Question 1

The only zone of the ocean with sufficient light for photosynthesis is the ________.

Accepted Answer

The euphotic zone is the layer of the ocean closest to the surface where sufficient light penetrates for photosynthesis to occur. The aphotic zone is the layer of the ocean where light cannot penetrate and no photosynthesis occurs, while the disphotic zone is the layer where some light does penetrate, but not enough for photosynthesis to occur. Therefore, only choice A is correct.

Question 2

The total productivity of upwelling areas is greater than the total productivity of open-ocean areas.

Accepted Answer

False

Question 3

The plankton, benthos, and nekton are subdivisions of the ________.

Accepted Answer

D

Question 4

Greater mixing and nutrients from the land cause the coastal areas to generally have higher primary productivity than the open ocean.

Accepted Answer

Coastal areas receive more nutrients from the land through runoff and mixing with freshwater, which results in higher primary productivity compared to the open ocean. Additionally, shallow waters in coastal areas receive more sunlight than deeper waters in the open ocean, which also contributes to higher primary productivity.

Question 5

The total primary production of the world's oceans is determined more by the large seaweeds than it is by the single-celled microscopic phytoplankton.

Accepted Answer

The total primary production of the world's oceans is primarily determined by the single-celled microscopic phytoplankton, which make up the base of the marine food web. While large seaweeds do contribute to primary production in coastal areas, they are not the primary drivers on a global scale.

Question 6

Organisms that float, but cannot swim against the tides and waves, are known as ________.

Accepted Answer

Plankton are organisms that float in water and are unable to swim against currents and waves. They are classified into two types: phytoplankton (plants) and zooplankton (animals). Examples of plankton include tiny algae, bacteria, and jellyfish. Photon and aphoton are not related to this topic. Nekton refers to animals that are able to swim and move independently of ocean currents, and benthos refer to organisms that live on the ocean floor.

Question 7

At low latitudes, primary production is controlled more by the seasonality of the sunlight than by the availability of nutrients.

Accepted Answer

At low latitudes, primary production is often limited more by the availability of nutrients than by the seasonality of sunlight, as these regions typically receive ample sunlight year-round.

Question 8

The standing stock of a population is equivalent to its biomass.

Accepted Answer

The standing stock of a population refers to the total biomass of that population, so the statement is true.

Question 9

The shorter food chains of coastal and upwelling areas generally are more efficient than longer open-ocean food chains.

Accepted Answer

This is because coastal and upwelling areas have a greater abundance of primary producers and higher levels of nutrient availability, leading to a greater biomass of primary consumers, which in turn supports a higher biomass of top predators. Therefore, energy is transferred more efficiently through shorter food chains in these areas. In contrast, open-ocean food chains are longer and less efficient due to lower nutrient availability and lower biomass at each trophic level.

Question 10

If both primary productivity and grazing are large, the standing stock cannot be small.

Accepted Answer

Even if both primary productivity and grazing are large, the standing stock can still be small if the rate of consumption by grazers matches or exceeds the rate of production by primary producers, leading to a low accumulation of biomass at any given time.

Question 11

Productivity tends to be higher in the open ocean than the coastal ocean.

Accepted Answer

Productivity tends to be higher in the coastal ocean than in the open ocean due to the greater availability of nutrients from river runoff, upwelling, and the continental shelf's shallower waters, which allow for more sunlight penetration and photosynthesis.

Question 12

Gross primary production is the rate of production of organic material by photosynthesis required for both the respiration of the plants or algae and the production of new material.

Accepted Answer

Gross primary production includes both the production of organic material required for respiration and the production of new material through photosynthesis.

Question 13

Approximately 15 percent of the world's ocean area produces eighty-five percent of the ocean's harvest.

Accepted Answer

This statement is true according to research conducted by the United Nations. This means that a small percentage of the world's ocean area is responsible for producing the majority of the seafood that humans consume.

Question 14

In grams of carbon per square meter per day, the open-ocean environment is as productive as a tropical rainforest.

Accepted Answer

The open-ocean environment is not as productive as a tropical rainforest. While both environments play an important role in the Earth's carbon cycle, the rate of photosynthesis and carbon fixation is much higher in rainforests than in the open ocean.

Question 15

If the rate of uptake of dissolved inorganic carbon by phytoplankton is measured, the rate of production of organic matter can be calculated.

Accepted Answer

This is because phytoplankton use dissolved inorganic carbon (DIC) as a source of carbon to fuel their growth and reproduction. Through photosynthesis, they convert DIC to organic matter, the rate of which can be calculated from the rate of uptake of DIC.

Question 16

Net primary production equals gross primary production minus the respiration requirements of plants or phytoplankton.

Accepted Answer

This statement is true. Net primary production is the amount of energy that is available for consumption by heterotrophs, and it is calculated by subtracting the energy that is consumed by plants or phytoplankton through respiration from the gross primary production.

Question 17

Nutrients tend to be liberated by decomposition of organic matter at depth and returned to the surface by the physical processes of vertical circulation.

Accepted Answer

Nutrients are released through decomposition of organic matter, and they are recirculated to the surface through vertical circulation processes such as weathering, erosion, or volcanic activity.

Question 18

Primary productivity per square meter of ocean surface is, on the average, higher in the neritic zone than in the oceanic zone.

Accepted Answer

This is because the neritic zone receives more sunlight and nutrients from land runoff, which promotes the growth of phytoplankton and other marine organisms. The oceanic zone, on the other hand, has limited nutrient availability and lower sunlight intensity, which restricts primary productivity.

Question 19

In temperate regions, both winter mixing and summer's increasing solar radiation control primary production.

Accepted Answer

In temperate regions, winter mixing brings nutrients to the surface, allowing for increased primary production. In the summer, increased solar radiation also drives primary production.

Question 20

The upper boundary of the aphotic zone is determined by the depth of solar light penetration.

Accepted Answer

The aphotic zone is the portion of the ocean where there is no sunlight and photosynthesis cannot occur. The upper boundary of the aphotic zone is determined by the depth at which solar light penetration is too weak to support photosynthesis. Therefore, the statement is true.

Quiz 12: The Plankton, Productivity, and Food Webs