Biology Flashcards: Describe Matter Movement In Ecosystems

What this deck covers

This deck focuses on Describe Matter Movement In Ecosystems, giving you a quick way to review the definitions, rules, and examples that matter most for Biology.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: What is the most direct way carbon atoms in a dead tree return to the atmosphere?

Answer: Decomposition and respiration releasing $CO_2$. Decomposer respiration releases carbon stored in wood as $CO_2$.

Flashcard 2: What process returns carbon to the atmosphere as $CO_2$ from living organisms?

Answer: Cellular respiration. All organisms break down organic compounds and release $CO_2$.

Flashcard 3: What is the most direct way carbon atoms in a dead tree return to the atmosphere?

Answer: Decomposition and respiration releasing $CO_2$. Decomposer respiration releases carbon stored in wood as $CO_2$.

Flashcard 4: Which environmental condition most strongly favors denitrification?

Answer: Low oxygen (anaerobic) soils or sediments. Denitrifying bacteria use nitrate as an electron acceptor without oxygen.

Flashcard 5: Which statement best describes how matter moves through ecosystems compared with energy?

Answer: Matter cycles; energy flows one-way through trophic levels. Matter is recycled while energy is lost as heat at each trophic level.

Flashcard 6: What is carbon sequestration in ecosystems?

Answer: Long-term storage of carbon in biomass, soils, oceans, or rocks. Carbon is removed from active cycling and stored long-term.

Flashcard 7: Which term describes the movement of elements through living and nonliving parts of Earth?

Answer: Biogeochemical cycle. Elements move through biological, geological, and chemical processes.

Flashcard 8: What is assimilation in the nitrogen cycle?

Answer: Uptake of $NO_3^-$ or $NH_4^+$ to build organic nitrogen compounds. Plants absorb inorganic nitrogen to synthesize proteins and nucleic acids.

Flashcard 9: What is ammonification (mineralization) in the nitrogen cycle?

Answer: Decomposers convert organic nitrogen to $NH_3$/$NH_4^+$. Releases nitrogen from dead organisms back to the soil.

Flashcard 10: Which option correctly traces carbon atoms from air into a wolf? Choose the best sequence.

Answer: $CO_2$ → grass → rabbit → wolf. Shows carbon moving through a complete food chain from producer to tertiary consumer.

Flashcard 11: What is a flux in biogeochemical cycling?

Answer: The rate of movement of matter between reservoirs. Measures how fast matter moves from one pool to another.

Flashcard 12: What is an ecosystem nutrient reservoir (pool) in matter cycling?

Answer: A storage location for matter, such as soil, biomass, or atmosphere. These pools hold matter temporarily during biogeochemical cycles.

Flashcard 13: What is denitrification in the nitrogen cycle?

Answer: Bacterial conversion of $NO_3^-$ to atmospheric $N_2$ (and $N_2O$). Returns nitrogen to the atmosphere, completing the cycle.

Flashcard 14: Which option correctly traces nitrogen atoms from air into a plant protein? Choose the best sequence.

Answer: $N_2$ → fixation → $NH_4^+$/$NO_3^-$ → assimilation. Shows nitrogen conversion from atmospheric gas to bioavailable form to organic compounds.

Flashcard 15: Identify the process: bacteria convert $NO_3^-$ into $N_2$ gas in waterlogged soil.

Answer: Denitrification. Bacteria reduce nitrate to nitrogen gas in oxygen-poor conditions.

Flashcard 16: What is the phosphorus cycle and what key feature distinguishes it from the nitrogen cycle?

Answer: Phosphorus cycles via rocks/soil; it has no major atmospheric gas phase. Phosphorus lacks a gaseous form and moves only through solid/liquid phases.

Flashcard 17: Identify the process: decomposers convert organic nitrogen in dead leaves into $NH_4^+$.

Answer: Ammonification (mineralization). Bacteria break down organic nitrogen compounds to release ammonium.

Flashcard 18: Identify the process: bacteria convert $NH_4^+$ to $NO_3^-$ in aerated soil.

Answer: Nitrification. Bacteria oxidize ammonium to nitrate in well-oxygenated soil.

Flashcard 19: Which reservoir stores the largest amount of carbon on Earth on geologic time scales?

Answer: Sedimentary rocks and carbonate minerals. These geological formations hold carbon for millions of years.

Flashcard 20: What is the nitrogen cycle?

Answer: The movement of nitrogen among atmosphere, soil, water, and organisms. Nitrogen moves between air, soil, water, and living organisms.

Flashcard 21: What is the correct term for the total mass of living organic matter in a given area?

Answer: Biomass. Measures the total amount of living organic matter present.

Flashcard 22: Which option best distinguishes macronutrients from micronutrients in ecosystem matter cycling?

Answer: Macronutrients are needed in larger amounts; micronutrients in trace amounts. Macronutrients like carbon and nitrogen are needed in large quantities.

Flashcard 23: What is biomagnification, and does it describe cycling of matter or accumulation in food webs?

Answer: Accumulation in food webs; it is not a nutrient cycle. Toxins concentrate up food chains rather than cycling through ecosystems.

Flashcard 24: What is nitrogen fixation?

Answer: Conversion of atmospheric $N_2$ into ammonia ($NH_3$)/$NH_4^+$. Breaks the strong triple bond in $N_2$ to make bioavailable nitrogen.

Flashcard 25: Which organisms carry out most biological nitrogen fixation in ecosystems?

Answer: Nitrogen-fixing bacteria (free-living or in root nodules). They have the enzyme nitrogenase that converts atmospheric $N_2$.

Flashcard 26: What is nitrification in the nitrogen cycle?

Answer: Bacterial conversion of $NH_4^+$ to $NO_2^-$ then $NO_3^-$. Oxidizes ammonia to nitrites then nitrates in aerobic conditions.

Flashcard 27: Which option best describes where matter goes when a hawk eats a mouse?

Answer: Matter is incorporated into hawk biomass and released as waste and $CO_2$. Matter is either assimilated into tissues or excreted as waste.

Flashcard 28: What is the primary source of carbon atoms that plants use to build sugars in photosynthesis?

Answer: Carbon dioxide ($CO_2$) from the atmosphere. Plants fix atmospheric $CO_2$ during photosynthesis to make glucose.

Flashcard 29: What is the primary source of nitrogen atoms for most plants in natural ecosystems?

Answer: Nitrate ($NO_3^-$) or ammonium ($NH_4^+$) in soil. These are the bioavailable forms of nitrogen that plant roots can absorb.

Flashcard 30: What is the primary source of phosphorus for plants and algae in ecosystems?

Answer: Phosphate ions ($PO_4^{3-}$) from weathered rock/soil. Rock weathering releases phosphate ions that plants can uptake.