cell signalling and homeostasis

Question 1

examples of external stimuli that plants and animals respond to

Answer 1

temperature
changing seasons
recognising a predator

Question 2

internal stimuli

Answer 2

build-up toxins
changes in ph
blood pressure

Question 3

what to do with stimulis

Answer 3

monitor and organisms must respond to changes

Question 4

what is the stimulus

Answer 4

environmental change

Question 5

what is the response

Answer 5

the way and organism change its behaviour or physiologywh

Question 6

why do we need communication systems (endocrine and nervous)

Answer 6

to survive, organisms need to respond to what is going on internally and externally, ensures information is passed on from one part of organisms to another part

Question 7

why are communication systems so important for multicellular organisms

Answer 7

multicellular organisms has differentiated cells which perform specialised function. one cell monitor, the other respond. cells need to communicate over long distance. organ systems must coordinate response

Question 8

how do plants monitor and respond to internal and external environmments

Answer 8

use of chemical messages like hormones
e,g. montotropism, growth of plant towards a light source

Question 9

what is the signal type for neuronal system

Answer 9

elecctrical

Question 10

what is the signal type for endocrine system

Answer 10

chemical
(hormones)

Question 11

what is the speed of signal for neuronal

Answer 11

fast, targets cell in milliseconds

Question 12

what is the speed of signal for endocrine

Answer 12

slow, travelling in bloodstream

Question 13

cell signalling

Answer 13

one cell will release a chemical that is detected by another cell. the second cell will respond to this signal. process can be done wither between adjacent cells and over long distances

Question 14

cell signalling in hormonal system

Answer 14

cells in endocrine system release their signals (hormones) into blood. only recognised by target cells, longer-term response

Question 15

cell signalling in neuronal system

Answer 15

interconnected network of neurones that signal to each other across synapse junctions, rapid response to stimuli

Question 16

cell signalling signals

Answer 16

specific shape complementary to that of cell surface receptor on target cell

Question 17

definition of homeostasis

Answer 17

The maintenance of an organism’s internal environment within set limits, despite changes in internal and external factors

Question 18

Which conditions are maintained by homeostasis?

Answer 18

Body temperature

Blood glucose concentration

Blood salt concentration

Water potential of the blood

Blood pressure

Carbon dioxide concentration

Question 19

standard response pathway

Answer 19

Stimulus – receptor - communication pathway (cell signalling) – effector – response

Question 20

Sensory receptors

Answer 20

monitor changes in the external and internal environments. E.g., temperature receptors in the skin (external) or in the brain internal

Question 21

Communication pathway

Answer 21

neuronal system or hormonal system to transmit signals from receptor cells to effector cells – via a coordination centre brain

Question 22

input

Answer 22

Messages sent from receptors to coordination centre

Question 23

output

Answer 23

Messages sent from coordination centre to effectors

Question 24

Effector cells

Answer 24

bring about a response (e.g., muscle cells contracting)

Question 25

negative feedback

Answer 25

return conditions back to the
optimum whenever they deviate from the normal.

Question 26

Positive Feedback

Answer 26

amplifies the change.
The
effectors respond to further increase the level away from the normal level.

Question 27

example of positive feedback

Answer 27

In early childbirth the release of the hormone
oxytocin stimulates uterine contractions.

The contractions trigger a positive feedback reaction.

More oxytocin is released, initiating more
contractions.