IB Biology Topic 4

Ecology

The science of the relationships between organisms and their environments.

Organism

an individual living thing that uses energy, reproduces, responds, grows, and develops

Species

a group of similar organisms that can breed and produce fertile offspring

Population

group of individuals of the same species that live in the same area

Community

all living, or biotic, things in an area

Ecosystem

all biotic (living) and abiotic (nonliving) things in an area

Autotroph

- also known as a producer
- an organism capable of making its own food from inorganic substances using light or chemical energy.
- eg. Green plants, algae, and certain bacteria

Heterotroph

An organism that obtains organic food molecules by eating other organisms or substances derived from them.

Carbon cycle

the continuous process by which carbon is exchanged between organisms and the environment

Trophic level

step in a food chain or food web

Food chain

shows the transfer of energy between organisms:

the energy in the carbon compounds (food) is released through respiration. much of this energy is lost as heat.

Food web

network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem

Pyramid of energy

- diagram shows relative amounts of energy or matter within each trophic level in a food chain / web
- length of the bar represents energy transferred (unit \= KJ m^-2 yr^-1)

10% Rule

Only 10% of the energy in one trophic level gets passed onto the next trophic level; the rest is lost as heat or is not digested or ingested

Biological magnification

increasing concentration of a harmful substance in organisms at higher trophic levels in a food chain or food web

Producer

organism that can capture energy from sunlight or chemicals and use it to produce food from inorganic compounds; also called an autotroph

Consumer

organism that relies on other organisms for its energy and food supply; also called a heterotroph

Primary Consumer

Consumer that feeds directly on producers;
The animal that directly eats the producer;
this category includes organisms that consume producers (plants and algae).

Secondary Consumer

An organism that eats primary consumers;
A member of the trophic level of an ecosystem consisting of carnivores that eat herbivores;
eats primary consumers

Tertiary Consumer

An organism that eats secondary consumers;
The third trophic level of consumer in a food chain; A carnivore that eats other carnivores.

Detritivore

organism that feeds on plant and animal remains and other dead matter (ex. vultures, earthworms, crabs, etc.)

Saprotroph

an organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion (e.g. mushrooms, bacteria);
Obtains nutrients from decaying organic matter

Precautionary Principle

The principle that states that when an activity raises threats of harm to human health or to the environment, safety should prevail and control measures should be initiated even if cause-and-effect relationships are not yet fully established

Detritus

nonliving organic matter; typically includes decaying dead organisms as well as fecal matter

Habitat

the area where an organism lives, including the biotic and abiotic factors that affect it

Abiotic

non-living

Biotic

living

Greenhouse effect

happens naturally
short wave (visible light) radiation passes through Earth's atmosphere

much is reflected, but some is absorbed and transferred to heat. Some heat as infrared (long wavelength) is reflected back into the atmosphere.

Potential problems associated with climate change

1) ice habitats are melting (albedo decreases, permafrost melts)
2) flooding (destruction of habitats)
3) desertification and oceans acidify
4) more extreme weather events
5) species extinction
6) movement of species further north\=
7) destruction of food webs

Microorganism

an organism that is microscopic, or too small to be seen by the unaided human eye; examples include bacteria, archaea, most protists, and some fungi

Chemoautotrophs

Autotrophic bacteria that derive energy from inorganic sulfur compounds; often live in deep-ocean vents, bacteria

Quadrat Sampling

Sampling of an area using small squares to count the population of an area

Fundamental Niche

all of the places a species can live if no competition;

The entire range of resource opportunities an organism is potentially able to occupy within an ecosystem

Transect

use string across a place where you collect data, collect the data of whatever passes the string

Natality

Birth rate;

increases population size as offspring are added to the population

Immigration

Migration to a new location;
Movement of individuals into a population

Emigration

Movement of individuals out of an area.

Mortality

Death rate

Competition

A common demand by two or more organisms upon a limited supply of a resource; for example, food, water, light, space, mates, nesting sites.

Predation

An interaction in which one organism captures and feeds on another organism

Parasitism

A relationship in which one organism lives on or in a host and harms it.

Mutualism

A relationship between two species in which both species benefit

Biomass

A measure of the total dry mass of organisms within a particular region.

Biosphere

The area on and around Earth where life exists

Biome

A group of ecosystems that share similar climates and typical organisms.

Invasive Species

species that enter new ecosystems and multiply, harming native species and their habitats

Biomagnification aka Bioaccumulation

accumulation of pollutants at successive levels of the food chain;
the process by which the concentration of toxic substances increases in each successive link in the food chain

CFCs

Chlorinated Fluorocarbons are chemicals that break down the ozone layer

Trophic Level

Each step in a food chain or food web;
The position of an organism in relation to the flow of energy and inorganic nutrients through an ecosystem (e.g., producer, consumer, and decomposer).

cohort

A population group unified by a specific common characteristic, such as age, and subsequently treated as a statistical unit.

Top-down limiting factors

Population growth pressures applied by other organisms at higher trophic levels, e.g. predation.

Bottom-up limiting factors

Factors that limit population growth by affecting resources or lower tropic levels (e.g. interspecific competition for resources, nutrient cycling, producers).

Eutrophication

A process by which nutrients, particularly phosphorus and nitrogen, become highly concentrated in a body of water, leading to increased growth of organisms such as algae or cyanobacteria.

keystone species

a species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically. ie - wolf, PNW starfish, tiger shark, sea otter, wildebeast, etc.

biological control

the intentional release of a natural enemy to attack a pest population

Nutrient cycling

cycles that maintain the supply of inorganic nutrients; ex nitrogen cycle

chi square test

A statistical method of testing for an association between two categorical variables, such as the association between two species

organic nutrients

contain carbon and hydrogen atoms and are usually the products of living things

inorganic nutrients

chemical elements, compounds, and other substances necessary to sustain life processes that are not chemically carbon-based.

photosynthesis

Conversion of light energy from the sun into chemical energy.

respiration

The process by which cells break down simple food molecules to release the energy they contain; creates ATP, heat, and CO2

methane

A greenhouse gas produced by bacteria from hydrogen and carbon dioxide

peat

a brown, soil-like material characteristic of boggy, acid ground, consisting of partly decomposed vegetable matter. It is widely cut and dried for use in gardening and as fuel.

carbon flux

Amount of carbon exchanged between earth's carbon pools per unit time

carbon pool

a place where large amounts of carbon collect

combustion

A rapid reaction between oxygen and fuel that results in fire

longer-wave radiation

absorbed by greenhouse gases that retain the heat in the atmosphere

short-wave radiation

wavelengths of radiation emitted by the sun, especially ultraviolet, visible, and short infrared radiation