Key Concepts
- 1Parts of the human brain?
- 2What are plant hormones?
Important Formulas & Facts
Fore-brain (cerebrum — thinking, memory, senses), Mid-brain (reflex movements of head/neck), Hind-brain (cerebellum — balance; medulla — involuntary actions like breathing, heart rate).
Auxin (cell elongation, phototropism), Gibberellin (stem growth, germination), Cytokinin (cell division), Abscisic acid (inhibits growth, stress response), Ethylene (fruit ripening).
Must-Know Questions
Q1Which part of the brain controls involuntary actions like blood pressure, salivation and vomiting?
Medulla oblongata (part of the hind-brain) controls involuntary actions such as blood pressure, salivation, and vomiting.
Q2What is a reflex arc? Draw a neat labelled diagram.
A reflex arc is the pathway taken by nerve impulses in a reflex action. Components in order: Receptor (sense organ) → Sensory/Afferent neuron → Relay neuron (in spinal cord) → Motor/Efferent neuron → Effector (muscle/gland). Reflex actions are sudden, involuntary responses to stimuli that do not involve thinking (e.g., pulling hand away from a hot object). The spinal cord processes the response, not the brain.
Q3Which hormone is responsible for the 'fight or flight' response?
Adrenaline (epinephrine) is secreted by adrenal glands during emergency/stress situations. It increases heart rate, breathing rate, and blood flow to muscles — preparing the body to fight or flee.
Q4What is the function of the cerebellum?
The cerebellum (part of hind-brain) controls posture, balance, and coordination of voluntary movements. It ensures precision and smooth, coordinated body movements.
Q5Differentiate between nervous control and hormonal control in humans.
Nervous control: (1) Uses electrical impulses. (2) Transmission through neurons. (3) Very fast response. (4) Short-lived effect. (5) Specific — acts on a particular organ. (6) Controlled by brain and spinal cord. Hormonal control: (1) Uses chemical messengers (hormones). (2) Transmission through blood. (3) Slower response. (4) Long-lasting effect. (5) Widespread — may affect multiple organs. (6) Controlled by endocrine glands.
Practice Control and Coordination
Reinforce what you just revised with practice questions