Biology NCEA-Level 3

Mimicry

A harmless animal looks like a poisonous one.

Tropism

A plant growth response to a directional stimulus.

Auxin

A plant hormone that lengthens cells.

Phytochrome

A plant pigment that controls the photoperiodic response.

Crepuscular

When an animal is active around sunrise and sunset.

Hierarchy

When animals are ranked. A linear hierarchy is where every animal is above or below another; there are no equals.

Intraspecific

Within one species.

Allelopathy

Chemical inhibition of one species by another. Basically the same as antibiosis, except that the definition emphasises the chemical connection.

Circa

Circa is used to describe endogenous rhythms that either fall short of or exceed the geophysical cycle.

Entrainment

Forcing the free running period to follow an external pattern.

Gause's competitive exclusion principle

If two species have the same niche they cannot remain for long in the same habitat. One will lose out and be eliminated (or at least reduced to a very small population.)

Sun compass

A biological clock that enables a migrating bird or insect to fly using the sun and continuously adjust its angle to the sun while flying.

Nastic movement

A plant response that is independent of the direction of the stimulus. The response is not a growth response, but usually involves cell water (turgor) pressure.

Short-day Plant

A plant that flowers in short days, during autumn or winter.

Day Neutral Plant

A plant that flowers independently of the day length or season

Long-day plant

A plant that flowers with increasing day length, usually over 12 hours.

Circalunar

A rhythm of about 1 month.

Circaannual

A rhythm of about 1 year.

Circatidal

A rhythm of about 12.5 hours.

Circadian

A rhythm of about 24 hours.

Exogenous

A rhythm that continues only when external cues are present.

Kinesis

A whole-body response of animals where the response is independent of the stimulus direction, but may depend on the intensity of the stimulus.

Nocturnal

Active at night.

Diurnal

Active during the day.

Home range

An area that an animal uses for food, but will not defend.

Territory

An area used by an animal for feeding or breeding, that the animal will defend.

Endogenous

An internal rhythm that occurs when there are no external cues. It is caused by a biological clock.

Mutualism

An interspecific relationship where both benefit

Parasitism

An interspecific relationship where one individual is benefited and the other harmed.

Predation

An interspecific relationship where one individual is benefited and the other is harmed, eg a predator eats its prey, and a parasite is smaller and lives in or on its host.

Commensalism

An interspecific relationship where one organism benefits, but the other is unaffected.

Antibiosis

An interspecific relationship where one organism is harmed, but the other is unaffected.

Migration

Annual mass movement of animals, from breeding areas to other non-breeding areas and then returning. In animals only.

Stimulus

Anything that causes an organism to react.

Interspecific

Between two different species.

Biological clocks

Internal timing systems that continue without external clues, and control (to some extent) the timing of activities of plants and animals.

Taxis

Movement of an animal or part of its body towards or away from a directional stimulus.

Homing

The ability to find and return to the home site. In animals only.

Free running period

The natural period of the rhythm if there are no external cues.

Habitat

The place or environment in which specific organisms live.

Photoperiodism

The response of plants to lengths of day (or night).

Zeitgeber

Time signal for a biological clock. Eg sunrise and sunset, temperature, tidal movement, day length.

Phase shift

To change the start times of a rhythm, but not its period.

Ambivalence

When a gesture contains elements of dominance and submission.