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LGS A-Level OCR Biology - Unit 5 - Plant and Animal Responses Part 5

Biology25 CardsCreated about 1 month ago

This flashcard deck covers key concepts from Unit 5 of the OCR Biology syllabus, focusing on plant and animal responses. Topics include muscle contraction mechanisms, neuromuscular junctions, energy supply for muscles, heart rate regulation, and differences between plant and animal hormones.

Characteristics of sliding filament model

Z lines get closer; Sarcomeres shortens; I band narrows; H zone narrows
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Key Terms

Term
Definition
Characteristics of sliding filament model
Z lines get closer; Sarcomeres shortens; I band narrows; H zone narrows
What does simultaneous contraction of several sarcomeres allow
Myofibrils and then muscle fibres to contract —-> enough to pull a bone
Neuromuscular junction
Action potential arriving at axon of motor neurone opens VG Ca2+ to flood into tip; Vesicles of acetylcholine to move towards membrane & fuse; Acetylc...
Cross bridge muscle contraction cycle
Tropomyosin is blocking myosin binding site in actin; Ca2+ binds to troponin causing a conformational change, tropomyosin moves; Myosin heads bind to ...
Where does SR get Ca^2+
Active absorption from sarcoplasm
Supply of ATP for muscular contraction
Aerobic respiration - oxidative phosphorylation; Anaerobic respiration - glycolysis; Glycogen —> glucose Creatine phosphate can combine w/ ADP to form...

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TermDefinition
Characteristics of sliding filament model
Z lines get closer; Sarcomeres shortens; I band narrows; H zone narrows
What does simultaneous contraction of several sarcomeres allow
Myofibrils and then muscle fibres to contract —-> enough to pull a bone
Neuromuscular junction
Action potential arriving at axon of motor neurone opens VG Ca2+ to flood into tip; Vesicles of acetylcholine to move towards membrane & fuse; Acetylcholine diffuses across synapse and binds to receptors on sarcolemma; Na+ channels open and wave of depolarisation passes down transverse tubules; Passes to SR which releases Ca2+ into the sarcoplasm
Cross bridge muscle contraction cycle
Tropomyosin is blocking myosin binding site in actin; Ca2+ binds to troponin causing a conformational change, tropomyosin moves; Myosin heads bind to actin, forming cross bridges between filaments; Myosin heads move, pulling the actin filament. ADP and Pi are released during the power strike; A new ATP molecule attaches to myosin head, breaking cross bridge; ATP hydrolyses and myosin head returns to its orig. position
Where does SR get Ca^2+
Active absorption from sarcoplasm
Supply of ATP for muscular contraction
Aerobic respiration - oxidative phosphorylation; Anaerobic respiration - glycolysis; Glycogen —> glucose Creatine phosphate can combine w/ ADP to form ATP
Where is creatine phosphate found
Sarcoplasm
Supply of energy of slow twitch muscle
Aerobic respiration
Supply of energy for fast twitch muscle
Anaerobic respiration
Where is the cardiovascular centre
Medulla oblongata - this alters the excitation wave frequency
Frequency of heart excitation
60-80 bpm
What is the heart rate regulated by
SAN | Nerves connect cardiovascular centre to the SAN
Nerves involved in controlling heart rate
Accelerans | Vagus
Accelerans
Causes release of noradrenaline at SAN; Increases HR (sympathetic)
Vagus nerves
Causes release of acetylcholine at SAN, reduces HR (parasympathetic)
Sensory inputs that increase HR
Increased muscle movement (muscle stretch receptors); Decrease in pH (chemoreceptors); Adrenaline in blood
Sensory inputs that decrease HR
Increase in bp (stretch receptors - carotid sinus) | Decrease in dissolved CO2 (chemoreceptors)
Why do plants kept in the dark grow taller than those in the light
Auxin is more present in the dark
Plant growth substances vs animal hormones
Hormones travel faster in animals; Synthesised in endocrine glands vs cells sites; Slow acting in plants vs fast acting in animals
Why is temp controlled in investigations on effect of plant hormones
So temp does not affect results as temp affects enzyme activity
Why are monkeys used for human research
Closely related; Both primates; Similar physiology
Actions of parasympathetic nervous system
Increases blood flow to digestive system, allows peristalsis; Decreases HR; Decreases airway diameter; Sexual arousal; Constricts pupils
Why is glycogen found in striated muscle
Glycogenolysis; Glucose can undergo glycolysis to produce ATP; Energy storage
Uses of mitochondria in muscular contraction
ATP attaches to ATPase on the myosin head; Hydrolysis to release ADP and Pi during power stroke, allows myosin heads pull the actin filaments; Needed for myosin head to detach; Protein synthesis; Ca 2+ pumps in SR
Internal organs affected by SNS/PNS
Heart; Lungs; Liver; Intestines