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Report
B7: Biology Across the
Ecosystem
Biology in Action
A. Blackford
Revision is important!
WARNING
• This PowerPoint is not a substitute
for active revision using notes, the
workbook and revision guide.
• You also need to do plenty of past
papers to get exam practice.
• Good luck!
Harvesting the sun
• Most of the energy used by living
things ultimately came from the sun
• Plants harvest this energy by
PHOTOSYNTHESIS. They are
AUTOTROPHS
• Animals are HETEROTROPHS and
need to eat ready made food.
Cycles in Nature
• Energy flows through the living system
• Nutrients (like CARBON and
NITROGEN) are CYCLED in the system
Trapping Sunlight Energy
• What happens to the light energy that
hits the leaf?
60% wrong
wavelength
5% passes
straight through
33% lost as
heat energy
35% absorbed
By chlorophyll
2% to
new growth
Leaves are green because RED and BLUE light
is absorbed for use in photosynthesis and
GREEN light passes through or is reflected.
Photosynthesis
The Equation for Photosynthesis
Carbon dioxide + Water
6CO2
6H2O
Light energy
Chlorophyll
• Light energy splits
water into
hydrogen and
oxygen
• The reaction takes
place in
CHLOROPLASTS
Glucose
C6H12O6
+ Oxygen
6O2
What is the glucose used for?
• Glucose is a carbohydrate
• It is the starting point for FATS,
PROTEINS (with nitrates from the
soil) other carbohydrates and
CELLULOSE (for the cell wall)
• Changed into starch for storage
(starch does not upset the OSMOTIC
balance of the cell).
• For energy from respiration
18
energy
e.g. seed germination
other sugars
GLUCOSE
protein
cytoplasm
starch
cellulose
cell walls
storage e.g. starch in potato
fruits
The rate of Photosynthesis
• Changing the light intensity changes the rate of
photosynthesis – up to a point!
Light is NOT
limiting the rate of
photosynthesis
(something else is)
Light is limiting
the rate of
photosynthesis
Increasing light intensity
Limiting factors (carbon dioxide)
Light is
limiting
all the
way
along this
line.
Increasing the CO2
concentration increases the
final rate of photosynthesis
Light is NOT
limiting the rate
here. Carbon
dioxide IS.
Compensation point
• At the compensation point the amount of
carbon dioxide produced by respiration is
equal to the amount of oxygen being produced
by photosynthesis
• Plants cells
produce CO2 all
the time (from
respiration)
• There are two
compensation
points each day
The carbon cycle
Vegetation
Feeding relationships
Oak tree
Insect
Sparrow
Kestrel
Producers
1o Consumer
2o Consumer
3o Consumer
Producers
Herbivore
Carnivore
Carnivore
1st trophic
level
2nd trophic
level
3rd trophic
level
4th trophic
level
Increasing Size (usually)
Decreasing Number (usually)
Pyramids of number or biomass?
• Counting the
number of
organisms
along a food
chain will
usually give a
pyramid of
numbers (but
not always)
Pyramid of biomass
If the total mass of the organisms at
different trophic levels are taken a
pyramid of biomass is produced
Life underground
• Soil organisms are
responsible for
recycling nutrient
such as nitrogen
• They are
responsible for the
decay of dead
animals and plants
Soil
microbes
Bacteria
Fungi
Approx numbers per
gram of soil
1 000 000 000
1 000 000
Nematodes
500 000
Flatworms
100 000
Insects
5000
Living together 1
• Commensalism
• One organism benefits but the other isn’t
harmed e.g. seeds sticking to the fur of animals
for dispersal.
• Mutualism
• Both organisms in a relationship benefit e.g.
clown fish are protected by anemone tentacles
and they drop bits of food that the anemone
feeds on (see your revision guide for more
examples)
Living together 2
• Parasitism
• Only one of the organisms benefit from
this arrangement, the other is harmed
by it.
These are dust mites in a human eye
lash follicle. They are 0.4 mm long.
Most people have some. They LOVE
makeup and will thrive if it is not taken
off properly at night!
Human parasites
• These can get into the body by:
• Food or water
• Through nose, mouth, anus, genitial and
urinary tracts
• Insect bites
• Burrowing under the skin
Tapeworms 1
•
•
•
•
•
•
•
•
Live in the human gut
Can be very long (10m for fish tapeworm)
Their head and suckers grip the gut wall
They have a thick skin (cuticle) so they are
not digested
They can respire anaerobically
They have male and female organs
They produce huge numbers of egg (6m a
year from cow tapeworm
The head (scolex) constantly produces new
‘segments’ that break off from the tail
Tapeworms 2
• Tapeworm eggs must
develop in the
muscles of other
animals (pig, cows,
fish) before
infecting humans
• The tapeworms form
a cyst in the muscle
• Humans eat
undercooked or raw
meat and the
tapeworm develops in
the gut.
Tapeworms in the
stomach of a dog
Malaria
• Caused by a
microscopic animal
called a protozoan
• Transmitted by
mosquitoes (they
are the VECTORS
for this disease).
• 300-500 million
infected worldwide,
annual deaths 2
million
Sickle cell anaemia
• This is a genetic disorder caused by a
recessive allele.
• Faulty haemoglobin is made that changes
shape at low oxygen concentrations
• This causes the red blood cells to ‘sickle’
and clog capillaries.
• Sickle cell anaemia protects heterozygous
individuals from malaria so the allele is
more common in areas
that have endemic
malaria
‘Sickled’ red
blood cell
Normal red
blood cell
Inheriting sickle cell anaemia
Parent 1
Parent 2
• The sickle cell
allele is recessive
(A is normal and a
is the sickle allele)
• Aa individuals are
carriers
• aa individuals are
affected
A
a
A
a
AA
Aa
Normal
Carrier
Aa
aa
Carrier
Affected
Living factories
• Antibiotics
• Penicillin made by the fungus Penicillium which
is grown in huge fermenters and the fungus
secretes the antibiotic into the liquid
• Enzymes
• Rennin can come from cows stomachs or fungus
and is used in cheese manufacturing
• Microbes for food
• Microbes for food is called single celled protein
(SCP)
• Quorn is pressed fungal hyphae
Genetic modification (GM)
• Genes are taken from one species and
added to another (e.g. human insulin
genes added to bacteria to produce
insulin)
• Human genes are added to bacterial
PLASMIDS
• These are added to another bacterial
cell which will produce the human
chemical
Genetic modification (GM)
• Genes are taken from one species and added to
another in plant crops this may be resistance to
disease
Against GM crops
For GM crops
Genes could make plant produce
toxins
Food safety organisations check
for these
GM crops may irreversibly change
the ecosystem
Farmers may benefit from
healthier crops and lower costs
Poor farmers can’t afford the
seed. Crops are infertile
Some GM technology shared and
yield is bigger
EU consumers won’t buy the
products
Consumers in other countries will
buy the products
Genetic testing
• Gene probes are used to test for
some ‘faulty’ genes
• Faulty genes stick to the probe.
These can be seen by
• UV – a fluorescent molecule sticks to the
DNA and glows under UV light
• Autoradiography – gene probe made
from radioactive DNA which blacken Xray film
Blood
White blood cell
Fight infection. Some
produce antibodies,
others engulf invaders
Red blood cell
Carry oxygen in haemoglobin
as OXYHAEMOGLOBIN
Also present
Platelets
Cell fragment that trigger blood clotting (not shown here)
Plasma
The liquid part of blood which also carries nutrients and hormones
Blood Types ABO system
• Giving a patient an incompatible transfusion
will cause their blood to clot and kill them!
• Plasma antibodies will make this happen
• Blood group O is
the universal
donor (why)
• Blood group AB
is the universal
recipient (why)
Inheriting blood groups
• There are 3 different alleles for this
gene
• A is co-dominant with B
• A and B are dominant over O
• Everyone has 2 of these alleles
•
•
•
•
AO and AA are blood group A
BO and BB are blood group B
AB is blood group AB
OO is blood group O
Predicting blood groups
Examples of how blood groups are inherited
Parent with blood
group AB
O
A
B
A
AO
BO
AB
Group A
Group B
AO
BO
Group A
Group B
Parent with blood
group B(O)
Parent with blood
group O(O)
O
Parent with blood
group A(O)
B
Group AB
O
AO
Group A
O
BO
Group B
OO
Group O
The heart
• The heart is
really 2 pumps
side by side
• 2 upper
chambers are the
atria
• 2 lower chambers
are the
ventricles
• Blue represents
deoxygenated
blood
• Red represents
oxygenated blood
Aorta
(to body)
Vena cava
(from body)
Pulmonary artery
(to lungs)
Pulmonary
vein
(from lungs)
Right
atrium
Left
atrium
Valve
Right
ventricle
Left
ventricle
Arteries and Veins
• Arteries have
• Thick walls
• A pulse (pressure waves
from the heart beat)
• Veins have
• Thinner walls than arteries
as the pressure is lower
• Valves to stop blood
flowing backwards
Capillaries
• Have walls one cell thick
• Have very small diameter
(about the size of a red
blood cell)
• Have walls that ‘leak’
• Oxygen and nutrients are
taken to the cells
• Carbon dioxide and waste, like
urea, go back into the vessels
Double circulation
• For
every
trip
around
the body
and
lungs ,
blood
must
pass
through
the
heart
TWICE
LUNGS
Blood is
OXYGENATED
START
RA pumps blood
into the RV
R VENTRICLE
Pumps blood
to the lungs
END
Deoxygenated
blood returns
To RA
L. ATRIUM
Pumps blood
to LV
Oxygenated
blood returns
to the heart
L.VENTRICLE
Pumps blood
to the rest
of the body
CAPILLARIES
Blood loses
oxygen in the
capillaries
Respiration
• Aerobic respiration
Glucose +
C6H12O6
Oxygen
6O2
Carbon dioxide
+ Water
6CO2
• Aerobic respiration takes place in
MITOCHONDRIA
6H2O
Lungs and diffusion
• Lungs are efficient at getting oxygen
into the lungs because them make
diffusion efficient
•
•
•
•
Thin walls to the alveoli
Large surface area
Ventilation of the lungs
Diffusion gradient kept
high
• Good blood supply
Anaerobic respiration
• Respiration without oxygen
In Plants and Yeast
Glucose
Carbon dioxide
+
Ethanol
In Human Muscles
Glucose
Lactic acid
In both cases some energy is produced
(but not as much as in aerobic respiration)
and is used to make ATP, the energy
currency of the cell
Exercise and the oxygen debt
• Lactic acid builds
up during
strenuous
exercise
• Removing it from
the muscles
requires oxygen
• The amount
needed is the
oxygen dept
The skeleton
• The skeleton has a number of jobs to
do
• Protects vital organs (brain, spine
ovaries)
• Makes red blood cells in the marrow of
‘long bones’
• Stores the minerals calcium and
phosphorus
• Forms a system of levers with muscles
attached for movement
Knee joint structure
Muscle
Femur
Tendon
(thigh bone)
Tough and
nelastic attaches
muscle to bone
Cartilage
Smooth, covers
The end of bones
To help movement
Patella
(knee cap)
Ligaments
Synovial fluid
Made by synovial
Membrane.
Lubricates and
Nourishes the
joint
Tough elastic
tissue holding
bones together
Tibia
(shin bone)
Moving the arm
Sports injuries
• Remember RICE
•
•
•
•
Rest (immobilise the injury)
Ice (anaesthetic apply covered)
Compression (snugly bandage the injury)
Elevation (raise limb to drain fluid)
• During recover
• Simple stretching
• Aerobic exercise
The End

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