Transcript Document

21/07/2015
AQA Science
Biology 3
Diffusion Revision
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Diffusion is when particles spread from an area of high
concentration to an area of ___ concentration. The particles
move along a “concentration _____” and this process takes no
_____ (it’s a “passive” process”). Diffusion can be accelerated
by increasing the _______ of the particles, which makes them
move _______.
Words – faster, low, gradient, temperature, energy
Active Transport
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In diffusion substances moved along a concentration gradient.
In active transport, substances move against this gradient:
Outside cell
Inside cell
Cell membrane
This process takes ______ and
this comes from ___________.
It enables cells to take in
substances even though there
are in very small __________.
Root hair cells take in ______
using active transport.
Words – concentration, energy,
respiration, nutrients
Diffusion in the Body
Cells use diffusion to swap
the oxygen they need for
the carbon dioxide they
no longer want:
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Oxygen
diffuses in
Out goes
waste CO2
Other examples of where diffusion happens in humans:
Alveoli in the lungs
Villi in the intestines
Diffusion in Villi
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In the intestine, large food molecules are broken down into
smaller ones that then diffuse into the blood through villi in
the intestine.
Villi also have a very good blood supply and a large surface
area. They have tiny folds in their cell membrane called
microvilli, which increase the surface area.
The Respiratory System
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Diffusion in the lungs
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Oxygen diffuses in and carbon dioxide diffuses out of blood in
the lungs:
CO2
Alveoli have three things that help them to do this job: a
massive surface area, a moist lining that is only one cell thick
and a very good blood supply.
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Diffusion and Active Transport in plants
Mineral
More
concentrated
Carbon dioxide diffuses
into the leaf through
holes in the bottom
surface.
Less
concentrated
…while plant nutrients are taken
in by root hair cells using active
transport.
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Photosynthesis – the 4 things you need
SUNLIGHT
Gives the plant energy
CHLOROPHYLL
WATER
Travels up
from the roots
CARBON DIOXIDE
Enters the leaf through small
holes on the underneath
The green
stuff
where the
chemical
reactions
happen
Structure of the Leaf
Lots of
chlorophyll
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Large
surface area
Transparent
Thin
structure
Packed with
chloroplasts
Network of
veins
Lots of air
spaces
Holes
Transpiration
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1) Water evaporates
through the stomata
2) Water passes back into the
leaf through xylem vessels by
osmosis
3) Water is then pulled upwards
through the xylem tissue
4) This is replaced by water
entering from the root tissue
5) Water enters root hair cells by
osmosis to eventually replace the
water lost through respiration
Factors affecting transpiration
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1) High light intensity
This causes the stomata to open thereby
increasing the rate of water loss.
2) High temperatures
This increases the speed of molecule movement
and so speeds up transpiration.
3) Increased wind
This will blow the molecules away and so speeds
up transpiration.
4) High humidity
This decreases the concentration gradient and
so slows transpiration down.
Water loss
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Water loss through the stomata is biggest on a hot,
dry, windy day. Plants that live in these conditions
often have a thicker waxy layer.
Controlling water loss
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Carbon dioxide enters a leaf through the ________. These
cells are also responsible for controlling the ______ content
of the ____…
The ______ cells control how wide the
stomata opens (if at all). If too much
water is being lost through the stomata
then the guard cells will _____ to prevent
further loss.
Water and carbon
dioxide enter here
No more water
and carbon
dioxide allowed in
Words – water, close, stomata, guard, leaf
The Circulatory system
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The circulatory system is responsible
for pumping ______ around the body.
We need blood to be taken around the
body because blood contains ________
and _______. These are needed so
that all the ____ in our bodies can
produce _____ through _________.
The main organs in the circulatory
system are the _____, the lungs and
the kidneys.
Words – energy, heart, blood, glucose,
respiration, oxygen, cells
“Double Circulation”
1) Blood gets pumped
from the heart to the
lungs and picks up oxygen.
The haemoglobin in the
cells becomes
oxyhaemoglobin
5) After the oxygen and
glucose have been removed
for respiration the blood is
sent back to the heart and
starts again
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2) The blood is then
taken back to the
heart…
3) The heart pumps
the blood to the
intestine (where
oxygen and glucose
are removed). The
oxyhaemoglobin is
split up into oxygen
and haemoglobin…
4) … and to the rest of
the body (where oxygen
is also removed)
Arteries, veins and capillaries
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Arteries carry high pressure
blood away from the heart.
They have smaller lumen and
no valves.
Capillaries have thin walls
(one cell thick) to allow
glucose and oxygen to pass
through. Also used to
connect arteries to veins.
“Lumen”
Veins carry low pressure blood back to the
heart. They have thinner, less elastic walls and
have valves to prevent backflow of blood.
The four parts of blood
1. RED BLOOD CELLS – contain haemoglobin
and carry ______ around the body. They
have no _______ and a large surface area.
2. PLATELETS – small bits of cells that lie
around waiting for a cut to happen so that
they can ____ (for a scab).
3. WHITE BLOOD CELLS – kill invading
_______ by producing _________ or
engulfing (“eating”) the microbe.
These three are all carried around by the
PLASMA (a straw-coloured liquid). Plasma
transports CO2 and ______ as well as
taking away waste products to the ______.
Words – antibodies, clot, kidneys,
oxygen, nucleus, glucose, microbes.
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(Aerobic) Respiration
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Every life process (e.g. growth) needs ENERGY.
___________ is the process our bodies use to produce
this energy:
Glucose + oxygen
water + carbon dioxide + ENERGY
The glucose we need comes from ______ and the oxygen
from _________. Water and carbon dioxide are breathed
out. The MAIN product of this equation is _________.
Muscles also contain glycogen, which can be quickly
converted into glucose.
Words – breathing, energy, respiration, food
Heart
rate/min
225
The Effect of Exercise
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Breathing
rate/min
Rest
Exercise
100
Recovery
175
75
125
50
75
25
5 mins
10 mins
15 mins
20 mins
During exercise the following things happen: heart rate increases,
breathing increases and arteries supplying muscles dilate. These three
things all help muscles to get the oxygen and glucose they need.
Anaerobic respiration
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Unlike aerobic respiration, anaerobic respiration is when
energy is provided WITHOUT needing _________:
Glucose
lactic acid + a bit of energy
This happens when the body can’t provide oxygen quick enough
for __________ respiration to take place.
Anaerobic respiration produces energy much _______ than
aerobic respiration but only produces 1/20th as much.
Lactic acid is also produced, and this can build up in muscles
causing ______ and an oxygen ______.
This “debt” then needs to be “repaid” by deep breathing to
________ the lactic acid.
Words – debt, oxygen, fatigue, oxidise, aerobic, quicker
Kidneys
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Kidneys are responsible for controlling ion, urea and
water content.
Blood in
Kidneys are made up of two
important tissues – BLOOD
VESSELS and TUBULES.
Blood out
Ureter (tube that takes
urine down to bladder)
Kidneys
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Kidneys work in 3 stages:
Blood vessel
1. ULTRAFILTRATION - Lots of water and
products of digestion are squeezed out of
the blood and into tubules under pressure.
2. SELECTIVE REABSORPTION – the blood
takes back the things it wants (e.g. glucose
and ions) even though this means going
against a concentration gradient.
3. WASTE – excess water, excess ions and
any urea are now removed through the
ureter
Tubule
Dialysis
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Sometimes kidneys can fail due to infections, toxic substances
or genetic reasons. One possible answer is to use a dialysis
machine:
Partially permeable membranes
Sugar
Dialysis fluid
Sugar
Blood
Dialysis fluid
Urea
Urea
Urea and salt diffuse out of the blood into the dialysis fluid.
Also, the dialysis fluid contains the same concentration of
sugar and minerals as the blood so these don’t diffuse.
Kidney transplants
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Instead of dialysis a kidney could be transplanted into the
patient.
This option is cheaper than dialysis but it
requires a _______ (a normal person can still
function with one kidney). This donor must have
a similar ______ type to the patient. Also, the
new kidney might be rejected by the body’s
______ system which will try to destroy the new
organ. To work around this problem the patient
can take “immunosuppresant ___” which suppress
the immune system. Transplanted kidneys only
work for around nine years and then the patient
has to return to _______.
Words – dialysis, donor, immune, tissue, drugs
Micro organisms
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Micro organisms are tiny living organisms such as bacteria,
viruses and fungi.
Cell wall
Bacteria is used for making yoghurts and
cheese.
Yeast is a single-celled organism used in
making alcoholic drinks and bread.
Nucleus
Cytoplasm
The difference between these two processes is whether the
yeast respires aerobically or anaerobically:
Aerobic respiration:
Sugar
Water + carbon dioxide
Anaerobic respiration
(fermentation):
Sugar
Alcohol + carbon dioxide
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Using micro organisms to make food
To make alcoholic drinks _____ is needed. In
wine, this sugar comes from the natural sugars in
the _____. In beer, the sugar is provided by
carbohydrates which are digested by _______ (a
process called “______”). The sugars are then
extracted and fermented and hops are added to
give the beer its ________.
In yoghurt production bacteria is added to warm
____. The bacteria ferments the sugar in the
milk (lactose) to produce ______ ____. The
lactic acid causes the milk to clot and turn into
yoghurt.
Words – lactic acid, malting, sugar, enzymes,
grapes, milk, flavour
Louis Pasteur
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I did a lot of work on germs in the 1850s.
The process of “pasteurising milk” is named
after me.
Research task:
Find out what Pasteur did and the experiments
he performed with their conclusions.
Extension task:
Find out about the work of earlier scientists
Lazzaro Spallanzani and Theodor Schwann and
how their work proved that the traditional
idea of “spontaneous generation” was wrong.
Pasteur,
1822 - 1895
Fermenters
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A fermenter is a controlled environment (i.e.
a large device) that provides ideal conditions
for micro organisms to grow and feed.
Micro organisms
Water
cooled
jacket
Temperature
sensor
pH sensor
Outlet tap
Sterile air
supply
Penicillin
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I (accidentally)
discovered penicillin in
1928
Alexander
Fleming,
1881-1955
Today, penicillin is grown in ________ which
use sugar and other ________ (sources of
nitrogen). The penicillium fungus only starts
producing penicillin when the food runs out.
Another fungus used on a large scale is fusarium, which is used
to make mycoprotein (a _______-rich food suitable for
_________). The fungus is grown on starch under ________
conditions and the biomass is harvested and purified.
Words – aerobic, nutrients, fermenters, protein, vegetarian
Biofuels
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Biofuels are fuels that are “made” biologically. For example:
•
Manure or other waste that can be
used to release _______ (biogas)
•
Corn or sugar cane that can undergo
anaerobic respiration in a fermenter
and then distilled to produce ______
like bio-ethanol.
Biofuels have two main advantages
over traditional fuels – they are
______ and ________.
Words – alcohols, cleaner, burnt,
renewable, methane
Biogas
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Task: Find a diagram of a biogas generator
and explain how it works. To do this you should
include answers to the following questions:
1) What is the main part of biogas?
2) What process goes on inside the generator?
3) What raw materials go inside the generator and where do
they come from?
4) What does the generator produce and what do you use
these products for?
Extension – find out how different types of biogas
generator are used in different conditions and why.
Growing micro organisms
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Method:
1) Sterilise the
inoculating loop
2) Dip the loop in the bacteria
and spread it across the agar
3) Secure (but don’t
seal) the lid with tape
Questions:
1) Why are you sterilising the loop?
2) What does the agar do?
3) Why is the lid not sealed all the way around?
4) Why would you not want to culture your bacteria at 37OC?