Biology Paper 1 Essays
Essay 1............................................................................................................................... 2
Essay 2: Protein Synthesis................................................................................................. 3
Essay 3: Spermatogenesis................................................................................................. 4
Essay 3: Thermoregulation................................................................................................. 5
Essay 4: Regulating water and balance..............................................................................6
Essay 5: Eyes and Hearing and Balance.............................................................................7
, Essay 1.
Describe the mechanism that leads to an increase in the metabolic rate and the
mechanisms involved in increasing the glucose level and decreasing the CO2 level back
to normal
Increasing the metabolic rate
- To increase the metabolic rate the level of thyroxin must increase
- The pituitary gland is stimulated
- to secrete more TSH
- which stimulates the thyroid gland
- to secrete more thyroxin (Any 4)
Increasing the level of glucose
- As a result of the decrease in glucose level the pancreas is stimulated
- to secrete glucagon
- which stimulates the conversion of stored glycogen to glucose
- in the liver/muscles
- The glucose is then released into the bloodstream
- The glucose level in the blood increases and returns to normal (Any 5)
Decreasing the level of CO2
- High CO2 levels stimulate the receptor cells in the carotid artery
- The stimulus is converted to an impulse
- and sent to the medulla oblongata
- which stimulates the heart to beat faster
- bringing blood with CO2 quickly to the lungs
- It also stimulates the breathing muscles
- to increase the depth and rate of breathing
- CO2 is exhaled quickly from the lungs
- The CO2 level in the blood decreases and returns to normal (Any 8)
Essay 1............................................................................................................................... 2
Essay 2: Protein Synthesis................................................................................................. 3
Essay 3: Spermatogenesis................................................................................................. 4
Essay 3: Thermoregulation................................................................................................. 5
Essay 4: Regulating water and balance..............................................................................6
Essay 5: Eyes and Hearing and Balance.............................................................................7
, Essay 1.
Describe the mechanism that leads to an increase in the metabolic rate and the
mechanisms involved in increasing the glucose level and decreasing the CO2 level back
to normal
Increasing the metabolic rate
- To increase the metabolic rate the level of thyroxin must increase
- The pituitary gland is stimulated
- to secrete more TSH
- which stimulates the thyroid gland
- to secrete more thyroxin (Any 4)
Increasing the level of glucose
- As a result of the decrease in glucose level the pancreas is stimulated
- to secrete glucagon
- which stimulates the conversion of stored glycogen to glucose
- in the liver/muscles
- The glucose is then released into the bloodstream
- The glucose level in the blood increases and returns to normal (Any 5)
Decreasing the level of CO2
- High CO2 levels stimulate the receptor cells in the carotid artery
- The stimulus is converted to an impulse
- and sent to the medulla oblongata
- which stimulates the heart to beat faster
- bringing blood with CO2 quickly to the lungs
- It also stimulates the breathing muscles
- to increase the depth and rate of breathing
- CO2 is exhaled quickly from the lungs
- The CO2 level in the blood decreases and returns to normal (Any 8)
