Standard 13

Lesson 1Food Chain- a succession of

organisms in an ecological community that constitutes a continuation of food energy from one organism to another as each consumes a lower member and in turn is preyed upon by a higher member.

Lesson 1Food chains are also called trophic social networks which describe the eating relationships between species in an ecosystem. Organisms are connected to the organisms they consume by lines representing the direction of organism or energy transfer. It also shows how the energy from the producer is transferred to the consumer. Most of the times a food chain refers to a graph where only connections are recorded, and a food network or ecosystem network refers to a network where the connections are given weights representing the quantity of nutrients or energy being transferred. Trophic levels may contain either a single species or a group of species that are presumed to share both predators and prey. They usually start with a plant and end up with a carnivore.

Lesson 1Lesson 1The food chain consists of four main parts:The food chain consists of four main parts:• The Sun: which provides the energy for everything The Sun: which provides the energy for everything

on the planet.on the planet.• Producers: these include all the green plants. Producers: these include all the green plants.

These are also known as autotrophs every, since These are also known as autotrophs every, since they make their own food. Ultimately, organisms is they make their own food. Ultimately, organisms is dependent on plants for oxygen and food. dependent on plants for oxygen and food.

• Consumers: in short, consumers are every Consumers: in short, consumers are every organism that eats something else. They in organism that eats something else. They in herbivores, carnivores, parasites, and herbivores, carnivores, parasites, and decomposers.decomposers.

• Decomposers: these are mainly bacteria and fungi Decomposers: these are mainly bacteria and fungi that convert dead matter into gases such as that convert dead matter into gases such as carbon and nitrogen to be released into the air, carbon and nitrogen to be released into the air, soil, and water. Fungi, and other organisms that soil, and water. Fungi, and other organisms that break down dead organic matter are known as break down dead organic matter are known as saprophytessaprophytes. .

Lesson 1

The bottom layer of the energy pyramid has plants and other producers. The middle layer has herbivores. They eat plants and other producers. The top layer has types of carnivores. They eat the herbivores and maybe some other carnivores. In a healthy ecosystem, there are lots of producers, and some herbivores but not many carnivores.

Lesson 2

Energy Pyramid- a pyramid showing the energy flow in an ecosystem.

Example of an energy pyramid

Lesson 2

For the ecosystem to function energy must be available and it must be transferred. Why? Because of the First and Second Laws of Thermodynamics. The First Law states that energy can neither be created or destroyed, but can be converted to one form to another. The Second Law states that everything is running downhill or, more formally, everything in the universe is going from a more organized state to a less organized one.

Lesson 3

FOOD WEBS - is a model that shows all the possible feeding relationships between organisms living in an ecosystem.

Lesson 3• food webs are more accurate models than food chains. • A food web is actually several food chains joined

together, Because most organisms depend on more than one species for food

• Food chains are overly simplistic as representatives of what typically happens in nature

• The food chain shows only one pathway of energy and material transfer.

• The food web is divided into two broad categories: the grazing web, which typically begins with green plants, algae, or photosynthesizing plankton, and the detrital web, which begins with organic debris

• These webs are made up of individual food chains. In a grazing web, materials typically pass from plants to plant eaters (herbivores) to flesh eaters (carnivores). In a detrital web, materials pass from plant and animal matter to bacteria and fungi (decomposers), then to detrital feeders (detritivores), and then to their predators (carnivores).

LESSON 3• Generally, many interconnections exist within food webs• Food webs shows how energy and material flow through a

community of species as a result of these feeding relationships connected by lines or arrows called "links", and the species are sometimes referred to as "nodes" in food web diagrams

• The pioneering animal ecologist. • Typically, species are Charles Elton (1927) introduced the concept of the

food web (which he called food cycle) to general ecological science. • The herbivores are usually preyed upon by carnivores, which get the

energy of the sunlight at third-hand, and these which has no enemies, and which forms, as it were, a terminus on this food cycle. There are, in fact again may be preyed upon by other carnivores, and so on, until we reach an animal, chains of animals linked together by food, and all dependent in the long run upon plants. We refer to these as 'food-chains', and to all the food chains in a community as the 'food-cycle.'"

• A food web differs from a food chain in that the latter shows only a portion of the food web involving a simple, linear series of species connected by feeding link

• A food web aims to depict a more complete picture of the feeding relationships, and can be considered a bundle of many interconnected food chains occurring within the community

Lesson 3Examples of food web

charts.

Questions

Question 1:

What is a food chain?

Answer

A succession of organisms in an ecological community that constitutes a continuation of food energy from one organism to another as each consumes a lower member and in turn is preyed upon by a higher member.

Question 2

What is the difference between a food chain and a food web?

Answer

A food web differs from a food chain in that the latter shows only a portion of the food web involving a simple linear series of species connected by feeding link

Question 3

What do food webs do?

Answer

Food webs shows how energy and material flow through a community of species as a result of these feeding relationships connected by lines or arrows called links.

Question 4

What is another name for the food chain?

Answer

Trophic Social Networks

Question 5

What does a food chain show?

Answer

The food chain shows only one path way of energy and material transfer.

Question 6

What is an energy pyramid?

Answer

An energy pyramid is a pyramid showing the energy flow in an ecosystem.

Question #7

What do food chains refer to?

Answer

They usually refer to graphs.

Question #8

What does the food chain consist of?

Answer

The main parts of the food chain are the sun, producers, consumers, and decomposers.

Question #9

What do the lines on the food chain represent?

Answer

The direction of organisms or energy transfer.

Question #10

What do food webs show?

Answer

A food web shows how energy and material flow through a community.

Question #11

What are the two categories that food webs are categorized into?

Answer

The two categories that food webs are classified in is the grazing web and the detrital web.