Biology Further Notes

My AQA Notes for GCSE Further Biology :)

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Biology Revision
Exchanging Materials
Osmosis and Diffusion
Water and dissolved substances automatically move along a concentration
gradient. They move from high concentration to low concentrations. They move
by osmosis and diffusion.
Active Transport
Substances are sometimes absorbed against a concentration gradient. But this
means using energy from respiration. This is known as active transport.
Plants absorb ions from very dilute solutions by active transport.
Active transport takes place in the opposite direction to normal diffusion.
Sugar and ions which can pass through cell membranes, can also be moved by
active transport.
In humans, sugar can be absorbed from the intestine and from the kidney
tubules by active transport.
Exchanging Materials in Humans

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Humans have organ systems which are specialised to help the exchange of
materials. For example...
the villi in your small intestine
the alveoli in your lungs
Villi in the Small Intestine
Villi line the walls of your small intestine. They have a massive surface area and
an extensive network of capillaries.
This network absorbs the products of digestion by:
diffusion
active transport
The Breathing
System
The breathing system involves the heart and
the lungs. It takes air into and out of the body.…read more

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Exchanging Materials in Plants
Leaves are broad, thin and flat with lots of internal
air spaces. This provides a large surface area,
making them efficient at photosynthesis.
Leaves have stomata on their under surface in order
to...
let carbon dioxide in
let oxygen out (by diffusion)
(The exchange of substances is reversed during the
respiration)
But photosynthesis, also leads to loss of water
vapour in a process called transpiration. Water loss
is the price the plant must pay to photosynthesise.…read more

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The Circulatory System
The Circulatory System
A transport system is vital to our bodies
as we have cells in every part of us. This
transport system is called the
circulatory system.
Three important elements:
the medium (blood),
the pump (heart)
the pipes (blood vessels)
Humans have two circulatory systems:
double circulation. One carries blood
from your heart to your lungs and
back again to exchange oxygen and
carbon dioxide with the air.…read more

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In other organs, oxyhaemoglobin splits into
haemoglobin and oxygen.
Blood Vessels
You have three main types of blood vessels. They are adapted to carry out
particular functions within your body, although they are all carrying the same
blood.
Blood Vessels Distinctive Features
Your arteries carry blood away from your heart to the organs of
your body. This is unusually oxygenated blood so it is bright
red. They stretch as the blood is forced through them and go
back into shape afterwards..…read more

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Aerobic Respiration
When glucose is combined with oxygen inside living cells, it breaks down and
releases energy. (The energy is contained inside the glucose molecule)
This process is called aerobic respiration.
The energy released during aerobic respiration is used to make your muscles
contract.
Aerobic respiration occurs during normal day-to-day activity and provides for
most of our energy needs.
It doesn't produce energy as quickly as anaerobic respiration.…read more

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If no oxygen is present, glucose in living cells can't break down completely.
Instead, a little energy is released very quickly inside your cells. This is anaerobic
respiration.
The waste product from anaerobic respiration is lactic acid which accumulates in
your tissues. When this happens, your muscles become fatigued.
After exercise, your body needs oxygen to break down the lactic acid; the oxygen
needed is called an oxygen debt.
Anaerobic respiration involves the incomplete breakdown of glucose.…read more

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If the kidneys fail, the body has no ways of removing excess substances. This will
ultimately result in death.
Each kidney is made up of two important issues:
blood vessels
tubules
How the Kidneys Function
Blood vessels take the blood through the kidney,
where unwanted substances end up in millions of
tiny tubules. These tiny tubules eventually join
together to form the ureter. The substances flow
through the tubules into the ureter, which leaves
the kidney and ends up in the bladder.…read more

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Kidney Transplants
A kidney transplant allows a diseased kidney to be replaced by a healthy one from
a donor. This is only performed if both kidneys fail (one kidney can do a good job).
The main problem with kidney transplants is the
possibility of rejection by the immune system.…read more

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How Yeast Works
Yeast can't respire without oxygen (anaerobic respiration) to produce ethanol
(alcohol) and carbon dioxide.
This is called fermentation and it has many industrial applications.
Yeast can also respire with oxygen (aerobic respiration) to produce water and
carbon dioxide.
Aerobic respiration produces more energy and is necessary for the yeast to grow
and reproduce.…read more

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