AQA Biology 2

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  • Created on: 18-08-11 14:49
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Biology 2
Unit 1
Life and cell
Human and animal cells
Nucleus-genetic material control the activities of the cell
Cytoplasm-were most the chemical reactions take place
Cell membrane- holds cell together and controls what goes in and out
Mitochondria-reactions for respiration take place
Ribosome's-where proteins are made in the cell
Plants have some extra features
Cell wall-supports the cell
Permanent vacuole-contains cell sap
Chloroplast-were photosynthesis takes place
Organised Cells
1. Cells make tissues
2. Tissues make organs
3. And organ makes organ system
4. Which then equals whole body
Specialised cells
Red blood cells
Concave shape gives a large surface area for absorbing oxygen
Packed with haemoglobin
No nucleus more room for haemoglobin
Diffusion
Diffusion is the passive movement of particles from an area of high concentration to an area of low
concentration
Cell membrane in a plant or animal cell allow small thing like glucose amino acid water and oxygen to
come in but big molecules like starch and protein cannot fit through the membrane.
The overall net movement is particle moving in and out
Two areas of a concentration is called concentration gradient
Rate of diffusion depends on
Distance- the smaller the distance more quickly the diffusion happens
Concentration gradient-substance diffuse faster if there's a big difference in concentration
Temperature
Srani

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Biology 2
Surface area- more space equal more faster to get to the other side
Osmosis
Osmosis is the movement of water molecules across a partially permeable membrane from a region
of high water concentration to a region of low water concentration
Osmosis is a type of diffusion that allows only water to let pass
Photosynthesise
Carbon dioxide + water glucose + oxygen
Photosynthesis is process that produces food (glucose) and it happen in chloroplast and inside that
there is a substance called chlorophyll which…read more

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Biology 2
Monoculture which a plants grown in the same field year after year
The same plants need the same mineral which can be used up by other plants leaving none for the
others
One deficiencies causes a poor growth and reduces the plants
The carbon cycle
1. The whole thing is powered photosynthesise. Carbon dioxide is removed from the
atmosphere by the plants and used make carbohydrates fats and protein in the plants
2.…read more

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Biology 2
Movement-the muscles contract therefore needed more energy
Keeping the body temperature- body produces heat eventually losing it to the surrounding
so the body need to constantly keep producing heat as it important
Decay
Decomposers are a group of microorganism which include bacteria and fungi which feed on
dead organisms and waste
Detritus feeder such as maggots start the process of eating dead then the fungi digest
everything
The waste products are carbon dioxide and water and mineral for plants
Decay is actually called…read more

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Biology 2
Biological catalysts-Enzymes
Body reactions known by enzymes
Special chemical are known as catalyst
Enzymes are large proteins made from long amino acids
Enzymes are protein catalyst that speed up chemical reactions
Catalyst increases the speed of reaction and are not changed by
the reaction or used up but they control
Each enzyme is very specific and can only catalyse a certain
reaction.…read more

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Biology 2
Product water oxygen
Enzymes products
Breaking it
Down
Respiration involves many reactions which are catalysed by enzymes
As respiration releases the energy that the cell needs to do just about everything
Respiration is a process of releasing energy from the breakdown of glucose and goes on in
every cell
it happen in plants
Respiration is the process of releasing energy from glucose which goes on in every cell
Anaerobic respiration uses oxygen, it the most efficient way to release from glucose.…read more

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Biology 2
Bile neutralises the stomach acid and emulsifies which made from liver, stored in gall bladder and
released into small intestine. Stomach has hydrochloric acid which bile neutralises to make conditions
alkaline which the enzymes work best at.…read more

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Biology 2
Disadvantages
Develop allergies
Enzymes can be denatured by even a small increase in temperature
Contamination with other enzymes
Homeostasis
Homeostasis is the maintance of a constant internal environment
Six main things need to be controlled
Body temperature
Water content
Ion content
Blood sugar
Waste products
Carbon dioxide
Urea
Body temperature
Enzymes work at 37 degrees. There is a thermoregulatory centre in the brain which acts like a
personal thermostat. Receptors that is sensitive to the temperature of the blood flowing through
brain.…read more

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Biology 2
Proteins cannot be stored so excess amino acids are converted into fats and carbohydrates. This
process occurs in the liver. Urea is produced as waste product. Urea is poisonous. Released in the
blood stream. The kidneys then filter it out of the blood and excrete from the body in urine.
Adjustment of ion content
Ions such as sodium are taken into the body. If the ion content of the body is wrong. This
mean too much or too little is drawn by osmosis.…read more

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Biology 2
Diabetic can check their blood sugar using a glucose-monitoring device. They prick their finger to get
a drop of blood for the machine to check.
Insulin and diabetes
Insulin was discovered by Banting and Best
Banting and best experiment
1. In 1920 Banting and best managed to successfully isolate insulin
2. They tied string around a dog pancreas so that a lot of the organ wasted away-but the bits
which made the hormone were left intact
3.…read more

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