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Official AQA Biology Unit 3 14th May 2013 NEW SPEC

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I think it links with this bit;
"land, with toxic chemicals such as pesticides and
herbicides, which may be washed from the land
into waterways."
Reply 561
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C-king
6
how is the villi adapted to exchange food into the blood?
Original post by C-king
how is the villi adapted to exchange food into the blood?


-Thin Walls
- Microlvilli which give it a large surface area
- Good blood supply from the capillaries maintains the concentration gradient and assists quick absorption
Original post by C-king
how is the villi adapted to exchange food into the blood?


Villi, folded many times and have micro villi, this drastically increases the surface area.
Have a rich blood supply, to maintain a concentration gradient
They are one cell thick shorter diffusion path.
Have lots of mitochondria to release energy for active transport.
Reply 564
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s.was99
Each villus has many microvilli on its surface to vastly increase surface are for diffusion. Each villus contains a capillary which provides a rich blood supply and therefore a constant gradient for diffusion to occur. The lining of each villus is thin to minimize the distance for diffusion to occur.
Reply 565
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C-king
6
Original post by sneakbo2
-Thin Walls
- Microlvilli which give it a large surface area
- Good blood supply from the capillaries maintains the concentration gradient and assists quick absorption


Also it can move molecules into blood by active transport and diffusion, meaning food molecule snever diffuse out of blood or are wasted in faeces
What are the environmental effects of building dams to supply water?
Not sure if its in the spec but its in the Nelson Thorns book
Why do farmers farm Herbivores as opposed to carnivores? (2 marks) - This is a past paper question that has come up many times so I think it's useful to learn
B2

what does recessive and dominant allele mean?
Original post by sneakbo2
Why do farmers farm Herbivores as opposed to carnivores? (2 marks) - This is a past paper question that has come up many times so I think it's useful to learn


Shorter food chain = more energy converted to growth
Reply 570
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s.was99
Original post by Unknown505
What are the environmental effects of building dams to supply water?
Not sure if its in the spec but its in the Nelson Thorns book


Destruction of habitats and possible deforestation is all I can think for this one
Original post by MacDaddi
Shorter food chain = more energy converted to growth


Yeah thats one, the other is always that it's cheaper to feed them
Reply 572
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C-king
6
Original post by sneakbo2
Why do farmers farm Herbivores as opposed to carnivores? (2 marks) - This is a past paper question that has come up many times so I think it's useful to learn


this is to reduce the stages in the food chain so that more energy can reach the consumer to make biomass

Original post by Unknown505
What are the environmental effects of building dams to supply water?
Not sure if its in the spec but its in the Nelson Thorns book


building dams damages the habitats of animalas and plants, aslo makes neabry areas dry as can dry up rivers, apart from that dunno...
Original post by s.was99
Destruction of habitats and possible deforestation is all I can think for this one


Also infertile and land dryout.
why is human urine yellow, when most of its contents are colorless?
Original post by Unknown505
why is human urine yellow, when most of its contents are colorless?


UROBILLINS are in the urine which are the breakdown of haemoglobin in the liver
Reply 576
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C-king
6
Original post by Unknown505
why is human urine yellow, when most of its contents are colorless?


As this is because urine contains urobilins, these are made through bthe break down of haemoglobin
Original post by Unknown505
What are the environmental effects of building dams to supply water?
Not sure if its in the spec but its in the Nelson Thorns book


Dams are created so reservoirs are created. they are breeding grounds for mosquitoes which can pass on malaria
Original post by MrDonIlyas
UROBILLINS are in the urine which are the breakdown of haemoglobin in the liver


Do we need to know about urobillins for tomorrow?? :eek:
Original post by WillowXxx
Do we need to know about urobillins for tomorrow?? :eek:


Thats all we have to know.

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