Flow of Energy Year 11 Biology Unit 1

Key Knowledge • Describe the ways in which energy flows through ecosystems • Recognise the matter cycles within ecosystems • Understand the key role of producers and decomposers in ecosystems • Become aware of trophic levels • Give examples of biochemical cycles

Ecosystems require energy • Energy is not recycled energy must be continually supplied to the ecosystem • Sunlight

Ecosystems require energy • Producer organisms trap energy and convert it to chemical energy (ecosystem would not exist without them) 6 CO 2+12 H 2 O C 6 H 12 O 6 + 6 H 2 O + 6 O 2 • Some energy used for producers own requirements • Some energy stored for consumers = net primary production

Biozone 1. Plants as producers 2. Energy Inputs and Outputs Page 112 Page 292

Energy Production Rates • Vary for each ecosystem • Eg: Tropical rain forests and coral reefs high. • Production rates vary due to factors such as light and water availability

Biozone 1. Primary productivity Page 301

Different energy source • No sunlight? ? Eg Deep ocean • Producers include sulfur bacteria. • Known as chemosynthetic – Energy released by chemical reactions NO PRODUCERS = NO ECOSYSTEM

Trophic Levels Feeding Levels Trophic Level Organism at that level Source of chemical energy First Producers Photosynthesis Second Primary Consumers (herbivores) Eat producers Third Secondary Consumers (Carnivores) Eat plant-eaters Fourth Tertiary Consumers (Top Carnivores) Eat Predators See Fig 14. 12 Page 446

Energy Flow • Available energy gets less at each trophic level • Eg: 100 units of energy taken in - 39 units heat loss - 60 units wastes (detritivores and decomposers) - 1 unit build organic matter as part of growth available to be transferred

A rough rule of thumb • About 10% of the energy entering a trophic level is available for transfer to the next level.

Biozone • Energy Flow in an Ecosystem Page 299

Showing energy transfers • Food chains and food webs show chemical energy transfers. • HINT: Despite what the diagram suggests, food webs are often very complex.

Biozone 1. Food Chains 2. Constructing a food web Page 293 Page 295

Ecological Pyramids • Information about numbers and other aspects of organisms at each trophic level

Ecological Pyramids • Pyramid of numbers – Number of organisms at each trophic level – Does not take into account the sizes of the organisms

Ecological Pyramids • Pyramid of biomass – Total dry organic matter of organisms at each trophic level – Measured in units of mass per unit area

Pyramid of Biomass Pyramid of numbers

Ecological Pyramids • Pyramid of energy – Amount of energy input to each trophic level – Can never be inverted WHY? ? ?

Biozone 1. Ecological pyramids Page 303

Biochemical Cycles Cycling of matter • Matter cycles within the ecosystem and is reused. • At times matter (such as carbon, nitrogen and phosphorous) are found in the living component of the ecosystem and at others in the non living component of the ecosystem.

Carbon Cycle

Nitrogen Cycle

Phosphorous Cycle

Water Cycle

Your Task 1. Make an annotated drawing of each of the cycles 2. Complete Biozone activities Page 312319

Chapter Review Questions Page 469 Questions 2, 3, 4, 7, 8