Habitats and Ecosystems – BIO2 Review

These flashcards cover key concepts from the lecture on habitats, limiting factors, plant and animal adaptations, tolerance ranges, keystone species, trophic control, biomes, and climographs.

What is a habitat?

The environment in which a species normally lives, or the specific location of a living organism.

What is meant by the distribution of a species?

The range of places within its habitat where a species is found.

What are limiting factors?

Ecosystem components that restrict the distribution and numbers of a species’ population.

Which two broad categories can limiting factors be divided into?

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

Give two examples of biotic limiting factors.

Predation and competition for resources (intraspecific or interspecific).

Give three examples of abiotic limiting factors.

Light, temperature, and soil pH (others include salinity, rainfall, wind velocity, etc.).

What is the difference between density-dependent and density-independent limiting factors?

Density-dependent factors vary with population size, whereas density-independent factors affect populations regardless of size.

How do endotherms (homeotherms) and ectotherms (poikilotherms) differ in temperature regulation?

Endotherms regulate their own body temperature and can occupy a wider range of habitats; ectotherms rely on environmental heat sources and have narrower thermal ranges.

Why does body size (surface area : volume ratio) matter for animal temperature tolerance?

A smaller SA:V ratio helps conserve heat, affecting where animals can survive thermally.

Why is territory considered a limiting factor for animals?

Territorial boundaries influence access to mates, food, shelter, and predator avoidance, leading to intra- or interspecific competition.

How can food availability limit animal distribution?

Some animals depend on specific food species or seasonal resources, restricting their range or prompting migrations.

Why do high temperatures threaten plants?

They speed up water loss by evaporation, potentially causing dehydration.

What problem can freezing temperatures cause for plants?

Freezing can expand water in the xylem, splitting trunks; some plants counter this by producing antifreeze proteins.

Why is water availability a critical limiting factor for plants?

Water is needed for photosynthesis and to maintain cell turgor pressure.

What are xerophytes and hydrophytes?

Xerophytes (e.g., cacti) are adapted to dry environments; hydrophytes (e.g., rice) are adapted to waterlogged soils.

How do plants adapt to low light availability?

Low-growing plants often have darker green leaves with more chlorophyll to maximize photosynthesis.

Why does high soil salinity limit most plants?

It can be toxic and makes water uptake via osmosis more difficult.

What are halophytes?

Plants (e.g., mangroves) adapted to tolerate high salinity levels.

State the Law of Tolerance in ecology.

Populations survive best within optimal ranges of a limiting factor, with survival dropping in zones of stress and becoming impossible in zones of intolerance.

Name the three regions of a species’ tolerance curve.

Optimal zone, zones of physiological stress, and zones of intolerance.

List five environmental conditions required for coral reef formation.

Depth

What mutualistic relationship is essential for hard corals?

Hard corals host zooxanthellae algae that photosynthesize and supply nutrients.

Define a keystone species.

An organism that has a disproportionately large effect on its community’s structure and diversity.

What is top-down control in an ecosystem?

Suppression of prey populations or behaviors by higher trophic levels, causing trophic cascades.

What is bottom-up control in an ecosystem?

Limitation of higher trophic levels due to insufficient resources or energy at lower levels.

What is a biome?

A geographical area with a particular climate that supports a specific community of flora and fauna.

What is the biosphere?

The total area on Earth where all living things exist—the sum of all biomes.

Give four examples of major terrestrial biomes.

Tropical rainforest, desert, tundra, and temperate grassland (others include taiga, chaparral, savannah, etc.).

What does a climograph display?

Average temperature and precipitation of a location, revealing its seasonal climate pattern.

How can a climograph help identify a biome?

By comparing a region’s average yearly temperature and rainfall to known biome ranges.