Question 1

The term trophic refers to:

Accepted Answer

The term trophic refers to feeding relationships in an ecosystem. It describes how energy and nutrients flow between different organisms through food chains and food webs. Trophic levels are defined based on an organism's position in a food chain or web, with primary producers at the base and top predators at the highest level.

Question 2

Which of the following is an example of intraspecific competition?

Accepted Answer

Intraspecific competition is competition between individuals of the same species. The scenario described in choice C, where two individuals in a population of clownfish attempt to use the same anemone as habitat, is an example of intraspecific competition.

Question 3

The subtidal zone is the area:

Accepted Answer

The subtidal zone is the area between the intertidal zone (where the tide goes in and out) and the edge of the continental shelf (where the ocean drops off into deeper waters). It is always covered by water and is not exposed to the air at low tide.

Question 4

Self-regulating of population numbers acts only when the population is:

Accepted Answer

Self-regulation of population numbers typically acts when the population is large, as density-dependent factors such as competition for resources, predation, disease, and territoriality become more significant and limit further growth.

Question 5

Nitrogen fixation is performed at sea by:

Accepted Answer

Nitrogen fixation is primarily performed by cyanobacteria in the ocean, which are capable of converting atmospheric nitrogen into a form that can be utilized by other organisms. Seaweeds and phytoplankton may also play a minor role in nitrogen fixation, but it is mainly performed by cyanobacteria. Zooplankton do not play a role in nitrogen fixation.

Question 6

Besides fixation by photosynthesis a large amount of carbon dioxide may be deposited in the oceans in the chemical form of:

Accepted Answer

Carbon dioxide can react with water and calcium ions in seawater to form calcium carbonate, which can then accumulate as sediment on the ocean floor. This process is known as oceanic carbon sequestration and plays a significant role in regulating the global carbon cycle.

Question 7

In competitive exclusion,which of the following is true?

Accepted Answer

In competitive exclusion, one species is a better competitor for resources, leading to the exclusion of the other species from the habitat.

Question 8

An algae begins to produce chemical defenses after it has been grazed upon by a herbivore.This is an example of:

Accepted Answer

The phenomenon described here is known as inducible defense. The algae is induced to produce chemical defenses only after it has been grazed upon by a herbivore. This response is not pre-existing but initiated by the presence of a herbivore.

Question 9

Sessile organisms are part of the:

Accepted Answer

Sessile organisms are those that are anchored in one place and do not have the ability to move from one place to another. These organisms are typically found on or within the ocean floor and are therefore part of the benthic community, which includes organisms that live on or in the seabed.

Question 10

In a salt marsh,a fish eats decaying material from around the base of Spartina grass plants.A snail scrapes algae from the stalks of the Spartina grass.These species can coexist in the same area because they have:

Accepted Answer

The fish and the snail inhabit the same habitat, which is the salt marsh, but they occupy different niches. The fish eats decaying material around the base of the Spartina grass plants, while the snail scrapes algae from the stalks of the same plant. They're not competing for the same resources, and they're not directly harming each other, so they can coexist in the same area. Therefore, the best choice is C: the same habitat but different niche.

Question 11

Organisms that are classified as benthic would most likely be found in the:

Accepted Answer

Benthic organisms live on or near the ocean floor, and the Abyssal zone is the deepest part of the ocean floor where these organisms are typically found. The Neritic zone refers to the shallow, near-shore area while the Pelagic zone refers to the open ocean. The Oceanic zone refers to the area beyond the continental shelf, and the Epipelagic zone refers to the uppermost layer of the ocean where enough light penetrates for photosynthesis to occur.

Question 12

In the carbon cycle,seaweeds and plants play a fundamental role by:

Accepted Answer

Seaweeds and plants decrease the amount of carbon dioxide in the atmosphere through the process of photosynthesis, where they convert carbon dioxide and water into glucose and oxygen, thus reducing atmospheric CO2 levels.

Question 13

The amount of chlorophyll in the water is a direct estimate of:

Accepted Answer

Chlorophyll is a pigment found in the chloroplasts of photosynthetic organisms such as phytoplankton. Therefore, the amount of chlorophyll in the water is directly related to the standing stock or abundance of phytoplankton.

Question 14

Competive exclusion may be affected by:

Accepted Answer

Competitive exclusion can be affected by the abundance of a resource, disturbances to habitat, and temperature changes, so all of the answer choices are correct.

Question 15

A population's carrying capacity is:

Accepted Answer

Carrying capacity is the number of individuals that a habitat can support with the available resources, such as food and water. It is not affected by the growth rate of the population, nor is it a predetermined constant for all habitats. The comparison of birth rate and death rate can give an indication of whether a population is growing or declining, but it does not directly determine the carrying capacity of the habitat.

Question 16

A chiton increases the abundance of its prey,a corraline algae,by feeding on the algae which stimulates growth of that algae.This is an example of:

Accepted Answer

This is an example of an indirect interaction, where the chiton's feeding behavior indirectly benefits the corraline algae by stimulating its growth.

Question 17

A disadvantage of resource partitioning is:

Accepted Answer

Resource partitioning involves sharing resources to minimize competition. However, one disadvantage is that the size of competing populations may decrease if the partitioning is not effective or if the resources are too limited. This can lead to decreased survival and reproduction rates for the populations.

Quiz 10: An Introduction to Marine Ecology