Topic 4 Flashcards
(25 cards)
What is the significance of surface area to volume ratio in living organisms?
It affects the transport of molecules in living organisms.
As organisms increase in size, the surface area to volume ratio decreases, necessitating mass transport systems.
Why do organisms need a mass transport system and specialised gas exchange surfaces as they increase in size?
To efficiently transport substances and facilitate gas exchange.
Larger organisms have higher metabolic demands, making simple diffusion inadequate.
What is the fluid mosaic model?
It describes the structure of the cell surface membrane.
This model illustrates the dynamic nature of the membrane, with proteins embedded in a phospholipid bilayer.
What are the mechanisms of passive transport?
Diffusion, facilitated diffusion, osmosis.
Facilitated diffusion occurs through carrier proteins and protein channels.
What factors affect how molecules are transported across cell membranes?
Solubility, size, charge.
These properties influence the ability of molecules to pass through the membrane.
How can large molecules be transported into and out of cells?
Through endocytosis and exocytosis via vesicles.
Endocytosis involves the uptake of materials, while exocytosis is the release of materials.
What is the formula for water potential?
Water potential = turgor pressure + osmotic potential (ψ = P + π).
This formula is used to determine the water potential in plant cells.
What role does ATP play in active transport?
It provides energy for the transport process.
Active transport moves substances against their concentration gradient.
What is the process of phosphorylation of ADP?
It requires energy to convert ADP into ATP.
This is a key mechanism for energy storage in cells.
How are insects adapted for gas exchange?
Through specialized structures such as tracheae.
These structures efficiently transport oxygen directly to tissues.
What role do stomata play in gas exchange in flowering plants?
They regulate the intake of carbon dioxide and release of oxygen.
Stomata open and close to balance water loss and gas exchange.
What are the components of the circulatory system?
Heart, arteries, veins, capillaries.
These components work together to transport blood throughout the body.
What are the advantages of a double circulatory system in mammals?
Higher pressure for blood to the body, separation of oxygenated and deoxygenated blood.
This allows for more efficient oxygen delivery to tissues.
What is myogenic stimulation of the heart?
It refers to the heart’s ability to generate its own rhythm.
The sinoatrial node (SAN) initiates the heartbeat.
What is the function of platelets in blood clotting?
They form a plug and release clotting factors.
This initiates a cascade leading to the formation of fibrin.
What is atherosclerosis?
A condition characterized by the buildup of plaque in arteries.
It can lead to serious cardiovascular diseases.
What is the Bohr effect in relation to haemoglobin?
It describes the decrease in oxygen affinity of haemoglobin in response to increased carbon dioxide levels.
This mechanism enhances oxygen delivery to tissues during high metabolic activity.
What is the oxygen dissociation curve of haemoglobin?
It illustrates how haemoglobin’s oxygen binding changes with varying oxygen concentrations.
The curve is sigmoidal, indicating cooperative binding.
What is the significance of fetal haemoglobin’s oxygen affinity?
Fetal haemoglobin has a higher affinity for oxygen than adult haemoglobin.
This allows efficient oxygen transfer from mother to fetus.
What factors influence the interchange of substances through tissue fluid?
Hydrostatic pressure and oncotic pressure.
These forces determine the movement of fluids and solutes between blood and tissues.
How do xylem and phloem tissues function in plant transport?
Xylem transports water and minerals, while phloem transports sugars.
Their structural differences reflect their specific transport roles.
What are the apoplastic and symplastic pathways in plants?
Apoplastic pathway involves movement through cell walls, symplastic pathway through cytoplasm.
These pathways facilitate water movement within plants.
What factors affect the rate of transpiration in plants?
Temperature, light, humidity, movement of air.
These environmental conditions can enhance or reduce transpiration rates.
What is the mass-flow hypothesis?
It explains the movement of sugars through phloem tissue.
While widely accepted, it has strengths and weaknesses in explaining phloem transport.
