Chapter 53

Question 1

Define ecosystem.

Answer 1

• consists of the multiple communities of organisms that live in an area along with abiotic (non-living) components such as the soil, climate, water, and atmosphere.

Question 2

Define primary producer/autotroph.

Answer 2

• an organism that can synthesize its own food from inorganic sources.

Question 3

How do primary producers obtain nutrients/food?

Answer 3

They transform the energy in sunlight or inorganic so pounds into chemical energy stored in sugars.

Question 4

Define gross primary productivity (GPP).

Answer 4

Gross primary productivity is the total amount of chemical energy produced in a given area and time period.

Question 5

What are the two ways primary producers use chemical energy?

Answer 5

1) cellular respiration
2) growth and reproduction

Question 6

Energy (in the form of chemicals) that is used to assimilate into tissue for growth or reproduction is from _____________________.

Answer 6

net primary productivity (NPP)

Question 7

Define biomass.

Answer 7

-organic material that non-photosynthetic organisms can eat.

Question 8

What does NPP (net primary productivity) represent?

Answer 8

the amount of energy available to consumers and decomposers.

Question 9

What do decomposers/detritivores feed on?

Answer 9

They feed on detritus which is the waste products or dead remains of other organisms.

Question 10

What percentage of incoming sunlight is captured by plants? Why is this so efficient/inefficient?

Answer 10

0.8% this is inefficient because the photopigments absorb only a fraction of light wavelengths available. The rates are reduced in the winter and in dry conditions photosynthesis stalls. The efficiency of enzymes is temperature dependent.

Question 11

What does a food chain depict about an ecosystem?

Answer 11

A food chain connects the tropic levels in a particular ecosystem.

Question 12

Compare the decomposer food chain with the grazing food chain.

Answer 12

Decomposing food chain- made up of species that eat the dead remains of organisms
Grazing food chain- composed of the network of herbivores (primary consumers) and the organisms that eat herbivores (secondary consumers)

Question 13

What does a food web depict about an ecosystem?

Answer 13

Food webs are a compact way of summarizing energy flows and documenting the complex trophic interactions that occur in ecosystems

Question 14

The amount of energy consumed by primary consumers verses primary decomposers varies enormously among habitats. In the forest, is more of the biomass transferred to primary consumers or decomposers? What about in a marine system?

Answer 14

In a forever the biomass is tied up in digestible wood and is not transferred to other organisms until it decays with the help of decomposers.
In a marine system the production is done by primary consumers.

Question 15

What is the characteristic pattern of energy transfer that all ecosystems share? Why does this pattern occur?

Answer 15

The total biomas produced each year is greatest at the lowest trophic level and declines at higher levels.

This pattern occurs because only a fraction of the total energy consumed is used for growth and reproduction.

Question 16

Define productivity and efficiency in regards of a pyramid of productivity.

Answer 16

Productivity is a rate measured in units of biomass produced per unit of area each year.
Efficiency is a ratio the fraction of biomass transferred from one trophic level to the next

Question 17

In general, what percentage efficiency of biomass transfers between trophic levels?

Answer 17

10%- 20%

Question 18

In general, is NPP higher on land or in the oceans? Explain.

Answer 18

NPP on land is much higher than it is in the oceans because more light is available to drive photosynthesis on land that in marine environment.

Question 19

What is the productivity (both global and local) of terrestrial ecosystems limited by?

Answer 19

Limited by a combination of temperature and availability of water and sunlight.

Question 20

Name the two terrestrial environments that cover less than 5% of the Earth’s surface, but together account for over 30% of total NPP.

Answer 20

Tropical wet forests and tropical seasonal forests.

Question 21

List the most productive habitats among aquatic ecosystems.

Answer 21

Algal beds, Cora reefs, wetlands, and estuaries.

Question 22

Explain the function of nucleic acids, carbohydrates, lipids, and proteins in a cell.

Answer 22

Nucleic acids: DNA as a genome, RNA as intermediate
Carbohydrates: energy, storage, structure
Lipids: plasma membrane, storage.
Proteins: transport contraction, structure, enzymes, storage, etc.

Question 23

Where in their environment do primary producers collect carbon, nitrogen, and phosphate from?

Answer 23

Carbon- from atmosphere
Nitrogen- from soil by plants
Phosphate- from soil by plants

Question 24

If the plant tissue is eaten, the nutrients pass to _________ (decomposers/consumers). If the plant tissue dies, the nutrients pass to ________ (decomposers/consumers).

Answer 24

Consumers, decomposers.

Question 25

Define biogeochemical cycle.

Answer 25

The path that an element takes as it moves from abiotic systems through organisms and back again.

Question 26

Define photosynthesis and cellular respiration in regards to the pathway of carbon through its biogeochemical cycle. (Hint: It’s the carbon cycle!)

Answer 26

Photosynthesis- removes carbon out of the atmosphere and incorporates it into plant tissue.
Cellular respiration- real eases carbon incorporated into living organisms to the atmosphere in the form of CO2.

Question 27

Define greenhouse gas. What is the example of a greenhouse gas given in the notes?

Answer 27

Greenhouse gas- a gas that traps heat radiated from Earth and keeps it from being lost to space. EX: CO2

Question 28

Americans represent less than ____% of the world population, but contribute ____% of CO2 emissions.

Answer 28

5%, 20%

Question 29

What are the two forms of nitrogen that plants can utilize?

Answer 29

Ammonium and nitrate