How does human activity affect ecosystems, and how can these impacts be reduced?
Explain how human activities (pollution, habitat destruction, resource use and the enhanced greenhouse effect) disrupt ecosystems and reduce biodiversity, and evaluate ways to reduce these impacts (NYSSLS LS2 and LS4, cause and effect; stability and change).
A NYSSLS-level answer on human impact for the New York Life Science: Biology Regents: how pollution, habitat destruction, resource use and the enhanced greenhouse effect disrupt ecosystems and reduce biodiversity, and how these impacts can be reduced.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this topic is asking
NYSSLS LS2 and LS4 want you to explain how human activity disrupts ecosystems and reduces biodiversity, and to evaluate ways to reduce these impacts. On the Life Science: Biology Regents this is often a data cluster (a falling number of species, rising carbon dioxide) where you identify the cause, explain the effect, and suggest an action. The crosscutting concepts are cause and effect and stability and change.
Habitat destruction
A common exam cluster shows the number of species falling as land is cleared. The explanation is direct: removing the habitat removes what species need to live, so they decline (linking to biodiversity and its value).
Pollution
Pollution is the release of harmful substances into the environment. Air pollution can harm organisms and contribute to problems such as acid rain; water pollution (for example fertilizer runoff or chemicals) can poison aquatic life or cause excess algal growth that removes oxygen and kills fish; and land pollution (waste, plastics) can harm wildlife. Pollutants can also build up along food chains, so top consumers receive the highest doses.
Overuse of resources
When humans take resources faster than they are replaced, populations crash. Overfishing can collapse fish stocks; overhunting has driven species toward extinction; clearing for timber or farming removes producers. Sustainable management means taking no more than a population can replace, so it can recover.
Climate change and the enhanced greenhouse effect
A warming, changing climate shifts habitats and conditions faster than many species can adapt or move, contributing to extinction and disrupting ecosystems (for example by changing the timing of seasons or the ranges of species). This links human activity directly to the loss of biodiversity and the risk of extinction (see speciation and extinction).
Reducing the impact
Humans can reduce these impacts, and the exam may ask you to suggest or evaluate an action:
- Protect and restore habitats (reserves, national parks, reforestation).
- Reduce pollution (treat waste, cut emissions, reduce plastic).
- Use renewable energy (solar, wind) instead of fossil fuels, and improve energy efficiency, to cut carbon dioxide.
- Manage resources sustainably (fishing quotas, sustainable farming and forestry).
Evaluating an action means weighing how well it would work against its costs and practicality.
Try this
Q1. Explain how clearing a forest reduces biodiversity. [2]
- Cue. It removes the habitat (food, shelter, breeding sites) that species depend on, so those species decline or disappear, lowering the number of species.
Q2. Explain how burning fossil fuels contributes to a warming climate. [2]
- Cue. It releases carbon dioxide, a greenhouse gas that traps heat in the atmosphere; more carbon dioxide traps more heat, raising global temperatures (the enhanced greenhouse effect).
Exam-style practice questions
Practice questions written in the style of NYSED exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Regents (Life Science sample, 2024)3 marksA graph shows that as a forest is cleared for farmland over 50 years, the number of bird species in the area falls steadily. (a) State the human activity responsible. (b) Explain why clearing the forest reduces the number of bird species. (c) Suggest one action that could reduce this loss of biodiversity.Show worked answer →
A 3-point constructed-response item assessing cause and effect and analyzing data.
(a) 1 point: habitat destruction (deforestation / clearing land for farming).
(b) 1 point: clearing the forest removes the birds' habitat (nesting sites, food and shelter), so species that depend on the forest decline or disappear, reducing biodiversity.
(c) 1 point: any reasonable action, for example protecting or restoring forest (reforestation), creating protected areas/reserves, or using farming methods that keep some habitat.
Markers reward habitat destruction, loss of habitat reducing species, and a valid conservation action.
Regents (Life Science CR, 2025)2 marksBurning fossil fuels adds carbon dioxide to the atmosphere. (a) Explain how this contributes to the enhanced greenhouse effect and a warming climate. (b) State one way humans can reduce this impact.Show worked answer →
A 2-point item on the enhanced greenhouse effect.
(a) 1 point: carbon dioxide is a greenhouse gas that traps heat in the atmosphere; adding more by burning fossil fuels traps more heat, raising global temperatures (the enhanced greenhouse effect).
(b) 1 point: any valid action, for example using renewable energy instead of fossil fuels, improving energy efficiency, or protecting and planting forests that absorb carbon dioxide.
Markers reward carbon dioxide trapping heat and a valid mitigation action.
Related dot points
- Explain what biodiversity is, why genetic and species diversity matter for the resilience of populations and ecosystems, and how human activity threatens it (NYSSLS LS4, stability and change; cause and effect).
A NYSSLS-level answer on biodiversity for the New York Life Science: Biology Regents: what biodiversity is, why genetic and species diversity make populations and ecosystems more resilient, and how human activity threatens it.
- Describe the levels of ecological organization (organism, population, community, ecosystem) and the roles of biotic and abiotic factors and the producers, consumers and decomposers within an ecosystem (NYSSLS LS2, systems and system models; structure and function).
A NYSSLS-level answer on ecosystem structure for the New York Life Science: Biology Regents: the levels of ecological organization, biotic and abiotic factors, and the roles of producers, consumers and decomposers.
- Explain how energy flows one way through food chains and webs and is lost at each trophic level, and how matter (carbon and nitrogen) cycles through an ecosystem (NYSSLS LS2, energy and matter; using mathematics).
A NYSSLS-level answer on energy flow for the New York Life Science: Biology Regents: food chains and webs, trophic levels and the energy pyramid, why energy is lost at each level, and how carbon and nitrogen cycle through an ecosystem.
- Explain how populations grow and how limiting factors and carrying capacity control population size, interpreting population-growth graphs (NYSSLS LS2, stability and change; analyzing data).
A NYSSLS-level answer on population dynamics for the New York Life Science: Biology Regents: how populations grow, the limiting factors that control them, carrying capacity, and how to interpret population-growth graphs.
- Explain how new species form when populations become reproductively isolated and diverge, and how environmental change can lead to extinction (NYSSLS LS4, cause and effect; stability and change).
A NYSSLS-level answer on speciation and extinction for the New York Life Science: Biology Regents: how reproductive isolation and divergence form new species, and how environmental change and a poor match of traits lead to extinction.
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)