AQA A Level Biology Topic 6: Organisms Respond to Changes in Their Environments

Flashcards created based on AQA A Level Biology Topic 6 notes focused on the responses of organisms to environmental changes.

Stimulus

A change in an organism's internal or external environment that can elicit a response.

Tropism

The growth of a plant in response to a directional stimulus.

Positive Tropism

Growth towards a stimulus.

Negative Tropism

Growth away from a stimulus.

Homeostasis

The maintenance of a stable internal environment within restricted limits.

Pacini Corpuscle

A type of mechanoreceptor that detects pressure changes.

Gravitropism

Growth response of a plant to gravity, where shoots bend away and roots bend towards gravitational pull.

Phototropism

Growth response of a plant towards light.

Neurotransmitter

Chemical messengers that transmit signals across a synapse.

Myogenic

Muscle that can contract without external electrical impulses.

Resting Potential

The resting state of a neuron where the inside is negatively charged relative to the outside.

Action Potential

A rapid rise and subsequent fall in voltage or membrane potential across a cellular membrane.

Baroreceptor

A sensory receptor that detects changes in blood pressure.

Chemoreceptor

A sensory receptor that responds to chemical stimuli, such as changes in blood pH or carbon dioxide levels.

Liver's Role in Glycogenesis

Converts glucose into glycogen for storage.

Liver's Role in Glycogenolysis

Converts glycogen back into glucose when needed.

Second Messenger Model

A mechanism by which hormones like adrenaline and glucagon exert their effects through intracellular signaling pathways.

Antidiuretic Hormone (ADH)

Hormone that regulates water balance by increasing the permeability of the collecting duct to water.

Osmoregulation

The control of water potential in the blood.

Skeletal Muscle Contraction

The process in which myosin heads slide actin filaments along themselves, causing contraction.