16.1 and 16.2: Homeostasis and feedback mechanisms

Question 1

Homeostasis

Answer 1

the maintenance of an internal environment within restricted limits in organisms, the ability to return to an optimum point.

Question 2

The importance of homeostasis

3

Answer 2

• enzymes that control reactions work at a suitable rate
• changes to water potential may affect cells by osmosis causing shrinking or bursting]
• gives organisms a wider geographical range as they can control their internal environments

Question 3

Control mechanisms

Answer 3

The control of any self-regulating system involves a series of stages that feature:
-optimum point, receptor, coordinator, effector, feedback mechanism

Question 4

Optimum point

Answer 4

The point at which the system operates best

Question 5

What monitors the optimum point…

Answer 5

a receptor=

detects any deviation from the optimum point

Question 6

A receptor informs the…

Answer 6

coordinator=

which coordinates information from receptors

Question 7

Where a coordinator send appropriate instructions to

Answer 7

an effector=

often a muscle or a gland, which brings about the changes needed to return to the system to the optimum point

Question 8

The return of a system to normality because of an effector

Answer 8

a feedback mechanism=

by which a receptor responds to a stimulus created by the change to the system brought about by the effector

Question 9

Most control systems use

Answer 9

negative feedback

Question 10

Negative feedback

Answer 10

When a stimulus causes the corrective measures to be turned off and this tends to return the system to its original optimum level

Question 11

Positive feedback

Answer 11

Occurs when a deviation from the optimum causes changes that result in an even greater deviation from the normal