.food chains &

food webs.ISN page 169.

• Food Chain

• Food Web

– Arrows?

• Producers

• Consumers

– Primary– Secondary– Tertiary

• Pyramid of Biomass

– Rule:

food chains & food webs 169

Food Chain• A simple diagram that

shows one part of an ecosystem.

• Transfer of energy from one organism to another

What is a food web?• Shows the

interactions of predators and prey in an ecosystem

What do the arrows indicate in a food web?

• They indicate the flow of energy from one organism to another.

• If a worm is eaten by a robin, does the arrow point to the worm or the robin?

• Producers make their food from the sun’s energy. They are also called autotrophs.

• Name 2 producers• Algae, bladderwrack

• Primary consumers eat producers. They are also called heterotrophs or herbivores.

• Name 3 primary consumers.• Grey mullet, flat winkle, limpet, sea urchin

• Secondary consumers eat primary consumers. They are also called carnivores.

• Name 3 secondary consumers.• Crab, seal, lobster, herring gull

• Tertiary consumers eat secondary consumers. • Are there any?• Yes…….seal, herring gull

Pyramid of Biomass• BIOMASS: how much

a population of organisms weighs

• The greatest amount of biomass is found in the producers.

• The least amount in the tertiary consumers.

10% Rule: Only 10% of the available energy passes on to the next trophic level

food chains & webs

Food Web Practice: 170• Identify the:• 1. Producers• • 2. Primary Consumers• • 3. Secondary Consumers• • 4. Herbivores• • 5. Carnivores• • 6. Omnivores• • 7. What elements are missing

from this food web?

1. What happens to matter within a food chains?2. What happens to energy within a food chain?3. In a pyramid of numbers, what would you not expect to find ?4. What is the carbon cycle?5. What is a niche? Give an example.6. What is an abiotic factor of an ecosystem?7. What are ecosystems based on?8. What do food producers need to make sugar?

ECOSYSTEMS NOTES