exam Flashcards
(34 cards)
What is phylogenetics?
The study of evolutionary relationships between organisms using features like DNA and protein sequences.
What are phylogenetic trees?
Diagrams that show inferred evolutionary relationships based on shared characteristics or molecular evidence.
What is the structure of the human heart?
4 chambers: right atrium, right ventricle, left atrium, left ventricle; includes valves and blood vessels.
What happens during atrial systole?
Atria contract, AV valves open, blood pushed into ventricles.
What happens during ventricular systole?
Ventricles contract, AV valves close, semilunar valves open, blood exits heart.
What is the role of the SAN in the heart?
The sinoatrial node initiates the heartbeat and acts as the natural pacemaker.
What does an ECG trace show?
Electrical activity of the heart: P wave (atria), QRS complex (ventricles), T wave (recovery).
What is the structure of arteries?
Thick muscular walls, small lumen, carry blood away from the heart.
What is the difference between open and closed circulatory systems?
Open systems bathe organs directly; closed systems keep blood within vessels.
What is the Bohr effect?
Increased CO₂ lowers blood pH, reducing haemoglobin’s oxygen affinity and promoting oxygen release.
How does myoglobin differ from haemoglobin?
Myoglobin has a higher oxygen affinity and stores oxygen in muscles.
Why is fetal haemoglobin different?
It has a higher oxygen affinity to absorb oxygen from maternal blood.
What is the function of xylem?
Transports water and minerals from roots to leaves using cohesion-tension.
What is the function of phloem?
Transports sugars (mainly sucrose) from source to sink via mass flow.
How are xerophytes adapted to dry conditions?
Thick cuticle, sunken stomata, rolled leaves, reduced stomata, hairy surfaces.
How are hydrophytes adapted to aquatic environments?
Air spaces for buoyancy, stomata on upper surface, reduced cuticle, less xylem.
What is translocation in plants?
The transport of organic solutes, mainly sucrose, through the phloem from source to sink.
What is the source in translocation?
A region that produces or releases sugars, such as mature leaves.
What is the sink in translocation?
A region where sugars are used or stored, such as roots, growing tissues, or developing fruits.
What is the mass flow hypothesis?
A theory suggesting that sucrose moves through the phloem by pressure flow from source to sink.
What are stomata?
Pores on the surface of leaves that allow gas exchange and transpiration.
How do guard cells control stomatal opening?
They take up water and become turgid to open, or lose water and become flaccid to close.
How do insects perform gas exchange?
Through a tracheal system consisting of spiracles, tracheae, and tracheoles.
What is the role of spiracles?
Openings on the insect body that allow air to enter and exit the tracheal system.
