Lec 19

Question 1

Primary production

Answer 1

Chemical energy of food molecules generated by autotrophs, derived from the fixation (reduction) of CO2 during photosynthesis

Energy source for all organisms in all ecosystems

ALMOST all ecosystems are powered by photosynthesis (a few by cellular respiration)

Question 2

Gross primary production (GPP)

Answer 2

Total amount of carbon fixed by autotrophs in an ecosystem

Autotrophs use approximately HALF of the carbon fixed by photosynthesis for cellular respiration to maintain their own cells, tissues, and organs

Question 3

Net primary production (NPP)

Answer 3

NPP = GPP - cellular respiration by the autotrophs

NPP represents the biomass gained by an autotroph by way of growth and reproduction

Energy leftover for consumption by herbivores and decomposers
-Carnivores consume it INDIRECTLY

Dominant measure of productivity in an ecosystem

Question 4

Primary production generally refers to _________-

Answer 4

NPP

Question 5

_________ are the main primary producers in terrestrial ecosystems

Answer 5

Plants

Question 6

______________ are responsible for most of the primary production in aquatic ecosystems

Answer 6

Phytoplankton

Question 7

Allocation of NPP to different organs can be adjusted by plants to ________________________

Answer 7

Offset deficiencies in resources

Question 8

Desert plants allocate more NPP to _______ because soil nutrients and water are scarce

Answer 8

roots

Question 9

Rainforest plants allocate more NPP to _______ because competition for light is intense

Answer 9

leaves

Question 10

NP in terrestrial ecosystems is controlled mostly by _____-

Answer 10

climate

Question 11

Temperature influences the ___________ that facilitate photosynthesis

Answer 11

enzymes

Question 12

As temperature _________, NPP ____________

Answer 12

increases, increases

Question 13

At very high temperatures, NPP may __________ if the photosynthetic enzymes become denatured

Answer 13

decreased

Question 14

Water availability influences photosynthesis via the ___________________________________

Answer 14

Opening and closing of stomata

Question 15

As precipitation ___________, NPP ____________-

Answer 15

increases, increases

Question 16

With very high precipitation, NPP may __________ because of greater cloud cover and less sunlight

Answer 16

decrease

Question 17

NPP in aquatic ecosystems is controlled mostly by ______________

Answer 17

nutrient availability

Question 18

NPP in _______ ecosystems such as lakes is often limited by _________-

Answer 18

Lentic, phosphorus

Question 19

Studies that experimentally add ______ to lakes result in massive _________ in ______________ (a major component of phytoplantkon)

Answer 19

Phosphorous, increases, cyanobacteria

Question 20

NPP in ________ ecosystems such as rivers and streams is ____________-

Answer 20

Lotic, usually low

Question 21

Water flow _________________

Answer 21

Limits phytoplankton growth

Question 22

The majority of the energy in ______ systems is derived from _____________________

Answer 22

Lotic, terrestrial organic matter

Question 23

NPP varies greatly in marine ecosystems

Answer 23

Coral reefs, kelp forests, and estuaries are VERY productive

In the open ocean, NPP is limited mainly by nitrogen and iron

Question 24

Where light penetrates, NPP will ______ with added nitrogen and/or iron in the ocean

Answer 24

INCREASE

Question 25

_____ of global NPP is attributed to terrestrial ecosystems, with the remaining _____ attributed to aquatic (marine, specifically) ecosystems

Answer 25

54%, 46%

Question 26

The average rate of NPP on land is ____ than that in the ocean, but the two are _____ in their total NPP due to the huge volume occupied by the ocean

Answer 26

higher, nearly equal

Question 27

The highest rates of NPP on land are found in the _______

Answer 27

Tropics

Question 28

Tropical zones have ______________, leading to high rates of NPP

Answer 28

high temperatures and precipitation

Question 29

_________________- account for high amounts of oceanic NPP in relation to their limited area

Answer 29

Coastal zones

Question 30

_______________ accounts for the majority of oceanic NPP due to its massive volume

Answer 30

The open ocean

Question 31

The deep sea was once thought to have few forms of life because of its ____ (no ___ penetrates, so no ______________ occurs)

Answer 31

Darkness, light, photosynthesis

Question 32

In 1977, a new kind of ecosystem was discovered in the ________

Answer 32

Deep sea

Question 33

____________ were found, along with a unique community of marine invertebrates (including ________________________

Answer 33

Hydrothermal vents; polychaete worms, clams, crabs, and echinoderms

Question 34

How doe these organisms obtain energy in Hydrothermal vents?

Answer 34

Not from photosynthesis
-No light

Not from detritus
-The rate at which dead organisms from the upper ocean accumulate on the deep ocean floor is very slow

During chemosynthesis, bacteria use chemicals such as hydrogen sulfide (H2S) as high-energy electron donors (rather than relying on light to split H2O) to reduce CO2 into organic carbon

Such prokaryotes (bacteria and archaea) are called chemoautotrophs

Question 35

___________________________ have these bacteria (chemoautotrophs) living _________ within their bodies

Answer 35

Hydrothermal vent clams and worms, symbiotically

This allows a diverse community of organisms to exist in locations previously believed to be barren and inhospitable to life

NPP is very HIGH here

Question 36

Secondary production refers to the energy derived from the ____________________ that were produced by other organisms

Answer 36

Consumption of organic molecules (consuming food)

Question 37

Some organic matter consumed by heterotrophs is _________________, while some is used up during_____________ and some is __________ (lost with urine and feces)

Answer 37

incorporated into biomass, cellular respiration, egested

Question 38

Net secondary production (NSP) = ____________________

Answer 38

Ingestion - cellular respiration - egestion

Question 39

NSP in most ecosystems is only a ________ of NPP

Answer 39

small fraction

Only about 10% of NPP makes it to NSP