Question 1

Net primary production is

Accepted Answer

Net primary production refers to the amount of energy that photosynthetic organisms (autotrophs) convert from sunlight into chemical energy (as biomass) minus the energy they use for their own metabolic processes. This energy becomes available to other organisms in the ecosystem, primarily heterotrophs, through consumption.

Question 2

Oceans, the atmosphere, and fossil fuels are large reservoirs of

Accepted Answer

Oceans, the atmosphere, and fossil fuels are large reservoirs of carbon, which cycles through these and other reservoirs in various forms, including carbon dioxide and organic matter.

Question 3

In a grassland of Kansas, 1,000 grams of grass are produced per square meter per year by all the different grass species. A theoretical upper limit to the biomass of secondary consumers that can be supported in this ecosystem is

Accepted Answer

The theoretical upper limit to the biomass of secondary consumers in an ecosystem is typically around 10% of the biomass available at the previous trophic level (primary consumers), which in turn is about 10% of the biomass of the producers. Given that the grass (producers) biomass is 1,000 grams, primary consumers (herbivores) would theoretically be supported up to 100 grams (10% of 1,000 grams), and secondary consumers (carnivores eating the herbivores) would be supported up to 10 grams (10% of 100 grams).

Question 4

In 1956, people in Minamata, Japan, began to exhibit severe neurological disorders and birth defects. This problem was eventually attributed to methylmercury, a water-insoluble and breakdown-resistant chemical formed from mercury dumped into the adjacent bay by a local factory. Which of the following types of seafood would have the highest levels of methylmercury, and therefore cause the severest effects?

Accepted Answer

Tuna, being higher up in the food chain, would accumulate higher levels of methylmercury through the process of biomagnification. Each step up the food chain concentrates the toxin more, making top predators like tuna the most contaminated.

Question 5

If you are attempting to minimize the amount of mercury in your diet, you should eat

Accepted Answer

Producers such as fruits and vegetables are at the bottom of the food chain and do not accumulate mercury through the process of biomagnification, unlike animals higher up in the food chain.

Question 6

What is biological magnification?

Accepted Answer

Biological magnification refers to the accumulation of toxic substances, such as pesticides or heavy metals, in the tissues of organisms at successively higher levels in a food chain.

Question 7

Bacteria that live in deep-sea thermal vents use energy from inorganic hydrogen sulfide (H 2S) to make organic molecules from carbon dioxide and are thus

Accepted Answer

Bacteria that use energy from inorganic compounds like hydrogen sulfide to make organic molecules from carbon dioxide are performing chemosynthesis, a process similar to photosynthesis but without sunlight. This makes them producers, as they are able to produce organic compounds necessary for the ecosystem from inorganic substances.

Question 8

Which of the following terms correctly describes carnivores?

Accepted Answer

Carnivores are organisms that eat other animals. They are typically considered secondary consumers in a food chain because they consume primary consumers (herbivores). Autotrophs are organisms that produce their own food (like plants), detritus consumers break down dead material, primary consumers are herbivores that eat plants, and "consumer producers" is not a standard ecological term.

Question 9

Phosphorus, which is often a limiting nutrient in ecosystems, is important because it

Accepted Answer

Phosphorus is crucial for the formation of vital biological molecules like ATP (which stores and transfers energy in cells), cell membranes (phospholipids), and nucleic acids (DNA and RNA), making it essential for life processes in plants and animals.

Question 10

The three major reservoirs of carbon are

Accepted Answer

The three major reservoirs of carbon are oceans, the atmosphere, and fossil fuels. Oceans absorb a significant amount of carbon dioxide from the atmosphere, acting as a major carbon sink. The atmosphere contains carbon dioxide, which is a critical greenhouse gas. Fossil fuels, which include coal, oil, and natural gas, are formed from the remains of ancient plants and animals and represent a significant carbon store.

Question 11

A snake that eats a small rabbit that feeds on grass is classified as a(n)

Accepted Answer

Secondary consumers are organisms that eat primary consumers. In this scenario, the snake eats the rabbit, which is a primary consumer because it feeds on grass (a primary producer). Therefore, the snake is a secondary consumer.

Question 12

Autotrophs gain energy from

Accepted Answer

Autotrophs, such as plants and certain bacteria, produce their own food through photosynthesis or chemosynthesis, using sunlight and inorganic nutrients, rather than consuming other organisms.

Question 13

__________is (are) a crucial nutrient reservoir of phosphorus that is available to organisms.

Accepted Answer

Rocks are a crucial nutrient reservoir of phosphorus available to organisms, as phosphorus is released from rocks through weathering processes and then becomes available for use in biological systems.

Question 14

Which nutrient cycle lacks an atmospheric reservoir?

Accepted Answer

The phosphorus cycle lacks an atmospheric reservoir because phosphorus does not typically exist as a gas and is primarily found in rocks, soil, and sediments.

Question 15

Which of the following components is NOT involved in the phosphorus cycle?

Accepted Answer

The phosphorus cycle does not involve the atmosphere significantly because phosphorus is not found in a gaseous state under normal conditions. Instead, it cycles through rocks, soil, water, and living organisms.

Question 16

Which trophic level has the LEAST biological magnification?

Accepted Answer

Primary producers, such as plants and algae, are at the bottom of the food chain and do not accumulate toxins or pollutants through the process of biological magnification like organisms higher up in the food chain do. Biological magnification occurs more in higher trophic levels as they consume organisms that have already accumulated toxins.

Question 17

The community of detritivores, such as earthworms, millipedes, slugs, and pseudoscorpions, living in the leaf litter on the shady floor of a deciduous forest obtains its energy and nutrients primarily from

Accepted Answer

Detritivores obtain their energy and nutrients primarily through the decomposition of dead organic matter, such as the leaves of deciduous trees that fall to the forest floor.

Question 18

In open-water marine ecosystems, the__________ occupy the same trophic level as the giant sequoias (redwoods) in the forests of California.

Accepted Answer

Phytoplankton, like giant sequoias, are primary producers in their respective ecosystems, converting sunlight into energy through photosynthesis and forming the base of the food web.

Question 19

If a couple was attempting to get pregnant, which foods should they eat to avoid ingesting high amounts of toxins?

Accepted Answer

Organic grains, fruits, and vegetables are less likely to contain high amounts of toxins compared to the other options. High-fat fish and high-level carnivores like tuna often accumulate more toxins through bioaccumulation. Microwaving in plastic can release harmful chemicals, and DDT is a known toxic pesticide.

Question 20

Detritus feeders consume

Accepted Answer

Detritus feeders, also known as detritivores, primarily consume dead organic matter, which includes the remains of plants and animals as well as fecal material.

Quiz 29: Energy Flow and Nutrient Cycling in Ecosystems