Biology - Ecology terms

IB Biology ecology terms

Properties of oxygen

Present as a diatomic molecule, very reactive, is the basis of a majority of biological respiratory processes

Why can’t anaerobic microbes survive in oxygen?

They do not have the required enzymes to detoxify oxygen radicals.

End with -ase

Enzymes

Superoxide dismutase

An enzyme that transforms oxygen radicals into Water and Oxygen

Catalase

An enzyme that breaks down Hydrogen peroxide to Water and Oxygen
H2O2 - H2O + O2

Thermophiles

Organisms that thrive in areas with high temperatures

Aerobic respiration

Respiration that requires oxygen to break down glucose

Anaerobic respiration

Respiration that does not use oxygen as an electron carrier

Thioglycolate broth

Medium of growth for bacterium that is rich in glycolates

Microaerophiles

Aerobes that produce ATP via aerobic respiration / fermentation. Requires between 5 - 15% atmospheric oxygen for growth

Aerotolerant Anaerobe

Produces ATP via anaerobic respiration, and can conduct fermentation. O2 can be present, but is not used for respiration.

Autotrophs

Organisms that produce their own food through photosynthesis or chemosynthesis

Heterotrophs

Organisms that cannot make their own food and rely on other organisms (plants and animals) for nutrition

Oxygen radicals

Molecules containing oxygen that have 1 unpaired valence electron - very reactive

Halophiles

Organisms that thrive in areas with high salinity

Decomposers

Organisms that feed off of dead matter, and help break down organic into their basic chemical compositions

Ecosystem

The culmination of abiotic and biotic factors working in tandem to make a community of living organisms.

Habitat

A geological area with biotic and abiotic factors suited to an organism’s traits

Niche

What the organism’s role in an ecosystem is

Fundamental niche

An organism’s predicted role in an ecosystem - what it ideally would occupy

Realised niche

The role that an organism actually occupies in any given ecosystem / community

Specialist species

Species that are reliant on specific biotic or abiotic factors

Generalist species

Species that have no preference, and are adapted to suit a majority of biotic / abiotic factors.

Adaptive radiation

When a speciation occurs, species from a common ancestor start divulging in variety, and more and more different variants appear.

Range of tolerance

The measurement of intensity in abiotic factors before the species is unable to survive.

Obligate anaerobes

Prokaryotic organisms that are poisoned by O2 and use fermentation / anaerobic respiration

Obligate aerobes

Prokaryotic organisms that require O2 for cellular respiration.

Facultative anarerobes

Uses both aerobic and anaerobic respiration - prefers aerobic respiration.

Types of nutrition

Autotrophic (Photosynthesis, Chemosynthesis), Heterotrophic (Holozoic, Saprotrophic, Parasitic)

Photosynthetic nutrition

Production of ATP through photons from light

Holozoic nutrition

Nutrition taken into the organism, and internally digested

Mixotrophic

Can use either autotrophic or heterotrophic methods of nutrition intake

Saprotrophic

Organisms that externally secrete enzymes to digest food, then take in the broken down molecules - Feeds on organic matter

Competitive exclusion principle - Gause’s law

If two species occupy the same niche, one species will eventually outcompete the other, and the other will die off

Niche partitioning

When two species occupy the same niche, but have evolved to occupy different areas and can co-exist

Spatial niche partitioning

Organisms live in the same niche, but different space

Temporal niche partitioning

Organisms live in the same niche, but are active at different times - different mice are awake during different times of the day.

Species pool

The total amount of species in any given area

Species sorting

The distribution of a species is dependent on the biotic and abiotic factors of an ecosystem

Intraspecies

Inside a species

Interspecies

Between species

What information do niche relationships provide?

Community structure: Total community niche space, Niche overlap, and Niche breadth of individual species

Characteristics of high species diversity

Lots of species due to weaker competition and lots of resources.

Ecological equivalents

Species that live in different geographic locations but have the same ecological niche

Species exclusion

When two species coexist, one species is always better adapted, and will lead to the other one dying out

How do species control competitors?

Avoidance or Predation

What happens in separate niches?

Species do not interfere with each other

What happens in slightly overlapping niches?

Niche partitioning and competition

What happens in slightly overlapping niches after niche partitioning?

Less competition, speciation into two separate niches

What happens when niches overlap too much?

Gause’s law / Competitive exclusion principle occurs - one species dies out.

Outcomes of competitive exclusion

One species goes extinct, and/or niche is divided, and species divulges further.

Total exclusion

When species A has a bigger niche than species B - leads to A being generalist and B being specialist

Competitive release

Species expands their niches in response to removal of a competitor

Detrivores

Organisms that feed on detritus - organic matter like soil.

Osmotrophy

Taking up dissolved substances

Phagotrophic

Engulfing bacteria and other cells as particulate prey

Auxotrophic

Algae that are unable to synthesize essential components such as the vitamins of the B12 complex / fatty acids and must import them

Types of herbivores

Grazers, Browsers, Granivores, Frugivores, Nectivores, Phloem feeders

Grazers

Herbivores that feed on leaf tissue

Browsers

Herbivores that feed on wood tissue

Granivores

Herbivores that feed on seeds

Frugivores

Herbivores that feed on fruit

Nectivores

Herbivores that feed on nectar

Phloem feeders

Herbivores that feed on sap

Plant apparency

Plants avoid herbivory by decreasing apparency in spatial / temporal refuges

Endophytes

Symbiotic plant prokaryotes

Elemental defenses

Inorganic chemical defences that must be concentrated from environment

Positive tropism

Movement of a plant towards a stimulus

Negative tropism

Movement of a plant away from a stimulus

Geotropism

Growth in response to gravity

Phototropism

Growht in response to light

Thigmotropism

Growth in response to touch

Thermotropism

Growth in response to heat

Hydrotropism

Growth in response to water

Chemotropism

Growth in response to chemical stimuli

Epiphytes

Commensalistic plants that live on trees

Shade tolerant / avoiding plants

Plants that can / ‘t survive in shade