Ecological Niches Review

What is a niche?

The functional position and role of an organism within its environment.

What 2 factors does a niche consist of?

All abiotic and biotic interactions that contribute to an organism's survival.

What are the 2 components of an ecological niche?

Abiotic and biotic.

What is the abiotic component of an ecological niche?

The habitat and associated resources (sunlight, temperature, oxygen levels, etc.).

What is the biotic component of an ecological niche?

An organism's activity patterns and interactions (mode of nutrition, competition).

Are niches unique?

Yes, because if they are not, it leads to direct competition for space and resources.

Can 2 species share the exact same niche? Why?

No, it leads to a struggle for survival (down fitness).

What would competition within a niche lead to?

Competitive exclusion and resource partitioning.

What is competitive exclusion?

One species will use the resources more efficiently and drive the other species towards local extinction.

What is resource partitioning?

Both species will alter their usage of the habitat to divide the available resources between them.

Because of competition, species may not be able to do what with their potential niche?

occupy the entirety of their potential niche

What is a fundamental niche?

The entire set of conditions under which an organism can survive and reproduce (where it could live).

What does the fundamental niche represent?

The theoretical habitat where an organism could live.

What is a realised niche?

The set of conditions utilised by an organism after interactions with all other species (actual habitat).

What does the realised niche represent?

The actual habitat where an organism lives.

What are 2 ways of finding an organism's niche?

By its method of respiration and how it gets its food for metabolism.

What must all organisms do?

Respire to make ATP.

What are obligate anaerobes?

Organisms that respire anaerobically and cannot survive in the presence of oxygen.

What is 1 example of obligate anaerobes?

Intestinal bacteria.

What are obligate aerobes?

Organisms that respire aerobically and cannot survive in the absence of oxygen.

What are 2 examples of obligate aerobes?

Almost all animals and fungi.

What are facultative anaerobes?

Organisms that tolerate the presence or absence of oxygen by using either form of respiration.

What is an example of facultative anaerobes?

Yeast.

What are the 2 forms of nutrition?

Autotrophic and heterotrophic.

What is autotrophic nutrition?

The process of synthesising organic compounds (food) from inorganic substances (e.g., CO2, H2O).

What is heterotrophic nutrition?

Using carbon compounds obtained from feeding on other organisms to synthesise the organic molecules needed.

What are the 2 branches of autotrophic nutrition?

Photosynthesis and chemosynthesis.

What are the 2 branches of heterotrophic nutrition?

Holozoic and saprotrophic.

What is photosynthesis?

The use of energy from the absorption of light to synthesize food.

What is chemosynthesis?

The use of energy from chemical reactions to synthesize food.

What is holozoic nutrition?

A type of heterotrophy that consumes food and breaks down organic material internally.

What is saprotrophic nutrition?

A type of heterotroph that secretes enzymes to break down organic material externally.

What do most autotrophs undergo?

Photosynthesis.

What are the 3 examples of photosynthetic autotrophs?

All plants, most algae, and certain bacteria.

What are the 3 steps of holozoic nutrition?

Food is ingested, digested internally, absorbed and assimilated.

What are the 3 types of organisms that are heterotrophic holozoic?

Consumers, scavengers, and detritivores.

What do scavengers feed on?

Carrion.

What do consumers feed on?

Living organisms.

What do detritivores feed on?

Detritus.

What are saprotrophs usually referred to as?

Decomposers.

What 3 organisms do saprotrophs include?

Bacteria, fungi, and moulds.

What are mixotrophs?

Organisms that use both autotrophic and heterotrophic nutrition.

What are the 2 types of mixotrophs?

Obligate mixotrophs and facultative mixotrophs.

What is an obligate mixotroph?

An organism that must use both forms of nutrition.

What are facultative mixotrophs?

Organisms able to survive using only one form of nutrition.

What are 3 examples of mixotrophs?

Euglena, dinoflagellates, and coral.

What is Euglena?

A fresh water protist.

How is Euglena mixotrophic?

It contains chlorophyll (autotrophic) and feeds on detritus (heterotrophic).

What are dinoflagellates?

Mixotrophic marine plankton.

How is coral mixotrophic?

It makes organic compounds via symbiotic algae.

How are Venus fly traps mixotrophic?

They feed on small insects as a source of nutrients in waterlogged soil (low nitrogen availability).

Are Archaea metabolically diverse?

Yes.

What are the 4 kinds of nutrition for Archaea?

Phototrophs, lithotrophs, organotrophs, and methanogens.

What are phototrophs?

Organisms that convert light to ATP.

What are lithotrophs?

Organisms that convert inorganic substances to ATP.

What are organotrophs?

Organisms that convert organic substances to ATP.

What are methanogens?

Organisms that produce methane as a byproduct.

How do lianas have an adaptation to max capacity to absorb sunlight?

rooted in soil originally and grow woody vines may use tree trunks to climb towards the light

How do plants in the overstory max capacity to absorb sunlight

emergent trees extend above forest canopy

How do plants in the understory max capacity to absorb sunlight?

possess larger leaves

How do strangler epiphytes have an adaptation to max capacity to absorb sunlight?

grow on the branches of other plants, then grow roots down to the soil

What are two plant defenses against herbivores?

Spines/thorns act as a physical deterrent; leaves contain poison and bitter compounds.

What are the four adaptations of herbivores against plant defenses?

Specialized mouthparts (mandibles) for feeding, gut flora of ruminants possess enzymes to digest plant sugars, ability to metabolize plant toxins, animals have specific teeth (molars) for grinding.

What are three adaptations prey have against carnivores?

Tough exoskeletons or shells, camouflage or mimicry, certain behaviors to avoid predation (like feigning death).

What are three adaptations predators have against prey adaptations?

Pointed teeth and sharp claws, neurotoxins and venoms, certain behaviors that aid predation like hunting in packs.

What does dentition infer about diets?

It indicates the type of plant or animal matter consumed.

What does the dentition look like for herbivores?

Broader jaw muscles, larger premolars, thicker enamel for grinding through vegetation.

What does the dentition look like for carnivores?

Narrow jaws, small teeth with tightly packed incisors, canines for cutting softer meat.

What does a comparison of dentition in human fossils show?

A clear shift towards smaller jaws in Homo fossils due to a higher proportion of meat in the diet (ex: Paranthropus (older) have a larger jaw than Homo fossils)

What are the two types of energy systems?

Open systems and closed systems.

What do open systems do?

Exchange both energy and matter with their surroundings.

What do closed systems do?

Exchange energy but not matter with their surroundings.

What type of system are ecosystems?

Open systems.

What does an ecosystem consist of?

All interactions between a group of organisms and their environment.

What does each ecosystem require to sustain life?

Energy, primarily from sunlight.

What is the principal source of energy for almost all ecosystems?

Sunlight, which is converted to stored chemical energy.

What does photosynthesis use sunlight for?

To convert light energy into chemical energy.

What does cellular respiration do with stored chemical energy?

Releases it for use by living organisms.

What are the sources of energy for communities that cannot use sunlight?

These communities are in the deep sea and underground caves. They derive energy by oxidizing inorganic molecules.

What are photoautotrophs?

Organisms that convert light energy to chemical energy via photosynthesis.

Where is chemical energy stored in photoautotrophs?

In organic carbon compounds.

Some phototrophs convert light to chemical energy without…

synthesizing carbon compounds

What's the difference between phototrophs that don't make carbon compounds and photoautotrophs?

they don't undergo photosynthesis and gain organic compounds via feeding

What are chemoautotrophs?

Organisms that derive energy from oxidation reactions involving inorganic compounds.

What are four examples of inorganic compounds used by chemoautotrophs?

Ammonia, hydrogen gas, hydrogen sulfide, iron oxide.

Where are chemoautotrophs typically located?

In environments where no light can penetrate, such as deep sea or underground.

Example of a chemoautotrophic organism

Iron-oxidising soil bacteria

What do oxidation reactions involve?

The release of high energy electrons from inorganic molecules.

What do chemoautotrophs use energy from oxidation reactions for?

To synthesize organic compounds.

What is cellular respiration?

How living organisms release energy from organic compounds.

How is the energy from cellular respiration released?

By oxidation reactions; it's transferred to coenzyme ATP

What does the complete breakdown of organic compounds require - to do what?

oxygen for higher yield of ATP

What is a trophic level?

The relative position of an organism in a feeding sequence.

What are the four levels of the food chain?

Producer, primary consumer, secondary consumer, tertiary consumer.

Where do autotrophs get their energy from?

Sunlight and oxidation reactions.

Why are autotrophs called producers?

They make their own organic compounds without relying on other organisms.

What organisms are included in producers?

All plants, most algae, and some bacteria.

What are consumers?

Heterotrophs that feed by internal digestion.

What level of the food chain do consumers occupy?

All but the first level.

What do herbivores feed on?

Vegetation.