Year 1 and AS Biology Glossary

A comprehensive collection of vocabulary terms and definitions related to Year 1 and AS Biology, covering key concepts and terminology essential for understanding the subject.

abiotic factors

Non-living conditions in a habitat.

activation energy

The energy required to initiate a reaction.

active site

Area of an enzyme with a shape complementary to a specific substrate, allowing the enzyme to bind a substrate with specificity.

active transport

Movement of particles across a plasma membrane against a concentration gradient; energy is required.

adenosine diphosphate (ADP)

A nucleotide composed of the nitrogenous base adenine, a pentose sugar, and two phosphate groups. It is formed by the hydrolysis of ATP.

ATP adenosine triphosphate

A nucleotide composed of the nitrogenous base adenine, a pentose sugar, and three phosphate groups. It is the universal energy currency for cells.

agglutinins

Chemicals (antibodies) that cause pathogens to clump together so they are easier for phagocytes to engulf.

alleles

Different versions of the same gene.

amino acids

Monomer used to build polypeptides and thus proteins.

anabolism (anabolic)

Reactions of metabolism that construct molecules from smaller units, requiring energy from the hydrolysis of ATP.

analogous structures

Structures that have adapted to perform the same function but have a different origin.

anaphase

Third stage of mitosis when chromatids are separated to opposite poles of the cell.

antibiotic-resistant bacteria

Bacteria that undergo mutation to become resistant to an antibiotic.

antibiotics

Chemicals or compounds that kill or inhibit the growth of bacteria.

antibodies

Y-shaped glycoproteins made by B cells of the immune system in response to the presence of an antigen.

antigen

Identifying chemical on the surface of a cell that triggers an immune response.

antigen−antibody complex

Complex formed when an antibody binds to an antigen.

antigen-presenting cell (APC)

Cell that displays foreign antigens complexed with major histocompatibility complexes on their surfaces.

antisense strand

Strand of DNA that runs 3’ to 5’ and acts as a template strand during transcription.

anti-toxins

Chemicals (antibodies) that bind to toxins produced by pathogens.

apoplast

Cell walls and intercellular spaces of plant cells.

apoplast route

Movement of substances through the cell walls and cell spaces by diffusion and active transport.

arrhythmia

An abnormal rhythm of the heart.

artefacts

Objects or structures seen through a microscope created during the processing of the specimen.

artificial active immunity

Immunity resulting from exposure to a safe form of a pathogen, e.g., vaccination.

artificial passive immunity

Immunity resulting from the administration of antibodies from another animal against a pathogen.

asexual reproduction

Production of genetically identical offspring from a single parent.

assimilates

Products of photosynthesis transported around a plant.

atrial fibrillation

An abnormal heart rhythm when the atria beat very fast and incompletely.

atrio-ventricular node (AVN)

Stimulates ventricles to contract after imposing a slight delay.

autoimmune disease

Condition resulting from an autoimmune response.

autoimmune response

Response when the immune system acts against its own cells.

autotrophic

Organisms that acquire nutrients by photosynthesis.

B effector cells

B lymphocytes that divide to form plasma cell clones.

B lymphocytes (B cells)

Lymphocytes that mature in the bone marrow and are involved in antibody production.

B memory cells

B lymphocytes that provide immunological memory.

belt transect

Two parallel lines marked along the ground for sampling.

Benedict’s reagent

An alkaline solution used in chemical tests for reducing sugars.

beta pleated sheet

Secondary protein structure where polypeptide chains fold into a zigzag, flat, sheet-like pattern, held together by hydrogen bonds between the C=O (carbonyl) groups of one amino acid and the H-N (amine) groups of another.

binomial nomenclature

Scientific naming of a species with a two-part Latin name.

biodiversity

Variety of living organisms present in an area.

biuret test

The chemical test for proteins. Colour change from Blue to Purple

Place 3cm3 of food solution into test tube

• add 3cm3 of dilute sodium hydroxide solution

• mix

• add 10 drops of dilute copper sulfate solution

• mix

• if proteins are present, turns purple

Negative test - remains blue

Bohr effect

Effect of carbon dioxide concentration on oxygen uptake by haemoglobin.

bradycardia

Slow heart rhythm of below 60 beats per minute.

breathing rate

Number of breaths taken per minute.

bulk transport

Active transport of large molecules into or out of a cell.

bundle of His

Conducting tissue composed of Purkyne fibres passing through the septum of the heart.

callose

Polysaccharide important in plant response to infection.

carbaminohaemoglobin

Compound formed when carbon dioxide combines with haemoglobin.

carbohydrates

Organic polymers composed of carbon, hydrogen, and oxygen.

carbonic anhydrase

Enzyme that catalyzes the reaction between carbon dioxide and water.

cardiac cycle

Events of a single heartbeat, composed of diastole and systole.

carrier proteins

Membrane proteins that assist in the transport of substances.

cartilage

Strong, flexible connective tissue found in many areas of the body.

catabolism (catabolic)

Reactions of metabolism that break molecules down into smaller units, releasing energy.

catalase

Enzyme that catalyzes the breakdown of hydrogen peroxide.

cell cycle

Ordered sequence of events in a cell resulting in division.

cell signalling

System of intercellular communication.

cellulose

Polysaccharide in plant cell walls made from beta glucose.

cell wall

Strong but flexible layer surrounding some cell types.

centrioles

Components of the cytoskeleton of most eukaryotic cells.

centromere

Region where two chromatids are held together.

channel proteins

Membrane proteins that provide a hydrophilic channel.

checkpoints

Control mechanisms of the cell cycle.

chiasmata

Sections of DNA that become entangled during crossing over.

chloride shift

Movement of chloride ions into red blood cells during gas exchange.

chloroplasts

Organelles responsible for photosynthesis in plant cells.

chromatids

Identical copies of DNA held together at a centromere.

chromatin

Uncondensed DNA in complex with histones.

chromosomes

Condensed and coiled DNA structures.

circulatory system

Transport system of an animal.

clonal expansion

Mass proliferation of antibody-producing cells.

clonal selection

Theory that exposure to a specific antigen stimulates proliferation of specific cells.

closed circulatory system

System where blood is enclosed within blood vessels.

Clostridium difficile

Species of bacteria resistant to most antibiotics.

codon

Three-base sequence of DNA or RNA coding for an amino acid.

cofactors

Non-protein components necessary for enzyme function.

cohesion-tension theory

Model explaining movement of water through a plant.

communicable diseases

Diseases that can be passed between organisms.

community

All populations of living organisms in a habitat.

companion cells

Cells next to sieve tube elements that provide metabolic support.

competitive inhibitor

Inhibitor that competes with substrate for an enzyme's active site.

complementary base pairing

Specific hydrogen bonding between nucleic acid bases.

compound light microscope

Microscope using two lenses to magnify an object.

condensation reaction

Reaction forming a larger molecule and releasing a water molecule.

continuous variation

Characteristic that can take any value within a range.

contrast staining

Treating cell components to increase visibility.

convergent evolution

Evolution of similarities in organisms due to similar environments.

correlation coefficient

Statistical test for relationship between two data sets.

countercurrent exchange system

System for exchanging materials when two components flow in opposite directions.

counterstain

Application of a second stain of a contrasting color.

crossing over

Exchange of DNA between homologous chromosomes during meiosis.

cytokines

Cell-signaling molecules produced in response to infection.

cytokinesis

Cell division stage that results in genetically identical daughter cells.

cytolysis

Bursting of a cell due to hydrostatic pressure.

cytoplasm

Internal fluid of cells containing organelles and cytoskeleton.

cytoskeleton

Network of fibers in the cytoplasm of eukaryotic cells.

denatured (denaturation)

Change in protein structure resulting in loss of function.

deoxyribonucleic acid (DNA)

Molecule responsible for storage of genetic information.

diastole

Stage of cardiac cycle when the heart relaxes.