16.1+2

Question 1

Homeostasis

Answer 1

Maintaining internal environment within restricted limits in organisms through returning to optimum point(balanced equilibrium)

Question 2

Examples of features homeostasis controls

Answer 2

blood pH
water potential
pH
bgc
temperature

Question 3

Importance of homeostasis for enzymes/ proteins

Answer 3

• control biochemical reactions
  -temp change can reduce rate of reactions or denature
  -need to maintain constant internal temperature

Question 4

Importance of homeostasis for cells

Answer 4

• osmotic movement of water into/out of cells
  -can cause cells to shrink/expand and become non-functional
• must maintain bgc
• need steady respiration source

Question 5

optimum point

Answer 5

the point at which system operates best

Question 6

receptor

Answer 6

detects any deviation from optimum point

Question 7

co-ordinator

Answer 7

coordinates info from receptors and sends instructions to effector

Question 8

effector

Answer 8

muscle or gland that brings about changed needed to return system to optimum point

Question 9

feedback mechanism

Answer 9

receptor responds to stimulus created by change to system brought about by effector

Question 10

Negative feedback

Answer 10

change produced by control system leads to change in stimulus detected by receptor and turns system off
- returns to optimum point

Question 11

Positive feedback

Answer 11

Deviations from optimum point causes changes that result in even greater deviation from normal

Question 12

Positive example

Answer 12

• influx of sodium in neurones
• hypothermia

Question 13

Many separate mechanisms

Answer 13

greater degree of control