Chapter 20

endothermic

A chemical reaction requires energy to proceed. This would be

Endothermic

A(n) ________ chemical reaction must absorb energy in order to proceed.

energy is neither created nor destroyed

According to the first law of thermodynamics

900 kcal/m2/yr

An ecologist studying productivity in a sample of grasses measures gross primary productivity as 1000 kcal/m2/yr and autotrophic respiration as 100 kcal/m2/yr. Based on these calculations, the net primary productivity would be

The rate of energy storage as organic matter after respiration is net primary productivity. Water containing phytoplankton are placed in a light and dark bottle and allowed to incubate. In the light (clear) bottle, O2 is produced in photosynthesis and consumed in respiration. Lacking light to drive the process of photosynthesis, only respiration occurs in the dark bottle.

Define net primary productivity, and describe an experiment for how it can be measured

Allochthonous inputs of both DOM and POM vary seasonally with the volume of water from streams and rivers that flows into the lake. In contrast, in smaller lakes allochthonous inputs can be significant.

Describe the changes that might be expected to occur in allochthonous and autochthonous sources of carbon in the energy balance of flowing-water ecosystems from the smaller headwater streams to larger river systems

if temperatures are low, rates of photosynthesis and productivity will be low regardless of the availability of water. Reduced moisture conditions result in an increased allocation to roots at the expense of leaves

Describe the effects of temperature, moisture, length of photosynthetic period, and nutrient availability on net primary productivity in terrestrial ecosystems

herbivores

Detrital food chains contain all of the following except

less than 1 percent

Estimates of HANPP range around 20 percent, yet what percent of total heterotrophic biomass do humans make up?

Net primary production is the energy available to the heterotrophic component of the ecosystem. This net energy allocated to production is called secondary production. Secondary production represents the formation of living mass of heterotrophic organisms over some period of time (grams per unit area per unit time). It is the heterotrophic equivalent of net primary production by autotrophs. Secondary productivity is greatest when the birthrate of the population and the growth rate of individuals are highest.

Explain the difference between primary production and secondary production. How is secondary production affected by primary production?

This pattern occurs because not all energy is used for production. An ecological rule of thumb is that only 10 percent of the energy stored as biomass in a given trophic level is converted to biomass at the next-higher trophic level. These differences directly influence the rate of energy transfer from one trophic level to the next-higher level.

Explain why energy is lost as it is transferred from one trophic level to another. What are the effects of energy loss on the biomass of different trophic levels?

stomata

For photosynthesis and productivity to occur, a plant must open its ________ to take in carbon dioxide.

high turnover rate of plankton

How does the open ocean have the highest relative net primary productivity while having one of the lowest mean biomass per unit area?

100 kcal

If herbivores eat 1000 kcal of plant energy, approximately how much energy will be converted into the tissues of herbivores?

compensation

In a body of water, the depth at which the availability of light is such that the rate of photosynthesis equals the rate of respiration is called the ________ depth.

detrital

In most terrestrial and many aquatic ecosystems, the ________ food chain is the dominant pathway of energy flow.

nitrogen and iron

In the surface waters of oceans, the two most limiting nutrients for primary productivity are

open-water aquatic ecosystems

In which situation is the detrital food chain not more dominant than the grazing food chain?

roots

Low-moisture conditions favor allocation by a plant to

high reflectance in the NIR and low reflectance in VIS.

NPP can be measured via satellite data because vegetation has

production

Net primary ________ is the energy available to the heterotrophic component of the ecosystem.

and mean annual rainfall increases

Net primary productivity in an ecosystem increases as mean annual temperature

tropical latitudes near the equator.

Net primary productivity is generally greatest at

autochthonous

Organic carbon produced within an ecosystem is termed ________.

photosynthesis

Plants assimilate energy through the process of

aquatic ecosystems dominated by phytoplankton

Rates of herbivory are highest in

biomass

Relative net primary productivity is the ratio of net primary productivity to standing ________.

primary production.

Secondary production is limited primarily by

second

The ________ law of thermodynamics states that when energy is transferred or transformed, part of the energy assumes a form that cannot pass on any further

standing

The amount of accumulated organic matter found in an area at a given time is the ________ crop biomass.

dead organic matter

The base of the detrital food chain is formed by

phosphorus

The presence of which element is highly correlated with NPP?

consumption efficiency.

The ratio of energy consumed at the next trophic level over what is produced is known as

trophic efficiency

The ratio of the productivity of one trophic level over what its organisms consume is known as

allochthonous carbon

The river continuum concept suggests that one of the following is higher in headwater streams.

Within any ecosystem there are two major food chains: the grazing food chain and the detrital food chain. In the grazing food chain, the source of energy is living plant biomass or net primary production. In the detrital food chain, the source of energy is dead organic matter or detritus. the grazing food chain is not the major one in most terrestrial and many aquatic ecosystems. Only in some open-water aquatic ecosystems do the grazing herbivores play the dominant role in energy flow.

What are the two main food chains of ecosystems? Which is more dominant in terrestrial ecosystems and why?

low

What level of productivity would one predict with high levels of water supply but low temperatures?

equator

Where are the areas of highest NPP?

pine forest

Which ecosystem has the highest actual evapotranspiration?

light

Which factor is the primary control of productivity in aquatic systems?

insects

Which group has the highest production efficiency?

GPP - R = NPP

Which of the following formulas are correct regarding productivity?

spider

Which of the following has the highest assimilation efficiency?

30-60 years old

Which of the following tree stands would you predict has the highest NPP?

endothermic carnivore, such as a lion

Which organism is most likely to have the highest assimilation efficiency

W

Which pathway leads to the detrital food chain?

India

Which region represents the highest HANPP as a percentage of local NPP

lack of trophic efficiency

Why are there not seven or eight levels to a trophic food chain?

because primary production is lower

Why might secondary production be lower in grasslands than in forests?

detrital

Within any ecosystem, the two major food chains are the ________ food chain and the grazing food chain

Production

________ efficiency is the ratio of production to assimilation, which measures how efficiently the consumer incorporates assimilated energy into secondary production

Gross

________ primary productivity is the total rate of photosynthesis or energy assimilated by plants.