# Metabolic Rate Final

Content type
User Generated
Subject
Biology
School
Grossmont College
Type
Homework
Rating
Showing Page:
1/13
Exercise 9
METABOLIC RATE AND THERMOREGULATION
IN MAMMALS
Student Learning Outcomes
At the completion of this exercise you should:
(1) Be able to calculate the surface area to volume ratios for 3 cubes with different dimensions.
(2) Be able to explain the relationship between surface area to volume ratios and
thermoregulation costs in endothermic animals.
(4) Be able to describe the design of an experiment that could be used to measure the metabolic
rate of several mammals of different size.
(5) Be able to explain how the measurement of Oxygen consumption in an animal can be used
to estimate energy expenditure.
(6) Be able to diagram the summary equation for Cellular Respiration.
Introduction
A fundamental characteristic of life is the requirement for energy. As we know, the sun is the
ultimate source of energy for all organisms, being initially transformed into the chemical energy
of carbohydrate through photosynthesis. Thus, begins the flow of energy through life.
Subsequent chemical reactions in plants produce the three major classes of energy-rich organic
nutrients: carbohydrates, fats, and proteins. Energy is brought to heterotrophic organisms in the
food they consume. Specifically, the energy is contained in the organic molecules of life.
Organisms use their energy for a variety of natural processes, for example, locomotion, active
transport across cell membranes, cell division, growth, and the ongoing synthesis of new
molecular cell components. Some classes of animals, called endotherms, also use their energy
to keep warmer than their environments. However, before the energy stored in food molecules
can be used for cellular work, the molecules must be chemically broken down to release the
energy, and the energy must be transformed to ATP (adenosine triphosphate), the "energy
currency" of life. This process occurs in all living cells and is called cellular respiration.
Cellular respiration is a sequence of enzyme-catalyzed reactions which release energy from the
chemical bonds of organic nutrients. While some of this energy becomes heat, approximately
39% is "captured" in a high-energy phosphate bond (~ P
i
diphosphate) to form ATP. All living processes are powered by the energy carried in ATP.
Eventually, when the energy has been used as much as possible by the organism, it is all lost to
the environment as heat.
Most organisms require gaseous oxygen for cellular respiration and are therefore called aerobic.

Showing Page:
2/13
The exceptions are certain bacteria and fungi, which are anaerobic, not requiring oxygen for
cellular respiration. Aerobic cellular respiration produces 19 times more ATP than anaerobic
respiration. This gives aerobic organisms a tremendous energy advantage, especially when there
is limited food available.
Question 1. Explain the difference between autotrophic organisms and
heterotrophic organisms.
Autotrophic organisms can synthesize their own food through the process of
photosynthesis/chemosynthesis. These include plants, algae, and some bacteria. On the
other hand, heterotrophic organisms consume autotrophs to meet their nutritional and
energy needs. These include herbivores (goats, grasshoppers), carnivores (lion, tiger), and
omnivores (monkey, bear) among others.
Question 2. If there is an "energy advantage" for organisms which use aerobic respiration, do you
suppose this could explain why there are more aerobic species than anaerobic species? Explain
The Earth’s atmosphere is about 21% oxygen. The oxygen in the air is highly utilized by
the aerobic organisms for respiration. This is one driving force of aerobic respiration.
Second, aerobic respiration produces a significant amount of energy relative to anaerobic
respiration. This allows the higher survival and reproductive success of aerobic organisms
relative to that of anaerobic organisms
I. Endotherms: The Relationship between Size and Oxygen Consumption
In this section, we turn our attention to those animals which use a substantial portion of their
energy to keep their body temperatures relatively constant and (usually) warmer than their
environments. These animals are called endotherms by biologists, but you may have also heard
them called "warm-blooded," a poor, non-scientific term. Most endotherms are mammals or
birds, which also closely control their body temperatures by internal thermoregulation, using a
control center in their brains called the hypothalamus.
When physiological variables are maintained within relatively narrow limits, as is temperature in
most avian and mammalian endotherms, we say there is homeostasis. Homeostasis is the result
of balance within an organism. If the animal has nearly constant body temperature, we can
hypothesize that the heat lost must be exactly balanced by the heat produced.
Today we will attempt to test the above hypothesis. Recall that heat is energy. Energy itself is
difficult to measure, so we will try to measure it indirectly. Since an animal's energy input
comes from food metabolism through aerobic cellular respiration, we can easily measure it by
observing the animal's rate of oxygen uptake.
However, body temperature homeostasis results from balance between both energy input and
energy output. Therefore, to make our experiment complete, we also must also consider the
animal's rate of heat (energy) loss to the environment (energy output). As we have observed,
energy is very difficult to measure directly. Since endotherms lose heat to the environment
mostly at their surfaces, today we will use an animal's body surface area to estimate its rate of
heat loss.

Showing Page:
3/13

End of Preview - Want to read all 13 pages?
Access Now
Unformatted Attachment Preview
Exercise 9 METABOLIC RATE AND THERMOREGULATION IN MAMMALS Student Learning Outcomes At the completion of this exercise you should: (1) Be able to calculate the surface area to volume ratios for 3 cubes with different dimensions. (2) Be able to explain the relationship between surface area to volume ratios and thermoregulation costs in endothermic animals. (4) Be able to describe the design of an experiment that could be used to measure the metabolic rate of several mammals of different size. (5) Be able to explain how the measurement of Oxygen consumption in an animal can be used to estimate energy expenditure. (6) Be able to diagram the summary equation for Cellular Respiration. Introduction A fundamental characteristic of life is the requirement for energy. As we know, the sun is the ultimate source of energy for all organisms, being initially transformed into the chemical energy of carbohydrate through photosynthesis. Thus, begins the flow of energy through life. Subsequent chemical reactions in plants produce the three major classes of energy-rich organic nutrients: carbohydrates, fats, and proteins. Energy is brought to heterotrophic organisms in the food they consume. Specifically, the energy is contained in the organic molecules of life. Organisms use their energy for a variety of natural processes, for example, locomotion, active transport across cell membranes, cell division, growth, and the ongoing synthesis of new molecular cell components. Some classes of animals ...
Purchase document to see full attachment
User generated content is uploaded by users for the purposes of learning and should be used following Studypool's honor code & terms of service.

Anonymous