Organisms respond to changes in their internal and external environments — AQA A-Level Biology
In summary: Organisms respond to changes in their internal and external environments is a key topic in AQA A-Level Biology. Key exam tip: Use precise terminology for nerve impulses (e.g., depolarisation, repolarisation, hyperpolarisation)
Exam Tips for Organisms respond to changes in their internal and external environments
- Use precise terminology for nerve impulses (e.g., depolarisation, repolarisation, hyperpolarisation)
- Ensure clear distinction between the roles of insulin and glucagon
- When describing heart rate control, explicitly link chemoreceptors and pressure receptors to the medulla
- Practice interpreting graphs related to action potentials and hormone concentration changes
- Be prepared to apply knowledge of synaptic transmission to explain the effect of drugs
Common Mistakes
- Confusing negative feedback with positive feedback
- Failing to mention the role of ATP in muscle contraction or active transport
- Misunderstanding the second messenger model of hormone action
- Confusing the roles of the SAN, AVN, and Purkyne tissue
- Inaccurate description of the sliding filament mechanism
- Incorrectly describing the role of ADH in the collecting duct
Marking Points
- Stimulus-receptor-coordinator-effector-response pathway
- Pacinian corpuscle structure and generator potential
- Rod and cone cell differences in sensitivity and acuity
- Myogenic heart stimulation and autonomic nervous system control
- Resting potential, action potential, and refractory period mechanisms
- Synaptic transmission and summation (temporal/spatial)
- Neuromuscular junction structure and function
- Sliding filament theory of muscle contraction (actin, myosin, calcium, ATP)
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