Topic 9 - Ecosystems and Material Cycles Flashcards
Define the following words:
- Individual
- Population
- Community
- Ecosystem
- Individual: A single organism
- Population: All organisms of one species in a habitat
- Community: All organisms of different species in a habitat
- Ecosystem: A community of organisms along with all the abiotic conditions
Finish the sentence: In a community, organisms are ______________
Interdependent
Name 4 abiotic factors and how they affect communities:
- Temperature: Only able to live in specific ranges of heat
- Amount of Water: Needed for all life
- Light Intensity: Plants can’t grow without it
- Level of pollutants: They kill organisms
Name 2 biotic factors and how they affect communities:
- Competition: Animals fighting over food causes them to starve and die
- Predation: Animals get eaten by those higher in the food chain
How can you study the distribution fo small organisms?
By using a transect
How does a transect work?
- It is a grid of 100 squares (for a 1m x 1m transect)
- Thus, the amount of squares filled with said organism is the percentage distribution
- It can be moved to other areas to improve the accuracy
Devise a method to study the distribution of plants:
- Set a tape measure of an appropriate distance along the area you are studying
- Plac a transect at the start of this line
- Record percentage cover
- Repeat steps 2-3 until you reach the end of the tape measure
- Plot your results on a graph
What is a source of energy for nearly all life on Earth?
The Sun
What is each stage of a food chain called?
A trophic level
Why do food chains rarely have more than 4 or 5 trophic levels?
Because so much energy is lost through waste and heat transfer that the top predator would have to eat so many of its prey to gain enough energy to even survive, and this is not sustainable in any way
What two things does a pyramid of biomass show?
- Weight of creatures at each level if you put them all together
- Energy at each trophic level
Why does a pyramid of biomass have a wider base than the top?
- Because energy is lost as you move up trophic levels
- Fewer predators than producers
What is the standard efficiency of energy transfer between trophic levels?
Around 10%
Define biodiversity:
The variety of plant and animal life in the world or in a particular habitat, a high level of which is usually considered to be important and desirable.
How does using too many fertilisers have an impact on water-based life?
- Nitrates flow into the ocean when it rains
- Algae now grow quickly and block out sunlight
- Plants can’t photosynthesise and thus die
- Decomposers use up oxygen feeding on the plants
- No oxygen, so fish die
