5.1.1 Communication and homeostasis

Question 1

Why do multicellular organisms need a communication system?

Answer 1

• to respond to internal/external changes
• cells rely on eachother + organs work together for homeostasis

Question 2

Which factors need to be constant inside cells?

Answer 2

• Cell pH
• Temperature
• Water potential
• Blood glucose
  concentration

Question 3

Why is it important to keep conditions inside cells constant?

Answer 3

• enzymes function properly under certain conditions
  e.g. pH and temperature
• Outisde specific conditions enzymes do not function - organism can die

Question 4

Give 4 examples of internal change in an organism

Answer 4

1) Blood glucose concentration
2) heart rate
3) internal temperature
4) cell pH

Question 5

Give 4 examples of external chnage in an organism

Answer 5

1) humidity
2) light intensity
3) sudden sound
4) external temperature
5) smell
6) taste

Question 6

What is the process called where cells communicate with eachother ?

Answer 6

Cell signalling

Question 7

Define cell signalling

Answer 7

a complex system of intercellular communication

Question 8

What are 2 examples of systems whose purpose is cell signalling?

Question 9

Define negative feedback

Answer 9

a mechanism that reverses a chain in a variable bringing the level back to the norm/optimum

Question 10

Define positive feedback

Answer 10

When a change takes place, systems in the body act to reinforce the change

Question 11

Define homeostasis

Answer 11

the maintenance of a dynamic equilibrium within narrow ranges in the body

Question 12

What are 4 factors that need to be kept constant within a narrow range in animals?

Answer 12

• blood glucose levels
  -temperature
• blood water levels

Question 13

draw a flow chart outlining the processess and components involved in negative feedback

Answer 13

do on flashcard

Question 14

Define Effector in relation to negative feedback

Answer 14

effector - responds to the changes

Question 15

Define Receptor in relation to negative feedback

Answer 15

receptor - detects the changes

Question 16

What does ‘constant’ mean in terms of homeostasis?

Answer 16

the maintenance of a constant internal environment despite changes in internal and external conditions

Question 17

Define Thermoregulation

Answer 17

thermoregulation - the regulation of core body temperature through behavioural and or physiological means

Question 18

Define Endotherm

Answer 18

endotherm - organisms that rely on their metabolic processes to warm their body and maintain their core temperature
e.g. birds + mammals

Question 19

Define Ecotherm

Answer 19

ectoderm - organisms that rely on external sources of heat to regulate its body temperature
e.g. reptiles, fish, insects

Question 20

Define Core Body Temperature

Answer 20

the temperature of the internal organs deep within the body

Question 21

Why is ‘warm blooded’ and ‘cold blooded’ inappropriate terms for endotherms/ecotherms?

Answer 21

ecotherms can regulate their body temperature and maintain a body temperature as high as endotherms.
-Ecotherms do not actually have cold blood

Question 22

Why does temperature need to be maintained within a narrow range with cells?

Answer 22

for optimum enzyme rate
- if temperature too low = metabolic rate is v. slow bc collision rate between substrates and enzymes low
- if temperature too high =
enzymes denature and metabolic rate declines

Question 23

What are 4 ways that heat is transferred between an organism and their environment?

Answer 23

• Conduction
• Radiation
• Convection
• Evaporation

Question 24

Explain the 4 ways heat is transferred between an organism and their environment?

Answer 24

• Conduction
  heating as a result of collision
  of molecules e.g. water+ground
  -Radiation
  transmission of electromagnetic
  waves to and from the air, water,
  ground
  -Convection
  heating and cooling by currents
  of air, water - warm air/water
  rises+cooler air/water sinks=
  convection current around
  organism
• Evaporation
  objects cool as water evaporates
  from a surface