B3 1.1 - 1.3
- osmosis is the diffusiom of water
- water diffuses from a dilute solution to a more concentrated soloution through a partially permeable membrane
- water moves into or out of cells by osmosis throgh the cell membrane
1.2 Active Tansport
- active transport allows clls to take in sunstances against a concentration gradient
- active tansport uses energy from respiration
- ions can from dilute solutions, and other substances such as sugar can be absorbed by active transport.
1.3 The Sports Drink Dilemma
- most soft drinks contain: water to replace water when lost when sweating; sugar to replace sugar used for energy release in exercise; mineral ions to replace those lost in sweating
- for normal levels of exercise, water is likely to be as effective as a sports drink.
B3 1.4 - 1.6
1.4 Exchanging Materials - The Lungs
- large organisms need exchange surfaces
- exchange surfaces have features to make them efficient
- the lungs are adapted to be an efficent echange surface
1.5 Ventilating the Lungs
- the breathing system is designed to move air im and out of the lungs
- ventilation occurs due to changes of pressure inside the chest
1.6 Artificial Breathing Aids
- Reasons for artifical breathing aids: if the alveoli are damaged the surface area for gas exchange is reduced: if the tubes leading to the lungs are narrowed, less air can be moved through them: if the person is paralysed their muscles will not work to pull the ribcage up and out
- breathing aids which force measured amounts of air in the lungs use positive pressure
B3 1.7 - 1.9
1.7 Exchange in the gut
- the villi are an efficient exchange surface for the absorption of the soluble products of digestion by diffusion or active transport
- villi provide a large surface area and have a good blood supply.
1.8 Exchange in plants
- the stomata in plant leaves allow carbon dioxide to diffuse into the leaf from the atmostphere
- leaves are flat and thin with internal aire spaces to increase the surface area for diffusion of gases
- root hair cells increase the surface area of roots.
- water is lost from the leaves be evaporation
- the water vapour escapes the leaf through the stomata when the open to allow carbon dioxide to enter the leaf
- wilting can protect the leaf from excessive water loss.
B3 2.1 - 2.3
2.1 The circulatory system and the heart
- the double circulation system in humans consists of blood vessels, blood and the heart
- the heart is the organ that pumps blood around the body
- valves prevent backflow of blood
2.2 Keeping the blood flowing
- arteries, viens and capillaries are the main types of blood vessel
- substances diffuse between the blood and the cells in the capillaries
- blocked or narrow arteries can be widened by stents, damaged heart valves can be replaced
2.3 Transport in the Blood
- blood plasma transports dissolved food molecules, Co2 and urea. Plasma also contains blood cells.
- the red blood cells carry oxygen from the lungs to the cells. the white cells are part of the defence system
- plateles are invloved in blood clotting.
B3 2.4 - 2.5
2.4 Artifical or real?
- there are advantages and disadvantages when using artificial blood and artificial hearts
- they are useful when real blood or donor hearts are not available
2.5 Transport systems in plants
- flowering plants have two transport tissues
- xylem transports water and mineral ions from the roots to the stems and the leaves
- phloem transports food, such as dissolved sugar, from the leaves to other parts of the plant.
B3 3.4 - 3.6
3.4 Kidney transplants
- a diseased kidney can be replaced by a healthy kidney
- the donor kidney must be a very good 'match'
- the immune system has to be suppressed or it is likely to reject the new kidney.
3.5 Controlling body temperature
- enzymes work in a very narrow temperature range
- body temperature is monitored and controlled to kepp it within this narrow range.
3.6 Treatment and temperature issues
- both dialysis and kidney transplats have advantages and disadvantages
- see AQA Science Biology Revision Guide for more information (page 86)
B3 3.7 - 3.8
3.7 Controlling blood glucose
- the level of glucose in the blood is controlled by hormones
- in type 1 diabetes the blood glucose level risesto high levels because it is not controlled properly.
3.8 treating diabetes
- type 1 diabetes is treated with insulin injections
- new methods are being tried or developed to treat diabetes.
B3 4.1 - 4.4
4.1 the effects of the population explosion
- the human poulation is increasig rapidly
- humans are using more resources and producing more waste and pollution
4.2 land and water pollution
- humans are responsible for pulling both land and waterways
4.3 air pollution
- sulfur dioxide dissolved in rain makes it more acid
- acid rain can effect organisms both directly and indirectly
4.4 deforestation and peat destruction
- forest are cut down to clear land for farming
- deforestation leads to a reduction in biodiversity and an increase in CO2 in the atmostphere
- destruction of peat bogs also releases carbon dioxide
B3 4.5 - 4.7
4.5 Global warming
- the climate of the Earth is getting warmer
- global warming affects living organisms.
- ethanol based fuels can produced by anaerobic fermentation of sugars from plants
- the ethanol ditilled from the fermentation prduct can be used as fuel in motor vehciles
- boigas is mainly methane. it is made by the anaerobic ferentation of a wide range of waste substances and plant material containing carbohydrates.
- biogas can be made on a large or a small scale
- many different microorganisms are involved in biogas production
B3 4.8 - 4.10
4.8 making food production efficient
- short food chains make food production more efficient
- food production can be controlled to reduce energy wastage
4.9 sustainable food production
- fish stocks can be maintained by controlling fishing quotas and net size
- the fungus fusarium produces mycoprotein
4.10 environmental issues
- human activities affet both local and global environments
- there is alot of evidence for environmental change
- scientists need to check the validity and the reproducibility of the data collected.