Biology paper 2 model answers
Unit 5 Homeostasis and response
Q.1 Define homeostasis (2 marks)
• Regulation of internal conditions of an organism….
• ….. to maintain optimum conditions for function in response
to changes.
Q.2 What is the purpose of reflex actions? (2 marks)
• Reflex actions are rapid and automatic
• They prevent harm and injury to the organism
Q.3 Explain the changes that occur to enable the eye to focus
on a near object (4 marks)
• The ciliary muscles contract
• The suspensory ligaments slacken
• The lens becomes thicker and more rounded
• Light is refracted more by the lens
Q.4 Explain how long sightedness is corrected (4 marks)
• When long sighted the image is focused behind the retina
• Convex lens glasses are used
• To refract light more before it reaches the lens
• So the image is now focused on the retina
Q.5 Explain how the human body regulates temperate when
body temperature raises too high (4 marks)
• The thermoregulatory centre in the brain contains receptors
sensitive to temperature
• The skin contains temperature receptors and sends
, impulses to the thermoregulatory
centre
• If body temperature is too high the blood vessels near the
surface of the skin dilate so more heat is
radiated from the surface of the skin.
• Sweat is produced by sweat glands, heat energy from the
body causes the water in the sweat to
evaporate
Q.6 Explain why the pituitary gland is referred to as the
“master gland” (3 marks)
• The pituitary glandsecretes hormones into the blood in
response to changing body conditions
• These hormones act on other glands to stimulate them to
secrete other hormones to bring about
effects
Q.7 Explain the ways that the body monitors and controls
blood glucose concertation (6 marks)
• The pancreas detects the rise in blood glucose
concentration after eating a meal
• The pancreases release insulin into the blood
• Insulin causes glucose to be converted to glycogen in the
liver and muscles
• Blood glucose concentration returns to normal, this is
detected by the pancreas and the release of
insulin stops
• The pancreas detects a fall in blood glucose after fasting or
exercise
• The pancreas releases glucagon into the blood
Unit 5 Homeostasis and response
Q.1 Define homeostasis (2 marks)
• Regulation of internal conditions of an organism….
• ….. to maintain optimum conditions for function in response
to changes.
Q.2 What is the purpose of reflex actions? (2 marks)
• Reflex actions are rapid and automatic
• They prevent harm and injury to the organism
Q.3 Explain the changes that occur to enable the eye to focus
on a near object (4 marks)
• The ciliary muscles contract
• The suspensory ligaments slacken
• The lens becomes thicker and more rounded
• Light is refracted more by the lens
Q.4 Explain how long sightedness is corrected (4 marks)
• When long sighted the image is focused behind the retina
• Convex lens glasses are used
• To refract light more before it reaches the lens
• So the image is now focused on the retina
Q.5 Explain how the human body regulates temperate when
body temperature raises too high (4 marks)
• The thermoregulatory centre in the brain contains receptors
sensitive to temperature
• The skin contains temperature receptors and sends
, impulses to the thermoregulatory
centre
• If body temperature is too high the blood vessels near the
surface of the skin dilate so more heat is
radiated from the surface of the skin.
• Sweat is produced by sweat glands, heat energy from the
body causes the water in the sweat to
evaporate
Q.6 Explain why the pituitary gland is referred to as the
“master gland” (3 marks)
• The pituitary glandsecretes hormones into the blood in
response to changing body conditions
• These hormones act on other glands to stimulate them to
secrete other hormones to bring about
effects
Q.7 Explain the ways that the body monitors and controls
blood glucose concertation (6 marks)
• The pancreas detects the rise in blood glucose
concentration after eating a meal
• The pancreases release insulin into the blood
• Insulin causes glucose to be converted to glycogen in the
liver and muscles
• Blood glucose concentration returns to normal, this is
detected by the pancreas and the release of
insulin stops
• The pancreas detects a fall in blood glucose after fasting or
exercise
• The pancreas releases glucagon into the blood
