What does Module 6 of the Life Science: Biology Regents cover?

Module 6 covers ecosystems under NYSSLS LS2 (with links to LS4): the levels of ecological organization and the roles of biotic and abiotic factors and producers, consumers and decomposers; how energy flows one way through food webs and is lost at each trophic level while matter cycles; how limiting factors and carrying capacity control population size; how organisms interact through competition, predation and symbiosis and how communities change through succession; and how human activity disrupts ecosystems and reduces biodiversity.

Why is only about 10 percent of energy passed to the next trophic level?

At each trophic level most of the energy is used for the organisms' own life processes, such as respiration and movement, and is lost as heat. Not all of an organism is eaten or digested either. So only about 10 percent of the energy at one level is passed on to the next. This is why an energy pyramid narrows toward the top and why food chains rarely have more than four or five links.

What is carrying capacity?

The carrying capacity is the maximum population size that an environment can support over the long term, given its resources. As a population approaches the carrying capacity, limiting factors such as food, space, predators and disease increase the death rate and lower the birth rate until births balance deaths. The population then levels off and fluctuates around the carrying capacity; if it overshoots, it tends to fall back.

What are the types of symbiosis?

Symbiosis is a close, long-term relationship between two species. Mutualism benefits both species (for example a bee and a flower). Commensalism benefits one while the other is unaffected (for example a bird nesting in a tree). Parasitism benefits one, the parasite, while harming the other, the host (for example a tick on a deer). To classify a relationship, ask who benefits and who is harmed.

How does human activity reduce biodiversity?

Habitat destruction removes the food, shelter and breeding sites that species depend on, so they decline. Pollution harms organisms and damages food webs. Overuse of resources, such as overfishing, reduces populations faster than they recover. Burning fossil fuels raises carbon dioxide, enhancing the greenhouse effect and warming the climate, which shifts habitats. These impacts can be reduced by protecting habitats, cutting pollution, using renewable energy and managing resources sustainably.

New YorkBiology

NY Regents Life Science: Biology Module 6 ecology: a complete overview of ecosystems, energy flow, populations, relationships and human impact

A deep-dive guide to Module 6 of the New York Life Science: Biology Regents: ecosystem structure and organization, energy flow and matter cycling, population dynamics and carrying capacity, ecological relationships and succession, and human impact on ecosystems, with the cluster patterns NYSED repeats.

Generated by Claude Opus 4.818 min readLS2Updated 2026-06-02

Reviewed by: AI editorial process; not yet individually human-reviewed

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What Module 6 actually demands
Ecosystem structure
Energy flow and matter cycling
Population dynamics
Relationships and succession
Human impact
Check your knowledge

What Module 6 actually demands

Module 6 is the ecology core of the Life Science: Biology Regents. Under the New York State Science Learning Standards it is disciplinary core idea LS2, Ecosystems: Interactions, Energy, and Dynamics (with links to LS4 for biodiversity). It covers how ecosystems are structured, how energy and matter move through them, what controls populations, how organisms interact and communities change, and how humans affect it all. The dominant crosscutting concepts are energy and matter and stability and change, and most clusters are built on data: food webs, energy pyramids, population-growth graphs, and trends in species or carbon dioxide.

This guide ties together the matching dot-point pages, each with its own practice questions: ecosystem structure and organization, energy flow and matter cycling, population dynamics and carrying capacity, ecological relationships and succession, and human impact on ecosystems.

Ecosystem structure

Ecology is studied at levels: organism, population (one species), community (all species together) and ecosystem (community plus abiotic surroundings). Biotic factors are living; abiotic factors are non-living (water, light, temperature). Organisms have feeding roles: producers make food by photosynthesis, consumers eat others, and decomposers break down dead matter and recycle nutrients. The ecosystem works as a system of interacting parts.

Energy flow and matter cycling

Energy enters from the Sun, is captured by producers, and flows one way along food chains, being lost as heat at each step. Only about 10 percent passes to each next trophic level, so an energy pyramid narrows upward and food chains are short. Matter (carbon, nitrogen), by contrast, is conserved and cycles: decomposers return nutrients for producers to reuse. Energy flows one way; matter cycles. The exam tests the 10 percent rule as a calculation and the energy-versus-matter contrast as an explanation.

Population dynamics

Populations grow quickly when resources are plentiful but are held in check by limiting factors (food, space, predators, disease). The carrying capacity is the maximum population an environment can support; as a population nears it, the death rate rises until births balance deaths and the population levels off and fluctuates. Overshooting leads to a fall. The exam tests this through population-growth graphs: identify the carrying capacity, name limiting factors, and explain the levelling off.

Relationships and succession

Organisms interact through competition (for a shared limited resource), predation (predator eats prey), and symbiosis: mutualism (both benefit), commensalism (one benefits, the other unaffected) and parasitism (one benefits, the other harmed). Communities change over time through ecological succession, a predictable sequence from pioneer species toward a relatively stable climax community. The exam asks you to classify relationships and to recognize succession.

Human impact

Human activity disrupts ecosystems and reduces biodiversity: habitat destruction removes what species need; pollution harms organisms and food webs; overuse of resources crashes populations; and burning fossil fuels raises carbon dioxide, enhancing the greenhouse effect and warming the climate, which shifts habitats. Impacts can be reduced by conservation, cutting pollution, renewable energy and sustainable resource use. The exam often gives a data trend and asks for the cause, the effect, and an action.

Check your knowledge

A mix of recall, calculation and application questions covering Module 6. Attempt them under timed conditions, then check against the solutions.

Explain the difference between a population and a community. (2 marks)
State the role of decomposers in an ecosystem. (2 marks)
An energy pyramid shows producers with $8\,000$ kJ. About how much reaches the secondary consumers (two levels up)? (2 marks)
Explain why an energy pyramid narrows toward the top. (2 marks)
Explain why matter cycles but energy does not. (2 marks)
Define carrying capacity. (2 marks)
State two limiting factors that could control a population. (1 mark)
Name the three types of symbiosis and state who benefits in each. (2 marks)
Explain how habitat destruction reduces biodiversity. (2 marks)

Solutions

Q1: A population is all the members of one species in an area; a community is all the populations (all the species) living and interacting there.
Q2: They break down dead organisms and wastes, releasing nutrients back into the ecosystem for producers to reuse.
Q3: About 10 percent per level: $8\,000 \rightarrow 800 \rightarrow 80$ kJ, so about $80$ kJ reaches the secondary consumers.
Q4: Only about 10 percent of the energy passes to each next level; the rest is used in life processes and lost as heat, so less energy is available higher up.
Q5: Matter is conserved and cycles (returned by decomposers and respiration); energy is lost as heat at each transfer and cannot be reused, so it must keep entering from the Sun.
Q6: The maximum population size an environment can support over the long term, given its resources.
Q7: Any two of: food supply, water, space, predators, disease, competition.
Q8: Mutualism (both benefit), commensalism (one benefits, the other unaffected), parasitism (one benefits, the other harmed).
Q9: It removes the food, shelter and breeding sites that species depend on, so those species decline or disappear, lowering the number of species.

Sources & how we know this

New York State P-12 Science Learning Standards (Life Science) — New York State Education Department (2016)
Educator Guide to the Regents Examination in Life Science: Biology — New York State Education Department (2025)