Back to AI Flashcard MakerBiology /LGS A-Level OCR Biology - Unit 5 - Plant and Animal Responses Part 4
Why are endorphins released in the fight or flight response?
Wounds inflicted don't prevent activity
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Key Terms
Term
Definition
Why are endorphins released in the fight or flight response?
Wounds inflicted don't prevent activity
Why must plants be able to respond to their environment?
Cope w/ changing conditions | Avoid antibiotic stress
How does auxin cause cell elongation (2 marks)?
Loosens rigid cellulose framework | Osmotic uptake of water allows cell elongation
Why do cut plants w/ agar blocks w/ auxin placed on the rhs bend to the lhs?
Auxin produced at tip; Diffuses laterally to rhs; Cells on rhs exhibit greater elongation; Bending to the left
How does auxin act as a selective weedkiller?
Rapid cell elongation so plant grows too quickly; No extra lignified tissue; Stem collapses or loss of extra water from leaves
What happens when the apex is removed from a plant?
Once apex is removed, auxin production stops; Apical dominance is stopped; Lateral growth is not inhibited and lateral buds develop
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| Term | Definition |
|---|---|
Why are endorphins released in the fight or flight response? | Wounds inflicted don't prevent activity |
Why must plants be able to respond to their environment? | Cope w/ changing conditions | Avoid antibiotic stress |
How does auxin cause cell elongation (2 marks)? | Loosens rigid cellulose framework | Osmotic uptake of water allows cell elongation |
Why do cut plants w/ agar blocks w/ auxin placed on the rhs bend to the lhs? | Auxin produced at tip; Diffuses laterally to rhs; Cells on rhs exhibit greater elongation; Bending to the left |
How does auxin act as a selective weedkiller? | Rapid cell elongation so plant grows too quickly; No extra lignified tissue; Stem collapses or loss of extra water from leaves |
What happens when the apex is removed from a plant? | Once apex is removed, auxin production stops; Apical dominance is stopped; Lateral growth is not inhibited and lateral buds develop |
Types of muscle? | Skeletal (voluntary); Cardiac; Involuntary (smooth) |
Voluntary (skeletal muscle)? | Striated; Multinucleate; Regularly arranged —> contraction in one direction; Attached to bone by tendon; Tubular; Nerves from peripheral, somatic (rapid) |
Cardiac muscle? | Specialised striated (parallel myofibrils); Branched fibres; Uninucleated; Cross bridges allow simultaneous contraction; Dark bands - intercalated discs; Nerves from autonomic nervous system |
Involuntary (smooth muscle)? | Non striated; Nerves from autonomic nervous system; No reg. arrangement - diff cells can contract in diff directions; Fibres are spindle shaped and uninucleated; Used in hollow organs (peristalsis) |
Sarcolemma? | Plasma membrane that encloses bundles of muscle fibre |
Why may the sarcolemma fold in? | Spread impulse throughout sarcoplasm; | Contract at the same time |
Sarcoplasm? | Shared cytoplasm within muscle fibres |
How are muscle fibres formed? | Fusion of several embryonic muscle cells - gap between adjacent cells would be a weakness (That’s why it’s multinucleate) |
Sarcoplasmic reticulum? | Modified version of ER | Provides strength and stored Ca^2+ |
Protein filaments? | Myosin | Actin |
Muscle organisation? | Muscle; Fascicles; Muscle fibres; Myofibrils; Protein filaments |
Connective tissue? | Tendons |
Light band (I)? | Thin actin held together by Z line |
Dark band (A)? | Both actin and myosin; Entire length of myosin; Myosin held together by M line |
M line? | Midpoint of myosin | Has no heads |
Z line? | Found at the centre of each light band |
Sarcomere? | Functional unit of muscle; From one Z line to another; Sub unit of myofibrils |
Why is muscle considered a tissue? | Muscle fibre; Blood vessels; Nerves; Connective cells |