Unit 2.3 - Metabolic Rate

• What is metabolic rate?

  The quantity of energy consumed by an organism per unit time.
• How is energy generated in cells?

  Aerobic respiration
• What is the word equation for aerobic respiration?

  Glucose + oxygen -> Carbon dioxide + water + energy.
• What can metabolic rate be measured as?

  Oxygen consumption per unit time, carbon dioxide production per unit, energy production (heat) per unit time.
• What can we use to measure metabolic rate?

  Calorimeters, respirometers, oxygen and carbon dioxide probes.
• What does a calorimeter do?

  Measures heat produced by an organism over a period of time. Heat produced is transferred to surrounding water. Temperature is measured over a period of time. This allows metabolic rate to be calculated.
• What does a respirometer do?

  Measures 02 uptake or C02 output of an organism over a period of time. Air with CO2 removed is used by the organism. The CO2 it breathes out is also absorbed. This decreases the volume of air in the system, drawing the liquid up the tube. Volume of CO2 absorbed = volume of O2 used.
• What do oxygen and carbon dioxide probes do?

  Calculate the volume of oxygen that an organism consumes and the volume of carbon dioxide that it gives out.
• What happens when there is an increased energy demand?

  Metabolic rates increase and therefore the consumption of oxygen increases and aerobic respiration increases.
• What organisms have higher metabolic rates?

  Birds and mammals.
• What organisms have the lowest metabolic rate?

  Fish
• Describe circulatory system in fish

  Blood only passes through 2 chambered heart once in each circuit. Heart contains 1 atrium and 1 ventricle. Single circulatory system.
• Describe circulatory system in reptiles and amphibians

  System is incomplete because there is only one ventricle and two atria. Deoxygenated blood from body mixes with oxygenated blood from lungs. Amphibians diffuse oxygen from their moist skin. Double incomplete system.
• Describe circulatory system in birds and mammals

  Two ventricles and two atria. Complete double system allows higher metabolic rates to be maintained. No mixing of the blood. Oxygenated blood can be pumped out at a higher pressure. Enables more efficient oxygen delivery to cells.