J9Web

FOOD CHAIN, FOOD WEB, ENERGY PYRAMID

MAGNETIC MANIPULATIVE

INTRODUCTION

For the purposes of this lab we will make the following two assumptions:

  1. All life on earth begins with the energy of the sun. (Can you think of life that does not begin with the sun?)
  2. The word plant includes all photosynthetic organisms, including organisms such as algae and protists.

A characteristic of life is that all living organisms need energy. The sun emits more energy than could ever be used, but with current technology most of this energy is either unavailable or lost. At the present time, except for very small applications of solar cells, plants are what humans and all other organisms depend on for the energy necessary to sustain life. Plants have the ability to make their own food from sunlight and are known as autotrophs, a word that means “self feeding.” Since plants are so important in capturing this energy and making it available to all other life forms, we call them primary producers. All other organisms fall into the category of consumers or hetertrophs, which means “other feeder.” Organisms that feed directly on plants are primary consumers. These organisms are mostly animals and could also be called plant-eaters or herbivores. Consumers which feed on the plant-eaters are secondary consumers and are also called meat-eaters or carnivores. Tertiary consumers make up the next level and are basically larger carnivores. Sometimes, but not often, another level exists which is referred to as the quaternary consumer. All food chains include decomposers which break dead organisms down into their natural elements for recycling. It should be noted that decomposers, which consist of bacteria and fungi, can and do exist at all levels in a food chain.

PURPOSE

  1. To have students construct a food chain and a food web, given a list of organisms.
  2. To have students trace the flow of energy through a food chain or food web.
  3. To have students understand the recycling of material in food chains and food webs.
  4. To help students visualize and explain the shape of an energy pyramid.

SAFETY

Follow all lab safety precautions.

MATERIALS

There are bags for 6 student teams.

The bags for each team contain:

8 green-bordered organisms2 yellow-bordered organisms

5 blue-bordered organisms20 arrows (5 of each type)

5 red-bordered organisms4 trophic level cards

2 purple-bordered organisms

PROCEDURE

PART A. Creating a food chain.

  1. Each group of students should have two bags – set 1 (used for parts A & B) and set 2 (used in part C).
  2. Using the cards in set 1, students will create five different food chains with ascending trophic levels. Each food chain should be a reasonable facsimile of what would occur in nature. Card placement should be similar to Figure 1.
  3. The name of the trophic level should be placed to the left of the food chains.
  4. Place the yellow-bordered sun in the upper left corner of your multiple food chains.
  5. Place the yellow-bordered card on the lower right of your food chains.
  6. Answer the questions under Analysis Part A.

FIGURE 1

PART B. Creating a food web.

1. In nature, all food chains are interlinked. Collectively all of these food chains form a food web. In part B you are to create a food web containing four major food chains.

2. To create the food web, you will use the display from Part A and the arrows in your bag.

3. The new food chains should be formed between any of the organisms.

4. Use the same type of arrow to illustrate the new food chains that can be formed by using organisms from several of the chains formed in Part A.

5. Remember, energy flows to the next highest level so arrows should always angle up.

6. Answer the questions under Analysis Part B.

PART C. Creating an energy pyramid or biomass pyramid.

  1. The object of Part C is to place all of the organism cards in the shape of a pyramid

(see Figure 2) .

  1. Separate all organism cards into stacks by their border color: green, blue, red, and purple.
  2. Place the eight green cards in a horizontal row at the bottom of the board.
  3. Above the green cards make a row of five blue cards. Remember to make a pyramid.
  4. Next make a row using four of the red cards
  5. Finally, place one of the purple cards at the top.
  6. Answer the questions under Analysis Part C.

FIGURE 2

STUDENT DATA SHEETName ______

J9WebDate ______

ANALYSIS

PART A.

  1. What kind of organism do all the food chains begin with? Why?
  1. Does each horizontal row have the same color border?
  1. Why can’t a deer or an eagle be a primary producer?
  1. Where can decomposers be found in these food chains?
  1. What remaining card can be placed at the top of each food chain?
  1. What remaining card can be placed at the bottom of each food chain?
  1. How do these cards make a cycle?

PART B.

1. Do the new food chains all begin with plants? Why?

2. Do the new food chains cross each other? Why?

3. Why can the interconnected food chains be considered a food web?

4. Why do most organisms have more than one source of energy?

5. What would happen if the organisms at one level of a food web were destroyed?

PART C.

  1. What is biomass?
  1. What is the relationship between the shape of the pyramid and how much biomass is in each trophic level?
  1. Why can there only be a maximum of 4 or 5 trophic levels in a food chain or an energy pyramid?
  1. If only 10 % of the energy at one level can be passed to the next, how many kilograms of wolves can you have if you start with 1000 kilograms of acorns?

Revised 10/11ASIM Biology: EnvironmentPage 1 of 5