AP Biology Unit 3.2

Why do organisms need energy?

To organize

Does energy cycle or flow?

Energy flows—it enters and exits the system but does not cycle.

Does matter cycle or flow?

Matter cycles—it moves between organisms and the environment but stays within the ecosystem.

What elements are essential for building macromolecules?

Carbon

What happens when an organism has a net gain of energy?

It stores energy and grows.

What happens when an organism has a net loss of energy?

It loses mass and may die.

What is an autotroph?

An organism that uses CO2 to build organic compounds using environmental energy.

What is a photoautotroph?

An autotroph that captures light energy to perform photosynthesis.

What is a chemoautotroph?

A prokaryote that uses inorganic molecules for energy and performs chemosynthesis.

What is a heterotroph?

An organism that consumes organic compounds produced by other organisms.

What are examples of heterotrophs?

Herbivores

What is the difference between detritivores and decomposers?

Detritivores ingest decomposing matter; decomposers break it down chemically.

What is an r-selected species?

Species that produce many offspring with low survival rates.

What is a K-selected species?

Species that produce few offspring with high survival rates.

What is the benefit of alternating between asexual and sexual reproduction?

It allows organisms to respond to changes in energy availability.

What are examples of organisms that alternate reproduction methods?

Jellyfish and sponges.

What are the three plant life cycles?

Annuals

What is an annual plant?

A plant that completes its life cycle in one growing season.

What is a biennial plant?

A plant that blooms in its second year.

What is a perennial plant?

A plant that lives and blooms for multiple years.

What is metabolism?

The set of life-sustaining chemical reactions in cells and organs.

How do endotherms regulate body temperature?

They use metabolic heat from cellular respiration.

How do ectotherms regulate body temperature?

They rely on external sources and behavioral changes.

What is the difference in food intake between endotherms and ectotherms?

Endotherms eat more often to produce heat; ectotherms eat less.

What is a food chain?

A single path of energy flow through an ecosystem.

What is a food web?

A complex network showing multiple energy paths and organism interdependence.

What is a trophic level?

A feeding level in a food chain (e.g.

What is primary productivity?

The rate at which producers capture and store energy.

What is the 10% rule?

Only ~10% of energy is transferred to the next trophic level.

What does an ecological pyramid show?

The flow of energy

Which pyramid level has the most energy?

Producers.

Which pyramid level has the least biomass?

Top carnivores.

What is a biogeochemical cycle?

The movement of nutrients between living and nonliving components.

What are reservoirs?

Places where elements are stored long-term.

What are the major processes in the water cycle?

Precipitation

What are the major reservoirs in the water cycle?

Oceans

What are the major processes in the carbon cycle?

Photosynthesis

What are the major reservoirs in the carbon cycle?

Atmosphere

What are the major processes in the nitrogen cycle?

Fixation

What are the major reservoirs in the nitrogen cycle?

Atmosphere

What are the major processes in the phosphorus cycle?

Weathering

What is unique about the phosphorus cycle?

It has no atmospheric component.

Which macromolecules need carbon?

Carbohydrates

Which macromolecules need nitrogen?

Proteins

Which macromolecules need phosphorus?

Nucleic acids

What returns nutrients to the soil?

Decomposers.

What cannot be recycled in an ecosystem?

Energy.

What is the biggest difference between energy and nutrient flow?

Nutrients are recycled; energy is not.

How do plants contribute to the carbon cycle?

They absorb CO2 during photosynthesis and release it during respiration.