Biology Units 3 and 4

QCE Biology

Biodiversity

The variability among Earth’s living organisms

Ecosystem Biodiversity

Variation between types of ecosystems in a geographical location

Species Biodiversity

The different populations, or species, in a particular ecosystem.

Stability

How well an ecosystem can cope with changes

Genetic Biodiversity

Diversity between organisms of the same species

As biodiversity increases…

Stability increases.

Spatial Comparison

Comparing biodiversity over an area

Temporal comparison

Comparing biodiversity over time

Simpsons Diversity Index (SDI)

A method used to measure the species diversity of ecosystems directly and uses both species richness and abundance.

Species Richness

The number of different species within a particular area

Relative abundance

A measure of number of individuals of a particular species in relation to the total number of individuals of all species in the area, expressed as a percentage

Percentage frequency

A measure of how often a species appears within the quadrats sampled, expressed as a percentage

Percentage cover

Measures the percentage of area covered by a particular organism

Sampling

The process of collecting data about an ecosystem’s features or diversity without surveying or counting everything.

Random Sampling

Where every individual or group has an equal chance of being selected- unbiased so representative of whole area

Bias

When certain features influence data making decisions less objective

Systematic sampling

Selects a sample from a larger population in a structured way- unbiased but uses a repeated sampling pattern

Stratified sampling

Some ecosystems need to take height and depth into account, creating different levels called strata

Strata

Different levels or areas of an ecosystem

Biotic Factor

All living components of an ecosystem that influence it and other organisms within it.

Biotic Factor-Competition

When more than one individual wants the same limited resource.

Interspecific competition

Organisms from different species compete for the same resources

Intraspecific competition

Organisms for the same species compete for the same resources-more common than interspecific competition.

Carrying capacity

The maximum stable population size that can be maintained over a period of time in a habitat

4 Biotic Factors

Food availability, competition for resources, predation, disease

Competitive exclusion principle

Two species cannot occupy the same niche at the same time

Predator

Organism that eats another organism

Prey

An organism that is hunted and eaten

Symbiosis

A close, prolonged relationship between organisms of different species- at least one organism must benefit

Mutualism

Both organisms benefit from the relationship e.g. humans and bacteria

Commensalism

One organism benefits, and the other is unaffected e.g. whales and barnacles

Parasitism

One organism benefits and the other is harmed e.g. dogs and ticks

Ammensalism

One organism is unaffected and the other is harmed- not symbiotic because there is no benefit

Abiotic Factor

Physical or chemical features that affect living things (anything non-living)

Abiotic factor examples

Space, shelter, water, nutrients, temperature

Linnean System

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Species (1st definition)

A group of organism which can interbreed to produce live, fertile offspring

Species (2nd definition)

A group of organisms with morphological or genetic similarity

Potential Evapotranspiration Ratio (PER)

Part of the Holdridge life zone classification- the amount of water plants would evaporate or transpire if enough water was available

Bio temperature

Climate temperature that can support life- greater than 0

Ecosystem

The combination of all the abiotic and biotic factors in a particular area

Habitat

Where an organism lives- ecosystems contain many habitats

Population

All of the organisms of one species in a particular habitat

Community

All the populations of different species living in the same place at the same time

Ecological niche

The role of an organism within its environment- how it obtains energy, interacts with other species, interacts with its environment

Ecoregion

A large area that has a distinct geography and contains a collection of organisms which are distinct from the area next to it

Uniform distribution

When organisms are spaced at roughly equal distances, happens when: there is strong competition, resources are limited, organisms maintain territory

Random distribution

When each organisms position is completely independent of other organisms, happens when: environmental conditions are consistently favourable throughout the area, no strong competition, resource availability doesn’t vary

Clumped distribution

When organisms gather in groups, happens when: resources are patchily distributed, organisms are social. reproduction leads to offspring staying close to parents

Population size

The number of organisms from the same species in a habitat

Intrinsic growth

How much a population would grow based solely on birth and death rates

r-Strategists

Take advantage of brief breeding opportunities by producing many fast growing young- high intrinsic growth rates and can survive unpredictability

K-strategists

They thrive in stable environments with steady, reliable food sources- raise fewer offspring and invest more in each offspring over a long period

Carrying capacity

The maximum number of organisms an environment can support without harming the ecosystem

Producers

Photosynthesising organisms responsible for providing accessible energy for the whole ecosystem

Consumer

Non-photosynthesising organisms that must gain energy from other organisms

Ecological Niche

An organism’s role within it’s environment—includes all interactions with biotic and abiotic factors

Competitive Exclusion Principle

No two species can occupy the same niche at the same time—if they do, they will compete against each other