Nervous and Endocrine
Define one main difference between nervous and endocrine signalling in animals
Nervous uses electrical impulses via neurons (fast, short-lived); endocrine uses hormones in bloodstream (slower, long-lasting).
What do chemoreceptors monitor in the blood? Give one chemical parameter.
CO2 concentration (or pH, O2).
Identify the brain region primarily responsible for balance and coordination.
Cerebellum
List two substances blood transports that are important for integration between organs.
Oxygen, carbon dioxide, hormones, nutrients (glucose), urea, antibodies.
Define phototropism and state which plant part typically shows positive phototropism.
Phototropism: growth in response to light; shoots (apical shoots) usually show positive phototropism (grow toward light).
Name the gland pair (one in brain, one below it) that together regulate many endocrine functions.
Hypothalamus and pituitary gland
Where are baroreceptors located and what do they detect?
In the aorta and carotid arteries; they detect stretch/blood pressure changes.
Give one example of a conscious and one unconscious process, and state which CNS structure primarily controls each.
Conscious: decision making (cerebral cortex). Unconscious: breathing/heartbeat (medulla oblongata).
Define “emergent property” and give one example from animal physiology mentioned in the content.
Property arising from integrated parts producing novel functions; e.g., a cheetah’s speed from integrated muscular, skeletal, nervous, circulatory systems.
What is an auxin efflux carrier and how does its polar localisation affect auxin distribution?
Protein pumps that export auxin from cells; polar placement directs auxin flow, creating concentration gradients.
Describe how epinephrine prepares the body for “fight or flight” — give two physiological effects.
Examples: bronchiole dilation, increased heart rate and stroke volume, glycogen → glucose release from liver, redirected blood flow to muscles, pupil dilation
Describe the negative feedback loop that increases ventilation rate when CO2 rises: sensor → control centre → effectors → response.
Chemoreceptors detect ↑CO2 → medulla respiratory centre → increased nerve signals to diaphragm/intercostal muscles → ↑rate/depth of ventilation → ↓CO2.
Sketch (describe) the basic pathway of a pain reflex arc: receptor → sensory neuron → interneuron → motor neuron → effector. Explain why the brain is often bypassed.
Receptor (nociceptor) → sensory neuron → interneuron in spinal cord grey matter → motor neuron → skeletal muscle contracts; bypasses brain for speed; brain later perceives pain.
Explain how baroreceptor input can change heart rate via neural pathways; include the effector (organ) and expected change when blood pressure rises.
↑BP stretches baroreceptors → increased firing to medulla → parasympathetic output ↑ / sympathetic ↓ → SA node activity decreases → heart rate falls (to lower BP)
Explain how auxin promotes cell elongation in shoots (mention cell-wall acidification and loosening).
Auxin induces H+ secretion into apoplast, acidifying cell wall, loosening cellulose cross-links, allowing cell elongation.
Explain how hormones reach target tissues and why they can affect cells far from the secreting gland.
Hormones are secreted into blood plasma and carried to distant target cells that have specific receptors for the hormone.
Explain how positive feedback in fruit ripening works with ethylene; why is this beneficial for synchronized ripening?
Ethylene stimulates ripening and stimulates more ethylene production (positive feedback) → rapid, synchronized ripening among neighboring fruits.
Explain how the hypothalamus interacts with the pituitary to control other endocrine glands (mention releasing factors and posterior storage).
Hypothalamus secretes releasing factors to anterior pituitary; hypothalamic hormones are transported/stored in posterior pituitary for release.
Describe how changes in blood CO2 produce a pH change; write the chemical equilibrium (CO2 reaction) in words (no equations required).
CO2 reacts with water to form carbonic acid, lowering pH; increased CO2 → more carbonic acid → decreased pH; decreased CO2 → less carbonic acid → increased pH.
Describe an experimental setup students could use to measure quantitative phototropic responses in seedlings (what to measure and how).
Grow seedlings in boxes with controllable lateral light holes; vary light angle; measure angle of curvature of shoots with protractor over time; use replication and metric units.
Outline the roles of myelinated vs unmyelinated nerve fibres in nerve conduction and relate to signal speed.
Myelinated fibres enable saltatory conduction (faster); unmyelinated conduct more slowly.
Compare how the cardiovascular control centre and respiratory control centre use sensory input to produce coordinated responses during exercise.
Cardiovascular centre receives baroreceptor/chemoreceptor signals to adjust heart rate/stroke volume; respiratory centre uses chemoreceptor signals to adjust ventilation — both can act simultaneously during exercise to match oxygen delivery and pH.
Describe two roles of the medulla oblongata in homeostatic regulation and the sensory inputs it uses.
Medulla controls breathing and heart rate via inputs from baroreceptors and chemoreceptors; coordinates autonomic output to heart and respiratory muscles.
Connect the role of the enteric nervous system to peristalsis and explain why swallowing is different in control.
ENS coordinates peristalsis involuntarily along gut; swallowing and defecation initiation are voluntary via CNS, but downstream peristalsis is ENS-driven.
Explain the interaction between auxin and cytokinin in determining root vs shoot development; include relative concentration outcomes.
High auxin:cytokinin ratio promotes shoot formation; high cytokinin:auxin promotes root formation — relative concentrations direct organogenesis.