AQA Biology Unit 3 (B3)

Useful definitions for everything you'll need to know for an AQA Biology exam, good luck :)

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  • Created by: laura
  • Created on: 13-05-13 17:16
Diffusion
Dissolved substances/ Particles moving from an area of high concentration to an area of low concentration, e.g scent moving through a room or gas exchange in the lungs.
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Osmosis
The movement of water molecules only, dilute -> concentrated solution (of the solute) or high to low of water.
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Active Transport
The movement of particles against a concentration gradient, requires some energy (produced by respiration).
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Semi/ Partially Permeable Membrane
A membrane that only allows some particles of a certain size through.
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Sports Drinks + Exchange of Materials
Sports drinks contain water, sugar and ions. They contain sugar for energy and water + ions to replace those lost in sweat. If these are not replaced, the cells don't function normally
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Qualities Of A Good Exchange Surface
Moist, big concentration difference, rich blood supply, lare surface area.
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Exchange in the Lungs
Alveoli let oxygen into the blood and take carbon dioxide out.
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Exchange in Digestion
Villi (with micro-villi on them) help increase the surface area of the intestines so that diffusion can happen faster.
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Exchange in Roots
Roots have root hair cells that collect water by osmosis, which then travells through differnt cells until it reaches the Xylem.
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Breathing System
Lungs, Thorax, Ribcage, Diaphragm and Abdomen.
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Breathing In
Expand ribcage, lower diaphragm, thoracic capacity expands, lung volume increases, lung pressure decreases, air is drawn into the lungs to equalise pressure.
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Breathing Out
Contract ribcage, raise diaphragm, thoracic cavity contracts, decreases lung volume, increases pressure in lungs, air is expelled to equalise pressure.
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Stomota
Small holes, mostly present on the lower side of the leaf, open and close to allow CO2 to enter and water to escape. Their size is controlled by guard cells.
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Wilting
A process that happens if too much water is lost, guard cells generally close in time to stop this happening.
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Transpiration
Water loss through leaves because of evapouration from stomata.
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Good conditions for Transpiration
Hot, windy and dry.
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A Potometre
A device used to measure the amount of water taken up by plants. Works by calculating the distance that a bubble moves.
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Circulatory System
Transports substances around the body, the heart pumps the blood
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Main parts of the heart
Deoxygenate blood - Right Atrium and Right Ventricle, Oxygenated blood - Left Atrium and Left Ventricle.
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Vena Carva
Main vein that takes blood (deoxygenated) into the heart.
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Pulmonary Artery
Takes blood (deoxygenated) from the heart to the lungs
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Aorta
Takes blood (oxygenated) to the rest of the body.
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Pulmonary Vein
Brings blood (oxygenated) from the lungs back to the heart
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Valves
Ensure blood flows in the correct direction and does not come bak the wrong way.
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Stents
Hold arteries open allowing them to carry blood by holding the walls up.
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Ateries
Oxygenated blood (except pulmonary artery), carry blood away from heart, high pressure, small lumen, thick and elastic walls, no valves.
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Veins
Deoxygenated blood (except pulmonary vein), carry blood to the heart, low pressure, large lumen, thinner walls, can have valves.
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Capillaries
Carry both types of blood, carry blood away to body cells, pressure is variable, tiny lumens, very thin walls (only one cell thick),walls are permeable membranes, no valves.
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Blood composition
Plasma, white blood cells, red blood cells and platelets.
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Plasma
Transports gases, roducts of digestion and urea.
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RB Cells
Contain haemoglobin which carries oxygen. Oxyhaemoglobin is produced when these two react.
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WB Cells
Help fight infection by producing antibodies + antitoxins, and engulf pathogens.
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Platelets
Help the blood to clot.
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Xylem
Transport water and mineral ions from the roots to the stems and leaves.
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Phloem
Carry dissolved sugars from leaves to the rest of the plants.
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Transpiration Stream
When molecules of water stick together so as water drops and evapourates through the leaves, more water is brought up.
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Homeostasis
Keeping internal body conditions constant, e.g temperature.
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Waste Products in the body
Carbon Dioxide, Urea, in some cases water.
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Production of Urine
A healthy kidney filters the blood, reabsorbes the glucose, dissolves ions and as much water as the brain says that the body needs.
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Dialysis
Works like a healthy person's kidney by removing waste products from the blood.
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Hemodialysis
Dialysis outside of the body.
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Peritoneal Dialysis
Absorbing waste products from the abdominl cavity using a dialysate solution.
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Advantages of Kidney Transplants
Lasts a long time, gives you more freedom, after recovery you can have a normal life.
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Disadvantages of Kidney Transplants
Very exensive for the NHS, you have to take immuno suppresant drugs for the rest of your life, regular tests are required, there are a shortage of available organs due to a lack of donors, organs have to meet certain requirements.
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Organ rejection
This is when the antibodies of the recipients body may attack the antigens on the surface of the organ a they are 'foreign bodies'. To stop this you must take immuno-suppressant drugs.
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Temperature control
Controlled by thermo regulatory center in the brain, normal body temp shold be 37c.
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Cooling the body
Sweating, vaso dilation (blood vessels dilate to allow more heat loss through skin).
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Warming the body
Shivering prompts the muscles to respire creating heat, vaso constriction (blood vessels contract to prevent heat loss through skin).
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Sugar Control
Conrolled by pancreas (produces insulin to allow cells to take sugar from the blood).
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Glucagon
Produced by pancreas to allow stored glucogen to turn back ino glucose).
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Type 1 Diabetes
Pancreas doesn't produce enough insulin itself so blood glucose levels may rise too high.
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Other cards in this set

Card 2

Front

The movement of water molecules only, dilute -> concentrated solution (of the solute) or high to low of water.

Back

Osmosis

Card 3

Front

The movement of particles against a concentration gradient, requires some energy (produced by respiration).

Back

Preview of the back of card 3

Card 4

Front

A membrane that only allows some particles of a certain size through.

Back

Preview of the back of card 4

Card 5

Front

Sports drinks contain water, sugar and ions. They contain sugar for energy and water + ions to replace those lost in sweat. If these are not replaced, the cells don't function normally

Back

Preview of the back of card 5
View more cards

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