Unit 3 Lesson 5: Ten Percent Rule

Question 1

Why is energy needed for organisms

Answer 1

Energy is needed for organisms to undergo life processes. Some examples of life processes include growth, repair, development, maintenance of cells and tissues, and reproduction.

Question 2

Energy enters most ecosystems from the

Answer 2

sun

Question 3

producer

Answer 3

an organism, also known as an autotroph, that makes its own food. A plant is an autotroph.

Question 4

primary consumer

Answer 4

an organism, also known as an herbivore, that feeds on producers such as plants

Question 5

How does energey flow

Answer 5

Energy flows from lower levels upward when organisms in a higher level consume organisms in lower levels.

Question 6

photosynthesis

Answer 6

the process during which green plants and some other organisms use carbon dioxide and water to convert light energy into chemical energy

Question 7

secondary consumers

Answer 7

an organism that feeds on primary consumers (herbivores)

Question 8

tertiary (third) consumers

Answer 8

top-level consumers that are carnivores and feed on secondary consumers

Question 9

What happens to the biomass of organsims in trophic levels as we go up

Answer 9

Since there is less energy available at each level, this means the number of organisms, or biomass, also decreases in higher trophic levels.

Question 10

biomass

Answer 10

the amount of organisms in a given area or volume

Question 11

trophic level

Answer 11

the level in which organisms are found within the food chain

Question 12

In addition to energy pyramids, there is also an ecological pyramid called the

Answer 12

pyramid of biomass

Question 13

pyramid of biomass

Answer 13

the amount of biomass in each trophic level

Question 14

What would a pyramid of biomass look like in a land-based ecosystem

Answer 14

In land-based ecosystems, this usually aligns in shape to its energy pyramid.

Question 15

What would pyramid of biomass look like in a marine ecosystme

Answer 15

. In some ecosystems, such as marine ecosystems, the pyramid of biomass may be inverted.

Question 16

In some ecosystems, such as marine ecosystems, the pyramid of biomass may be inverted. Why is that?

Answer 16

Many marine ecosystems rely on phytoplankton as their producer, or base of the food web. Phytoplankton (as seen in the image below) are very tiny and reproduce and die rapidly. Since they reproduce quickly, they can still supply energy for the rest of the ecosystem while having a small biomass. The biomass of fish is larger since they typically have a larger mass and tend to live for several years.

Question 17

Although the ten percent rule is widely accepted, it is important to understand the actual efficiency of energy transfer to determine the health of the ecosystem. Farmers and scientists use energy transfer calculations to determine the percentage of energy that is being transferred from one trophic level to the next in an ecosystem. The following calculation is used:

Answer 17

Energy level transfered to next level/Total energy input ×100

Question 18

What is the approximate percentage of energy that is transferred from one organism to the next when consumed?

Answer 18

About 10 percent of the energy is available for the next organism when an organism is consumed.

Question 19

How many kilograms of hawk would an ecosystem support that contained 1000 kilograms of producers?

Answer 19

There would be enough energy to support just one kilogram of hawk in an ecosystem with 1000 kilograms worth of producers.

Question 20

If energy decreases as you move up the energy pyramid, why would the biomass decrease as well?

Answer 20

If energy decreases, there is not enough energy to sustain more organisms. This means there are fewer organisms in higher trophic levels.

Question 21

Describe an energy pyramid and why it is used to model the energy in an ecosystem.

Answer 21

An energy pyramid is a model that shows the flow and amount of energy in an ecosystem. There is less energy available as you move up trophic levels and the pyramid becomes smaller as you progress; this may reveal the relationship between energy and trophic levels.

Question 22

invasive species

Answer 22

any kind of living organism that is not native to the ecosystem and causes harm

Question 23

Invasive species can include

Answer 23

Invasive species can include plants, animals, parasites, and even seeds or eggs of organisms.

Question 24

What can invasive species harm

Answer 24

They can harm the health of the ecosystem, humans, and even the economy.

Question 25

. Invasive species grow and reproduce quickly without natural predators to keep them in check. What can this harm

Answer 25

This can harm the energy flow of an ecosystem. Predators may lose their source of energy and could become endangered or extinct.

Question 26

If invasive species reduce or wipe out the population of producers, wha towuld happen

Answer 26

If invasive species reduce or wipe out the population of producers, there may not be enough energy available for the rest of the organisms in the ecosystem. For example, an area that contained 3000 kilograms of producers contains enough energy to keep 3 kilograms of top or tertiary consumers alive. If the number of producers declines, then the tertiary consumers would have to compete for resources, and some would die.

Question 27

Human activities can unintentionally spread invasive species.

Answer 27

People can pick up organisms in the goods that they carry, and a ship can pick up organisms on its hull. Plants and pets can escape into the wild.

Question 28

Direct threats to the ecosystem from invasive species include

Answer 28

Direct threats to the ecosystem from invasive species include outcompeting native species for food and resources, causing or carrying diseases, and preventing a native species from reproducing.

Question 29

Zebra mussels are invasive species that threaten many bodies of water. Elaboratre

Answer 29

Zebra mussels filter out algae that is used by other organisms as energy. They also attach themselves to other mussels, and those mussels are not able to move or eat. Zebra mussels clog nuclear power plants’ water intake, and millions of dollars have been spent to have them removed. Zebra mussels reproduce quickly and outcompete native species for food and space.

Question 30

How can invasive species alter the availability of energy to native organisms in an ecosystem?

Answer 30

Invasive species can wipe out the producers in an ecosystem. This would limit the amount of energy that is left for the other organisms in the food web.

Question 31

If an ecosystem typically contains 5000 kilograms of producers, and the introduction of an invasive species reduces this to 2000 kilograms, what could happen to consumers in the highest trophic level?

Answer 31

The ecosystem originally has enough energy for five kilograms of the top-level consumers or those in the highest trophic levels. Having fewer producers means the ecosystem only has enough energy for two kilograms of the top-level consumers.