How do scientists define science?

a systematic way of learning about the natural world through observation, experimentation, evidence, and logical reasoning.

What makes science objective and self-correcting?

relies on measurable evidence rather than personal opinions. It is self-correcting because experiments can be repeated, results are peer-reviewed, and new evidence can revise or replace old ideas.

How does science rely on evidence and testable hypotheses?

Scientific claims must be supported by observable, measurable evidence. Hypotheses must be testable and falsifiable, meaning experiments or observations could show them to be wrong.

What did Newton mean by 'standing on the shoulders of giants'?

Isaac Newton meant that scientific progress builds on the discoveries and knowledge of earlier scientists. New ideas develop from past work rather than appearing independently.

What is a hypothesis? How is it different from just an idea?

a specific, testable explanation for an observation. Unlike a general idea, a hypothesis must be measurable and capable of being tested through experiments.

What makes a hypothesis testable?

It must be falsifiable, meaning there is a possible experiment or observation that could prove it wrong.

Why can we never 'prove' a hypothesis right, only disprove it?

Future evidence could always contradict current findings. Science works by eliminating incorrect explanations rather than declaring absolute proof.

What are the steps of the Scientific Method?

Make observations, Ask a question, Form a hypothesis, Conduct experiments, Analyze data, Draw conclusions, Communicate results

What does scientific literacy mean?

the ability to understand scientific concepts, evaluate evidence, and make informed decisions based on data.

Why is scientific literacy important for citizenship, politics, and economics?

helps people evaluate policies on issues like climate change, healthcare, and technology. In economics and politics, informed citizens can better assess evidence rather than misinformation.

How can pseudoscience influence policy if people lack scientific literacy?

Without scientific literacy, people may accept claims that lack evidence, leading to poor policy decisions based on misinformation.

How does the meaning of the word theory in science differ from everyday use?

In everyday language, a theory may mean a guess. In science, a theory is a well-tested, evidence-supported explanation of natural phenomena.

What makes a scientific theory strong?

It is supported by extensive evidence, has survived repeated testing, makes accurate predictions, and can be falsified.

What is a model? Why are all models simplifications?

A representation of an object, system, or process used to explain or predict behavior. Models simplify reality because including every detail would make them too complex to use.

What makes a model 'useful' even if it is not perfect?

A model is useful if it explains observations, predicts outcomes accurately, and helps scientists understand complex systems.

What are some examples of scientific models (solar system, sea level change)?

The solar system model, Climate models predicting sea level rise, The water cycle model, Atomic models

Why is some degree of uncertainty inherent to the process of science?

Measurements have limits, natural systems are complex, and new evidence can change conclusions. Absolute certainty is rarely possible.

How does repeated experimentation reduce uncertainty, and why do we approach an asymptotic 'line of fact' rather than absolute proof?

Repeated experiments refine results and reduce errors. Over time, evidence increasingly supports certain explanations, bringing us closer to reliable conclusions — but never absolute proof.

What is the biosphere?

The biosphere is the global sum of all ecosystems — all regions of Earth where life exists (land, water, and atmosphere).

How do biotic vs. abiotic factors influence where species live?

Biotic factors (living things like predators, competitors, food sources) and abiotic factors (temperature, water, sunlight, soil) determine whether a species can survive in an area.

How does the unequal distribution of solar radiation across the globe shape temperature patterns and in turn the distribution of biomes?

The equator receives more direct sunlight, creating warmer climates, while the poles receive less direct sunlight, creating colder climates. These temperature differences influence biome distribution.

How do air circulation patterns create wet and dry regions (e.g., tropics vs. deserts)?

Warm air rises at the equator, cools, and releases moisture, creating rainy tropical regions. Dry air descends around 30° latitude, leading to desert formation.

What causes seasonality and how does it change environmental conditions?

Seasonality is driven primarily by Earth’s axial tilt, and it reshapes environmental conditions by altering sunlight, temperature, precipitation, and biological activity throughout the year.

How do mountains and elevation influence climate (rain shadow effect, temperature drop)?

Mountains and elevation influence climate because rising air cools and loses moisture on the windward side while creating a dry rain shadow on the leeward side.

What is the difference between climate and weather?

Weather is the short‑term state of the atmosphere, while climate is the long‑term pattern of those conditions.

How do environmental pressures like temperature and water availability drive adaptation?

Environmental pressures like temperature and water availability drive adaptation by favoring traits that improve survival and reproduction under those specific conditions.

Can you think of examples of convergent evolution in different biomes (e.g., desert plants like cacti vs. euphroes)?

Convergent evolution occurs when unrelated species—such as cacti in the Americas and euphorbias in Africa—independently evolve similar drought‑resistant forms in similar biomes.

List some animal adaptations to different biomes?

thick fur in tundra species, water‑storage and nocturnal behavior in desert animals, and streamlined bodies in aquatic species.

What is a population?

A population is a group of individuals of the same species living in the same area at the same time.

What factors influence changes in population size?

births, deaths, immigration and emigration, also recourses and diseases/.

What does the equation ΔN = B + I – D – E represent?

population size change; Birth, immigrants, deaths, emigrants

How does exponential growth differ from linear growth?

What does the equation ΔNt = rNt describe?

exponential growth

How does the logistic growth model (ΔN = rNt (1 − N/K)) differ from exponential?

Exponential growth it increases at a constant percentage rate over time

What is carrying capacity (K) and what happens if a population overshoots it?

the maximum population size of a species that an environment can sustain

What’s the difference between density-dependent and density-independent factors?

Density-dependent factors affect populations based on their size, while density-independent factors impact populations regardless of size.

How do predator–prey cycles illustrate population limits?

demonstrate how populations of predators and prey interact and influence each other's growth. In general, as predator numbers increase, the prey population declines, leading to a decrease in predators.

Compare r-selected vs. K-selected species. What traits make them different?

R-selected species produce many offspring with minimal parental care, often maturing quickly and having short lifespans, thriving in unstable environments. K-selected species produce fewer offspring with significant parental care, mature slowly, and have longer lifespans, thriving in stable environments.

What are the three types of survivorship curves? What do they mean for life history?

Type I, II, and III survivorship curves describe whether most individuals survive to old age, die at a constant rate, or experience high early mortality, and each pattern reflects a species’ life‑history strategy such as investing heavily in few offspring or producing many with low survival.

What does the age structure of a population tell us about future growth?

A population’s age structure shows whether it has many young individuals who can drive rapid future growth or a larger older cohort that signals slower growth or potential decline, because the proportion of people in reproductive ages strongly shapes birth rates and long‑term population trends.

What are some social/economic issues related to differences in population age structure

create social and economic challenges because countries with many young people must invest heavily in education, jobs, and childcare, while aging populations face rising healthcare costs, pension pressures, and shrinking workforces. These imbalances shape dependency ratios, influence economic growth potential, and determine how societies allocate resources across generations.

How has human population size changed historically?

size remained relatively low and grew slowly for most of history, then surged rapidly over the past few centuries with agriculture, industrialization, and modern medicine driving exponential increases.

What are the possible consequences of continued human growth (resources, environment, sustainability)?

increases demand for food, water, land, and energy, which accelerates resource depletion, pollution, habitat loss, and climate pressures

What is an ecological community?

a group of different species that live together and interact within the same geographic area.

What are the main types of interspecific interactions and how are they represented with signs (e.g., predation (+, -)?

include predation (+/–), parasitism (+/–), mutualism (+/+), commensalism (+/0), and competition (–/–), each describing how two species affect one another. These sign pairs show whether each species benefits, is harmed, or is unaffected in the interaction.

How do competition and resource partitioning relate to the competitive exclusion principle?

Competition forces species with overlapping niches to either exclude one another or reduce conflict, and resource partitioning is the mechanism that allows coexistence by dividing resources in ways that avoid violating the competitive exclusion principle, which states that two species cannot occupy the same niche indefinitely.

What is an ecological niche?

An ecological niche is the role a species plays in its environment, including how it uses resources, interacts with other organisms, and responds to environmental conditions.

How do organisms defend themselves? (e.g. camouflage, aposematism)

defend themselves through camouflage, which helps them blend into their surroundings to avoid detection, and aposematism, which uses bright warning colors to signal toxicity,

How do food chains differ from food webs?

A food chain shows a single, linear pathway of energy flow, while a food web shows multiple interconnected feeding relationships within an ecosystem.

What are the trophic levels?

the positions organisms occupy in a food chain or food web, arranged from energy‑capturing producers at the base to various levels of consumers and finally decomposers.

What role do decomposers and detritivores play in ecosystems?

recycle dead organic matter, breaking it down and returning nutrients to the environment so ecosystems remain balanced and productive.

What is a trophic cascade? Can you give an example?

when something is removed and then added, aka When wolves were removed from Yellowstone, elk populations grew and overgrazed vegetation; when wolves were reintroduced, elk behavior and numbers changed

What does the energetic hypothesis say about food chain length?

that food chains stay short because energy is lost at each trophic transfer, limiting how many levels an ecosystem can support.

How does the energetic hypothesis explain the shape of a trophic pyramid?

How do bottom-up control and top-down control differ?

What are the three levels of biodiversity?

Why is biodiversity important for ecosystems and humans?

How is biodiversity measured?

What are foundational species, keystone species, and ecosystem engineers? How do they shape communities?

What is the difference between primary succession and secondary succession?

What is pioneer species vs those in a climax community?

How does the intermediate disturbance hypothesis explain biodiversity patterns?

What is an ecosystem, and how do biotic and abiotic factors interact?

Explain the difference between energy flow and nutrient cycling.

Define a system and explain what is meant by emergent properties.

Describe the difference between positive and negative feedback loops and give one ecological example of each.

Explain the concept of homeostasis in ecological systems.

Define energy and distinguish between kinetic and potential energy.

Explain the First and Second Laws of Thermodynamics and their ecological implications.

Describe how energy moves through trophic levels (producers → consumers → decomposers).

How is the sun's energy captured by plants?

Explain the 10% rule and how it limits the number of trophic levels.

Describe the Law of Conservation of Matter and how it applies to ecosystems.

Identify the major elements important to life and explain why they are important.

Explain the role of decomposers in recycling nutrients.

Describe how human activity can disrupt natural nutrient cycles.

Describe how water moves through the environment.

Explain how solar energy drives the cycle.

Explain how carbon moves between the atmosphere, biosphere, oceans, and geosphere.

Identify key processes: photosynthesis, respiration, decomposition, and combustion.

captures carbon from the atmosphere into organic molecules, while respiration releases CO₂ back as organisms break down those molecules for energy.

Define a carbon sink and describe examples.

any natural system that absorbs more carbon from the atmosphere than it releases, helping regulate Earth’s climate. Forests, oceans, and soils are major examples

Explain how human activities (e.g., fossil fuel burning, deforestation) alter the carbon cycle.

burning fossil fuels and deforestation alter the carbon cycle by releasing large amounts of carbon dioxide into the atmosphere and reducing the number of trees that can absorb it, which intensifies the greenhouse effect

Describe the link between increased CO₂ and climate change.

Increased CO₂ traps more heat in the atmosphere, strengthening the greenhouse effect and driving global warming that alters temperatures, weather patterns, and climate systems.

Explain how fertilizers and agriculture contribute to eutrophication and dead zones.

Fertilizers and agricultural runoff add excess nitrogen and phosphorus to waterways, causing rapid algal growth that depletes oxygen as the algae die and decompose, creating hypoxic dead zones where most aquatic life cannot survive.

Describe natural sources of sulfur (volcanoes, weathering, seafloor vents)

include **volcanoes**, which emit sulfur-rich gases; **weathering of sulfur‑containing rocks**, which releases sulfate into soils and water; and **seafloor hydrothermal vents**, which discharge sulfur compounds into the ocean.

Describe how burning fossil fuels contributes to acid rain.

releases sulfur dioxide (SO₂) and nitrogen oxides (NOₓ), which react with water vapor in the atmosphere to form sulfuric and nitric acids that fall as acid rain