FOOD WEBSFOOD WEBS

• Food contains nutrients and energy Food contains nutrients and energy needed for survival. needed for survival.

• When one organism is food for anotherWhen one organism is food for anothersome of the energy in the first organism some of the energy in the first organism (the food) is transferred to the second (the food) is transferred to the second organism (the eater).organism (the eater).

Energy Flow Through EcosystemsEnergy Flow Through Ecosystems

• Producers are organisms that take in and Producers are organisms that take in and use energy from the Sun or some other use energy from the Sun or some other source to produce food. source to produce food.

• Consumers are organisms that take in Consumers are organisms that take in energy when they feed on producersenergy when they feed on producers or other consumers.

• When organisms die, other organisms When organisms die, other organisms called decomposers take in energy as they called decomposers take in energy as they break down the remains of organisms.break down the remains of organisms.

Multiple ChoiceMultiple Choice

1. _________ are organisms that can’t 1. _________ are organisms that can’t make food.make food.

A. PlantsA. Plants C. ConsumersC. Consumers

B. EnzymesB. Enzymes D. ProducersD. Producers

ConsumersConsumers

Food ChainsFood Chains

• A A food chainfood chain is a model, a simple way of is a model, a simple way of showing how energy, in the form of food, showing how energy, in the form of food, passes from one organism to another.passes from one organism to another.

• When drawing a food chain, arrows When drawing a food chain, arrows between organisms indicate the direction between organisms indicate the direction of energy transfer. of energy transfer.

Food ChainsFood Chains

• Food chains usually have only three Food chains usually have only three or four links. This is because the or four links. This is because the available energy decreases from one available energy decreases from one link to the next link. link to the next link.

• In a food chain, the amount of In a food chain, the amount of energy left for the last link is only energy left for the last link is only a small portion of the energy in a small portion of the energy in the first link. the first link.

Short answerShort answer

10. Explain the steps of a food chain.10. Explain the steps of a food chain.

answeranswer

Food chains cycle matter and energy Food chains cycle matter and energy through an ecosystem. Carnivores and through an ecosystem. Carnivores and omnivores eat consumers. Herbivores eat omnivores eat consumers. Herbivores eat producers,producers,

Food WebsFood Webs

• A A food webfood web is a series of overlapping is a series of overlapping food chains that exist in an ecosystemfood chains that exist in an ecosystem.

• A food web provides a more complete A food web provides a more complete model of the way energy moves through model of the way energy moves through an ecosystem.an ecosystem.

Food WebsFood Webs

COMPLETIONCOMPLETION

COMPLETE THE STATEMENTCOMPLETE THE STATEMENT

3. Made of overlapping food chains3. Made of overlapping food chains

answeranswer

Food websFood webs

Short answerShort answer

9. Define a food chain and compare it with 9. Define a food chain and compare it with a food weba food web

answeranswer

A food chain is a simple way of showing A food chain is a simple way of showing how energy, in the form of food, passes how energy, in the form of food, passes from one organism to another, from small from one organism to another, from small producers to the predator at the top end of producers to the predator at the top end of the chain. A food web is a series of the chain. A food web is a series of interlocking food chains in an ecosystem.interlocking food chains in an ecosystem.

Ecological PyramidsEcological Pyramids

• Most of the energy in the biosphere Most of the energy in the biosphere comes from the Sun.comes from the Sun.

• Producers take in and transform only a Producers take in and transform only a small part of the energy that reaches small part of the energy that reaches Earth’s surface. Earth’s surface.

Ecological PyramidsEcological Pyramids

• An ecological pyramid models the An ecological pyramid models the number of organisms at each level of a number of organisms at each level of a food chain. food chain.

• The bottom of an ecological pyramid The bottom of an ecological pyramid represents the producers of an ecosystem. represents the producers of an ecosystem.

• The rest of the levels represent successive The rest of the levels represent successive consumers. consumers.

Energy PyramidEnergy Pyramid

• An energy pyramid compares the energy An energy pyramid compares the energy available at each level of the food chain in available at each level of the food chain in an ecosystem. an ecosystem.

• A pyramid of energy usually has three or A pyramid of energy usually has three or four levels. four levels.

• Only about ten percent of the energy at Only about ten percent of the energy at each level of the pyramid is available to each level of the pyramid is available to the next level. the next level.

The Cycles of MatterThe Cycles of Matter

• The law of conservation of mass states The law of conservation of mass states that matter on Earth is never lost or that matter on Earth is never lost or gained. It is used over and over again. gained. It is used over and over again.

• The carbon atoms in your body might The carbon atoms in your body might have been on Earth since the planet have been on Earth since the planet formed billions of years ago. They have formed billions of years ago. They have been recycled billions of times. been recycled billions of times.

CompletionCompletion

4. What has happened to energy in the 4. What has happened to energy in the environment?environment?

answeranswer

recycledrecycled

PhotosynthesisPhotosynthesis

• Living things are divided into two groupsLiving things are divided into two groups— producers and consumers—based on — producers and consumers—based on how they obtain their food.how they obtain their food.

• Organisms that make their own food, Organisms that make their own food, such as plants, are called producers.such as plants, are called producers.

• Organisms that cannot make their own Organisms that cannot make their own food are called consumers.food are called consumers.

PhotosynthesisPhotosynthesis

• Plants and many other producers can Plants and many other producers can convert light energy into another kind of convert light energy into another kind of energy—chemical energy.energy—chemical energy.

• The process they use is called The process they use is called photosynthesis.photosynthesis.

• During During photosynthesisphotosynthesis,, producers use light energy to producers use light energy to make sugars, which can be make sugars, which can be used as food.used as food.

Producing CarbohydratesProducing Carbohydrates• Producers that use photosynthesis are Producers that use photosynthesis are

usually green because they contain a usually green because they contain a green pigment called chlorophyll green pigment called chlorophyll (KLOR uh fihl).(KLOR uh fihl).

• Chlorophyll and other pigments are used Chlorophyll and other pigments are used in photosynthesis to capture to capture in photosynthesis to capture to capture light energy.light energy.

• In plant cells, these pigments are found in In plant cells, these pigments are found in chloroplasts.chloroplasts.

Producing CarbohydratesProducing Carbohydrates

• The captured light energy is used to drive The captured light energy is used to drive chemical reactions during which the raw chemical reactions during which the raw materials, carbon dioxide and water, are materials, carbon dioxide and water, are used to produce sugar and oxygen.used to produce sugar and oxygen.

• For plants, the raw materials come from For plants, the raw materials come from air and soil.air and soil.

· Glucose is another name for sugar

Producing Carbohydrates

• Some of the captured light energy is Some of the captured light energy is stored in the chemical bonds that hold stored in the chemical bonds that hold sugar molecules together.sugar molecules together.

Storing CarbohydratesStoring Carbohydrates• Plants make more sugar during Plants make more sugar during

photosynthesis than they need for photosynthesis than they need for survivalsurvival.

• Excess sugar is changed and stored as Excess sugar is changed and stored as starches or used to make other starches or used to make other carbohydratescarbohydrates.

• Plants use carbohydrates as food for Plants use carbohydrates as food for growth, maintenance, and reproduction.growth, maintenance, and reproduction.

• Consumers take in food by eating Consumers take in food by eating producers or other consumers.producers or other consumers.

Multiple ChoiceMultiple Choice

2. Producers use light energy to 2. Producers use light energy to make_________make_________

A. chlorophyll C. proteins

B. glucose D. starch

Consumers

glucose

Match each item with the correct statementMatch each item with the correct statement A. EcologyA. Ecology

B. Limiting factorB. Limiting factorC. Carrying capacityC. Carrying capacity ProducersProducersE. Nitrogen fixationE. Nitrogen fixationF. EnergyF. Energy

G. Biotic factorsG. Biotic factors PredationPredationI. AirI. AirJ. Abiotic factorsJ. Abiotic factors

K. MutualismK. MutualismL. WaterL. Water

5. ___5. ___ The 1The 1stst level of the food chain level of the food chain6. ___6. ___ One organism kills and feeds on One organism kills and feeds on another organism.another organism.7. ___ An organism that makes it own food.7. ___ An organism that makes it own food.

8.8. ___ Plant that contains chorophyll.

D.

H.

D.D.D.D.

RespirationRespiration• Some of the energy from the food you eat Some of the energy from the food you eat

is used to make you move.is used to make you move.

• Some of it becomes thermal energy, Some of it becomes thermal energy, which is why you feel warm or hot when which is why you feel warm or hot when you exercise.you exercise.

• Most cells also need Most cells also need oxygen to break down oxygen to break down food.food.

RespirationRespiration

• During During respirationrespiration, chemical reactions , chemical reactions occur that break down food molecules occur that break down food molecules into simpler substances and release their into simpler substances and release their stored energy.stored energy.

• Just as in photosynthesis, enzymes are Just as in photosynthesis, enzymes are needed for the chemical reactions of needed for the chemical reactions of respiration.respiration.

Breaking Down CarbohydratesBreaking Down Carbohydrates• The type of food molecules most easily The type of food molecules most easily

broken down by cells is carbohydrates.broken down by cells is carbohydrates.

• Respiration of carbohydrates begins in the Respiration of carbohydrates begins in the cytoplasm of the cell.cytoplasm of the cell.

• The carbohydrates are broken down into The carbohydrates are broken down into glucose molecules.glucose molecules.

• Each glucose molecule is broken down Each glucose molecule is broken down further into two simpler molecules.further into two simpler molecules.

• As the glucose molecules are broken As the glucose molecules are broken down, energy is released.down, energy is released.

Breaking Down CarbohydratesBreaking Down Carbohydrates

• The two simpler molecules are broken The two simpler molecules are broken down again. This breakdown occurs in down again. This breakdown occurs in the mitochondria of the cells of plants, the mitochondria of the cells of plants, animals, fungi, and many other animals, fungi, and many other organisms.organisms.

• This process uses oxygen, releases much This process uses oxygen, releases much more energy, and produces carbon more energy, and produces carbon dioxide and water as wastes.dioxide and water as wastes.

Related ProcessesRelated Processes• During photosynthesis and respiration, During photosynthesis and respiration,

what is produced in one, is used in the what is produced in one, is used in the other.other.

• Photosynthesis produces sugars and Photosynthesis produces sugars and oxygen, and respiration uses these oxygen, and respiration uses these products.products.

• The carbon dioxide and water produced The carbon dioxide and water produced during respiration are used during during respiration are used during photosynthesisphotosynthesis

11. Describe the processes of 11. Describe the processes of photosynthesis and respirationphotosynthesis and respiration

answeranswer

In photosynthesis energy from sunlight trapped by the chlorophyll in plant chloroplasts is used to produce glucose from carbon dioxide and water. Oxygen is given off in the process. In respiration, oxygen combines with glucose to release stored energy. Carbon dioxide and water are given off as waste products.