Armenia Biology Unified Exam key terms

A thin double layer of lipids and proteins that surrounds every cell, controls which substances enter or leave, and separates the cell's interior from its surroundings.

A specialised structure inside a cell, such as a nucleus, mitochondrion, or chloroplast, that performs a particular job for the cell.

An organelle with a folded inner membrane where aerobic respiration takes place, producing most of the ATP a cell uses for energy.

A green plant organelle containing chlorophyll in which light energy is captured and used to build sugars from carbon dioxide and water.

The net movement of particles from a region of higher concentration to a region of lower concentration, driven by random motion, without requiring energy input.

The movement of water across a selectively permeable membrane from a dilute solution toward a more concentrated one, until concentrations become more balanced.

A protein that speeds up a specific chemical reaction in living things by lowering the energy needed for it to occur, without being consumed itself.

The specific molecule that an enzyme binds to and converts into products during a catalysed reaction.

Loss of a protein's functional three-dimensional shape caused by heat, extreme pH, or other factors, usually making the protein, such as an enzyme, inactive.

A small molecule that stores usable chemical energy in its phosphate bonds and releases it to power cellular work when those bonds are broken.

The oxygen-requiring breakdown of glucose into carbon dioxide and water, releasing a large amount of energy captured as ATP.

The process by which green organisms use light energy to convert carbon dioxide and water into organic compounds, releasing oxygen as a by-product.

The green pigment in plants that absorbs light energy and makes it available for photosynthesis.

A segment of DNA that carries the instructions for making a particular protein or functional RNA molecule, and is passed from parents to offspring.

One of the alternative versions of a gene that can occupy the same position on a chromosome and may produce different traits.

The particular combination of alleles an organism carries for a gene or set of genes, whether or not those alleles are visibly expressed.

The observable characteristics of an organism, resulting from the interaction between its genetic makeup and its environment.

Describing an organism that carries two identical alleles for a particular gene.

Describing an organism that carries two different alleles for a particular gene.

A characteristic that appears in the offspring whenever at least one copy of its allele is present, masking the effect of a recessive allele.

A long double-stranded molecule that stores genetic information in the sequence of its nucleotide building blocks and is copied before cell division.

The process in which a segment of DNA is used as a template to build a complementary messenger RNA molecule.

The process in which ribosomes read messenger RNA and assemble amino acids into a protein according to the sequence of codons.

A sequence of three nucleotides in messenger RNA that specifies one amino acid or signals where protein synthesis should start or stop.

The copying of a DNA molecule to produce two identical DNA molecules, ensuring each new cell receives a full set of genetic instructions.

A small structure, free in the cytoplasm or attached to membranes, where amino acids are joined into proteins using messenger RNA as instructions.

A type of cell division in which one cell produces two genetically identical daughter cells, used for growth and repair of body tissues.

A specialised form of cell division that halves the chromosome number and produces genetically varied sex cells such as eggs and sperm.

The fusion of a male sex cell with a female sex cell, restoring the full chromosome number and forming the first cell of a new organism.

The single cell formed when a sperm and an egg fuse, which divides repeatedly to develop into a new organism.

The early stage of a developing organism, from the first divisions of the zygote until it takes on a recognisable body form.

The entire course of an individual organism's development, from fertilised egg through growth and maturity to death.

The loss of water vapour from plant leaves through small pores, which pulls water upward through the plant and helps cool it.

A tiny adjustable pore in the surface of a leaf, surrounded by guard cells, that allows gases and water vapour to pass in and out.

Plant tissue made of hollow conducting tubes that transports water and dissolved minerals from the roots upward to the rest of the plant.

Plant tissue that transports sugars and other organic substances made in the leaves to growing and storage parts of the plant.

The ability of an organism to keep its internal conditions, such as temperature and blood composition, within stable limits despite changes outside.

The nerve pathway that produces a fast, automatic response to a stimulus, usually without conscious control by the brain.

A nerve cell specialised for receiving, conducting, and transmitting electrical impulses within the nervous system.

A chemical messenger released by a gland into the blood, which travels to target organs and alters their activity.

The process by which individuals with inherited features that improve survival and reproduction leave more offspring, gradually changing populations over generations.

An inherited feature of an organism that increases its chance of surviving and reproducing in its particular environment.

Change over generations in the inherited characteristics of populations, often resulting in new species arising from earlier ones.

A community of living organisms together with the non-living surroundings they interact with, such as soil, water, and climate.

A sequence showing how energy and matter pass from one organism to another as each is eaten by the next.

The thin zone of Earth, including land, water, and air, where living organisms exist and interact with their surroundings.