IB Biology, Option C1, Species and Communities

Define ecosystem

All living organisms (biotic factors) in a given area along with their abiotic factors

Define habitat

Where a species lives

Define and give examples of abiotic factors

Non living elements of an ecosystem (temperature, water availability, light intensity, soil pH, soil salinity, available space)

Define and give examples of biotic factors

Living elements of an ecosystem (amount / type of predators, disease, parasites, competitors, predators, available prey)

Define limiting factor

Any factor which controls or limits population size of a species

What 2 things do organisms act as?

Energy sources, competitors

What 5 factors determine a species' optimal habitat?

SSWAF

Shelter, Space, Water, Air-content, Food

Define community

A group of populations living together in a habitat

Give an example of a predator and it's prey

The fox and the snow shoe hare

What needs to be maintained to sustain population?

Lower predator number than prey number (predator n° < prey n°)

What two characteristics do samples need to have to give reliable population analysis?

Random and representative

What 4 things does method of gathering population data depend on?

Desired accuracy, organism type, area size, available time

What can be used to estimate population size of a species?

Quadrats

Define transect

A line across a habitat followed to observe number of organisms at regular intervals

What is a belt transect?

A transect with quadrats at regular intervals

What to belt transects measure?

Percentage cover of organisms

What can line transects be used for?

Examining effects of habitat change on biodiversity

What affects organism distribution?

Presence of biotic and abiotic factors

What do kite diagram show?

Abundance of different organisms in a landscape, helping identify the impacts that biotic and abiotic factors have on each other in a particular ecosystem

Define niche

The unique/specific role of a species including habitat, community, interaction and abiotic factors

Define fundamental niche

Where a species could live

Define actualised niche

Where a species actually lives due to competition

Give an example of two species in an actualised niche

The small barnacle can live anywhere on a rock surface. The large barnacle can only live on one part of the rock surface, competing with the small barnacle by restricting its living area.

Give an example of two organisms struggling to live in the same niche

Two species of paramecium may fight over a niche. One wins, leading to decline of the other or narrowing the niche.

Define symbiosis

Different species depending on each other for survival in a symbiotic relationship

Outline the symbiotic relationship of coral and zooxanthellae algae

Algae:

- removes coral waste

- provides glucose, glycerol and amino acids (products of photosynthesis)

- produces oxygen for coral

Coral:

- protects algae

- provides compounds for photosynthesis

- produces proteins, fats, carbohydrates, and calcium carbonate

Define mutualistic relationship

Both organisms gain through associated living

Define herbivory relationship

Primary consumer eats plant / algae

Define parasitic relationship (parasitism)

An organism kills or harms another by feeding off it

Define predatory relationship (predation)

One organism feeds off another

Define commensalism

One organism benefits off an unaffected one

Define keystone species

A species with a disproportionate effect on a community through both biotic and abiotic factors, ensuring the survival of many other species and preventing collapse or drastic change of an ecosystem

Give an example of keystone species

The sea otter eat sea urchins which consume seaweed. This keeps the seaweed population healthy for other organisms.