Deck 47: Ecosystems

Question 1

Ecosystems have _____________.

A) energy inputs and outputs
B) one trophic level
C) no nutrient outputs; all nutrients are cycled
D) a and b

Answer 1

An ecosystem consists of a group of organisms together with their physical and chemical environment. In an ecosystem, there is a one-way flow of energy. Every ecosystem shows inputs and outputs of energy and nutrients.
Hence, the option (a) energy inputs and outputs is correct.
Food chain shows a sequence of trophic levels. Energy trapped by sun is transferred from first trophic to subsequent trophic levels.
Hence, the option (b) one trophic level is incorrect.
In biogeochemical cycles, nutrients are recycled whereas in ecosystem there is one-way flow of energy and nutrients.
Hence, the option (c) no nutrient outputs, all nutrients are cycled is incorrect.
Option (d) a and b is incorrect.

Question 2

Match the terms with suitable descriptions.

Answer 2

(a) Producers are organisms that can make their own food. Plants are producers. They synthesize food in the form of sugars with the help of carbon dioxide and water. The process called as photosynthesis takes place in the presence of chlorophyll and sunlight.
Hence,(a) matches with (d) 'capture sunlight energy'.
(b) Herbivores are primary consumers. They feed on producers or green plants to derive nutrition and meet out their energy needs.
Hence, (b) matches with (a) 'feed on plants'.
(c) Decomposers are organisms that feed on dead and decaying matter. In this way, decomposers help in cleaning the environment. Bacteria and fungi are decomposers.
Hence, (c) matches with (c) 'degrade organic wastes and remains to inorganic forms'.
(d) Detrivores feed on particles of decomposing organic matter, such as decaying bits of fallen leaves, remains of flesh left over by carnivores etc. For example, earthworms, crabs etc.
Hence, (d) matches with (b) 'feed on small bits of organic matter.'

Question 3

Marguerite is growing a vegetable garden in Maine. Eduardo is growing arugula in Spain. What are some of the variables that influence primary production in each of these locations

Answer 3

Primary productivity refers to the rate at which producers or green plants apprehend and store energy in their tissues during a specified interval of time. Typically the factors that will influence primary productivity in Maine and Spain depends on-
a. Number of producers present in that particular area in a specified interval of time.
b. Balance between photosynthesis and aerobic respiration.

Question 4

Organisms at the lowest trophic level in a tallgrass prairie are all ___________.

A) at the first step away from the original energy input
B) autotrophs
C) heterotrophs
D) both a and b
E) both a and c

Question 5

Look around you and name all of the objects, natural or manufactured, that might be contributing to amplification of the greenhouse effect.

Question 6

Decomposers are commonly __________.

A) fungi
B) animals
C) bacteria
D) a and c

Question 7

Polar ice shelves are vast, thickened sheets of ice that float on seawater. In March 2002, 3,200 square kilometers (1,410 square miles) of Antarcticas largest ice shelf broke free from the continent and shattered into thousands of icebergs. Scientists knew the ice shelf was shrinking and breaking up, but this was the single largest loss ever observed at one time. Why should this concern people who live in more temperate climates

Question 8

Trophic levels are ___________.

A) structured feeding relationships
B) a case of who eats whom in an ecosystem
C) a hierarchy of energy transfers
D) all of the above

Question 9

Fishes are a fine source of protein and of omega -3 fatty acids , which are necessary for the normal development of the nervous system. This would seem to make fish a good choice for pregnant women. But coal-burning power plants put mercury into the environment, and some of it ends up in fish. Eating mercury-tainted fish during pregnancy can adversely affect development of a fetal nervous system.
Tissues of predatory marine fishes, such as swordfishes, tunas, marlins, and sharks, have especially high levels of mercury. The Environmental Protection Agency has issued health advisories to pregnant women, suggesting that they limit their consumption of fish species most likely to be tainted with mercury. Although sardines are harvested from the same ocean, they have lower mercury levels and are not on the warning list. Explain why two species of fishes that live in the same place can have very different levels of mercury in their tissues.

Question 10

Primary productivity on land is affected by____.

A) nutrient availability
B) amount of sunlight
C) temperature
D) all of the above

Question 11

Methane, remember, is a gaseous molecule of one carbon atom to which four hydrogens are attached (Section 3.1). Methane hydrate is a methane molecule surrounded by an icelike lattice of water molecules, and it forms only at low temperatures, high pressures, and high concentrations of methane. Such conditions prevail beneath the seafloor and in the arctic tundra, where vast deposits of methane hydrate have formed in frozen peat bogs. The deposits typically are hundreds of meters thick.
Over millions of years, ancient organisms that died and sank to the ocean floor were buried in sediments. Their carbon-rich remains are food for anaerobic archaeans living far beneath the seafloor. The archaeans produce methane, which bubbles up to the seafloor. There, the high pressures and low temperatures freeze the methane into solid blocks of methane hydrates.
Again, ocean deposits of methane hydrate hold 10,000 to ll,000 gigatons of methane. The next largest deposit, in arctic regions, only amounts to hundreds of gigatons. Significant amounts of carbon continually enter and leave the deposits. For instance, bacterial activity continually converts some of the methane to carbon dioxide, which helps control the amount of methane that can escape into the atmosphere.
The oceanic reservoir of methane hydrates may contain more carbon than all of the known reserves of oil, coal, and natural gas. However, the deposits are highly unstable; ice fills spaces in sediments, so increases in pressure or ocean water temperature can trigger catastrophic landslides and tsunamis. Reflect again on the global carbon cycle, then list some of the consequences of a catastrophic release of methane in terms of global temperature, climate, glaciation and sea level changes, and the composition of ocean water.

Question 12

If biological magnification occurs, the ____________ will have the highest levels of toxins in their systems.

A) producers
B) herbivores
C) primary carnivores
D) top carnivores

Question 13

Disruption of the ____________ cycle is depleting aquifers.

A) hydrologic
B) carbon
C) nitrogen
D) phosphorus

Question 14

Earths largest carbon reservoir is _______________.

A) the atmosphere
B) sediments and rocks
C) seawater
D) living organisms

Question 15

The ___________ cycle is a sedimentary cycle.

A) hydrologic
B) carbon
C) nitrogen
D) phosphorus

Question 16

_____________ is often a limiting factor for plant growth.

A) Nitrogen
B) Carbon
C) Phosphorus
D) both a and c
E) all of the above

Question 17

Nitrogen fixation converts ___________ to ____________.

A) nitrogen gas; ammonia
B) nitrates; nitrites
C) ammonia; nitrogen gas
D) ammonia; nitrates
E) nitrites; nitrogen oxides