Qualification > Sciences
IGCSE BIOLOGY DOUBTS HERE !!!!
Ivo:
--- Quote from: acash09 on October 11, 2010, 07:15:24 pm ---Thanks guys and gals! Need something else, lol!
The drugs section in the syllabus - if someone has notes, could you post it here please?
I hate the drugs section ( except the good ones - antibiotics ), i never got those notes from my friends.
Much appreciated.
Acash09 - I'll keep smilin'! :P ;D
--- End quote ---
I don't think you'll need to know an awful lot about Drugs at IGCSE. The syllabus already provides a pretty good summary about what you need to know (in case you haven't looked already):
1) Define a drug as any substance taken into the body that modifies or affects chemical reactions body.
2) Describe the medicinal use of antibiotics for the treatment of bacterial infection.
3) Describe the effects of the abuse of heroin: a powerful depressant, problems of addiction, severe withdrawal symptoms and associated problems such as crime and infection e.g. HIV/AIDS.
4) Describe the effects of excessive consumption of alcohol: reduced self-control, depressant, effect on reaction times, damage to liver and social implications.
5) Describe the effects of tobacco smoke and its major toxic components (tar, nicotine, carbon monoxide, smoke particles) on the gas exchange system.
6) Explain why antibiotics kill bacteria but not viruses.
As you can see from the above, that's about as much as you'll need to know, maybe knowing a bit more about antibiotics won't do you any harm!
Hope this helps! 8)
Deadly_king:
--- Quote from: acash09 on October 11, 2010, 07:15:24 pm ---Thanks guys and gals! Need something else, lol!
The drugs section in the syllabus - if someone has notes, could you post it here please?
I hate the drugs section ( except the good ones - antibiotics ), i never got those notes from my friends.
Much appreciated.
Acash09 - I'll keep smilin'! :P ;D
--- End quote ---
I think this might help as well :D
http://www.s-cool.co.uk/gcse/biology/drugs.html
Just click on the respective titles to get your required notes ;)
Thanks for the help Ivo :)
acash09:
I think we need to rename this thread into "Acash09 - asking many boilogy doubts!" lol! ::)
Sorry, i've taken a lot of your time people, but i appreciate your help!
Another doubt - in 7.1.2 transpiration -
"discuss the adaptations of the leaf, stem and root to three contrasting environments, to include pond, garden and desert, with emphasis on local examples (where appropriate) and the factors described in the core"
&
7.1.3 translocation
"compare the role of transpiration and translocation in the transport of materials from sources to sinks, within plants at different seasons"
I know this is becoming to much but my igcse are getting nearer and nearer and i dont have time to look here and there for answers so please bear with me a few questions more :P
thanks again! acash09
Deadly_king:
--- Quote from: acash09 on October 12, 2010, 04:32:49 pm ---I think we need to rename this thread into "Acash09 - asking many boilogy doubts!" lol! ::)
Sorry, i've taken a lot of your time people, but i appreciate your help!
Another doubt - in 7.1.2 transpiration -
"discuss the adaptations of the leaf, stem and root to three contrasting environments, to include pond, garden and desert, with emphasis on local examples (where appropriate) and the factors described in the core"
&
7.1.3 translocation
"compare the role of transpiration and translocation in the transport of materials from sources to sinks, within plants at different seasons"
I know this is becoming to much but my igcse are getting nearer and nearer and i dont have time to look here and there for answers so please bear with me a few questions more :P
thanks again! acash09
--- End quote ---
Sorry........won't be able to help much since am busy with exams as well.
Try this though.......it might be helpful :)
Ivo:
--- Quote from: acash09 on October 12, 2010, 04:32:49 pm ---Another doubt - in 7.1.2 transpiration -
"discuss the adaptations of the leaf, stem and root to three contrasting environments, to include pond, garden and desert, with emphasis on local examples (where appropriate) and the factors described in the core"
--- End quote ---
Xerophytes (Desert plants)
They are plants that are able to exist in conditions where water is scarce. Cacti are xerophytes that survive in hot, dry (arid) desert regions. Cacti reduce water loss and conserve water in the following ways:
1) Their leaves are reduced to spines. This reduces the surface area of the leaf over which water can be lost.
2) A thick waxy cuticle covers the plant's surfaces and reduces transpiration.
3) They have swollen stems containing water-storage tissue.
4) They have a shallow, spreading root system to absorb quickly any water from rain and overnight condensation.
5) Many cacti have a round compact shape which reduces their surface area so there is less surface through which water can be lost.
6) They have shiny surfaces which reflect heat and light.
7) Their stomata are closed during the day to reduce water loss. They open their stomata at night to absorb the carbon dioxide which they store for use in photosynthesis during the day. Photosynthesis occurs in the outer layers of cells in their stems.
Hydrophytes (Pond plants)
(eg. Water lilies, Nymphaea sp.)
They are plants that grow submerged or partially submerged in water. Living in water has both its costs and benefits.
Buoyed up by water and with no need for water transport, floating plants save energy since they produce little or no xylem tissue.
Roots, if present, are for anchorage and since there is no need for the roots to absorb water or mineral ions, there are no root hairs. The leaves and stems of hydrophytes have little or no cuticle, since there is no need to conserve water.
The problem for hydrophytes is that carbon dioxide, which is needed for photosynthesis, diffuses through the water much more slowly than it does through air. The same applies for oxygen, needed for plant respiration, since it is not very soluble in water. Therefore many hydrophytes have an extensive system of air spaces in their stems and leaves through which gases diffuse quickly. These air spaces provide buoyancy to keep the plants close to the light and are a resevoir of oxygen and carbon dioxide.
Mesophytes (Garden plants)
(eg. Coleus, Solenostemon spp. - brightly coloured garden plants)
Garden plants are grown for their colourful, scented flowers, for their subtle leaf colours, for shade and to provide an attractive environment.
Mesophytes are terrestrial plants that usually have enough water and do not have such extreme adaptations to reduce water loss like those of xerophytes. Many garden plants are mesophytes, as gardeners can provide them with enough water even in parts of the world that might be dry for much of the year.
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