Chapter 2. Critical Analysis Question

Introduction

Questions 1 & 2

1. 1.

   Which of the following statements correctly describes the second law of thermodynamics?

   A.

   With each energy transfer the amount of available energy to do work is sustained.

   B.

   Energy cannot be transferred from one system to another.

   C.

   With each energy transfer there is less available energy to do work.

   Correct

   Incorrect

2. 2.

   Energy flows through an ecosystem based on the laws of thermodynamics, and the energy flow determines the trophic relationships. Unlike materials such as oxygen, carbon, water, phosphates, and nitrates, which are recyclable in an ecosystem, the available energy to do work is lost at each level. Let’s begin to explore more closely the transfers of energy in an ecosystem. What is the initial source of energy in an ecosystem?

   A.

   The Sun

   B.

   Plants

   C.

   Bacteria

   Correct

   Incorrect

Questions 3 & 4

3. 3.

   How is the Sun’s energy made available to consumers such as animals?

   A.

   Through the photosynthetic process, plants store solar energy in the form of sugars, starches, and other carbohydrates. Plant matter can be eaten by consumers to gain access to the stored energy.

   B.

   Through the process of respiration, animals can obtain solar energy by breathing in air.

   C.

   Through the process of nitrification, bacteria can convert solar energy into various nitrogen-based molecules that animals can consume to gain access to the stored energy.

   Correct

   Incorrect

4. 4.

   Now you know that plants, also known as primary producers, act as the middleman in the transfer of energy from the Sun to other consumers, such as herbivores, omnivores, and carnivores (or top predators). As a rule, about 80 to 90% of the available energy to do work is lost as it moves from one trophic level to the next. How is energy “lost” from one level to the next? Match the example to the correct type of loss.
   a. Some animals maintain a steady body temperature in order to live.	--------MovementHeatSome of the organism is not eaten
   b. Animals may hunt, play, reproduce, and so on, which means they are using up some of the energy they consumed to function, making less available to the next level of the trophic pyramid.	--------Metabolic activitiesMovementSome of the organism is not eaten
   c. A top predator leaves behind the bones or feathers of its prey, so the energy that went into creating those parts is not consumed and that energy is “lost.”	--------Metabolic activitiesMovementHeatSome of the organism is not eaten
   d. An herbivore uses energy to respire, to circulate blood, to digest food, and so on, so that energy is used and unavailable to the next higher trophic level when that organism is consumed.	--------Metabolic activitiesMovementSome of the organism is not eaten

Question 5

5. 5.

   Only about 10% of the energy at one trophic level is available to the next higher level. Fill in the following diagram.

   

   Tropic Level	Energy in kcal
   Secondary carnivore
   Primary carnivore
   Herbivores
   Primary producers	10,000

   As a consequence of the energy loss, food chains tend to be short. Also, in ecosystems, relatively few top predators can be supported as compared to large numbers of primary producers.

Critical Analysis Question

2.1 Activity Completed!