Question

the matter used to build the structure of an oak tree comes from where? (how does a sprout become a tree?
matter cycles (ecology): how do organisms get the stuff they need to survive from their environment?
model ideas

• the earth is a closed system with respect to matter
• matter is cycled by living things in an ecosystem: within the carbon cycle, unusable carbon in co₂ is \fixed\ by autotrophs so that it can become biologically useful (carbon in co₂ is converted into biomolecules in photosynthesis, and carbon from biomolecules is released as co₂ by all organisms in cellular respiration). likewise, nitrogen is \fixed\ by decomposers and made available to the system
• organisms within an ecosystem rely upon the movement (cycling) of matter in order to survive. if there is a disruption in the cycle—an organism in the ecosystem is removed, for example—then that could cause a population of organisms to either increase or decrease, depending upon matter (food) availability. if the population increases, they could exceed the carrying capacity of the environment, eventually causing the population size to decrease

define & give examples:

• decomposer:
• producer:
• consumer

what is the difference between a primary, secondary, and tertiary consumer?
use the diagram to show the movement of matter from one organism to another in an ecosphere:

Explanation:

The problem involves concepts like decomposers, producers, consumers, and matter cycles in ecosystems, which fall under Biology (a subfield of Natural Science). For defining decomposer: A decomposer is an organism that breaks down dead or decaying organisms, e.g., fungi (like mushrooms) or bacteria. Producer: An organism that makes its own food via photosynthesis/chemosynthesis, e.g., plants (grass) or algae. Consumer: An organism that eats other organisms for energy, e.g., animals (rabbit). Primary consumers eat producers, secondary eat primary, tertiary eat secondary (e.g., grass→rabbit→fox→bear: rabbit is primary, fox secondary, bear tertiary). Matter movement: Producers take in matter (CO₂, nutrients), consumers eat producers/other consumers, decomposers break down dead organisms, returning matter to the environment.

Answer:

• Decomposer: Organism that breaks down dead/decaying matter (e.g., fungi).
• Producer: Organism that makes food (e.g., grass).
• Consumer: Organism that eats others (e.g., rabbit).
• Primary consumer: Eats producers (e.g., rabbit eating grass); Secondary: Eats primary (e.g., fox eating rabbit); Tertiary: Eats secondary (e.g., bear eating fox).
• Matter movement: Producer (grass) → Primary consumer (rabbit) → Secondary consumer (fox) → Tertiary consumer (bear); Decomposers (fungi) break down dead bear/fox/rabbit/grass, returning matter to soil for producers.