Plant Growth Hormones: Auxins and Cell Elongation

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What is the main source of ATP needed by skeletal muscle?

Photosynthesis

Glycolysis

Oxidative phosphorylation (correct)

Creatine Phosphate breakdown

Which type of muscle fibre is specialized for slow contractions and adapted to long periods of exercise like marathon running?

Slow twitch fibres (correct)

Transition twitch fibres

Intermediate twitch fibres

Fast twitch fibres

What is the role of Creatine Phosphate in muscle contraction?

Produce carbon dioxide during respiration

Generate ATP by acting as a reserve supply of phosphate (correct)

Release oxygen for energy production

Convert glucose into lactic acid

Why do slow twitch fibres appear dark in color compared to fast twitch fibres?

Contain many mitochondria and myoglobin Signup and view all the answers

Which type of muscle fibre is adapted for rapid release of energy during intense exercise like sprinting?

Fast twitch fibres Signup and view all the answers

What is the function of the Glomerulus in the nephron?

Filter blood and allow filtration of molecules less than 69,000 Mr Signup and view all the answers

Why can't red blood cells and plasma proteins pass into the nephron?

Their large size prevents them from passing through the capillary endothelium Signup and view all the answers

Where does selective reabsorption primarily happen in the nephron?

Proximal convoluted tubule (PCT) Signup and view all the answers

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 Signup and view all the answers

What type of pressure builds up in the glomerulus due to the wider lumen of the afferent arteriole?

Hydrostatic pressure Signup and view all the answers

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 Signup and view all the answers

What is the role of Ca2+ in muscle contraction?

Ca2+ binds to troponin, allowing myosin-actin cross bridges to form Signup and view all the answers

Why are skeletal muscles described as striated?

Because of the striped appearance of the sarcomeres Signup and view all the answers

What is responsible for pulling actin molecules towards the center of the sarcomere during muscle contraction?

Myosin heads changing their angle Signup and view all the answers

What is the function of troponin during muscle contraction?

Moving tropomyosin away from myosin binding sites on actin Signup and view all the answers

What happens when myosin heads change their angle during muscle contraction?

Actin molecules are pulled towards the center of the sarcomere Signup and view all the answers

Why is ATP needed during muscle contraction?

To provide energy for myosin heads to return to their original conformation Signup and view all the answers

What is the role of auxins in cell elongation?

Transporting hydrogen ions into the cell walls Signup and view all the answers

What enzyme is responsible for loosening cellulose in cell walls?

Expansin Signup and view all the answers

How do auxins affect cell elongation in a shoot illuminated from all sides?

They distribute evenly causing elongation across the zone of elongation Signup and view all the answers

Which hormone is involved in controlling leaf abscission?

Ethene Signup and view all the answers

What happens as a leaf ages in terms of hormone levels?

Increase in ethene levels and decrease in both cytokinin and auxin levels Signup and view all the answers

What is the purpose of suberin formation below the abscission layer?

To prevent pathogens from entering Signup and view all the answers

What is the potential difference at the end of depolarisation?

+30mV Signup and view all the answers

How is repolarisation achieved in neurones?

By closing sodium ion channels and opening potassium ion channels Signup and view all the answers

What leads to hyperpolarisation in neurones?

Closing of sodium ion channels before potassium ions diffuse out Signup and view all the answers

What returns the potential difference back to -70mV after hyperpolarisation?

Sodium-potassium pump Signup and view all the answers

What happens during the refractory period of a neurone membrane?

Recovery stage of sodium channels Signup and view all the answers

How does an action potential travel along a neurone?

Through a wave of depolarisation with sodium ions moving through the cytoplasm Signup and view all the answers