AS and A-level Biology Specification Overview

These flashcards cover key concepts and terms from the AS and A-level Biology specification to aid in exam preparation.

Biological molecules

The fundamental chemical compounds that make up living organisms, including carbohydrates, lipids, proteins, and nucleic acids.

Monomers

Smaller units from which larger molecules are made; examples include monosaccharides, amino acids, and nucleotides.

Polymers

Molecules made from a large number of monomers joined together.

Condensation reaction

A chemical reaction where two molecules combine to form a larger molecule, resulting in the elimination of a molecule of water.

Hydrolysis reaction

A chemical reaction that splits a molecule into two smaller molecules, involving the addition of a water molecule.

Glycosidic bond

A type of covalent bond that links carbohydrate molecules together via condensation reaction.

Enzyme

A biological catalyst that lowers the activation energy of a reaction, increasing its rate.

Active site

The region on an enzyme where substrate molecules bind and undergo a chemical reaction.

Osmosis

The diffusion of water molecules across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Antigen

A molecule or part of a molecule that is recognized by the immune system and can provoke an immune response.

Speciation

The formation of new and distinct species in the course of evolution.

Ecosystem

A biological community of interacting organisms and their physical environment.

Gene expression

The process by which information from a gene is used to synthesize a functional gene product, typically a protein.

Mutation

A change in the nucleotide sequence of an organism's DNA, which can lead to alterations in phenotype.

Natural selection

The process through which organisms better adapted to their environment tend to survive and produce more offspring.

Homeostasis

The ability of an organism to maintain a stable internal environment despite changes in external conditions.

Biodiversity

The variety of life in the world or in a particular habitat or ecosystem, including species diversity and genetic diversity.

Photosynthesis

The process used by plants and other organisms to convert light energy into chemical energy stored in glucose.

Respiration

The biochemical process in which cells convert nutrients into energy and release waste products.

Cell cycle

The series of phases that a cell goes through in order to divide and reproduce, including interphase and mitosis.

Chromosome

A structure composed of DNA and proteins, containing the genetic information of an organism.