CSEC® Biology – Key Vocabulary

Essential vocabulary covering topics from cells and ecology to genetics, human physiology and biotechnology, aligned with the CSEC® Biology syllabus.

Biology

The study of living organisms and their interactions with each other and their environments.

Nutrition

The process by which living organisms obtain or make food.

Autotroph

An organism (e.g. green plant) that makes its own food from inorganic substances.

Heterotroph

An organism that obtains ready-made organic food from its environment.

Respiration

The process by which energy is released from food in living cells.

Aerobic respiration

Respiration that requires oxygen and releases large amounts of energy.

Anaerobic respiration

Respiration that takes place without oxygen and releases little energy.

Excretion

Removal of metabolic waste products from the body.

Movement

A change in the position of an organism or part of an organism.

Irritability (Sensitivity)

The ability of organisms to detect and respond to stimuli.

Growth

A permanent increase in size and complexity of an organism.

Reproduction

The process by which living organisms generate new individuals of the same kind.

Species

A group of organisms that can interbreed to produce fertile offspring.

Kingdom

The highest major category used to classify living organisms (e.g. Plantae).

Prokaryotae

Kingdom whose members lack true membrane-bound nuclei; DNA is free in the cell.

Eukaryote

An organism whose cells contain a true nucleus and membrane-bound organelles.

Ecology

The study of the interrelationships of living organisms with each other and their environment.

Habitat

The place where an organism lives.

Population

All the members of one species living in a particular habitat.

Community

All the populations of different species living together in a habitat.

Ecosystem

A community of living organisms interacting with their abiotic environment.

Niche

The role or position of an organism within an ecosystem.

Quadrat

A square frame of known area used for sampling organisms in a habitat.

Line transect

A tape or string laid across a habitat along which organisms touching the line are recorded.

Species density

The average number of individuals of a species per unit area.

Diffusion

Net movement of particles from a higher to a lower concentration.

Osmosis

Movement of water molecules through a selectively permeable membrane from dilute to concentrated solution.

Active transport

Movement of particles against a concentration gradient using energy from respiration.

Enzyme

A biological catalyst that speeds up chemical reactions without being changed itself.

Carbohydrate

Organic molecule composed of carbon, hydrogen and oxygen in a 2:1 ratio of H:O.

Protein

Large organic molecule made of amino acids containing carbon, hydrogen, oxygen and nitrogen.

Lipid

Fat or oil molecule made from glycerol and fatty acids; insoluble in water.

Photosynthesis

Process by which green plants convert carbon dioxide and water into glucose using sunlight energy.

Transpiration

Loss of water vapour from plant leaves through stomata.

Root pressure

Upward push of water in xylem created by active absorption in roots.

Translocation

Transport of dissolved organic food through phloem sieve tubes.

Xylem

Vascular tissue that transports water and mineral salts in plants.

Phloem

Vascular tissue that transports soluble organic food in plants.

Homeostasis

Maintenance of a constant internal environment within an organism.

Hormone

Chemical messenger secreted by an endocrine gland and transported in the blood.

Insulin

Pancreatic hormone that lowers blood glucose concentration.

Mitosis

Type of cell division producing two genetically identical diploid cells.

Meiosis

Reduction division producing four genetically different haploid gametes.

Gene

Section of DNA that codes for a specific protein or characteristic.

Allele

Alternative form of a gene occupying the same locus on homologous chromosomes.

Genotype

The genetic makeup or combination of alleles in an organism.

Phenotype

The observable characteristics of an organism resulting from its genotype and environment.

Dominant allele

Allele that is expressed in the phenotype even when only one copy is present.

Recessive allele

Allele expressed in the phenotype only when two copies are present.

Co-dominance

Inheritance pattern where both alleles express themselves in the heterozygote.

Mutation

A sudden change in a gene or chromosome producing new variation.

Natural selection

Process by which organisms best adapted to their environment are more likely to survive and reproduce.

Artificial selection

Human-directed breeding of organisms with desirable traits to produce improved varieties.

Genetic engineering

The manipulation of an organism’s DNA to change its traits.

Pathogen

A disease-causing organism such as a virus, bacterium, fungus or protozoan.

Vector

An organism that carries pathogens from one host to another.

Vaccination

Introduction of antigens into the body to stimulate immunity against a disease.

Antibody

Protein produced by lymphocytes that binds to and neutralises specific antigens.

Haemoglobin

Iron-containing protein in red blood cells that carries oxygen.

Plasma

Fluid portion of blood that transports dissolved substances.

Reflex action

Rapid, automatic response to a stimulus that does not involve conscious thought.