B7: Biology Across the B7: Biology Across the EcosystemEcosystem

Biology in Action

A. Blackford

Revision is important!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 sunHarvesting 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 NatureCycles in Nature• Energy flows through the living system• Nutrients (like CARBON and

NITROGEN) are CYCLED in the system

Trapping Sunlight EnergyTrapping Sunlight Energy• What happens to the light energy that

hits the leaf?60% wrong wavelength

35% absorbed By chlorophyll

5% passes straight through 2% to

new growth

33% lost as heat energy Leaves are green because RED and BLUE

light is absorbed for use in photosynthesis and GREEN light passes through or is reflected.

PhotosynthesisPhotosynthesis

• Light energy splits water into hydrogen and oxygen

• The reaction takes place in CHLOROPLASTS

The Equation for Photosynthesis

Carbon dioxide

+ WaterLight energy

+Glucose

OxygenChlorophyll6CO2 6H2

OC6H12O6 6O2

What is the glucose used for?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

GLUCOSE

storage e.g. starch in potato

starch

fruitsother sugars

e.g. seed germination

energy

cytoplasm

protein

cell walls

cellulose

18

The rate of Photosynthesis The rate of Photosynthesis • Changing the light intensity changes the rate

of photosynthesis – up to a point!

Light is limiting the rate of

photosynthesis

Light is NOT limiting the rate of

photosynthesis (something else is)

Increasing light intensity

Limiting factors (carbon Limiting factors (carbon dioxide)dioxide)

Light is limiting all the way

along this line.

Light is NOT limiting the rate here. Carbon

dioxide IS.

Increasing the CO2 concentration increases

the final rate of photosynthesis

Compensation pointCompensation point

• Plants cells produce CO2 all the time (from respiration)

• There are two compensation points each day

• At the compensation point the amount of carbon dioxide produced by respiration is equal to the amount of oxygen being produced by photosynthesis

The carbon cycleThe carbon cycle

Vegetation

Feeding relationshipsFeeding relationships

Producers 1o Consumer 2o Consumer 3o Consumer

Producers Herbivore Carnivore Carnivore

1st trophic level

2nd trophic level

3rd trophic level

4th trophic level

Oak tree Insect Sparrow Kestrel

Increasing Size (usually)

Decreasing Number (usually)

Pyramids of number or Pyramids of number or biomass?biomass?• Counting the

number of organisms along a food chain will usually give a pyramid of numbers (but not always)

Pyramid of biomassPyramid of biomassIf the total mass of the organisms at different trophic levels are taken a pyramid of biomass is produced

Life undergroundLife underground• Soil organisms

are responsible for recycling nutrient such as nitrogen

• They are responsible for the decay of dead animals and plants

Nematodes

1 000 000

Soil microbes

Bacteria

Fungi

Insects

1 000 000 000

100 000

500 000

5000

Flatworms

Approx numbers per

gram of soil

Living together 1Living 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 2Living 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 parasitesHuman 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 1Tapeworms 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 2Tapeworms 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

MalariaMalaria• 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 anaemiaSickle 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

Normal red blood cell

‘Sickled’ red blood cell

Inheriting sickle cell Inheriting sickle cell anaemiaanaemia• The sickle cell

allele is recessive (A is normal and a is the sickle allele)

• Aa individuals are carriers

• aa individuals are affected

Parent 1

Pare

nt

2

A

A

a

a

AaAA

Aa aa

Normal

Carrier

Carrier Affected

Living factoriesLiving 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)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)Genetic modification (GM)• Genes are taken from one species and added to

another in plant crops this may be resistance to diseaseAgainst 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

EU consumers won’t buy the products

Some GM technology shared and yield is bigger

Consumers in other countries will buy the products

Genetic testingGenetic 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 X-ray film

BloodBloodWhite blood cellFight infection. Some produce antibodies, others engulf invaders

Red blood cellCarry oxygen in haemoglobin as OXYHAEMOGLOBIN

Also presentPlateletsCell fragment that trigger blood clotting (not shown here)PlasmaThe liquid part of blood which also carries nutrients and hormones

Blood Types ABO systemBlood Types ABO system

• Blood group O is the universal donor (why)

• Blood group AB is the universal recipient (why)

• Giving a patient an incompatible transfusion will cause their blood to clot and kill them!

• Plasma antibodies will make this happen

Inheriting blood groups 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 groupsPredicting blood groups

Parent with blood group AB

Pare

nt w

ith b

lood g

roup

O(O

)

A B

OAO BO

OAO BO

Parent with blood group A(O)

Pare

nt w

ith b

lood g

roup

B(O

)

A O

BAB BO

OAO OO

Group A Group B

Group A Group BGroup A Group O

Group AB

Group B

Examples of how blood groups are inherited

The heartThe 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

Vena cava(from body)

Aorta(to body)

Pulmonary vein

(from lungs)

Pulmonary artery(to lungs)

Rightatrium

Leftatrium

Leftventricle

Valve

Rightventricle

Arteries and VeinsArteries 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

CapillariesCapillaries• 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 circulationDouble circulation• For

every trip around the body and lungs , blood must pass through the heart TWICE

R VENTRICLEPumps blood to the lungs

LUNGSBlood is

OXYGENATED

Oxygenated blood returns to the heart

L. ATRIUMPumps blood

to LV

L.VENTRICLEPumps bloodto the restof the body

CAPILLARIESBlood loses

oxygen in thecapillaries

STARTRA pumps blood

into the RV

ENDDeoxygenated blood returns

To RA

RespirationRespiration• Aerobic respiration

Glucose

+ Oxygen +Carbon dioxide

Water6CO26O2C6H12O6 6H2O

• Aerobic respiration takes place in MITOCHONDRIA

Lungs and diffusionLungs 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 respirationAnaerobic respiration• Respiration without oxygen

In Plants and Yeast

In Human Muscles

Glucose

Carbon dioxide

Ethanol

+

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 Exercise and the oxygen debtdebt

• Lactic acid builds up during strenuous exercise

• Removing it from the muscles requires oxygen

• The amount needed is the oxygen dept

The skeletonThe 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 structureKnee joint structureFemur

(thigh bone)

Tibia(shin bone)

Patella(knee cap)

Muscle

Ligaments Tough elastic tissue holding

bones together

Tendon Tough and

nelastic attaches muscle to boneCartilage

Smooth, coversThe end of bones

To help movement

Synovial fluidMade by synovial

Membrane. Lubricates and Nourishes the

joint

Moving the armMoving the arm

Sports injuriesSports 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 EndThe End