10 Questions
What is the total energy available for the grass in kJ?
4000 kJ
What percentage of energy is used in metabolism for the grubs?
90%
In the Pyramid of Numbers, which organism has the highest number?
Grass
What is the energy stored for the Thrust birds in kJ?
40 kJ
What trophic level do Thrust birds occupy in the food chain?
Tertiary consumer
What is the term used to refer to the total quantity of living organisms of all the species in a community?
Community biomass
In an ecological pyramid, which level typically contains the least amount of energy?
Tertiary consumers
What is the term used to describe the mass of a biological sample after removing its water content?
Dry mass
If each owl in the ecosystem eats 2 thrust birds, how many thrust birds would be needed for 3 owls?
6 thrust birds
In an ecosystem where each grub eats 150 grass blades, how many grass blades are needed for 4 grubs?
600 grass blades
Study Notes
Ecological Pyramids
Types of Ecological Pyramids
- Pyramid of Numbers: represents the number of organisms at each trophic level
- Pyramid of Biomass: represents the total mass of living organisms at each trophic level (usually measured as dry mass)
- Pyramid of Energy: represents the amount of energy available at each trophic level
Characteristics of Ecological Pyramids
- 10% of energy is passed on from one trophic level to the next, while 90% is used for metabolism and to keep the organism alive
- Pyramid of Numbers can have three possible shapes: most common, inverted, and another
- Pyramid of Biomass and Energy are typically narrower at the top and wider at the base
Example Food Chain
- Grass → grubs → thrust birds → owl
- Calculations for each trophic level:
- Total number of owls: 2
- Total number of thrust birds: 4 (2 owls x 2)
- Total number of grubs: 400 (4 thrust birds x 100)
- Total number of grass blades: 60,000 (400 grubs x 150)
Energy Pyramid
- Energy available at each trophic level:
- Grass: 4000 kJ
- Grubs: 400 kJ (10% of 4000 kJ)
- Thrust birds: 40 kJ (10% of 400 kJ)
- Owls: 4 kJ (10% of 40 kJ)
Biomass Pyramid
- Biomass at each trophic level:
- Grass: 0.05 g
- Grubs: 5 g
- Thrust birds: 300 g
- Owls: 500 g
Test your knowledge on ecological pyramids, including biomass, dry mass, and pyramid of numbers. Learn about the different shapes of pyramids and their significance in ecology.
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