29 Questions
What is the main source of ATP needed by skeletal muscle?
Oxidative phosphorylation
Which type of muscle fibre is specialized for slow contractions and adapted to long periods of exercise like marathon running?
Slow twitch fibres
What is the role of Creatine Phosphate in muscle contraction?
Generate ATP by acting as a reserve supply of phosphate
Why do slow twitch fibres appear dark in color compared to fast twitch fibres?
Contain many mitochondria and myoglobin
Which type of muscle fibre is adapted for rapid release of energy during intense exercise like sprinting?
Fast twitch fibres
What is the function of the Glomerulus in the nephron?
Filter blood and allow filtration of molecules less than 69,000 Mr
Why can't red blood cells and plasma proteins pass into the nephron?
Their large size prevents them from passing through the capillary endothelium
Where does selective reabsorption primarily happen in the nephron?
Proximal convoluted tubule (PCT)
What is the purpose of selective reabsorption in the proximal convoluted tubule (PCT)?
To reabsorb glucose, amino acids, water, and salts back into the bloodstream
What type of pressure builds up in the glomerulus due to the wider lumen of the afferent arteriole?
Hydrostatic pressure
Which molecules can pass through the barriers of the capillary endothelium, basement membrane, and Bowman’s capsule epithelium into the filtrate?
Glucose, amino acids, urea, ions, and hormones
What is the role of Ca2+ in muscle contraction?
Ca2+ binds to troponin, allowing myosin-actin cross bridges to form
Why are skeletal muscles described as striated?
Because of the striped appearance of the sarcomeres
What is responsible for pulling actin molecules towards the center of the sarcomere during muscle contraction?
Myosin heads changing their angle
What is the function of troponin during muscle contraction?
Moving tropomyosin away from myosin binding sites on actin
What happens when myosin heads change their angle during muscle contraction?
Actin molecules are pulled towards the center of the sarcomere
Why is ATP needed during muscle contraction?
To provide energy for myosin heads to return to their original conformation
What is the role of auxins in cell elongation?
Transporting hydrogen ions into the cell walls
What enzyme is responsible for loosening cellulose in cell walls?
Expansin
How do auxins affect cell elongation in a shoot illuminated from all sides?
They distribute evenly causing elongation across the zone of elongation
Which hormone is involved in controlling leaf abscission?
Ethene
What happens as a leaf ages in terms of hormone levels?
Increase in ethene levels and decrease in both cytokinin and auxin levels
What is the purpose of suberin formation below the abscission layer?
To prevent pathogens from entering
What is the potential difference at the end of depolarisation?
+30mV
How is repolarisation achieved in neurones?
By closing sodium ion channels and opening potassium ion channels
What leads to hyperpolarisation in neurones?
Closing of sodium ion channels before potassium ions diffuse out
What returns the potential difference back to -70mV after hyperpolarisation?
Sodium-potassium pump
What happens during the refractory period of a neurone membrane?
Recovery stage of sodium channels
How does an action potential travel along a neurone?
Through a wave of depolarisation with sodium ions moving through the cytoplasm
Learn about how auxins influence cell elongation by transporting hydrogen ions into cell walls, affecting the wall pH for expansins to loosen cellulose. Understand the process that enables the stretching and growth of plant cells under different light conditions.
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