B 4.2 Ecological Niches

What is an ecological niche?

The unique role a species plays involving biotic and abiotic factors.

What determines an organism’s habitat?

Its tolerance range for abiotic factors like temperature, salinity, and oxygen.

How do species reduce competition?

by changing how they live and what resources they use

How do interactions with other species influence niches?

Other species shape how a creature lives by providing help, protection, or essential supplies.

Why is a niche multi‑dimensional?

All niche requirements must be met for survival, growth, and reproduction.

What is a fundamental niche?

The full range of conditions a species can tolerate without competitors.

What is a realized niche?

A realized niche is the actual lifestyle a species lives when forced to share space and resources with rivals.

What happens when fundamental niches overlap?

Competitive exclusion.

What are two outcomes of competitive exclusion?

One species is excluded OR both have smaller realized niches.

Can a realized niche ever be larger than a fundamental niche?

no

What are obligate aerobes?

Organisms needing continuous oxygen.

What are facultative anaerobes?

Organisms that use oxygen if available but can live without it.

What are obligate anaerobes?

Organisms killed by oxygen.

Where do aerobes and anaerobes position themselves in a tube?

Aerobes at oxygen‑rich surface; anaerobes at anoxic bottom.

Which domains perform photosynthesis?

Eukaryotes (plants, algae) and cyanobacteria.

What is heterotrophic nutrition?

Obtaining food by ingestion.

What is autotrophic nutrition?

Producing food internally (e.g., photosynthesis).

What is a mixotroph?

An organism that can be both heterotrophic and autotrophic (e.g., Euglena).

What is holic nutrition?

Ingestion → digestion → absorption → assimilation → egestion.

What is saprotrophic nutrition?

External digestion via enzymes, then absorption.

Why are saprotrophs important?

They act as decomposers.

What is assimilation?

Using digested molecules to build micro‑ and macromolecules.

What makes archaea nutritionally diverse?

They use phototrophy, chemotrophy, or heterotrophy.

Do phototrophic archaea perform photosynthesis?

No — they absorb light but do not use chlorophyll.

What tooth adaptations do herbivorous primates have?

Large, flat molars for grinding vegetation.

What tooth adaptations do omnivorous primates have?

Flat molars plus sharp incisors/canines.

What are two herbivore mouthpart adaptations?

Tubes for sucking sap; jaws for chewing leaves.

What are two plant defenses?

Physical defenses (spines) and chemical toxins.

Why do some herbivores produce antitoxins?

To detoxify plant chemicals in an evolutionary arms race.

Give examples of predator and prey adaptations.

Predator: venom, sharp teeth, hunting behavior. Prey: camouflage, warning colors, schooling.