Lab #8 - Metabolism

Question 1

Aerobic Glycolysis

Answer 1

a series of reactions where oxygen is required to re-oxidize NADH to NAD +

Question 2

Respirometry

Answer 2

an animal is confined in a closed system in which the amount of oxygen consumed is measured over designated periods of time.

Question 3

Cellular Respiration

Answer 3

• the energy produced by the controlled oxidation of cellular fuels (carbs, lipids, proteins)

Question 4

Metabolism

Answer 4

• sum of all the chemical reactions that occur in an organism
• The three main purposes of metabolism are
  1. the conversion of the energy in food to energy available to run cellular processes
  2. the conversion of food to building blocks for proteins, lipids, nucleic acids, and some carbohydrates
  3. the elimination of metabolic wastes

Question 5

Metabolic Rate

Answer 5

the amount of energy used by an animal within a specific period of time

Question 6

Standard Metabolic Rate

Answer 6

An ectotherm’s resting energy expenditure per unit of time at a particular temperature

Question 7

Basal Metabolic Rate

Answer 7

An endotherm’s resting energy expenditure per unit of time

Question 8

Mass Specific Metabolic Rate

Answer 8

the rate at which organisms consume energy per gram of body weight per unit of time

Question 9

Endotherm

Answer 9

• warm-blooded animal
• regulate their own body temperature

Question 10

Ectotherm

Answer 10

• cold-blooded animal
• relies on its external environment in order to regulate its internal temperature

Question 11

explain the physiology that underlies CO2 production

Answer 11

• Cellular respiration converts ingested nutrients in the form of glucose (C6H12O6) and oxygen to energy in the form of adenosine triphosphate (ATP). CO2 is produced as a byproduct of this reaction
• Carbon dioxide production occurs in cells, mainly during glycolysis and the citric acid cycle during cellular respiration
• Following the citric acid cycle, all the carbon atoms originally present in glucose have been completely oxidized and released as carbon dioxide

Question 12

explain the physiology that underlies mass specific metabolic rate.

Answer 12

• Mass-specific metabolic rate: the rate at which organisms consume energy per gram of body weight per unit of time
• Smaller animals produce more carbon dioxide per gram of body weight than larger animals do

Question 13

Explain the difference between SMR/BMR (Standard/basal metabolic rate) and MMR (maximum metabolic rate). What is aerobic scope (also called aerobic metabolic scope)? Why does the aerobic scope of ectothermic animals decline as temperature rises?

Answer 13

• In mammals and birds, the basal metabolic rate is the stable, fasting, minimum rate of metabolism
• The metabolic rate of animals including insects, fish and amphibians is largely dependent on the environment. There is no metabolic rate that can be called basal for these animals
• Instead the minimum metabolism of fasting animals at a given external temperature is called the standard metabolic rate for that temperature
• the maximum rate of aerobic metabolism of an animal
• Aerobic scope is the difference between the standard and maximum metabolic rates
• As temperature increase above suitable, the aerobic standard metabolic rate is suggested to increase faster than the aerobic maximum metabolic rate leading to a reduction in the difference between them

Question 14

Explain why many endotherms can also be characterized as heterotherms or poikilotherms? What is the difference between a temporal and a regional heterotherm?
Describe the physiological benefits of temporal and regional heterothermy.

Answer 14

• Endotherm: maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions
• Heterotherm: varies between self-regulating their body temperature and allowing the surrounding environment to affect it
• Poikilotherm: an animal that varies its internal body temperature within a wide range of temperatures
• Endotherms can be characterized as poikilothermic animals because even if its body temperature varies, it can still remain higher than the temperature of the surrounding environment. They can be characterized as heterotherms because they switch between endo and ectotherm.
• Temporal heterothermy refers to body temperature differences in the same animal over time. Body temperature varies depending on environmental conditions
• Important for energy conservation. Minimize energy and water loss (change their insulation values seasonally in order to either conserve or release body heat)
• Regional heterothermy describes organism that are able to maintain different temperature zones in different regions of the body
• For example: penguins keep their feet the same temperature as the ice to avoid them sticking