Food Chains and Food Food Chains and Food WebsWebs

Science FoundationsScience Foundations

Predator and Prey Predator and Prey RelationshipsRelationshipsOne important interaction in the ecosystem is One important interaction in the ecosystem is

between predators and their prey. between predators and their prey.

Predators are organisms which hunt and feed Predators are organisms which hunt and feed on other organisms Whereas the living things on other organisms Whereas the living things that are eaten are referred to as prey.that are eaten are referred to as prey.

1.1. To maintain balance in the ecosystem, To maintain balance in the ecosystem, the the interaction between predator and prey interaction between predator and prey should not be disturbed.should not be disturbed.

ExampleExampleIn parts of the South, one natural predator of In parts of the South, one natural predator of

the white-tailed deer, the mountain lion, has the white-tailed deer, the mountain lion, has

been reduced in number. Because there are been reduced in number. Because there are

fewer mountain lions to prey on the deer, fewer mountain lions to prey on the deer, the the

deer population in some regions has risen deer population in some regions has risen

tremendously.tremendously.

WHY?

Food ChainFood ChainA A food chainfood chain is the relationship of organisms is the relationship of organisms

that depend on each other for energy or food. that depend on each other for energy or food.

It is a straight line relationship such as algae It is a straight line relationship such as algae

is food for fish which are food for squid which is food for fish which are food for squid which

are food for sharks. are food for sharks.

Food Web Food Web A A food webfood web is more complex and is a is more complex and is a

food food

chain with the interrelated chain of chain with the interrelated chain of organisms organisms

that depend on each other for food. that depend on each other for food.

If one organism is removed, other If one organism is removed, other organisms organisms

may be endangered or possibly die out.may be endangered or possibly die out.How Come?

Food WebFood Web

Carrying CapacityCarrying Capacity

Carrying capacityCarrying capacity is the number of is the number of individuals individuals

in a population that the resources can in a population that the resources can support. support.

This provides for a balanced ecosystem. This provides for a balanced ecosystem.

Trophic LevelsTrophic LevelsThe living things in an ecosystem can be The living things in an ecosystem can be divided into four levels. Each step in a food divided into four levels. Each step in a food chain or food web is called a chain or food web is called a trophic leveltrophic level. .

Producers are the first step.Producers are the first step.

Consumers are the next steps. Consumers are the next steps.

Each step depends on the step below it for Each step depends on the step below it for food and to provide its energy.food and to provide its energy.

ProducersProducersProducersProducers are the green plants and some are the green plants and some

bacteria and algae that are able to make bacteria and algae that are able to make their their

own food from water, the sun, carbon dioxide own food from water, the sun, carbon dioxide

in the air, and minerals in the soil. in the air, and minerals in the soil.

When plants make their own food, they use When plants make their own food, they use sunlight. This process is called sunlight. This process is called photosynthesisphotosynthesis..

What is Photosynthesis?What is Photosynthesis?

The The processprocess of photosynthesis is a of photosynthesis is a chemical reactionchemical reaction. .

It is the most important It is the most important

chemical reaction on our planet.chemical reaction on our planet.

What is the Equation for What is the Equation for the Chemical Reaction of the Chemical Reaction of

Photosynthesis?Photosynthesis?

What is the equation for What is the equation for the chemical reaction of the chemical reaction of

photosynthesis?photosynthesis?

What is the equation for What is the equation for the chemical reaction of the chemical reaction of

photosynthesis?photosynthesis?

Six molecules of carbon dioxide react with six molecules of water to form 1

molecule of glucose and six molecules of oxygen.

Describe PhotosynthesisDescribe Photosynthesis

The process of changing light energy The process of changing light energy to chemical energy to chemical energy

Energy stored as sugarEnergy stored as sugar Occurs in plants and some algae Occurs in plants and some algae Plants need light energy, COPlants need light energy, CO22, and H, and H22O O Takes place in the Takes place in the chloroplasts, using , using

chlorophyll, the green pigment in , the green pigment in plantsplants

What happens during What happens during photosynthesis?photosynthesis?

Plants capture light energy and use Plants capture light energy and use that energy to make glucosethat energy to make glucose

Sunlight provides the energy needed Sunlight provides the energy needed by chlorophyll to change molecules of by chlorophyll to change molecules of carbon dioxide and water into glucosecarbon dioxide and water into glucose

Oxygen is also released in this Oxygen is also released in this reactionreaction

What happens during What happens during photosynthesis?photosynthesis?

Carbon dioxide enters the leaf through Carbon dioxide enters the leaf through holes called holes called stomata

COCO2 2 combines with the stored energy in combines with the stored energy in the chloroplasts through a chemical the chloroplasts through a chemical reaction to make glucosereaction to make glucose

The sugar is moved through tubes in the The sugar is moved through tubes in the leaf to the roots, stems and fruits of the leaf to the roots, stems and fruits of the plantsplants

Some of the sugar is used right away by Some of the sugar is used right away by the plant for energy; some is stored as the plant for energy; some is stored as starch; and some is built into plant tissuestarch; and some is built into plant tissue

Why is this important to Why is this important to us?us?

We cannot make our own food (glucose, We cannot make our own food (glucose, energy), we must get our food from plants.energy), we must get our food from plants.

Plants are the first step in the food chain.Plants are the first step in the food chain.

Why is this important to Why is this important to us?us?

The oxygen released during The oxygen released during photosynthesis is necessary for all photosynthesis is necessary for all living things.living things.

Learn more about Learn more about photosynthesis at:photosynthesis at:

http://www.ftexploring.com/me/photosyn1.html

ConsumersConsumersConsumersConsumers are the animals that rely on are the animals that rely on

other other organisms for food. This group can be further organisms for food. This group can be further divided into three groups:divided into three groups: Primary consumersPrimary consumers are herbivores, or are herbivores, or

plant eaters. Examples – some insects, plant eaters. Examples – some insects, deer, or mice.deer, or mice.

Secondary consumersSecondary consumers are carnivores, or are carnivores, or flesh eaters. They feed on herbivores. flesh eaters. They feed on herbivores. Examples – snakes and coyotesExamples – snakes and coyotes

Tertiary consumersTertiary consumers can be carnivores or can be carnivores or omnivores, which eat both plants and omnivores, which eat both plants and animals. Example – hawks and humansanimals. Example – hawks and humans

ScavengersScavengersScavengersScavengers feed on dead organisms. feed on dead organisms.

They They

include ants and vultures.include ants and vultures.

DecomposersDecomposersDecomposersDecomposers are organisms that break down are organisms that break down

dead organic matter. This decomposition dead organic matter. This decomposition

produces many of the raw materials that are produces many of the raw materials that are

used by the producers in photosynthesis. used by the producers in photosynthesis.

Examples are bacteria, fungi and earthworms.Examples are bacteria, fungi and earthworms.

Symbiotic RelationshipsSymbiotic Relationships

Symbiosis = a beneficial relationship Symbiosis = a beneficial relationship between 2 organisms that live between 2 organisms that live together.together.

3 types of symbiosis3 types of symbiosis– Commensalism = 1 organisms benefits, Commensalism = 1 organisms benefits,

the other neither benefits or is harmed.the other neither benefits or is harmed.– Parasitism = 1 organisms benefits the Parasitism = 1 organisms benefits the

other is harmed.other is harmed.– Mutualism = both organisms benefit.Mutualism = both organisms benefit.

CommensalismCommensalism

Commensalism occurs Commensalism occurs in a relationship where in a relationship where one animal benefits one animal benefits and the other is and the other is unaffected.unaffected.

The dorsal fin of the The dorsal fin of the Remora is modified Remora is modified into a sucker. They into a sucker. They attach to sharks during attach to sharks during feeding and eat the feeding and eat the scraps. The sharks do scraps. The sharks do not try to eat the not try to eat the Remora.Remora.

ParasitismParasitism A parasite is an A parasite is an

organism that lives on or organism that lives on or in the body of another in the body of another organism (the host) organism (the host)

from whose tissues it from whose tissues it gets its nourishment, gets its nourishment, and and

to whom it does some to whom it does some damagedamage

Animals are Animals are parasitized by viruses, parasitized by viruses, bacteria, fungi, bacteria, fungi, protozoans, flatworms protozoans, flatworms (tapeworms and (tapeworms and flukes), nematodes, flukes), nematodes, insects (fleas, lice), insects (fleas, lice), and arachnids (mites). and arachnids (mites).

Plants are parasitized Plants are parasitized by viruses, bacteria, by viruses, bacteria, fungi, nematodes, and fungi, nematodes, and a few other plants.a few other plants.

The flea is common on dogs and cats

MutualismMutualism The clownfish can come The clownfish can come

in contact with the in contact with the stinging tentacles of the stinging tentacles of the sea anemone and not be sea anemone and not be harmed by them. harmed by them.

At the same time, it At the same time, it receives protection from receives protection from its enemies. its enemies.

The clownfish feeds The clownfish feeds the anemone by the anemone by gathering nutrients gathering nutrients and also leaving and also leaving nutritional waste on nutritional waste on the tentacles.the tentacles.

Ecological PyramidsEcological Pyramids

Ecological pyramidsEcological pyramids are diagrams that are diagrams that show show

each trophic level in a biome. There are each trophic level in a biome. There are three three

types:types: Energy pyramidEnergy pyramid Biomass pyramidBiomass pyramid Numbers pyramidNumbers pyramid

Energy PyramidEnergy Pyramid

The The energy pyramidenergy pyramid shows the transfer shows the transfer of of

energy from one level to the next. The energy from one level to the next. The bottom bottom

of the food chain shows the largest of the food chain shows the largest amount of amount of

energy which comes from the sun then as energy which comes from the sun then as you you

move up energy is used but also lost in the move up energy is used but also lost in the

form of heat energy.form of heat energy.

Energy PyramidEnergy Pyramid

Biomass PyramidBiomass PyramidTThe he biomass pyramidbiomass pyramid is based on is based on

the the

mass of organic material at each level.mass of organic material at each level.

Numbers PyramidNumbers PyramidThe The Numbers pyramidNumbers pyramid shows the relative shows the relative

numbers of organic material at each level.numbers of organic material at each level.