Module 3 Flashcards
What is the primary function of the respiratory system?
To facilitate gas exchange, allowing organisms to obtain oxygen and remove carbon dioxide.
Why do single-celled organisms not need transport systems?
They have a large surface area to volume ratio, allowing them to absorb gases by diffusion.
What adaptations do multicellular organisms have for gas exchange?
They have mass transport systems and exchange organs like lungs and intestines.
What are the adaptations of gas exchange surfaces?
They are extremely thin, have a large surface area to volume ratio, and maximize the concentration gradient.
What adaptations do alveoli have for efficient gas exchange?
Large surface area, good blood supply, short diffusion distance, moist surfaces, and location in the thorax.
Describe the pathway of air during respiration.
Air enters through the nose/mouth, travels down the trachea, branches into bronchi, divides into bronchioles, and reaches alveoli.
What is the role of goblet cells in the respiratory system?
They secrete mucus to trap dust and microorganisms, preventing infection.
How do inhalation and exhalation occur?
Inhalation involves diaphragm contraction and rib cage expansion; exhalation involves diaphragm relaxation and rib cage contraction.
What is a spirometer used for?
To measure the volume of air an individual can breathe in and out.
What is the counter-current system in fish gills?
Blood flows in the opposite direction to water, maintaining a concentration gradient for oxygen.
What is the difference between open and closed circulatory systems?
Open systems are not enclosed in blood vessels, while closed systems are contained within blood vessels.
What are the main functions of arteries?
To carry blood away from the heart under high pressure.
What is the role of valves in veins?
To prevent the backflow of blood as it returns to the heart.
What is tissue fluid?
Fluid that bathes cells, containing small substances that move out of capillaries.
What are the four chambers of the heart?
Two atria and two ventricles, with the left side handling oxygenated blood and the right side handling deoxygenated blood.
What is the cardiac cycle?
A sequence of contractions and relaxations of the heart muscle that moves blood through the heart.
What does myogenic contraction mean?
Cardiac muscle can contract on its own without nerve stimulation, coordinated by the sino-atrial node.
What prevents the electrical wave from reaching the ventricles?
A band of non-conducting tissue separates the atria and ventricles.
What is the role of the atrioventricular node (AVN)?
The AVN directs the electrical wave to the bundle of His after a delay.
What are the Purkyne fibres responsible for?
They cause the left and right ventricles to contract simultaneously from the bottom up.
What is an electrocardiograph?
A machine that records the electrical activity of the heart.
What does the P wave on an ECG represent?
The P wave is caused by the contraction of the atria.
What is the QRS complex on an ECG?
The QRS complex is a large spike caused by ventricular contraction.
What does the T wave on an ECG indicate?
The T wave results from the repolarisation of the ventricles as they relax.
What heart problems can ECG diagnose?
ECG can diagnose tachycardia, bradycardia, ectopic heartbeats, and fibrillation.
What is the primary function of haemoglobin?
Haemoglobin transports oxygen by binding to it in red blood cells.
What is the structure of haemoglobin?
Haemoglobin is a large, globular protein with a quaternary structure made up of four polypeptide chains.
What is the significance of the dissociation curve for haemoglobin?
It shows how saturated haemoglobin is with oxygen at different partial pressures.
What is the Bohr Effect?
The Bohr Effect describes how haemoglobin’s affinity for oxygen decreases at higher concentrations of carbon dioxide.
What is the role of the Casparian strip in roots?
The Casparian strip forces water to pass through a cell membrane, controlling substance entry.
What are the two pathways for water movement into xylem vessels?
The symplast pathway and the apoplast pathway.
What is transpiration?
Transpiration is the loss of water vapour through evaporation from a plant’s surface.
What factors affect the rate of transpiration?
Light intensity, temperature, wind, and humidity.
What is a potometer used for?
A potometer measures the amount of water uptake by a plant, estimating the rate of transpiration.
What is the purpose of shooting to acclimatise in plant experiments?
To ensure that all other variables are controlled, such as light intensity and humidity.
What is the procedure for measuring the speed of an air bubble in a capillary tube?
Shut the tap to close the capillary tube system, remove the end from the water until one air bubble forms, then place it back in the water. Record the starting position of the bubble and time its movement to calculate speed.
What can the speed of the bubble in a capillary tube estimate?
The rate of transpiration of the plant shoot.
What are xerophytes?
Plants adapted to living in regions where water is scarce, such as cacti, pineapple, and marram grass.
What is one adaptation of xerophytes that reduces evaporation?
A waxy layer on the epidermis, which is impermeable and reduces evaporation.
How do sunken stomata help xerophytes?
They shelter the stomata from wind, reducing the water potential gradient between the inside of the leaf and the outside.
What role do hairs on the epidermis play in xerophytes?
They trap water vapour, reducing the water potential gradient between the inside and outside of the leaf.
How do spines benefit xerophytes?
They reduce the surface area for water loss.
What is the function of rolled leaves in xerophytes?
They trap water vapour and reduce the surface area for water loss.
Why do xerophytes close their stomata?
To reduce transpiration during high temperature or light intensity conditions.
What are hydrophytes?
Plants that live in water, such as water lilies.
How do hydrophytes adapt to low oxygen levels?
They have stomata on the upper surface of their floating leaves to maximize gas exchange.
What is the purpose of air spaces in hydrophytes?
They help the plant float and store oxygen for aerobic respiration.
How do flexible leaves and stems benefit hydrophytes?
They prevent damage from water currents.
What is translocation in plants?
The movement of dissolved substances, such as sucrose and amino acids, from sources to sinks in the plant.
What are the two types of cells in the phloem involved in translocation?
Sieve tube elements and companion cells.
What happens to sucrose when it reaches a sink?
It is converted into starch for carbohydrate storage.
What is the mass flow hypothesis?
A theory explaining how solutes are transported from source cells into sinks through the phloem.
What is the first step in the mass flow hypothesis?
Sucrose moves from companion cells into sieve tube elements by active transport.
What occurs after sucrose moves into sieve tube elements?
It reduces the water potential of the sieve tube element.
What causes water to move into the phloem?
Osmosis, which increases hydrostatic pressure.
What maintains the pressure gradient in the phloem?
High hydrostatic pressure near the source cell and lower hydrostatic pressure near the sink cells.
What happens to solutes in the phloem?
They move down the pressure gradient towards the sink end.
What occurs when solutes enter sink cells?
They are converted into other molecules, such as starch.
What happens to water at the sink end of the phloem?
Water moves out of the phloem by osmosis, maintaining the hydrostatic pressure gradient.
What is active loading in the context of sucrose transport?
The process by which sucrose is actively transported into sieve tube elements with the help of companion cells.
How do companion cells create a hydrogen ion gradient?
By actively transporting hydrogen ions into the surrounding cells.
What happens when hydrogen ions move back into the companion cell?
They move through a co-transporter protein, bringing sucrose with them against its concentration gradient.
What is the final step in the active transport of sucrose?
Sucrose is transported from the companion cell into the sieve tube element.
