1 communication and homeostasis

Question 1

what is cell signalling

Answer 1

the way in which cells communicate with each other

Question 2

why do cells need to communicate with each other

Answer 2

maintain internal conditions (temperature, pH, aqueous environment, free from toxins etc.)

Question 3

what is a stimulus and response

Answer 3

change in environment
way in which the organism changes its behaviour/ physiology

Question 4

what will a good communication system do

Answer 4

cover the whole body
enable cell communication
enable rapid communication
enable specific communication
short and long term responses
ensure that different parts of the body work together

Question 5

compare nervous and hormonal system

Answer 5

nervous - uses neurones, electrical impulses, short lasting, quick response
hormonal - uses blood, hormones/ chemicals, long lasting, slow response

Question 6

what is the CNS and PNS

Answer 6

central nervous system (CNS) – the brain and the spinal cord
peripheral nervous system (PNS) – all of the nerves in the body

Question 7

why is a multicellular organism more efficient then a single celled organism

Answer 7

cells are differentiated = so are specialised to perform specific functions

Question 8

homeostasis

Answer 8

maintaining a constant internal environment around an optimum despite changes in external and internal factors

Question 9

examples of what homeostasis controls

Answer 9

temperarure
blood glucose concentration
blood salt concentration
blood water potential
blood pressure
CO2 concentration

Question 10

response pathway to a stimulus

Answer 10

stimulus - receptor - (cell signalling) - effector - response

Question 11

sensory receptors

Answer 11

cells that respond to a stimulus in the internal/external environment of an organism and can create action potentials

Question 12

effectors

Answer 12

cell/tissue/organ that brings about a response

Question 13

negative feedback

Answer 13

mechanism that brings conditions back towards equilibrium

Question 14

positive feedback

Answer 14

mechanism that increases a change, takes system further away from optimum

Question 15

hormones

Answer 15

chemicals/ cell signalling molecules that are produced by glands and released into the blood

Question 16

ectotherm

Answer 16

a type of organism that depends on its environment to maintain its body temperature

Question 17

endotherm

Answer 17

a type of organism which can regulate its own body temperature without relying on external heat sources

Question 18

temperature control in ectotherms

Answer 18

do not use internal energy sources
relies on behavioral responses
not warm enough = try to absorb more heat from the environment (move into sun, lie on warm surface, expose larger SA)
too hot = avoid gaining more heat, try to increase heat loss
(move out of sun, underground, reduce body SA exposed )

Question 19

advantages of ectothermy

Answer 19

do not use up energy to keep warm
less food used in respiration
more energy/nutrients converted to growth
find less food
survive for long periods without food

Question 20

disadvantages of ectothermy

Answer 20

less active in cooler temperatures
risk from predators whilst cold and unable to escape
cannot take advantage of food available when cold

Question 21

temperature control in endotherms

Answer 21

relies on effectors in the skin and muscles
chemical reactions release energy as heat
can increase respiration to release heat
physiological mechanisms - blood redirection

Question 22

advantages of endothermy

Answer 22

maintain fairly constant body temperature
remain active when cold environment - take advantage of prey
inhabit colder parts of the planet

Question 23

disadvantages of endothermy

Answer 23

use significant amounts of energy intake to maintain body temperature
need more food
may overheat

Question 24

role of hypothalamus

Answer 24

detects change in core body temperature
in the brain
sends quick impulses to prevent further change

Question 25

role of peripheral temperature receptors

Answer 25

monitor the temperature in the extremities
info is fed to the thermoregulatory centre in the hypothalamus
behavioural mechanisms can be initiated to maintain temp of the body