cause: THE BOLD AREA IS FOR WORSE AFFECTS

  • redness
  • swelling
  • warmth
  • pain
  • pus
  • high temp of 38 +
  • chills
  • aches and pains
  • confusion and dizziness
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  • make sure to read questions properly
  • use past papers
  • keep it up
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