HOMEOSTASIS

Question 1

What is homeostasis?

Answer 1

• Maintaining a constant internal environment despite changes to the external environment
  e.g. maintain co2 concentration, temperature conditions

Question 2

Why is homeostasis important?

Answer 2

-Enzymes won’t function properly
-Energy and resource allocation
-Controlling the movement of molecules

Question 3

How is homeostasis achieved?

Question 4

What is a positive feedback system?

Answer 4

• A change in the internal environment of a body is detected by sensory receptors and effectors reinforce to this change and increase the response
• E.g. Oxytocin stimulates the uterus to contract, pushing the baby head harder against the cervix producing more oxytocin, continues until baby is born

Question 5

What is a negative feedback system?7

Answer 5

• Effectors work to reverse the change and restore conditions to their basic level
• Work to reverse the initial stimulus
  E.g. Control of blood sugar levels by insulin and glucagon

Question 6

Examples of behavioural responses in ectotherms

Answer 6

• They can increase their body temperature through conduction by pressing their bodies against the hot ground
  E.g. Galapagos iguanas will contract their muscles increasing cellular metabolism to increase body temperature
• May bask in the sun, ortinetate their bodies so maximum SA is exposed to sun
  E.g. butterflies spread their wings and orientate towards sun
• To cool down, they may seek shade, hiding in cracks in rocks
• Press their bodies against cold rocks or emerge in available water or mud

Question 7

Examples of physiological responses in ectotherms

Answer 7

• Dark colours absorb more radiation than light colours
• Less food then endothermic as they use less energy regulating temperatures
• Lizards living in cold climates are dark coloured

Question 8

What does the term excretion mean

Answer 8

• The removal of waste products of metabolism in the body