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Food Chains and Food Webs

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1 Food Chains and Food Webs
Science Foundations

2 Predator and Prey Relationships
One important interaction in the ecosystem is between predators and their prey. Predators are organisms which hunt and feed on other organisms Whereas the living things that are eaten are referred to as prey. 1. To maintain balance in the ecosystem, the interaction between predator and prey should not be disturbed.

3 WHY? Example In parts of the South, one natural predator of
the white-tailed deer, the mountain lion, has been reduced in number. Because there are fewer mountain lions to prey on the deer, the deer population in some regions has risen tremendously. WHY?

4 Food Chain A food chain is the relationship of organisms
that depend on each other for energy or food. It is a straight line relationship such as algae is food for fish which are food for squid which are food for sharks.

5 Food Web How Come? A food web is more complex and is a food
chain with the interrelated chain of organisms that depend on each other for food. If one organism is removed, other organisms may be endangered or possibly die out. How Come?

6 Food Web

7 Carrying Capacity Carrying capacity is the number of individuals
in a population that the resources can support. This provides for a balanced ecosystem.

8 Trophic Levels The living things in an ecosystem can be
divided into four levels. Each step in a food chain or food web is called a trophic level. Producers are the first step. Consumers are the next steps. Each step depends on the step below it for food and to provide its energy.

9 Producers Producers are the green plants and some
bacteria and algae that are able to make their own food from water, the sun, carbon dioxide in the air, and minerals in the soil. When plants make their own food, they use sunlight. This process is called photosynthesis.

10 What is Photosynthesis?
The process of photosynthesis is a chemical reaction. It is the most important chemical reaction on our planet.

11 What is the Equation for the Chemical Reaction of Photosynthesis?

12 What is the equation for the chemical reaction of photosynthesis?

13 What is the equation for the chemical reaction of photosynthesis?
Six molecules of carbon dioxide react with six molecules of water to form 1 molecule of glucose and six molecules of oxygen.

14 Describe Photosynthesis
The process of changing light energy to chemical energy Energy stored as sugar Occurs in plants and some algae Plants need light energy, CO2, and H2O Takes place in the chloroplasts, using chlorophyll, the green pigment in plants

15 What happens during photosynthesis?
Plants capture light energy and use that energy to make glucose Sunlight provides the energy needed by chlorophyll to change molecules of carbon dioxide and water into glucose Oxygen is also released in this reaction

16 What happens during photosynthesis?
Carbon dioxide enters the leaf through holes called stomata CO2 combines with the stored energy in the chloroplasts through a chemical reaction to make glucose The sugar is moved through tubes in the leaf to the roots, stems and fruits of the plants Some of the sugar is used right away by the plant for energy; some is stored as starch; and some is built into plant tissue

17 Why is this important to us?
We cannot make our own food (glucose, energy), we must get our food from plants. Plants are the first step in the food chain.

18 Why is this important to us?
The oxygen released during photosynthesis is necessary for all living things.

19 Learn more about photosynthesis at:

20 Consumers Consumers are the animals that rely on other
organisms for food. This group can be further divided into three groups: Primary consumers are herbivores, or plant eaters. Examples – some insects, deer, or mice. Secondary consumers are carnivores, or flesh eaters. They feed on herbivores. Examples – snakes and coyotes Tertiary consumers can be carnivores or omnivores, which eat both plants and animals. Example – hawks and humans

21 Scavengers Scavengers feed on dead organisms. They
include ants and vultures.

22 Decomposers Decomposers are organisms that break down
dead organic matter. This decomposition produces many of the raw materials that are used by the producers in photosynthesis. Examples are bacteria, fungi and earthworms.

23 Symbiotic Relationships
Symbiosis = a beneficial relationship between 2 organisms that live together. 3 types of symbiosis Commensalism = 1 organisms benefits, the other neither benefits or is harmed. Parasitism = 1 organisms benefits the other is harmed. Mutualism = both organisms benefit.

24 Commensalism Commensalism occurs in a relationship where one animal benefits and the other is unaffected. The dorsal fin of the Remora is modified into a sucker. They attach to sharks during feeding and eat the scraps. The sharks do not try to eat the Remora.

25 Parasitism A parasite is an organism that lives on or in the body of another organism (the host) from whose tissues it gets its nourishment, and to whom it does some damage Animals are parasitized by viruses, bacteria, fungi, protozoans, flatworms (tapeworms and flukes), nematodes, insects (fleas, lice), and arachnids (mites). Plants are parasitized by viruses, bacteria, fungi, nematodes, and a few other plants. The flea is common on dogs and cats

26 Mutualism The clownfish feeds the anemone by gathering nutrients and also leaving nutritional waste on the tentacles. The clownfish can come in contact with the stinging tentacles of the sea anemone and not be harmed by them. At the same time, it receives protection from its enemies.

27 Ecological Pyramids Ecological pyramids are diagrams that show
each trophic level in a biome. There are three types: Energy pyramid Biomass pyramid Numbers pyramid

28 Energy Pyramid The energy pyramid shows the transfer of
energy from one level to the next. The bottom of the food chain shows the largest amount of energy which comes from the sun then as you move up energy is used but also lost in the form of heat energy.

29 Energy Pyramid

30 Biomass Pyramid The biomass pyramid is based on the
mass of organic material at each level.

31 Numbers Pyramid The Numbers pyramid shows the relative
numbers of organic material at each level.

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