B1 wjec new spec (2013) Section 1+2

Living things are all different. We can classify them into groups such as vertebrates, flowering plants and microorganisms. These are big groups that can be grouped smaller. Organisms with similar features or characteristics can be classified into smaller groups. Morphological or DNA analyses is used. 3 domain is proffered to the 5 kingdoms. Scientific names are used to identify different animals. it is the same all over the world unlike the common name. Organisms have behavioural and morphological adaptations that enable the organism to survive its environment. E.g. fresh water invertebrates in pond.  Competition for resources is in every habitat. its call interspecific if its between two different species and intraspecific if its between members of the same species. Organisms need resources from their environment such as water, sun light and food. 

Food Chains

TREE (producer)- Makes energy through photosynthesis. 

CATERPILLAR (consumer - herbivore)

SMALL BIRD (consumer 2 - carnivore)

HAWK (consumer 3 - top carnivore)

Put arrows in between to show the flow of energy.

Energy Lost in the Food chain

1) Much of the light energy can't be used by the plant because-

• most doesn't hit the plants
• Some is reflected from the leaf's surface e.g waxy cuticle
• only part of the light is used/useful and can be absorbed by chlorophyll    
• right colour- red / wrong colour - green
•  not all parts of plants used for photosynthesis 

2)Energy is lost from animals and plants

• Sun ----> 98% energy lost
• Producer ----> 90% energy lost
• Primary Consumer ----> 90% energy lost
• Secondary Consumer ----> 90% energy lost
• Teritary Consumer. it normally stops here.

Why is there no more than 3 consumers normally 

• Not enough energy to sustain another level
• Not enough energy is transferred.

Energy is lost by -

A) Respiration produces heat

B)  Death and decomposistion (including urine and faeces) as the energy goes into decomposers, Bacteria and Funghi

C) Not all of the organism is useful. 

D) Only energy used in  growth can be transferred. 

E) Energy is lost in movement or kinetic energy.

What is energy used for?

1) Respiration - all cells need energy to work, heat, repair

2)For Growth - when a plant grows, biomass increases. This can be transferred 

3) Transferred to decomposers ( fungi and bacteria)

4) For reproduction.

5) for movement (lost as kinetic)

They are not always the perfect pyramid shape and focus on the number of each organism rather than the biomass. there is one tree, 25 insects and 6 woodpeckers. the producer goes at the bottom.

Always the pyramid shape. The total mass of organisms on each level. oak tree weights more than caterpillars. lots of caterpillars weighs more than birds and although there are lots of fleas they are really light. The producer is at the bottom.

Putrification/ Rot/ Decay- all words that mean Decomposition.

The process of decay occurs to all dead organisms in the right conditioned. it is the breakdown of body matter in to small molecules. Decay happens because small organisms feed on the dead body. These microorganisms are called decomposers.

decomposers......

• need oxygen 
• correct temperature
• correct Ph
• moisture
• Small invertbrates eat the dead organisms
• microbes digest the dead organisms

Recycling is a natural process. Decomposers break down dead organisms and release the molecules as nutrients. The nutrients may be added to soil or used for growth. They are never wasted.

The carbon cycle

In the air Carbon exists as Carbon Dioxide. In plants and animals Carbon exists as three different molecules. 

• carbohydrates 
• proteins  
• fats   

The nitrogen cycle

Nitrogen is needed to make protein. Plants take it up from the soil in the form of nitrates (potassium nitrate) in the soil. Ammonia is released when they decay. Many animals excrete urea in their urine. Soil micro-organisms feed on animal urine, producing urease to transform the urea to ammonia

Indicator species help to indicate pollution. They have to have certain conditions to survive and these are not found in polluted areas. Some examples of indicator species are Lichton on Fresh water invertebrates.

Air pollution can be monitored by looking at lichen. Some types of lichen are very sensitive to the concentration of sulphur dioxide in the air. The number and type of lichen in a given area indicate how clean the air is

If raw sewage is released into a river the bacterial population in the water increases and uses up the oxygen. Some invertabrates ( mayfly larva) are good indicators as they are very sensitive to the concentration of dissolved oxygen in the water. So if they are present then the water is clean.

Some inverebrate species have adapted to live in polluted conditions ( sludgeworms ) so if they are present then theres a lot of pollution.

DDT was used during WW2 to kill mosqito's. it was later found to affect the shells of bird eggs. so it was banned. This is an example of Bio-accumulation.

Farmers spread fertiliser on the fields./ Untreated sewage gets put into the lake

it is washed down into a lake/pond. 

The nutrients in the fertiliser help the algea grow, this blocks out the sunlight.

Other plants cannot survive

As the plants and the algea decay the microbes that decompose them use up all the dissolved oxygen

Animals like fish suffocate with not enough dissolved oxygen

And the lake 'dies'.