Bio 3.3 Animal and Plant responses Module 1-4

Innate behaviour

An action or response that an organism performs automatically without needing to learn it. It is often genetic, like a pre-programmed instinct.

learned behavior

An action or response that an organism develops through experience and interaction with its environment. This behaviour can be modified over time.

Ecological niche

This describes all the resources an organism uses (food, water) and all of the roles it plays (eg: predator, prey, parasite), including its interactions with other species, its own species and its environment.

Stimulus

An environmental cue that organisms respond to.

Taxis

Directional movement response of an animal, towards or away from a stimulus

Kinesis

Non-directional movement response where an organism doesn't move towards or away from the stimulus, but its overall activity changes proportionally to the intensity of the stimuli.This increases its chances of finding favourable conditions or leaving unfavourable ones.

Klinokinesis

A type of non-directional kinesis response where an organism changes its rate of turning proportionally to the intensity of the stimuli. In unfavourable conditions the organism will turn more frequently to increase its chances of finding favourable conditions.

Orthokinesis

A type of non-directional kinesis response where an organism changes its speed proportionally to the intensity of the stimuli. In unfavourable conditions the organism will move faster to increase its chances of finding favourable conditions.

Chemical navigation

The use of chemical cues (such as pheromones, scents or chemical gradients) to navigate unfamiliar environments.

Solar navigation

The use of the sun’s position in the sky as a compass to determine direction when navigating. Animals use their biological clock to compensate for the sun’s movement across the sky throughout the day.

Stellar navigation

The use of stars in the night as a compass to determine direction when navigation. Animals use their biological clock to compensate for the stars movement throughout the night.

Landmark navigation

The use of environmental features such as trees, mountain ranges, coastlines as visual cues to navigate.

Magnetic field navigation

The ability of an organism to sense and use the Earth’s magnetic field as a compass to orientate themselves. These organisms often have specialised cells containing magnetic particles to help them detect magnetic fields.

Migration

A regular, mass movement of a population of animals from one geographic location to another, typically driven by seasonal changes to resources or breeding needs and usually involves a return trip.

Plumule

The first shoot/stem that appears from a germinating seed.

Radicle

The first root that appears from a germinating seed.

Tropism

A directional growth response of a plant towards or away from a stimuli.

Auxin

A plant hormone that promotes and inhibits cell elongation the the stem and roots of plants. It plays a key role in tropic responses of plants.

Meristem

Region of the plant where there is a high level of mitosis - when the hormone auxin is produced.

Nastic response

A non-directional movement response in plants that is rapid and reversible. The movement is caused by changes in turgor pressure.

Pulvini cells

Motor cells in plants that can quickly change their turgor pressure creating nastic movements.

Turgor pressure

The force exerted by the water inside a cell against the cell wall of a plant cell.

Turgid

When a plant cell is swollen and full of water.

Flaccid

When a plant cell has lost water reducing turgor pressure.

Thigmonasty

A non-directional movement response in plants to touch stimuli.

Photonasty

A non-directional movement response in plants to light intensity.

Nyctinasty

A non-directional movement response in plants to darkness. Often referred to as ‘sleep movements’ that are regulated by an internal biological clock.

Suprachiasmatic nucleus

The SCN is a cluster of cells in the hypothalamus of the brain that act as the internal biological clock controlling most circadian (daily) rhythms in animals.

Biological clock

An internal, genetically programmed system within an organism that regulates the timing of behaviours.

Diurnal

An activity pattern where animals are active during the daytime.

Nocturnal

An activity pattern where animals are active during the night-time.

Crepuscular

An activity pattern where animals are active at dawn and dusk. Often to avoid extremes of midday heat, night time cold or predators.

Circatidal

A biological rhythm that has a period of 12.4 hour cycles of tides.

Circadian

A biological rhythm that has a period of 24 hours.

Circalunar

A biological rhythm that has a period of 29.5 days, synchronised with the moon's phases.

Circannual

A biological rhythm that has a period of 365 days.

Exogenous Rhythm

A biological rhythm that is solely driven by an external cue from the environment. When the external cue is removed, the rhythm stops.

Endogenous Rhythm

A biological rhythm that is generated internally by the organism's biological clock and is entrained by external cues. In the absence of external cues, the rhythm will continue with its own ‘free running period’.

Free-running period

The natural length of an endogenous rhythm when the zeitgeber is removed and an organism is kept under constant environmental conditions.

Phase shift

The change in the timing of a biological rhythm in response to a new environmental cue.

Zeitgeber

The external environmental cue that synchronises or resets and organisms biological clock.

Entrainment/entrain

The process of an organism's biological clock being synchronised with the environment via an environmental cue.

Photoperiodism

Regulation of responses and behaviours using length of day

Phytochrome

A light sensitive plant pigment involved in measuring the photoperiod and controlling the flowering mechanism in plants. It exists in two forms, Pr and Pfr.

P_r (phytochrome red)

The ‘inactive form’ of phytochrome pigment. This form absorbs red light and is quickly converted during the day into Pfr, the active form.

P_fr (phytochrome far red)

The ‘active form’ of phytochrome pigment. This form absorbs far light and is slowly converted during the night into Pr, the inactive form.

Photoperiod

The length of daylight in a 24 hour cycle.

Critical day length

The specific length of daylight required to trigger flowering in plants.

Noctoperiod

The length of uninterrupted darkness in a 24 hour cycle.

Critical night length

The specific length of darkness required to trigger flowering in plants.

Long day plant

A plant that requires a photoperiod longer than the critical day length (or a noctoperiod shorter than the critical night length to trigger flowering). - Uses P_fr to trigger flowering

Short day plant

A plant that requires a photoperiod shorter than the critical day length (or a noctoperiod longer than the critical night length to trigger flowering). - Uses P_fr to inhibit flowering

Day neutral plant

A plant whose flowering is not determined via day or night length but other environmental cues.