Question 1

At higher and higher trophic levels, there are usually _____ and _______ animals.

Accepted Answer

According to the 10% rule, only about 10% of the energy from one trophic level is transferred to the next, which means that there is less energy available for the higher levels. As a result, there are fewer animals at higher trophic levels. However, those animals tend to be larger because they require more energy to sustain themselves.

Question 2

The coccoliths on the outside of coccolithophores are made of silica.

Accepted Answer

Coccolithophores have coccoliths that are made of calcium carbonate, not silica.

Question 3

In a simple food chain with 10% efficiency, a net primary production rate at the first trophic level is 10,000 units. How many units are available to the fourth trophic level?

Accepted Answer

With 10% efficiency, each trophic level will have 10% of the energy available at the previous trophic level. Therefore, the available energy to the fourth trophic level will be 10 units (10,000 x 0.1 x 0.1 x 0.1 = 10).

Question 4

An increase in the chlorophyll a content of a seawater sample with time yields a measurement of

Accepted Answer

Increase in chlorophyll a content indicates photosynthetic activity and the production of organic carbon by phytoplankton. Net production of organic carbon is the difference between the rate of photosynthesis and respiration, and is the best explanation for the observed increase in chlorophyll a content over time.

Question 5

Adding iron to the surface of the ocean has been shown to

Accepted Answer

Adding iron to the surface of the ocean has been shown to increase phytoplankton production for an initial short period, but the long-term effects are still unclear. Research studies have observed increases in phytoplankton biomass and primary productivity in response to iron fertilization experiments. However, there may be potential negative impacts on the overall ecosystem, such as changes in community composition and nutrient availability.

Question 6

As a general rule, total biomass _______, size of individuals _____, and number of individuals ______ as you move up a trophic pyramid.

Accepted Answer

Total biomass decreases because energy is lost at each trophic level, size of individuals generally increases because higher trophic levels often consist of larger predators, and the number of individuals decreases due to the energy pyramid structure where less energy is available to support fewer individuals at higher levels.

Question 7

Sargassum is the only large planktonic seaweed.

Accepted Answer

Sargassum is a genus of brown algae that is the only large planktonic seaweed. It is found in the Sargasso Sea, a region of the North Atlantic Ocean. Sargassum is a free-floating seaweed that does not attach to the bottom of the ocean. It is a major food source for many marine animals, including fish, turtles, and seabirds.

Question 8

If baleen whales eat krill that eat diatoms, krill represents the _______ trophic level.

Accepted Answer

Krill feed on diatoms, which are primary producers, making krill the second trophic level. Baleen whales, which consume krill, would be considered the third trophic level.

Question 9

Krill is the common name for copepods.

Accepted Answer

Krill are actually small, shrimp-like crustaceans, belonging to the order Euphausiacea.

Question 10

Net plankton are larger than nannoplankton.

Accepted Answer

Net plankton are larger in size, typically ranging from 20 micrometers to 2 millimeters, whereas nannoplankton are smaller, ranging from 2 to 20 micrometers.

Question 11

The most common nutrient that limits coastal productivity is

Accepted Answer

Nitrate is often the most common limiting nutrient in coastal ecosystems, as it is essential for the growth of phytoplankton and other aquatic plants.

Question 12

If the net primary production in a region is continually consumed by herbivores, the standing stock

Accepted Answer

The standing stock does not change if the net primary production is continually consumed by herbivores, as the amount of biomass produced is exactly balanced by the amount consumed.

Question 13

There is less biomass per unit volume available for harvesting in the open ocean, as compared to upwelling and coastal zones, because

Accepted Answer

Open ocean zones have lower nutrient concentrations compared to upwelling and coastal zones due to limited mixing events and lower input of nutrients from land. This limits primary productivity and thus reduces the biomass available for harvesting. Oxygen levels, salinity, and temperature may differ between these zones, but they do not directly affect the amount of biomass available for harvesting. Therefore, options B, C, D, and E are incorrect.

Question 14

The highest rates of productivity in temperate waters occur in

Accepted Answer

In temperate waters, the highest rates of productivity occur in spring. This is due to the combination of increasing light availability and nutrients being mixed into the upper layers of the ocean or lakes from winter mixing, leading to a spring bloom of phytoplankton.

Question 15

Which compound does not serve as a pigment in phytoplankton?

Accepted Answer

Hemoglobin is a protein found in the red blood cells of animals and has no role in the pigmentation of phytoplankton. Chlorophyll a, chlorophyll c, fucoxanthin, and phycoerythrin are all pigments found in various types of phytoplankton.

Question 16

A food web is

Accepted Answer

A food web is a diagram of interconnected food chains, showing the flow of energy and nutrients through an ecosystem. It includes producers, consumers, and decomposers, and illustrates the complex relationships between different species in an ecosystem. Option A is incorrect because a food web is not used for trapping marine organisms. Option C is incorrect because a trophic pyramid shows the flow of energy through a food chain, and is not inverse. Option D is incorrect because a food web is not specific to herring life histories. Option E is incorrect because a diagram of an organism's life history would not include other species and their interactions in an ecosystem.

Question 17

The period of highest productivity in polar areas is

Accepted Answer

In polar regions, the period of constant daylight during the summer leads to a bloom of phytoplankton, which are the base of the food chain. This increase in phytoplankton leads to a surge in productivity throughout the food web, making summer the period of highest productivity.

Question 18

The Redfield Ratio is

Accepted Answer

The Redfield Ratio, which describes the atomic ratio of carbon, nitrogen, and phosphorus found in phytoplankton and throughout the deep oceans, is C:N:P 106:16:1.

Question 19

In temperate waters, the timing of the phytoplankton bloom is influenced by

Accepted Answer

The answer of In temperate waters, the timing of the...

Question 20

The biomass of planktonic, unicellular algae in tropical regions

Accepted Answer

In tropical regions, the temperature and sunlight availability remain relatively constant throughout the year, leading to a nearly constant biomass of planktonic, unicellular algae.

Quiz 12: The Plankton, Energy, and Food Webs

At higher and higher trophic levels, there are usually _ and ___ animals.