Chapter 5

Chapter 5

The Web of Life

Food Chain

within an

such as between

and

examples

producers and light energy from the Sun

such as between

Interactions

environment

interactions between

living things

producers and consumers

predators and prey

interactions between living things and the physical characteristics of the environment

Web of LifeChapter 5

Copyright © 2010 Horizon Education, publishing as M. KOYLU

Primary Energy Source

• Organisms that first capture solar energy, the producers, include plants, some kinds of bacteria, and algae.

• Consumers are those organisms that consume plants or other organisms to obtain the energy necessary to build their molecules.

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Where do these organisms get their food and energy from?

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• The path of energy through the trophic levels of an ecosystem is called a food chain.

• The lowest trophic level of any ecosystem is occupied by the producers, such as plants, algae, and bacteria.

• Producers use the energy of the sun to build energy-rich carbohydrates.

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Food Chain in an Antarctic Ecosystem

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Plants are food producers.

Animals are food consumers.

Energy is transferred through a food chain, from food producer to food consumer.

Predators are animals that eat other animals.

Prey are animals eaten by other animals.

A food chain

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A food chain shows the food relationships among organisms and the transfer of energy through organisms in the form of food.

Example:

Grass Zebra Lion

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A food chain shows what is eaten.

The lettuce is eaten by the rabbit.

The fly is eaten by the thrush.

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Food chains always start with a plant.

The lettuce is eaten by the slug, the slug is eaten by the bird.

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Food chains also show predator-prey relationships. Identify the predators and prey below.

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Put on your thinking cap…

Can a predator be a prey of another animal? Give an example to support your answer.

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A predator can also be a prey!

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Write a food chain based on this photograph.

Which is the producer?

Which is the consumer?

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Write a food chain based on the photographs below. Identify the producer, consumers, predator and prey.

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Do you agree with Tom and Corrine? Why?

Meat-eaters are bigger than plant-eaters. Predators

are larger than prey!

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• Food Chain:

– set of food (energy) transfer from trophic level to trophic level

Carnivore

Carnivore

Carnivore

Herbivore

Plant

A terrestrial food chain

Quaternary consumers

Tertiary consumers

Secondary consumers

Primary consumers

Producers

Carnivore

Carnivore

Carnivore

Zooplankton

Phytoplankton

A marine food chain

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Do you eat only one type of food?

What is the advantage of eating a variety of food?

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• At the second trophic level are herbivores, animals that eat plants or other primary producers. They are the primary consumers.

• A herbivore must be able to break down a plant’s molecules into usable compounds.

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• At the third trophic level are secondary consumers, animals that eat herbivores. These animals are called carnivores.

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• Some animals, such as bears, are both herbivores and carnivores; they are called omnivores.

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• Detritivores are organisms that obtain their energy from the organic wastes and dead bodies that are produced at all trophic levels.

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• Bacteria and fungi are known as decomposers because they cause decay.

• Decomposition of bodies and wastes releases nutrients back into the environment to be recycled by other organisms.

• In most ecosystems, energy does not follow simple straight paths because animals often feed at several trophic levels. This creates an interconnected group of food chains called a food web.

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Animals can be

part of more than

one food chain.

Food chains linked to form food webs.Food webs show

energy from food

producers food

consumers.

Food webs show predator-prey relationships.

Predators limit the prey while, the prey limit the predators in their habitat.

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Food web – formed by interlinking food chains

Food chains:• Rice plant Sparrow• Rice plant Locust Sparrow

Food web: Locust

Rice plant Sparrow

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Food webs

• Formed by interlinking food chains

• Show the food relationships among organisms

• Show how energy is transferred through organisms in the form of food

• Show predator-prey relationships

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• In the wild, animals may eat more than one thing, so they belong to more than one food chain.

• To get the food they need, small herbivores may eat lots of different plants, and carnivores may eat many different animals.

owlfox

rabbits

grass

mice

berriesseeds


Quaternary,

tertiary,and secondary consumers

Tertiary and

secondary consumers

Secondary and

primary consumers

Primary consumers

Producers (plants)

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Construct a garden food web from the following food chains.

• Grass Grasshopper Lizard

• Grass Grasshopper Toad

• Grass Praying mantis Lizard

• Grass Grasshopper Praying mantis Toad

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Identify the predators and prey in the above food web.

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A food web in an African

grassland

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African grassland food web

• Identify the producers, plant-eaters and meat-eaters.

• Write down three food chains from the food web which involve the impala.

• Give an example of a prey and predator in the food web.

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If the population of zebras increases in the African grassland, what will happen to the population of lions?

Will the populations of the other organisms in the food web be affected? Explain.

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The farmers complain that the sparrows are eating too much rice grains and this affects their harvests.

Easy! Killing the sparrows will solve the problem!

Do you agree with Corrine? Why?

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Is it true…• … only large animals are consumers?

• … an organism higher in a food chain is a predator of all the organisms below it?

• … a change in the population of an organism in a food web only affects the populations of organisms directly linked to it?

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Put on your thinking cap…How are the organisms in a food web in a habitat affected when new types of organisms are introduced into the habitat?

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What is the missing link?

provide energy and nutrients to

Producers Consumers

nutrients death death

?

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Decomposers

Decomposers are organisms which break down dead and waste matter into simple substances, such as mineral salts, carbon dioxide and water.

E.g. Certain types of bacteria and fungi

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Are the following decomposers?Chapter 5


What would happen if there were no decomposers?

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Decomposers help to…

• … break down dead and waste matter so that they would not pile up on Earth.

• … recycle nutrients in the environment so that they will not run out.

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The missing link – Decomposers!Chapter 5


Simple substances like carbon dioxide, water and nutrients

Returned to the environment

Fungi Bacteria

breakdown

Dead plants, animals and wasteinto

whichare

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Do you agree with Tom and Corrine? Discuss.

All decomposers are micro-organisms.

I don’t think so. Dung beetles are not micro-organisms.

Organism

Population

Community

A living thing

Group of plants or animals of the same type, live and reproduce in the same place and in the same period of time.

Made up of many populations living together at the same time.

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Leaf Litter Community

Different populations of organisms can hide among the decaying leaves as it provides food and shelter.

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Rotting log Community

Fungi and mosses grow on the log providing food for slugs and snails, while the log provide shelter for both.

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Habitat Place where population can

find everything it needs to live and reproduce.

Different habitats can have different living conditions.

Therefore support different communities.

Examples of habitats

Can you name the habitats?

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Open fields receive sunlight and water plant populations food and shelter to many other organisms.

Plants provide animals below with shelter and place to reproduce.

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Aquatic plants can be classified as:•submerged•partially submerged•free-floating

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•The insects feed on wood.

•The animals feed on leaves, fruit and branches.

•The leaves also protect them from predators.

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Chapter WRAP-UP

Food chains & Food webs• link food producers to food consumers• show transfer of energy from food producers to food consumers• predator-prey relationship

Decomposers (bacteria and fungi) breakdown dead matter into simple substances

Population group of organisms of the same type, living and reproducing in the same surroundings

Community consists of different populations living in the same place.

Habitat place where organisms can find everything it needs to live and reproduce

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Education

Transcript of Chapter 5