Nutrient Cycling and the Carbon Cycle Study Guide

A comprehensive question-and-answer study set covering nutrient cycling, the four major nutrient cycles, the carbon cycle, carbon reservoirs, the greenhouse effect, and ozone-depleting substances.

What is nutrient cycling?

The continuous movement of elements and minerals between the living (biotic) and nonliving (abiotic) parts of an ecosystem, allowing nutrients to be reused repeatedly.

What is the difference between biotic and abiotic ecosystem components?

Biotic refers to living things, such as plants and animals, while abiotic refers to nonliving parts, such as air, water, and soil.

What are the four major nutrient cycles in ecosystems?

The carbon cycle, nitrogen cycle, phosphorus cycle, and water cycle.

What are limiting nutrients?

Nutrients that are difficult for plants to obtain and therefore limit their growth.

What role do detritivores, such as earthworms, play in recycling nutrients?

They consume dead organic matter and help break it down.

How do certain microbes assist plants with nitrogen uptake?

Some bacteria convert nitrogen gas ($N_2$) into forms plants can absorb, such as ammonium ($NH_4^+$) or ammonia ($NH_3$).

What occurs during the Input step of nutrient cycling?

Nutrients enter ecosystems from the atmosphere or through the breakdown and weathering of rocks and minerals.

What occurs during the Absorption & consumption step of nutrient cycling?

Plants absorb nutrients from soil or air, and animals get nutrients by eating plants or other animals.

What occurs during the Decomposition step of nutrient cycling?

Fungi, bacteria, and detritivores break down dead organisms and waste, returning nutrients to the soil and atmosphere.

What is carbon fixation?

The process where carbon is taken in and incorporated into organic matter.

Which biological process removes $CO_2$ from the atmosphere, and which processes release it?

Photosynthesis removes $CO_2$ from the atmosphere, while respiration and combustion release $CO_2$.

What forms of carbon are stored in the atmospheric reservoir?

Carbon dioxide ($CO_2$) and methane ($CH_4$) in the air.

Which carbon reservoir holds the largest amount of carbon?

The lithosphere, which includes rocks, limestone, and fossil fuels.

How do the timescales of the fast and slow carbon cycles compare?

The fast carbon cycle operates on a scale of days to years, whereas the slow carbon cycle involves very long-term geological storage, often lasting thousands to millions of years.

What mechanisms drive the slow carbon cycle?

Weathering, ocean absorption, and the long-term burial of organic matter.

In what three ways do human activities disrupt the carbon cycle?

Burning fossil fuels, deforestation (leaving fewer trees to absorb $CO_2$), and industrial processes such as cement production.

What is the difference between the natural greenhouse effect and the enhanced greenhouse effect?

The natural greenhouse effect is helpful because it keeps Earth warm enough for life, whereas the enhanced greenhouse effect is harmful because extra greenhouse gases trap too much heat and warm the planet.

What causes rising sea levels as an effect of the enhanced greenhouse effect?

Glaciers and ice melt, and warmer ocean water expands.

What are CFCs and how do they impact the environment?

CFCs (chlorofluorocarbons) are chemicals that damage the protective ozone layer, allowing more harmful ultraviolet (UV) radiation to reach Earth's surface.

What is the key functional difference between greenhouse gases and CFCs?

Greenhouse gases contribute to global warming by trapping heat in the atmosphere, whereas CFCs are known for damaging the protective ozone layer.