Transport Systems Flashcards
(28 cards)
Transport System in Unicellular organisms
Exchange happens via diffusion, osmosis and active transport.
They have a large surface area to volume ratio meaning the distance from the surface to the centre is small
Transport System in Multicellular organisms
They have multiple cell layers making the distance from the surface to the centre too long for diffusion alone
E.g in plants (vascular system)
- the xylem moves water and minerals from roots to shoots
- the phloem distributes sugars and amino acids throughout the plant
Role of the Xylem & Phloem
The xylem transports water and mineral ions from the roots to the other parts of the plant (in the transpiration stream)
The phloem transports sucrose and amino acids from where they are produced or stored to other parts of the plant (this is called translocation)
Absorption of Water by Root Hair Cells
They are adapted for the efficient uptake of water and mineral ions, they contain mitochondria which release energy for active transport. They also increase the surface area of plant roots.
Steps:
- Root hair cells take up mineral ions from the soil by active transport
- The water concentration of the cell cytoplasm is reduced due to the presence of mineral ions
- Water moves into root hair cell via osmosis
The route of water through the plant
Root hair cell -> Root cortex cells -> xylem -> leaf mesophyll cells
Transpiration
The loss of water vapour from the parts of the plant that are above ground
It’s caused by the evaporation and diffusion of water from a plant’s surface of the spongy mesophyll cells, most happens at the leaves
Transpiration function
- Transporting mineral ions
- Providing water to keep cells turgid in order to support the structure of the plant
- Providing water to leaf cells for photosynthesis
- Keeping leaves cool as heat energy is removed from the leaves when water evaporates
Factors affecting rate of transpiration
Air movement: As wind speed increases the rate of transpiration increases
Temperature: more kinetic energy
Humidity: reduces the diffusion gradient
Light intensity: photosyntesis
Transpiration Practical
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Components of blood
Red blood cells, White blood cells, plasma, platelets
Red blood cells
They are specialised cells which carry oxygen to respiring cells
They are full of haemoglobin, no nucleus which allows space for haemoglobin to be packed in, biconcave disc
Plasma
CO2 dissolved in the plasma and transported form respiring cells to the lungs
Digested food and mineral ions absorbed from the small intestine and delivered to cells around body
Urea is dissolved in the plasma and transported to the kidneys
White Blood Cells (Lymphocytes)
They produce antibodies.
- Antibodies are proteins with a shape that is complementary to the antigens on the surface of the pathogen
- This is a specific immune response
White Blood Cells (Phagocytes)
Phagocytes ingest pathogens, since they have a sensitive cell surface membrane, they can detect chemicals produced by pathogenic cells.
Once they encounter the pathogen, they will engulf it and release digestive enzymes.
This is a non-specific immune response
Immunity
White blood cells are the main component of the immune system. They prevent the infectious organism from reproducing
Response to infection (Immunity)
- The pathogens enter the blood stream and multiply
- Toxins and infection of cells cause symptoms in patient
- Phagocytes engulf and digest (non-specific response)
- Pathogens eventually encounters a lymphocyte which recognises its antigens
- Lymphocytes produce specific antibodies
- Lymphocytes clone itself
- Antibodies support the destruction of pathogens by recognising and binding to them
- Phagocytes engulf and digest and destroy pathogens
Vaccinations
It contains harmless versions of a pathogen.
Vaccines contain antigens that trigger an immune response:
- Lymphocytes recognise the antigens in the blood stream
- Lymphocytes produce antibodies specific to the antigen encountered
- Memory cells are produced from the lymphocytes
- These cells and antibodies remain in the blood stream
Platelets & Blood Clotting
These are fragments of cells that are involved in blood clotting.
A series of reactions occur within the blood plasma:
- Platelets release chemicals that cause soluble fibrinogen proteins to convert into insoluble fibrin
- This forms an insoluble mesh across the wound
- Red blood cells become trapped forming a clot, the clot dries and forms a scab
Structure & Function of the Heart
- Oxygenated blood from the lungs enter the left side of the heart and is pumped to the rest of the body
- Left ventricle has a thicker muscle wall than the right ventricle as it has to pump blood at high pressure around the body
- Deoxygenated from body enter the right side of the heart and is pumped to the lungs
-> Right ventricle is pumping blood at lower pressure to the lungs
Septum separates the two side of the heart - Blood is pumped towards the heart in veins and away from the heart in arteries
Coronary arteries supply the cardiac muscle tissue of the heart with oxygenated blood. (aerobic respiration) to continue muscle contraction - Valves present to prevent blood flowing backwards
The pathway of blood through the heart (right side)
Deoxygenated blood goes through the vena cava into the right atrium. The atrium contracts and the blood is forced through the tricuspid valve into the right ventricle. Ventricle contracts and the blood is pushed through the semilunar valve into the pulmonary artery. ALL LOW PRESURE preventing damage to capillaries in the lungs
The pathway of blood through the heart (left side)
Oxygenated blood returns via the pulmonary vein to the left atrium through the bicuspid valve into the left ventricle
The ventricle contracts and the blood is forced through the semilunar valve and out through the aorta. Thicker muscle walls of the left ventricle produces high enough pressure for the blood to travel around body
Exercise and heart rate
Heart pumps blood to respiring cells to supply oxygen and glucose and remove respiratory waste
Muscle cells respire faster to increase energy supply during exercise.
Nervous system response:
- increases heart rate to deliver oxygen and glucose more frequently
- increasing the volume of blood pumped to supply large amounts of oxygen and glucose
Heart disease
Diet too high in saturated fat + cholesterol can lead to coronary heart disease, lack of oxygen for heart muscle
Risk factors of coronary heart disease
Obesity - strain on heart
High blood pressure - increases the force of blood against artery walls
High cholesterol - speeds up the build up of fatty plaques in arteries
Smoking - increase in plaque build up and increase in blood pressure
