Lesson 1: factors, food relationships

• Biologie
• Middelbare school
• vwo
• Leerjaar 4

Ecology

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Learning objectives

• Distinguish organisation levels within ecology
• Distinguish between biotic and abiotic factors and describe their effect on organisms
• Explain the relationships between different trophic levels and the amount of energy they contain 

Biosphere

Biosphere

Biomes

Biomes

Ecosystem

Ecosystem

Community

Community

Habitat

Habitat

Environment

06:21

Autotrophs

Heterotrophs

Consumer

Producer

Carbon from organic matter

Carbon from inorganic matter

Animals

Plants

Feeding relationships

• Autotrophs: producers
• Heterotrophs: consumers

Food chain

• Each step is a trophic level
• Arrows represent energy transfer

Food web

• Show all feeding 
  relationships
• Trophic level can
  depend on food chain
  you focus on. 
  Example: rattlesnake
  can be secondary or
  tertiary consumer

Producer

Primary consumer

Secondary consumer

Tertiary consumer

With reference to the following statements about a woodland ecosystem.
Which statement describes a community?

1. All the oak trees
2. All the plants
3. All the plants and animals

Organisms that are responsible for returning matter back into the environment are the

1. herbivores
2. carnivores
3. omnivores
4. decomposers

Organisms that only eat plants are called

1. herbivores
2. omnivores
3. scavengers
4. carnivores

In the food web shown which organism would be called an omnivore?

1. Grasshopper
2. Frog
3. Mouse
4. Fungus

In the food web which organism would have the largest population?

1. Eagle
2. Mouse
3. Frog
4. Grasshopper

01:28

What do the arrows in food chains and food webs represent?

02:15

Energy lost

Three main reasons why only 10% of the energy passes to the next level:

1. Energy is lost through respiration (being used by the organism)
2. Not all the food is digested. There is still energy left in the undigested food
3. Most of the time there will be parts of the organism that are not consumed. The parts that are left still contain energy

Pyramids

Pyramids can be used to show a food chain and also include an extra piece of information.

You can have pyramids of numbers, biomass or energy.

Pyramids of numbers and biomass don't necessarily have a pyramid shape. The energy pyramid does, because only 10% of the energy carries to the next level.

The primary source for all energy used by animals on our planet is

1. the animals they eat
2. the plants they eat
3. sunlight absorbed by animals
4. sunlight absorbed by plants

Which of the following statements about the flow of energy in nature is NOT true?

1. A major portion of the energy from food is used to keep our bodies warm
2. A large amount of energy in food is needed for bodily functions
3. Some energy from the food we eat is lost as wastes which are passed from the body
4. Most of the food energy from one trophic level is passed on to the next trophic level

Which of the following is NOT one of the ways energy is lost to other organisms as it passes through a food web?

1. Cellular respiration
2. Growth and repair
3. As heat
4. As waste material

What is the average amount of energy that passes from one feeding level to the next in a food chain?

1. 10%
2. 25%
3. 50%
4. 100%

Homework

Worksheet food chains