CIE AS-LEVEL BIOLOGY 9700

Vocabulary flashcards covering key terms and definitions from the lecture notes.

Magnification

The number of times larger an image is than the actual size; depends on the magnification of the objective and eyepiece lenses.

Resolution

The ability to distinguish two separate points as distinct; limited by wavelength of radiation used.

Light microscope

Uses visible light (≈400–700 nm); lower resolution (≈200 nm); specimens can be alive; images are usually coloured with stains.

Electron microscope

Uses electron beams (very short wavelength); much higher resolution (≈0.1–0.5 nm); specimens are dead and viewed in a vacuum.

Nucleus

Large organelle enclosed by a double membrane; contains DNA and controls cell activities.

Nuclear pores

Gaps in the nuclear envelope allowing exchange of materials between nucleus and cytoplasm.

Nucleolus

Regions within the nucleus where ribosomal RNA is synthesized and ribosomes begin to form.

Rough endoplasmic reticulum (RER)

Ribosome-studded ER involved in synthesising and transporting proteins.

Smooth endoplasmic reticulum (SER)

ER without ribosomes; site of lipid synthesis and more diverse metabolic processes.

Golgi apparatus

Stack of flattened sacs that processes, modifies, sorts and packages proteins and lipids for secretion or delivery to lysosomes or membranes.

Mitochondrion

Organelle that generates ATP by aerobic respiration; contains its own circular DNA and 70S ribosomes.

Cristae

Folds of the inner mitochondrial membrane that increase surface area for energy production.

Matrix

Internal mitochondrial compartment containing enzymes, DNA, and ribosomes.

Porin

Protein in the outer mitochondrial membrane that forms a channel for water‑soluble molecules.

Inner membrane

Selective barrier forming the mitochondrial boundary and housing the electron transport chain.

Lysosome

Single-membrane organelle with hydrolytic enzymes that digest waste materials and damaged organelles.

Ribosome

Ribonucleoprotein particles that synthesize proteins; 80S in cytoplasm/RER, 70S in chloroplasts and mitochondria.

80S ribosome

Ribosomes in the cytoplasm and on the RER of eukaryotic cells.

70S ribosome

Ribosomes found in chloroplasts and mitochondria (and some prokaryotes).

Chloroplast

Plant cell organelle where photosynthesis occurs; contains chlorophyll and has thylakoids, grana, and stroma.

Thylakoids

Flattened membrane discs in chloroplasts that carry the light-dependent reactions.

Grana

Stacks of thylakoids within chloroplasts.

Stroma

Fluid around grana in chloroplasts where the Calvin cycle occurs.

Starch

Plant storage polysaccharide composed of amylose and amylopectin (α‑glucose units).

Amylose

Unbranched component of starch; forms a helix; primarily α‑1,4 glycosidic bonds.

Amylopectin

Branched component of starch; contains α‑1,4 and α‑1,6 glycosidic bonds.

Glycogen

Animal storage polysaccharide; highly branched, mainly α‑glucose units.

Cellulose

Plant cell wall polysaccharide made of β‑glucose units with β‑1,4 glycosidic bonds; forms microfibrils.

Tramglucose bonds (glycosidic bonds)

Bond between monosaccharide units formed by condensation; hydrolysis breaks them.

Triglyceride

Glycerol esterified to three fatty acids; primary energy reserve; saturated vs unsaturated.

Phospholipid

Lipid with a hydrophilic phosphate head and two hydrophobic fatty acid tails; forms a bilayer.

Glycolipid

Lipid with carbohydrate group attached; contributes to membrane stability and recognition.

Glycoprotein

Membrane protein with carbohydrate chains; involved in cell recognition and signaling.

Protein

A polymer of amino acids; composed of amino, carboxyl groups and side chains.

Peptide bond

Covalent bond between amino acids formed by condensation; hydrolysed during digestion.

Primary structure

Amino acid sequence in a polypeptide; determines higher levels of structure.

Secondary structure

Coiling/folding of polypeptide due to hydrogen bonds (α‑helix or β‑pleated sheet).

Tertiary structure

Three-dimensional folding of a protein stabilized by various bonds (H‑bonds, disulphide bridges, ionic, hydrophobic interactions).

Quaternary structure

Arrangement of multiple polypeptide chains into a functional protein.

Globular protein

Globular, water-soluble proteins (e.g., enzymes, haemoglobin) with a compact shape.

Fibrous protein

Long, insoluble proteins with structural roles (e.g., collagen, keratin).

Haemoglobin

Globular protein with four polypeptide chains and a heme group; carries oxygen.

Sickle cell anaemia

Genetic mutation in haemoglobin where a polar amino acid is replaced, causing insolubility and sickling.

Collagen

Fibrous protein in connective tissues; triple helix with glycine every third amino acid; cross-linked fibrils.

Hydrogen bonding

Weak bonds between polar molecules, important for secondary and tertiary structures.

Water as solvent

Polar solvent that enables most biochemical reactions and transport in cells.

Diffusion

Net movement of molecules from high to low concentration; passive process.

Facilitated diffusion

Passive movement of molecules down a concentration gradient via transport proteins.

Osmosis

Diffusion of water across a semi‑permeable membrane; governed by water potential (ψ).

Active transport

Movement of substances against a concentration gradient; requires ATP and carrier proteins.

Na+/K+ pump

Active transport pump that maintains cellular ion gradients by moving Na+ out and K+ in.

Endocytosis

Cellular uptake by engulfing material with the plasma membrane (phagocytosis/pinocytosis).

Exocytosis

Secretory vesicles fuse with the plasma membrane to release contents outside the cell.

Fluid mosaic model

Membrane structure with a dynamic bilayer of phospholipids and embedded proteins.

Phospholipid bilayer

Two layers of phospholipids forming the basic structure of membranes; amphipathic.

Channel protein

Membrane protein forming a watery pore for ions/mmall; can be gated.

Carrier protein

Membrane protein that changes shape to move substances across the membrane; can be used in active or facilitated transport.

Receptor (membrane protein)

Protein that binds specific molecules (ligands) to trigger a cellular response.

Antibody (immunoglobulin)

Y‑shaped glycoprotein with two heavy and two light chains that binds antigenic determinants.

Monoclonal antibodies

Identical antibodies produced from a single B‑cell clone; highly specific for a single antigen.

Vaccination

Introduction of antigenic material to stimulate an immune response and memory.

Active immunity

Immunity produced by the body in response to an antigen (natural infection or vaccination).

Passive immunity

Temporary immunity gained from antibodies produced outside the body (e.g., mother to fetus, antibody injections).

HIV/AIDS

HIV is a retrovirus that destroys T helper cells, leading to AIDS; AIDS is the syndrome with severe immune failure.

Antigenic shift/drift

Mutations in pathogens causing new antigens; drift = gradual changes, shift = major changes.

Antibiotics

Drugs that kill or inhibit bacteria by targeting cell walls, membranes, enzymes, or DNA/protein synthesis.

Penicillin

Antibiotic that inhibits crosslinking in bacterial cell walls, weakening them and causing lysis.

MDR/XDR TB

Drug‑resistant tuberculosis strains arising from incomplete or improper treatment; require alternative regimens.

Vaccination booster

Additional dose to re‑stimulate the immune system and enhance immunity.