Introduction to Ecology, Biodiversity & Earth Systems – Lecture Review

A comprehensive set of question-and-answer flashcards covering key concepts from ecology, biodiversity, population dynamics, Earth systems, soil science, and atmospheric science to aid exam preparation.

What does ecology study?

The interactions among living organisms (animals, plants, microbes) and between those organisms and their physical environment.

Define an ecosystem.

A community of living organisms interacting with each other and with the non-living components (water, air, soil, sunlight) of their environment.

What are the two main components of an ecosystem?

Biotic (living things) and abiotic (non-living factors).

Give three examples of abiotic factors.

Sunlight, water, and soil (also acceptable: air, temperature).

Name the three biotic categories found in an ecosystem.

Producers, consumers, and decomposers.

Which organisms are primary producers and how do they make food?

Plants (and some algae); they manufacture food through photosynthesis using sunlight.

What ecological role do decomposers play?

They break down dead organisms and recycle nutrients back into the ecosystem.

What is an ecological niche?

The specific role, job, or way of life of an organism within its environment, including what it eats, where it lives, and how it behaves.

Differentiate generalist and specialist species.

Generalists can live in many habitats and eat a wide variety of foods, whereas specialists require narrow habitat conditions or specific diets.

Provide one example of a generalist species.

Rat (other acceptable answers: cockroach, human).

Provide one example of a specialist species.

Panda, which feeds almost exclusively on bamboo.

What is symbiosis?

A long-term, close relationship between two different species.

In amensalism, how are the two species affected?

One species is harmed while the other is unaffected.

Describe commensalism.

One species benefits and the other is neither helped nor harmed.

Describe mutualism.

Both species involved receive a benefit.

What happens in parasitism?

One organism (the parasite) benefits at the expense of the host, which is harmed.

Define predation.

A biological interaction where a predator kills and eats its prey.

What is saprotrophism?

A relationship in which organisms (e.g., fungi) feed on decaying organic matter.

List two terrestrial biomes that experience low temperatures.

Tundra and taiga.

Which biome receives high rainfall and supports the greatest species diversity on land?

Rainforest.

What are the two main aquatic biomes?

Freshwater and marine biomes.

Define biodiversity.

The variety of life on Earth, including genetic, species, and ecosystem diversity.

What is genetic diversity?

Variation of genes within a single species.

Explain species diversity.

The number and variety of species present in a particular region.

What is ecosystem diversity?

The variety of ecosystems or habitats within a given area.

Give one reason biodiversity is important for ecosystems.

It increases resilience to disturbances such as storms, disease, or climate change.

Name the four categories of ecosystem services.

Provisioning, regulating, supporting, and cultural services.

Give one example of a provisioning service.

Food (e.g., meat, crops) or timber from forests.

What is a regulating service provided by ecosystems?

Natural pest control or climate regulation.

Identify a natural factor that can reduce biodiversity.

Events such as earthquakes, hurricanes, floods, or wildfires.

List three human activities that threaten biodiversity.

Deforestation, overfishing, and water pollution (others: fossil-fuel burning, industrial agriculture, pesticides, introduction of GMOs).

What is a population bottleneck?

A sharp reduction in the size of a population leading to loss of genetic diversity.

Why are specialist species at higher risk of extinction?

Their narrow diet or habitat requirements make them vulnerable if that resource is lost.

Describe island biogeography in one sentence.

Larger islands closer to the mainland tend to have more species than small, isolated islands.

What does ecological tolerance refer to?

The range of environmental conditions an organism can endure before stress or death occurs.

Differentiate short-term and long-term adaptations.

Short-term adaptations involve behavioral changes (e.g., altering feeding time); long-term adaptations involve physical or physiological changes across generations (e.g., thicker fur in cold climates).

Define a biological population.

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

Contrast r-strategists and k-strategists regarding reproduction speed.

r-strategists reproduce quickly with many offspring; k-strategists reproduce slowly with fewer, well-cared-for offspring.

Which survivorship curve (Type I, II, or III) is typical of humans?

Type I curve (low mortality in early and middle life, higher mortality at old age).

What is carrying capacity (K)?

The maximum population size an environment can sustainably support.

Name two factors that influence carrying capacity.

Availability of food and water (also acceptable: space, sunlight, shelter).

What dispersal pattern shows organisms evenly spaced from each other?

Uniform distribution.

Define biotic potential.

The maximum reproductive capacity of a population under ideal conditions.

Describe a J-curve population growth pattern.

Exponential growth that rises rapidly and then crashes when resources become depleted.

Describe an S-curve population growth pattern.

Growth starts slow, accelerates, and then levels off at carrying capacity.

What is a positive feedback loop in population dynamics?

A process that amplifies changes, such as more individuals leading to more births and further population growth.

Give an example of a density-dependent limiting factor.

Food availability, disease, or competition.

Give an example of a density-independent limiting factor.

Natural disasters like earthquakes or floods.

State the Rule of 70 formula for doubling time.

Doubling time (years) = 70 ÷ annual growth rate (%).

If a country’s growth rate is 2%, how many years will it take for its population to double?

35 years (70 ÷ 2 = 35).

Which age-structure diagram shape indicates a rapidly growing population?

A wide-based pyramid shape.

Define Total Fertility Rate (TFR).

The average number of children a woman is expected to have in her lifetime.

List two factors that can lower a country’s TFR.

Increased access to family planning and higher female education/employment rates.

Name the four major Earth systems.

Lithosphere, atmosphere, hydrosphere, and biosphere.

What plate boundary type creates new crust at the Mid-Atlantic Ridge?

Divergent boundary.

Which plate boundary is responsible for the San Andreas Fault’s earthquakes?

Transform boundary.

List the three primary components of soil.

Minerals, air & water, and organic matter.

What are the ideal percentage proportions of a healthy soil?

45% minerals, 25% air, 25% water, 5% organic matter.

Give two human practices that accelerate soil erosion.

Over-plowing and continuous monoculture (others: overgrazing, deforestation).

Which gas makes up about 78% of Earth’s atmosphere?

Nitrogen.

Which atmospheric layer contains nearly all weather events?

The troposphere.

Why is carbon dioxide considered a greenhouse gas?

It traps heat in the atmosphere, contributing to global warming.

What protective layer in the stratosphere absorbs harmful UV radiation?

The ozone layer.