O-Level Biology Core Concepts Vocabulary

Vocabulary flashcards covering core topics across Chapters 3 through 22, including cell transport, biological molecules, enzymes, nutrition, transport systems, respiration, excretion, homeostasis, genetics, and ecology.

Diffusion

The net movement of particles in solid, liquid or gaseous state, down a concentration gradient without the need of energy (passive).

Osmosis

The net movement of water molecules from a region of higher water potential to a region of lower water potential, through a partially permeable membrane.

Active Transport

A process in which energy from cellular respiration is used to move particles against a concentration gradient across a partially permeable membrane.

Turgor Pressure

The water pressure that is exerted onto the cell wall which causes the plant cell to expand without bursting.

Condensation

A chemical reaction in which $2$ smaller, simpler molecules are joined together to form a larger, complex molecule with the removal of $1$ water molecule.

Hydrolysis

A chemical reaction in which $1$ water molecule is used to break down a larger, complex molecule into $2$ smaller, simpler molecules.

Enzymes

Biological catalysts made of protein which speed up (alter) the rate of chemical reactions by lowering the activation energy required to start the reaction without being chemically changed at the end of the reaction.

Activation Energy

The minimum energy required for a chemical reaction to proceed or start.

Lock and Key Hypothesis

A hypothesis explaining enzyme specificity, where the enzyme acts as the lock with a unique active site and the substrate acts as the key with a complementary shape.

Peristalsis

Rhythmic wave-like antagonistic contractions of longitudinal and circular muscles to mix and propel the contents of the alimentary canal.

Digestion

The process whereby large, insoluble, complex molecules of food are broken down into smaller, soluble, simpler molecules to be absorbed into the circulatory system.

Assimilation

The distribution and use of the products of digestion as an energy source and conversion into other nutrients needed for growth and repair of body parts.

Deamination

The process in the liver where amino groups are removed from excess amino acids and converted to urea.

Detoxification

The process of converting harmful substances into harmless products, such as the breakdown of alcohol by alcohol dehydrogenase in the liver.

Photosynthesis

A multi-step process in which light energy absorbed by chlorophyll is transformed into chemical energy to synthesize glucose from water and carbon dioxide with oxygen released during the process.

Limiting Factor

A factor that directly affects the rate at which a process (e.g. chemical reaction) occurs if its quantity is changed.

Atherosclerosis

The narrowing of coronary arteries caused by deposits of lipids (fat and cholesterol) carried by the blood onto their inner walls.

Transpiration

The loss of water vapour from aerial parts of a plant, especially through the stomata of the leaves.

Translocation

The transport of manufactured food substances such as sucrose and amino acids in the phloem from leaves to other parts of the plant.

Aerobic Respiration

The oxidation of organic food substances (glucose), releasing a large amount of energy, carbon dioxide and water within the cells or tissues of an organism in the presence of oxygen.

Anaerobic Respiration

The breakdown of food substances (glucose) in the absence of oxygen, releasing less energy than aerobic respiration.

Excretion

The removal of metabolic waste products and toxic materials such as urea, uric acid, and creatinine from the body.

Homeostasis

The maintenance of a constant internal environment, keeping it within a narrow range.

Hormone

A chemical substance produced by endocrine glands, carried by the blood which alters the activity of one or more specific target organs and is then broken down by the liver.

Pollination

The transfer of pollen grains from an anther to a receptive stigma to bring male and female gametes together.

Gene

A fragment of a DNA molecule which contains genetic information (a unit of inheritance) that codes for a specific polypeptide which determines a physical characteristic of an organism.

Alleles

Alternative forms of the same gene which occupy the same relative locus on a pair of homologous chromosomes.

Genetic Engineering

The process of transferring genes from one organism to another by cutting individual genes from chromosomes of one organism and inserting them into cells of another organism.

Carbon Sink

An area that stores carbon compounds for an indefinite period and stores more carbon than it releases.

Bioaccumulation

The process where non-biodegradable toxins (such as DDT) accumulate in the body of a consumer throughout its lifetime.