Bio A: Unit 3

What are the potential effects of introducing too much nitrogen and phosphorus into an aquatic ecosystem?

Algae will grow out of control and eventually die off in large amounts. The decomposition depletes the water of oxygen, and fish/other aquatic organisms will die off.

In an ecosystem, which of trophic level has the most stored energy for use by other organisms?

Producers

What is common to all of the biogeochemical cycles?

Reservoirs and processes, living things as a reservoir, and it can be affected by human activities.

What are abiotic factors that could influence the flow of matter and energy in a biome?

Sunlight, atmospheric gases, and water; sunlight, gases, water, and solids.

How might the carbon cycle be affected if phytoplankton were to decrease in number?

The amount of carbon dioxide dissolved in the oceans would increase. At the same time, the amount of carbon being transferred from phytoplankton through the food web would decrease.

Which is a difference between the nitrogen and carbon cycles?

The nitrogen cycle requires a process called fixation, which makes the nitrogen more usable for living organisms. Nitrogen fixation is a process that manipulates nitrogen through chemical reaction into ammonium or nitrogen dioxide.

How does carbon move between the atmosphere and the biosphere in the carbon cycle?

- Plants use water and carbon dioxide from the atmosphere to make glucose and oxygen through photosynthesis - Animals and plants use glucose and oxygen for cellular respiration - Cellular respiration transforms glucose and oxygen into carbon dioxide and water - Animals and plants release carbon dioxide and water as a result of cellular respiration - Carbon dioxide is released by plants and animals and moves into the biosphere

Consider a pyramid model with a producer level, a primary consumer level, a secondary consumer level, and a tertiary consumer level. Which of the following statements are correct?

- The sun is the ultimate source of energy in an ecosystem. - Matter cycles and is generally conserved within or among ecosystems. - Energy flows through ecosystems, but only a certain amount of energy is transformed into biomass. - Energy flows through ecosystems, but some is lost to the environment as heat.

Why is an herbivorous diet more energy efficient than a carnivorous diet?

A herbivorous diet is more energy efficient than a carnivorous diet because energy is lost to the environment as heat and waste each time energy is transferred to a higher trophic level.

In the carbon cycle, the role of photosynthesis is to take in _ , and the role of cellular respiration is to give off _.

Carbon dioxide

Why are decomposers so crucial for the cycling of matter in ecosystems?

Decomposers return matter stored in living things to the soil. This allows matter to be "recycled" so that producers can again take it up.

How does energy and matter flow, interact, and change forms throughout the Earth system.

Energy enters the Earth system when it is captured by photosynthetic organisms, which capture and store it as chemical energy when they convert carbon dioxide and water into sugars. Consumers eat these organisms, using the energy contained in their matter to grow and reproduce. Energy that is not used is excreted in waste or transformed into heat and lost to the environment. When organisms die, their matter is recycled back into the system.

What is the relationship between river, estuary, and ocean ecosystems? How do matter and energy flow within and among these ecosystems?

Estuary ecosystems are located between river and ocean ecosystems. Their salinity varies, depending on the flow of freshwater from the river and the movement of salt water in and out with the ocean tide. Estuary ecosystems often act as nurseries for ocean organisms until they are big enough to survive in open water, so many organisms move back and forth between the two ecosystems.

Which of the processes in the water cycle are driven by energy from the sun?

Evaporation, melting, and transpiration. Energy from the sun causes water to melt and evaporate. Transpiration is the evaporation of water from leaves.

What is the relationship between a food chain and trophic levels?

Food chains illustrate the flow of energy (energy movement) from one trophic level to the next.

Which food chain correctly shows the direction that energy and matter flow through a forest ecosystem?

Fruit comes from plants, which are producers. Insects are primary consumers, sparrows are secondary consumers, and hawks are tertiary consumers.

How does the nitrogen-fixing bacteria play a crucial role in the nitrogen cycle?

Nitrogen-fixing bacteria convert nitrogen gas from the atmosphere into compounds such as nitrate and ammonia. Plants take up these compounds and incorporate them into their tissues via a process called assimilation. Plants are then eaten by animals, and nitrogen moves up the food chain.

Terms in scale from smallest to largest

Organism, population, community, ecosystem, biome, biosphere

How might the carbon cycle be altered after a large-scale reforestation effort?

This would decrease the amount of atmospheric carbon dioxide because the new trees would absorb carbon dioxide during photosynthesis. Over long periods of time, some of the carbon in these trees would undergo burial and become fossil fuels.