B3.2 Transport Systems In Plants And Animals Flashcards
How does carbon dioxide enter the plant?
Through diffusion in the leaves
How do minerals and ions enter the plant?
They are absorbed by the roots.
What are stomata?
Tiny pores on the underside of the leaf through which carbon dioxide, oxygen and water vapour can diffuse.
What is the function of guard cells?
To control the size of the stomata to control water loss.
What happens if the plant loses water faster than it is replaced?
Stomata can close to prevent wilting.
How is the surface area of the roots increased?
With root hair cells
How is the surface area of the leaves increased? (2)
- Flattened shape
- Internal air spaces (easier gas diffusion)
Describe the process of transpiration.
- Water diffuses from the soil into the roots
- Water travels up the stem through the xylem tissue (stuck together - cohesion - easier for water to travel up in a continuous column)
- Water travels up veins into leaves - diffuses out of veins into the leaves by osmosis.
- Water evaporating and diffusing from the leaves sets up a concentration gradient, continuously pulling water from the soil to other parts of the plant.
How does increased humidity affect the rate of transpiration?
It decreases it as high levels of water in the air decreases the concentration gradient.
How does increased light intensity affect the rate of transpiration?
- It increases it as:
- Photosynthesis increases and plants use more carbon dioxide and water
- Pores on leaves open which let carbon dioxide in cells and more water evaporates out.
How does increased temperature affect the rate of transpiration?
- It increases it as water molecules on the edge of the leaf leave because there is more kinetic energy.
How does increased wind movement affect the rate of transpiration?
- It increases it as air saturated water vapour moves away from the plant and is replaced with drier, keeping a steep concentration gradient (water conc. outside the leaf is lower than inside)
What is the function of the phloem tissue?
To carry dissolved sugars from the leaves to the rest of the plant.
Where specifically does the phloem tissue carry dissolved sugars?
- Growing regions e.g shoots
- Storage organs e.g bulbs
What is the function of the xylem tissue?
To transport water and mineral ions from the roots to the stem and leaves
What are the advantages of artificial hearts?
- Extends lifespan
- No rejection from immune system - no need to take immunosuppressant drugs
- No need for donor/match tissue
What are the disadvantages of artificial hearts?
- Parts can wear out/need repair
- Blood doesn’t flow through as smoothly, causes blood clots
- Surgery causes bleeding and infection
- Battery will need changing
- Discomfort from heart controller
What is required from artificial heart valves?
- Ability to prevent blood back flow
- Ability to not cause blood clotting
- Long lasting material
- Strength to withstand pressure
- Not to be rejected by the body
Why are stents used?
- Coronary heart disease is when arteries supplying the heart are blocked by fatty deposits, restricts blood flow.
- Stents are metal mesh tubes inserted into arteries keeping them open so blood can pass through to the heart muscle.
What is the disadvantage to stents?
- Over time, arteries can narrow again as stents irritate and make scar tissue grow.
- Patient has to take drugs to prevent blood clotting.
What is artificial blood made of?
A salt solution (“saline”)
What is artificial blood for?
It gives patients who have lost blood time to make new red blood cells as it keeps the blood pressure by replacing lost volume.
Blood is a t—–?
Tissue
What is the purpose of red blood cells?
To carry oxygen from the lungs to the rest of the body
What properties to red blood cells have adapting them to their purpose?
- Biconcave surface = higher surface area
- They have no nucleus = more space
Describe the reactions that occur when red blood cells transport oxygen.
- In the lungs the oxygen reacts with haemoglobin in the red blood cells to form oxyhaemoglobin.
- In body tissues, oxyhaemoglobin splits into oxygen and haemoglobin and oxygen is released to the cells.
What is the purpose of white blood cells?
To mount an immune response against pathogens
What do white blood cells have that red blood cells don’t?
A nucleus
What are platelets?
Small fragments of cells
What is the purpose of platelets?
To help blood clot at the site of a wound
What is the purpose of the blood plasma?
To carry:
- Red, white blood cells and platelets
- Urea from the liver to the kidney
- Carbon dioxide from other organs to the lungs
- Soluble products of digestion from the small intestine to body cells.
