Communication and homeostasis

Question 1

Need for communication systems in multicellular organisms

Answer 1

To respond when their internal and external environment changes and to coordinate organ function

Question 2

What is cell signalling

Answer 2

Communication between cells: electrical signals carried by neurons or chemical signals as hormones

Question 3

Principles of homeostasis

Answer 3

Homeostasis - internal environment is maintained within set limits around an optimum

Question 4

Define negative and positive feedback

Answer 4

Negative feedback - self regulatory mechanisms return internal environment to optimum when there is a fluctuation
Positive feedback - a fluctuation triggers changes that results in an even greater deviation from the normal level

Question 4

What is an endotherm

Answer 4

Organism that can regulate its body temperature independently of external sources. Thermoreceptors send signals to the hypothalamus which triggers a physiological or behavioural response

Question 4

What is an ecotherm

Answer 4

Organism that cannot increase its respiration rate to increase the internal production of heat, relies on external sources to regulate its body temperature

Question 4

What are receptors and effectors

Answer 4

Receptors: specialised cells located in sense organs that detect a specific stimulus
Effectors: usually muscles or glands which enable a physical response to a stimulus

Question 5

Physiological responses in temperature control in ecotherms

Question 6

Physiological responses in temperature control in endotherms

Question 7

Behavioural responses involved in temperature control in ecotherms

Question 8

Behavioural responses involved in temperature control in endotherms

Answer 8

Basking in the sun
Pressing against warm surfaces
Hibernation
Panting