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BIOLOGY PPE1
CORONARY HEART DISEASE/CARDIOVASUCULAR DISEASES
Cardiovascular diseases are diseases of the heart and blood vessels.
They’re non-communicable meaning they do not spread through human contact and are not infectious.
The coronary arteries branch out of the aorta and spread out into the heart muscle.
Their purpose is to provide oxygen to the muscle cells of the heart.
the oxygen is then used for respiration to provide energy from the muscle cells to contract.
For coronary heart disease, layers of fatty material build up inside the coronary arteries.
this causes the coronary arteries to narrow
reduces blood flow through them
results in lack of oxygen to the heart muscle
also results in heart attacks where the heart is starved of oxygen
TREATMENT:
Statin:
they’re drugs which reduce the level of cholesterol in the blood
slows down the rate of fatty material build up in the arteries
proved to be an effective treatment
also has unwanted side effects such as liver problems
Cardiovascular diseases can cause an almost full blockage of the arteries.
This can be treated using a stent
a tube which can be inserted into the artery to keep it open.
allows blood to flow normally through the artery
however, it will not stop other regions of the coronary artery from narrowing
it does not treat the underlying cause of the disease
Sometimes the heart valves do not fully open so the heart has to pump heart hard to get the blood through.
Other times the valves are leaky and cause patients to feel weak or tired.
TREATMENT:
When the valves are faulty, they can be replaced with a mechanical valve made of metal or a valve from an animal such as a pig.
Mechanical valves last a lifetime but increase the risk of blood clots.
patients will have to take anticlotting drugs
Valves from animals do not last as long and might have to be replaced.
drugs won’t have to be taken
Sometimes the heart cannot pump enough blood around the body.
This is called heart failure.
TREATMENT:
A donated heart or donated heart and lungs being used as a replacement.
however, there are not enough donated hearts to treat every patient
drugs will have to be taken by the patient to stop the rejection of the heart by the body’s immune system.
Some an artificial heart will temporarily given to a patient while they wait for a transplant or while allowing their weaker heart to rest.
All options increase the risk of clotting
All are also not long term solution.
CYSTIC FIBROSIS:
It is an inherited disorder
a disorder of cell membranes
Alleles can be dominant or recessive.
The dominant allele will also be expressed in the phenotype even if there is only one copy present.
A recessive allele is only expressed if two copies are present
Cystic Fibrosis is controlled by one gene.
The gene for cystic fibrosis has two alleles
the normal cell membrane function allele has the symbol ‘C‘
the defective cell membrane function allele has the symbol ‘c‘
In order to have cystic fibrosis, the person has to have two copies of the defective allele.
this means they have to inherit a defective allele from each parent
a person with a normal and defective allele DOES NOT have cystic fibrosis
they are instead called a carrier of the cystic fibrosis allele.
DIGESTIVE ENZYMES:
Large food molecules are digested by enzymes into smaller molecules.
The products of digestion are then absorbed into the bloodstream.
Enzymes catalyse(speed up) chemical reactions.
They are large protein molecules and they have a groove on their surface called the active site.
A substrate will attach onto the active site.
The substrate will fit perfectly into the active site.
If the substrate does not fit into the active site, the enzyme cannot break down the substrate.
This is also known as the LOCK AND KEY THEORY.
Proteins will be broken down with the protease enzyme.
Protease enzymes are found in the stomach, pancreatic fluid and the small intestine.
Proteins are long chains of chemicals called amino acids.
When digested, protease enzymes convert the protein back into the individual amino acids which are absorbed back into the bloodstream.
When amino acids are absorbed by the body cells, they are joined together in a different order to make human proteins.
Starch consists of a chain of glucose molecules.
Carbohydrates are broken down by enzymes called carbohydrase.
Starch is broken down by enzymes called amylase.
When carbohydrates are digested, they produce simple sugars.
Amylase is found in the saliva and pancreatic fluid.
Lipid molecules consists of a molecule of glycerol attached to three molecules of fatty acids.
Lipids are digested by the enzyme lipase.
This produces glycerol and fatty acids.
Lipase is found in the pancreatic fluid and small intestine.
Bile helps speed up digestion of lipids but bile is NOT an enzyme.
Bile converts large lipid droplets into smaller droplets.
it also emulsifies the lipid.
This also increases the surface area of lipid droplets.
And increases the rate of lipid breakdown by lipase.
Bile is alkaline.
It neutralises stomach acids.
It creates alkaline conditions in the small intestine.
Also increases the rate of lipids digestion by lipase.
GAS EXCHANGE:
The heart pumps blood to the lungs where the blood collects oxygen.
The blood will return to the heart and is pumped around the whole body where it delivers the oxygen to the body cells.
Air passes into the lungs through a tube called the trachea.
Rings of cartilage prevent the trachea from collapsing during inhalation.
The trachea splits into the two tubes called bronchi with one passing into each lung.
The bronchi subdivides into many smaller tubes called bronchioles.
The bronchioles end in tiny air sacs called alveoli.
The alveoli are where gases diffuse in and out of the bloodstream.
also known as the site of gas exchange.
Oxygen will diffuse into the bloodstream.
Carbon Dioxide will diffuse out of the bloodstream and back into the air.
ADAPTATIONS:
Millions of alveoli means that lungs have a huge surface area.
Alveoli have very thin walls so the diffusion path is very short.
Alveoli have a very good blood supply.
Once the oxygen diffuses into the blood, it is rapidly removed.
This ensures that the concentration gradient is as steep as possible.
By breathing, we also increase the rate of diffusion.
Breathing brings in fresh oxygen into the alveoli and takes away the carbon dioxide.
This makes the concentration gradient high for these gases
increasing the rate of diffusion.
REQUIRED PRACTICAL - FOOD TESTS:
TESTING FOR STARCH:
put food sample/solution into a test tube.
add a few drops of iodine which is a brown/orange colour.
If starch is PRESENT, it will turn blue/black.
If starch is NOT PRESENT, it will stay orange/brown.
TESTING FOR SUGARS:
put food sample/solution into a test tube.
add 10 drops of Benedict’s solution which is a blue colour.
place the test tube into a beaker half-filled with hot water or just a hot water bath.
leave it for 5 minutes
If a small amount of sugar is present, it will turn green.
If a larger amount of sugar is present, it will turn yellow.
If a lot of sugar is present, it will turn brick red.
TESTING FOR PROTEINS:
put food sample/solution into a test tube.
add 2cm³ of biuret solution which is also blue.
If protein is present, the solution will change from blue to purple/lilac.
TESTING FOR LIPIDS:
put food sample/solution into a test tube.
add a few drops of distilled water and ethanol and shake the solution gently.
If lipids are present, a white cloudy emulsion forms.
SPECIALISATION IN ANIMAL CELLS:
Most animal cells are specialised and have adapted to help them carry out their particular function.
When cells become specialised, scientists call it differentiation.
Sperm Cells:
The job of a sperm cell is to join with the ovum (egg cell). This is called fertilisation.
During fertilisation, the genetic information of the ovum and the sperm combine.
Sperm cells contain their genetic information in their nucleus. However, sperm cells only contain half the genetic information of a normal adult cell.
Sperm cells have a long tail to allow them to swim to the ovum. They are also streamlined to make this easier and swim faster.
Sperm cells are also packed full of mitochondria which provides energy for swimming.
They also contain enzymes to allow them to digest their way through the outer layer of the ovum.
Nerve Cell:
The job of a nerve cell is to send electrical impulses around the body.
The axon carries the electrical impulses from one part of the body to another.
Myelin insulates the axon and speeds up the transmission of the nerve impulses.
The end of the axon has synapses. They are junctions which allow the impulse to pass from one nerve cell to another.
Dendrites increase the surface area so that other nerve cells can connect more easily.
Muscle Cells:
Muscle cells can contract (get shorter)
They contain protein fibres which can change their lengths.
When a muscle cell contracts, these protein fibres shorten, decreasing the length of the cell.
They are also packed with mitochondria to provide energy for muscle contraction.
Muscle cells work together to form muscle tissue.
Plant Cells:
Plant cells are also EUKARYOTES.
They have all the same organelles as animal cells as well as three extra:
Cell wall which is made from cellulose. This helps to strengthen the cell.
Chloroplasts which contain chlorophyll and are sites of photosynthesis.
Permanent Vacuole which is filled with cell sap and helps to give the cell its shape.
SPECIALISATION IN PLANT CELLS:
Root Hair Cells:
These hairs increase the surface area of the root so that it can absorb water and dissolved minerals more efficiently.
Root hair cells do not contain chloroplasts because they are underground and aren’t exposed to any light.
Xylem Cells:
Xylem cells are found in the plant stem. They form long tubes.
The tubes carry water and dissolved minerals from the roots to the leaves.
They also have very thick walls containing lignin. This provides support to the plant.
Because the cell walls are sealed with lignin, the xylem cells can die.
The end walls between the cells have broken down.
They have no nucleus, cytoplasm, vacuole or chloroplasts.
This makes it easier for water and minerals to flow.
Phloem Cell:
Phloem tubes carry dissolved sugars up and down the plant.
The phloem contains two different types of cells:
Phloem vessel cells.
They have no nucleus but limited cytoplasm
Companion Cells
Every vessel cell has a companion cell connected by pores
The mitochondria in the companion cell provide energy to the phloem vessel cell.
The end walls of the vessel cells have pores called sieve plates.
These allow dissolved sugars to move through the cell interior.
PLANT TISSUES:
Like any other organs, the leaf contains different tissues.
The top and bottom of the leaf are covered with a layer of very thin cells called epidermal cells which form epidermal tissues.
The epidermis protects the surface of the leaf.
The upper epidermis is transparent
this allows light to pass through to the photosynthesis cells below.
It is also covered with a thin layer of oily material called the waxy cuticle.
this reduces the evaporation of water from the surface of the leaf.
The lower epidermis has tiny pores called stomata.
this allows carbon dioxide to enter the leaf and oxygen to leave.
this also helps to control the amount of water vapour that can pass out of the leaf.
There are also guard cells on either side of the stomata.
The palisade mesophyll consists of palisade cells.
they are packed full of chloroplasts.
chloroplasts contain chlorophyll which absorbs light energy needed for photosynthesis.
The spongy mesophyll is full of air spaces.
The air spaces allow carbon dioxide to diffuse from the stomata through the spongy mesophyll to the palisade cells.
oxygen also diffuses from the palisade cells through the spongy mesophyll to the stomata.
Xylem tissue transports water from the roots to the stem and leaves.
some of the water is then used in photosynthesis.
it also transports dissolved mineral ions such as magnesium which is used to make chlorophyll.
Phloem tissue transports dissolved sugars produced by photosynthesis from the leaves to the rest of the plant.
the sugars can be immediately used in respiration.
the sugars can also be stored for example as starch.
the movement of sugars and other molecules through phloem tissue is called translocation.
You can also find meristem tissue at growing tips e.g. shoots and roots.
they contain stem cells and can differentiate into different types of plant tissue.
VARIABLES:
INDEPENDANT VARIABLE:
A variable which is changed.
DEPENDANT VARIABLE:
A variable which you measure.
CONTROL VARIABLE:
A variable which you keep the same.
REQUIRED PRACTICAL - OSMOSIS:
Osmosis is the diffusion of water from a high concentration to a low concentration through a semi-permeable membrane.
When a cell is placed into water, water will move into the cell through osmosis and will expand.
When a cell is placed into a concentrated solution, water will move out of the cell through osmosis and will shrink.
METHOD:
Peel the potato as the skin can affect osmosis.
Use a cork borer to produce 3 cylinders of potato with the same diameter.
Use a scalpel to make the cylinders the same length.
Measure the length with a ruler and the mass with a balance.
Place each cylinder into a test tube.
In the first tube, put in 10cm³ of 0.5 molar sugar solution.
In the second tube, put in 10cm³ of 0.25 molar sugar solution.
In the third tube, put in 10cm³ of distilled water.
Leave the potatoes overnight to let osmosis take place.
Remove the potato from the test tubes and remove the surface moisture with a paper towel.
Measure the length and mass again then calculate the percentage change.
