Mass Transport Flashcards
State the definition of Mass Transport
The bulk movement of substances from a region of high pressure to a region of low pressure in transport systems
What is the Direction of blood flow in the heart?
Deoxygenated Blood enters right atrium and flows along the Vena Cava. Blood is then pumped to the right ventricle then out the pulmonary artery to the lungs. Gas exchange occurs and blood becomes oxygenated and returns through pulmonary vein. Enters the left atrium, pumped through left ventricle and exits the heart via aorta.
Explain how blood is supplied in the liver?
Liver is supplied with oxygenated blood in the hepatic artery. Deoxygenated blood leaves via the hepatic vein.
What is the vessel that links small intestine and liver?
It’s called the hepatic portal vein and the contents of this vessel can vary depending on what has been absorbed from the small intestine
Explain how the kidney is supplied with blood?
The kidney is supplied with oxygenated blood via the renal artery and leaves with deoxygenated blood via the renal vein
Explain the role of Coronary Arteries?
These are blood vessels branched from the aorta on the surface of the heart that supply the heart tissue with Oxygen + Glucose
Explain the role of Tendons in the Heart?
They are attached to valves and ensure valves don’t turn inside out during pressure changes
Explain the role of the Septum in the heart?
A Sheet of muscle that separates left and right side of the heart
Explain the role of the Thickest Cardiac Muscle?
Found on the left ventricle which means that the most forceful contractions can take place to pump blood all around the body.
What is Cardiac Output?
State the formula
The volume of blood pumped out of the heart per minute.
2 factors needed to calculate :
- Volume of blood pumped pumped out per contraction (Stroke Volume)
- No. of contractions per minute (Heart Rate)
Cardiac Output = Stroke Volume X Heart Rate
What does the xylem do?
Transport of water + minerals/ions from the roots up to the leaves
What does the phloem do?
Transports organic substances, mainly sucrose from the leaves to other parts of the plant (up + down)
What are the xylem + phloem together known as?
Vascular Bundle
What are the main features of the Xylem vessel when transporting water (3)
- Long Hollow tubes of dead cells so there is unrestricted flow of water along tube
- Have extra layer called lignin in cell walls. It’s a waterproof layer and provides strength + support
- Pits are areas with no lignin which allows for sideways movement of water between xylem vessels if a vessel is damaged.
Explain the Cohesion Tension Theory
Water molecules stick to each other by cohesion. (Hydrogen Bonding) which maintains a column of water molecules in the xylem vessel.
Adhesion is the water molecules sticking to the inside of the xylem vessel.
Water enters the palisade + spongy and energy is provided by the sun
At the leaf, transpiration takes place pulling entire column of water molecules upwards
What is Transpiration?
It is the evaporation of water from mesophyll cell walls into air spaces and then the diffusion of water vapour out of the leaf, through the stomata
Explain the 2 sites where Transpiration takes place
STOMATA - Evaporation of water from the mesophyll cell walls into air spaces and then the diffusion of water vapour out of the leaf thought the stomata.
CUTICLE - Evaporation of water from epidermal cells through waxy cuticle covering the leaf surface. This is impermeable so little water is lost here.
How does light Intensity affect Transpiration?
Stomata open to let CO2 to enter for photosynthesis. Stomata shuts in the dark when photosynthesis can’t happen. Higher light intensity increases rate of transpiration
How does temperature affect rate of transpiration?
Increasing temp = increased rate of transpiration. Molecules will have higher kinetic energy so rate of evaporation increases.
How does Air movement affect Transpiration?
In still air, moist air builds up. Reduces water potential gradient + decreases rate of Transpiration.
In windy conditions, moots air blown away + water potential gradient increases between leaf and outside so increases rate of transpiration.
How does Humidity affect rate of transpiration?
This is conc. of water vapour in the air.
If air is humid (rainy) water potential gradient decreases so rate of Transpiration decreases whereas in dry air it increases
State the definition of Translocation
This is the bulk movement of substances from high hydrostatic pressure at the source to low hydrostatic pressure at the sink
What are the main substances transported in the phloem
The main organic substance is sucrose. Also amino acids, mRNA and Viruses.
Explain the source of the plant
It is any region of the plant where sucrose is loaded into the phloem.
- Leaf: photosynthesis takes place producing glucose. Glucose converted to sucrose
- Storage organ where starch is stored
Explain the Sink in a plant
Any region of the plant where sucrose is removed from the phloem. The sugar is used in respiration or converted into starch for storage
Explain what happens at the source
1) sucrose actively loaded into phloem by companion cell. Energy from ATP and protein carrier needed (done through co transport in which H+ ions pumped out of cell leading to low conc in cell),
2) lower water potential
3) water follows by osmosis (less negative to more negative)
4) increases volume of water and generates high hydrostatic pressure
Explain what happens at the sink
1) Sucrose enter the sink cell (unloading)
2) Lower water potential of cell
3) water follows by osmosis
4) Low hydrostatic pressure produced
Name a technique used for evidence for Translocation
Tracers - radioactive carbon (C14) used to follow path of organic substances; sucrose. Plant supplied with 14CO2 for photosynthesis. Sucrose produced will have C14. X rays can be used to see areas where sucrose is transported to.
Name another technique used for evidence for Translocation
Ringing experiment - includes removing a ring of phloem tissue around circumference of plant. Xylem left to ensure water can be transported to plant. The removal will mean that sucrose cannot be transported past this point.
What evidence is there to contradict the Mass flow hypothesis
Suggestions show that amino acids are translocated more slowly than sucrose and claimed that different substances moving in opposite directions.
If the MASS FLOW HYPOTHESIS is correct, all substances would move at same rate, in the same sieve tube, at the same time
Describe the Mass Flow hypothesis for the mechanism of Translocation?
In Source, Sugars actively transported into phloem by Companion Cells which lowers water potential and water follows in by osmosis which generates a higher pressure causing movement to sink. Sugars can be used for respiration or storage
Contrast the processes of Facilitated Diffusion and Active Transport
F.D involves Protein Carrier or channel whereas Active Transport only uses protein carriers.
F.D requires no ATP where A.T does
F.D is down a Conc. Gradient whereas A.T is against one
What is cohesion?
Water molecules sticking together because they are polar
What cells make up phloem?
Sieve tube cells and companion cells
What are sieve tube cells?
Living cells with little cytoplasm and organelles that are hollow
What are companion cells?
Cells with many organelles that support sieve tube cells with ATP as sieve tube cells have no mitochondria
