VCE Biology key terms

The principle that all living things are made of one or more cells, that the cell is the basic unit of life, and that new cells arise only from existing cells by division.

A single-celled organism lacking a membrane-bound nucleus and other membrane-bound organelles; its circular DNA lies free in the cytoplasm, and examples include bacteria and archaea.

An organism whose cells contain a nucleus enclosing the DNA and other membrane-bound organelles such as mitochondria and endoplasmic reticulum; includes protists, fungi, plants and animals.

A specialised structure inside a cell that performs a particular function, such as a mitochondrion for respiration or a chloroplast for photosynthesis; many are membrane-bound compartments.

The selectively permeable phospholipid bilayer surrounding a cell that controls which substances enter and leave, using embedded proteins, cholesterol and carbohydrates.

The net passive movement of particles from a region of higher concentration to a region of lower concentration, driven by random motion until equilibrium is approached.

The passive diffusion of water across a selectively permeable membrane from a region of higher water potential to a region of lower water potential.

Movement of substances across a membrane against their concentration gradient using carrier proteins and energy released from ATP hydrolysis.

A double-membraned organelle where aerobic cellular respiration occurs; the inner membrane is folded into cristae to increase the surface area for ATP production.

A green organelle found in plant cells containing chlorophyll and stacked thylakoid membranes, where light energy is captured and converted into chemical energy during photosynthesis.

A protein that acts as a biological catalyst, lowering the activation energy of a specific reaction by binding its substrate at the active site.

The region of an enzyme where substrate molecules bind and the reaction is catalysed; its shape is complementary to the substrate and determines reaction specificity.

Loss of a protein's three-dimensional shape, and therefore its function, caused by factors such as high temperature or extreme pH that break hydrogen bonds.

The molecule on which an enzyme acts; it binds to the enzyme's active site and is converted into products during the catalysed reaction.

Adenosine triphosphate, the universal energy-carrying molecule of cells; hydrolysis of its terminal phosphate bond releases usable energy for cellular processes.

The process in chloroplasts by which light energy is used to convert carbon dioxide and water into glucose and oxygen, with light-dependent and light-independent stages.

The series of reactions in which cells break down glucose to release energy, captured as ATP; aerobic respiration uses oxygen, while anaerobic respiration does not.

A form of asexual reproduction in prokaryotes in which the cell replicates its DNA and divides into two genetically identical daughter cells.

Nuclear division producing two daughter nuclei with the same chromosome number as the parent cell, used for growth, repair and asexual reproduction in eukaryotes.

Reduction division producing four haploid daughter cells from one diploid cell, involving crossing over and independent assortment, which generates genetic variation in gametes.

The ordered sequence of events a cell passes through between divisions, including interphase (G1, S and G2 phases) and the mitotic phase.

The division of the cytoplasm following nuclear division, producing two separate daughter cells; it occurs by furrowing in animal cells and by cell plate formation in plant cells.

Exchange of segments of DNA between non-sister chromatids of homologous chromosomes during prophase I of meiosis, creating new combinations of alleles.

One of two or more alternative forms of a gene that occupy the same locus on homologous chromosomes and may produce different phenotypes.

The combination of alleles an organism carries for a particular gene or set of genes, which interacts with the environment to produce the phenotype.

The observable characteristics of an organism resulting from the expression of its genotype in a given environment.

Describing an allele that is expressed in the phenotype when present in either a heterozygous or homozygous genotype, masking the effect of the recessive allele.

Describing an allele whose effect on the phenotype is only expressed when two copies are present, that is, in a homozygous genotype.

A haploid reproductive cell, such as a sperm or egg, produced by meiosis and able to fuse with another gamete during fertilisation.

The diploid cell formed when two haploid gametes fuse during fertilisation; it divides by mitosis to develop into a new organism.

A visual arrangement of an individual's chromosomes, ordered by size and shape, used to detect abnormalities in chromosome number or structure.

A thread-like structure of DNA wrapped around histone proteins that carries genetic information; eukaryotic cells contain pairs of homologous chromosomes.

The process by which information in a gene is used to synthesise a functional product, usually a protein, involving transcription and translation.

The synthesis of a messenger RNA molecule from a DNA template, catalysed by RNA polymerase in the nucleus of eukaryotic cells.

The process at ribosomes in which the base sequence of mRNA is decoded into a chain of amino acids, using tRNA molecules that carry specific amino acids.

A sequence of three nucleotides in mRNA that specifies one amino acid or a stop signal during translation.

Messenger RNA, a single-stranded molecule transcribed from DNA that carries the coding sequence from the nucleus to ribosomes for translation.

A permanent change in the base sequence of DNA, which may alter the amino acid sequence of a protein and hence the phenotype.

The process by which individuals with inherited traits better suited to their environment survive and reproduce more successfully, increasing the frequency of those alleles in later generations.

An inherited characteristic that improves an organism's chance of survival and reproduction in its particular environment, arising over generations through natural selection.

A group of organisms whose members can interbreed to produce fertile offspring under natural conditions, and which are reproductively isolated from other such groups.

The formation of new species, occurring when populations become reproductively isolated and accumulate genetic differences over time, often following geographic separation.

A small circular piece of DNA separate from the main chromosome in prokaryotes, often carrying genes such as those for antibiotic resistance and able to be transferred between cells.