Definitions for OCR F214 Biology Exam

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  • Created by: JessicaL
  • Created on: 14-06-13 17:08
Autotroph
An organism that uses light/chemical energy and inorganic molecules to synthesise complex organic molecules.
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Heterotroph
An organism that ingests and digests complex organic molecules, releasing the chemical potential energy stored in them.
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Photosynthetic Pigments
Molecules that absorb light energy. Each pigment absorbs a different range of wavelengths in the visible region and has its own distinct peak of absorption (other wavelengths are reflected).
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Respiratory Substrate
Is an organic substance that can be respired.
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Excretion
Is the removal of metabolic waste from the body.
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Homeostasis
Is the maintenance of the internal environment of an organism in a constant state despite external changes.
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Negative Feedback
A process that brings about the reversal of a change in conditions. It ensures an optimum steady state can be maintained, as the internal environment is returned to its original set of conditions after any change.
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Positive Feedback
A process that increases any change detected by the receptors. This tends to be harmful, rare and doesn't lead to homeostasis.
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Endocrine Gland
A gland that secretes hormones directly into the bloodstream.
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Exocrine Gland
A gland that secretes molecules into a duct that transports them to where they are used.
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Hormone
A molecule released by endocrine glands directly into the blood. It acts as a messenger, carrying a signal from the endocrine gland to a specific target organ or tissue.
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Target Tissue
A group of cells that possess a specific receptor on their plasma (cell surface) membranes. The shape of the receptor will be complementary to the shape of the hormone molecule.
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First Messenger
A hormone that transmits a signal around the body.
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Second Messenger
A molecule that transmits a signal inside the cell.
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Other cards in this set

Card 2

Front

Heterotroph

Back

An organism that ingests and digests complex organic molecules, releasing the chemical potential energy stored in them.

Card 3

Front

Photosynthetic Pigments

Back

Preview of the front of card 3

Card 4

Front

Respiratory Substrate

Back

Preview of the front of card 4

Card 5

Front

Excretion

Back

Preview of the front of card 5
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