B4 - GCSE Biology

Biodiversity - the vairty of different speices living in a habitat

Population - the number of one speices in an area

Ecosystems - all the living things and their surrondings

Community - all the organisims living in an area

Habitiat - where an animal lives

Factors that affect distribution of living things include....

Living (biotic) - other competing spieces, prdators, shading plants, human activity, pathogens (diseases) & mates for production

Non-living (abiotic) - temprature, rainfall, sunlight, aspect (north/south facing), slopes, wind & soil type

Pooter - used to catch, identify and study them. Can have a magnifying glass on. Doesn't harm or kill animal

Net - used to catch larger insects such as butterflies, moths etc. Swept through long grass to catch. Doesn't harm or kill animal and easily realesed.

Pitfall trap - bugs fall into jar and a stone ontop keeps them from climbing escaping. Used to study and indentify, doesn't hurt or kill animal.

Quadrat - used to measure the distrubition of plants in different areas.

Transect - used to measure organisms in a particular area (pretty much a tape measure)

Capture - recapture method - used to measure number of insects in a particular area. Catch first sample and mark with paint, then set free. Catch a second sample and see how many are marked from your orginal catch. No. of beetles = no. in 1st day X no. in 2nd day / no. in 2nd day already marked

Artifical ecosystem - lower biodiversity, created by humans, not self-supporting as unwanted spieces are removed (eg - fishfarms, gardens, forestry plantation & resivoir)

Natural ecosystem - higher biodiversity, self-supporting (only need energy from sun) (eg- rainforest, river, lake & native woodland)

Features of a leaf:

• Width to absorb more light (increased surface area)
• Very thin to allow gasses to diffuse in and out quickly (carbon dioxide in, oxygen out)
• Green - contains chlorophyl which absorbs light
• Stork attaches to main plant
• Veins to transport water

Stomata are microscopic holes underneath leaves, which open to allow carbon dioxide in for photosynthesis. During the night they close becuase photosynthesis can't happen.

• Upper epidermis - transparent to let light through and stop water evaporating
• Palisade layer - near top of leaf, lots of chloroplats for photosynthesis, sugar factory
• Spongy layer - air spaces between cells allow Co2 to diffuse to palisade layer
• Lower epidermis - had guard cells and stomata to let Co2 in and oxygen out

• Temprature - hot tempratures cause rapid transipration because water molecules have greater kenetic engery, whereas in cooler tempratures transipration is slower because they have less kenetic energy
• Humidity - when the air is dry there is a big difference in the amount of water in the air, therefore transipration is quicker. When the air is wet, there is little difference in the amount of water in and around the leaf, so transpiration is slower.
• Light intensity - when there is more light, there is rapid transpiration becuase the stomata is open, but when there is little or no light, the stomata are closed so there is no transpiration
• Wind speed - when there is a lot of wind, transpiration is quicker as water vapour is blown away and this creates a steep water gradient. When there is little wind, transpiration slows, as water sits underneathe the leaf, keeping a shallow water gradient

• Water is taken in via the roots through the roots (the roots have hair to increase surface area - roots also absorb dissolved minerals)
• Water moves through the plant via xylem vessles
• And then leaves the leaves via transpiration

Xylem - transport water and minerals, water moves from root to leaves, are dead and hollow, called vessles and NOT tubes, help transpiration

Phloem - transport sucrose solution (SAP), sugar moves from leaves to roots/fruit/flower, are living tubes, called tubes and NOT vesseles, helps translocation

N (nitrate) - makes proteins and amino acids, helps cell growth (if no N growth will be slow, and have yellow, older leaves)

P (phosphates) - helps respirationa and growht, contains phosphurus needed for making DNA and cell membranes (if no P causes poor growth in roots and dicoloured leaves)

K (pottasium) - helps enzymes needed for photosynthesis and respiration (if no K poor growth in flower/fruit and discoloured leaves)

Mg (magnesuim) - required for making chlorophly (if no Mg causes yellow leaves)

Root hair cells give plants a big surface area for absorbing more minerals from the soil. The concentration of minerals outside the cell is lower than inside the cell, where there is a high concentration. This is becuase diffussion happens down a concentration gradient from high to low. In a root hair cell, diffusion can't take place so a different action called active transport happens instead. Active transport uses energy from repiration to pull minerals into the plant.

Decay is just another word for deconposition, which is the process of breaking down dead and waste materials to recyvle the minerals. It is carried out by decay microrginisms. 

Detrivtiores - animals like worms which eat waste

Oxygen - decomposers need this to do respiration and to stay alive

Plants - absorbs nitrogen form the soil when it is relseased by decomposers

Moisture - decomposers need water, as it gives a place for chemical reactions to happen and helps absorb food molecules 

Decomposers - things like bacteria and fungi which break waste food into tiny molecules

Nitrogen and Carbon - are released from rotting food

Warmth - decomposers need this to reproduce more

• Drop in acid - bacteria can not live in acid
• Make them very hot - high temprature kills bacteria and fungi
• Make them very cold - bacteria stop growing at 5C
• Sweeten them up - the sugar draws out the water via osmosis
• Salt them down - the salt draws out the water via osmosis
• Dry them out - by removing the water, the bacteria dies 

Fertilisers contain the chemical element nitrogen. They are used to help crops grow by boosting the level of nutrients. This makes the plants stronger and allows of more them to grow. As the demand for the crops is so great, the farmer no longer leaves a feild fallow to recover each year. He has to replace the nitrates with fertilisers to maintain high levles of production. A farmer may use manure or buy a chemical fertislier. 

However, after the chemicals are sprayed onto the soil, they can be washed into lakes and rivers, where they encourgae the growth of green plant-like algae. Microbes feeding on dead algea use up all the oxygen in the water, so fish and other organisms die. 

If these waters are used as sources of drinking water, there is a danger of pollution. Nirtates are poisonous and can cause cancer.

• Fertilisers - these contain nitrogen, phosporates and potassium which are needed by the plants and added to the soil
• Land availability - farmers can cut down trees and hedges to plant more crops
• Weed control (Herbicides) - these chemicals are used to stop weeds using soil and nutrients and blocking sunlight
• Insect pests (Insecticides) - these chemicals are used to kill off insects that are harmful to crops
• Fungal pests (Fungicides) - these are chemicals used to kill off fungi which are harmful to crops
• Good breeding - strong and high yeild crops have to be breed to provide enough produce at a good price 

• Advantages - more produce (by keeping them warm, they don't waste energy trying to stay warm, making sure all their energy goes into producing more eg - eggs) As well as this, animals are protected from predators
• Disadvantages - the life expectancy of the animals is lower, heating and running costs are higher, disease spreads very quickly and it is animal cruelty

Means using a livining thing instead of chemicals to control pests. 

• Advantages - no chemicals used, no need to repeat the treatment
• Disadvantages - may not eat the pest, may eat useful specices, predator pollution increases and the predator may not stay in the needed area