Factors affecting metabolic rate

Question 1

what is standard metabolic rate?

Answer 1

level required for resting lifestyle, no activity, digestion or stress

Question 2

what is resting metabolic rate?

Answer 2

level required for minimal activity (just existing)

Question 3

what is maximum metabolic rate?

Answer 3

max possible level during exercising activity

Question 4

what is Aerobic scope?

Answer 4

• extent to which MMR exceeds RMR
• max amount of oxygen available for aerobic activity (after accounting for processes required to maintain RMR)
• animals capacity to increase aerobic metabolic rate above maintenance levels
• aerobic scope increases with temp (as RMR & MMR does)

Question 5

What did Briggs and Post 1997 find?

Answer 5

found metabolic rate to have a strong association with environmental temp using muscle activity in trout as a proxy

Question 6

what influences metabolic rate?

Answer 6

• activity
• Mass
• temperature
• other factors (environmental oxygen, food, genetic differences)

Question 7

what is the effect of metabolism with mass?

Answer 7

• increases with mass
• mass specific metabolic rate decreases with mass (metabolic rate of a gram of tissue depends on animal size)
• 1g of tissue of smaller animal has higher metabolic rate (potentially cause they lose heat to the environment faster, surface body ratio) - but still unknown

Question 8

How does temperature effect metabolism?

Answer 8

• generally metabolic rate increases with temp
• differs between ectotherms and endotherms
• endotherms - Body temp maintained constant in TNZ, increases outside TNZ to gain/dissipate heat (evaporation, radiation, conductive, or convective cooling)
• ectotherms - don’t generate much heat, as temp increases body temp increases, metabolic rate increases with temp.

Question 9

what does Q10 represent?

Answer 9

• the temperature sensitivity of metabolism

- is highly conserved across all taxa

Question 10

what happens when metabolism reaches it’s maximum?

Answer 10

• metabolic rate declines

- organisms starts to die, become physiologically compromised (enzymes denature)

Question 11

Why does resting metabolic rate increase with temperature?

Answer 11

1, Universal temperature dependence of metabolism (UTD)
- temp governs metabolism through effects on rates of biochemical reactions

2. temperature affects aspects of cellular physiology such that there is an increase in ATP demand (and hence oxygen consumption) at higher cell temps.
   - indirect influence through a combo of energetic trade offs and evolutionary temperature adaptation.

Question 12

What are the limitations to UTD?

Answer 12

• Higher temps would automatically lead to higher metabolic rates (Gillooly et al, 2001)
• However, Clarke & Fraser 2004 showed that a range of organisms living at below 0-25 degrees have the same resting metabolic rate.
• Enzymes are adapted to the organisms environmental temp