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Responding to the Environment Key Words
Tropism: A directional growth response in which the direction of the response is determined by the
direction of the external stimulus.
Meristems: Unspecialised cells still capable of dividing in plants located in the buds and tips of roots
The Cerebrum: The largest part of the brain that is responsible for the elements of the nervous
system that are associated with being 'human' e.g. thought and imagination.
The Cerebellum: This is a part of the brain that controls the coordination of movement and posture.
The Hypothalamus: The part of the brain that controls the autonomic nervous system and endocrine
The Medulla Oblongata: The part of the brain that controls the unconscious actions of the body such
as heart rate, breathing movements and the action of smooth muscles e.g. in the gut.
Central Nervous System: This consists of the brain and spinal cord
Peripheral Nervous System: This consists of all the sensory and motor neurones that are outside of
the CNS. This connects the receptors and effectors to the CNS.
Neuromuscular Junction: A specialised synapse between the end of a motor neurone also called
the motor end plate, and the muscles fibre membrane.
Sarcomere: The smallest contractile part of the muscle.
CrossBridge: The attachment formed by a myosin head binding to the binding site on an actin
Stressor: A stimulus that causes the stress response, causing wear and tear on the body's physical
or mental resources.
Innate Behaviour: A response that occurs without the need for learning. It is a natural, inherited
response similar in all members of the same species and is always preformed in the same way in
response to the same stimulus.
Learned Behaviour: An animal's response that changes or adapts with experience. there is a range
of learned behaviours identified, from simply learning not to respond to a repeated stimulus, to the
ability to consider a problem and formulate a solution.
Hierarchy: This exists within a group where individuals have a place in the order of importance within
the group. This is often shown by individuals higher up in the hierarchy receiving more food, or having
the right to access to mate with others.