Biology gcse

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  • Created by: Andy andy
  • Created on: 18-05-11 12:50

Cells is where everything begins. All animals and plants are made of cells. they have some parts in common such as cell membrane, mitochondria, nucleus, cytoplasm and ribosomes. Plant cells also feature cell wall, chloroplasts and a permanent vacuole. All cells may be specialized to a particular function.different parts of a cell have different functions. the nucleus contains genetic material and it controls what happens in the cell. the cytoplasm is where the chemical processes take place and where enzymes are found. the cell membrane it controls what enters and exits the cell. the mitochondria is where energy is released by respiration and ribosomes is where protein synthesis. some smallest living organisms are made up of a single cell, while larger ones are made up of a lot of them and they can be specialized in one function like sperm cells. diffusion is the movement of particles from an area of high concentration to an area of low concentration and osmosis is the movement of water molecules through a partially permiable membrane from a region of high concentration to a region of low concentration and its very important to plants. if the concentration is equal on both sides the net exchange is zero.

plants use photosynthesis to produce food: they use carbon dioxide water and light energy to produce glucose and oxygen as a by-product. plants also need minerals such as nitrate and magnesium. Glucose is very important for a plant because they use it for respiration, making fruit and cell walls, make proteins and the rest is stored as starch. the 3 most important things a plant need to stay alive are carbon, hydrogen and oxygen. oxygen is used to release energy from food in respiration.

Pyramids of biomass are a form of diagram to reveal the mass of living material at each stage in a chain. the first level of a pyramid of biomass is always the producer while all the others are mainly consumers. the amount of energy decreases from one stage to the other because energy is transferred along food chains, and some of it its lost during this process. energy is released by respiration is movement, and it is also lost in waste materials and it always return to the enviroment, and this is why food chains are fairly short.

the efficiency of food production is to reduce energy lost and this is done by preventing animals to move too much and heating up the sorroundings, so that a balance is reached.

The carbon cycle is about carbon coming from the atmosphere and getting back there. carbon from atmosphere is respired by living things, then transferred to complex molecules and it then returns the atmosphere as CO2. materials from living things decay because micro-organisms digest them. this happens very fast in worm conditions and very slowly in cold ones.

Enzymes and digestion

Enzymes are biological catalysts. they work at a optimum temperature of 37 degrees and they have a optimum ph of 7. as the


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