GCSE Biology - Cell Biology (Topic B1)

Comprehensive vocabulary flashcards covering GCSE Biology Topic B1 (Cell Biology), including cell structures, microscopy, differentiation, stem cells, the cell cycle, mitosis, diffusion, osmosis, active transport, and gas exchange surfaces.

Eukaryotic Cells

Complex cells that contain a nucleus and other subcellular structures, including all animal and plant cells.

Prokaryotic Cells

Smaller and simpler single-celled organisms, such as bacteria, that lack a 'true' nucleus and membrane-bound organelles.

Nucleus

A subcellular structure that contains genetic material in the form of chromosomes and controls the activities of the cell.

Cytoplasm

A gel-like substance where most of the cell's chemical reactions occur, containing enzymes that control these reactions.

Cell Membrane

A partially permeable barrier that holds the cell together and controls what moves into and out of the cell.

Mitochondria

Subcellular structures where most of the reactions for aerobic respiration take place, transferring the energy that the cell needs to work.

Ribosomes

Tiny subcellular structures where proteins are synthesised (made) in the cell.

Cell Wall (Plant)

A rigid outer layer made of cellulose that supports, strengthens, and maintains the shape of plant and algal cells.

Permanent Vacuole

A plant cell organelle that contains cell sap, which is a weak solution of sugar and salts.

Chloroplasts

Organelles found in plant and algae cells where photosynthesis occurs to produce food; they contain chlorophyll which absorbs the required light.

Plasmids

Small rings of DNA found in bacterial cells that float freely in the cytoplasm alongside a single circular strand of DNA.

Light Microscope

An instrument that uses light and lenses to form an image of a specimen, magnifying individual cells and large subcellular structures like nuclei.

Electron Microscope

A microscope that uses electrons to form an image, offering much higher magnification and resolution than light microscopes to view structures like ribosomes and plasmids.

Resolution

The ability of a microscope to distinguish between two very close points, where a higher resolution yields a sharper image.

Magnification Formula

The mathematical equation used to calculate image or real dimensions: $\text{magnification} = \frac{\text{image size}}{\text{real size}}$, where both sizes share identical units.

Stain (Microscopy)

A chemical substance, such as iodine solution, added to a microscope specimen to highlight objects within a cell by adding colour.

Cover Slip

A thin, transparent square of glass or plastic lowered onto a microscope specimen at an angle to avoid trapping air bubbles.

Differentiation

The process by which an undifferentiated cell changes to develop specific subcellular structures and become specialised for a specific function.

Sperm Cell Adaptations

Possesses a long tail and streamlined head for swimming to the egg, abundant mitochondria to provide energy, and enzymes in its head to digest the egg cell membrane.

Nerve Cell Adaptations

Long structure to cover distance with branched connections at its ends to connect with other nerve cells and form an electrical network throughout the body.

Muscle Cell Adaptations

Elongated cell that provides space for contracting, packed with lots of mitochondria to generate energy for contraction.

Root Hair Cell Adaptations

Possesses long projections extending into the soil that provide a large surface area for absorbing water and mineral ions.

Phloem Cells

Specialised plant cells joined end to end with very few subcellular structures, forming tubes that transport food substances around the plant.

Xylem Cells

Hollow, elongated plant cells joined end to end that form continuous tubes to transport water and minerals throughout the plant.

Stem Cells

Undifferentiated cells capable of dividing to yield more undifferentiated cells and differentiating into specialised cell types.

Embryonic Stem Cells

Stem cells obtained from early human embryos that possess the potential to differentiate into any type of human body cell.

Adult Stem Cells

Stem cells found only in specific tissues like bone marrow that can only differentiate into certain cell types, such as blood cells.

Therapeutic Cloning

A technique creating an embryo with the identical genetic information as a patient so that harvested stem cells will not be rejected by the patient's body.

Meristems

Tissues located in the growing tips of plant roots and shoots that contain stem cells able to differentiate into any plant cell type throughout the plant's life.

Chromosomes

Coiled-up lengths of DNA molecules located in the nucleus that carry large numbers of genes controlling various characteristics.

Mitosis

The stage of the cell cycle where a cell's nucleus divides, producing two new daughter cells that are genetically identical to the parent cell.

Cell Cycle

A series of stages in body cells involving cell growth, DNA replication, and mitosis to produce new identical cells for growth and repair.

Diffusion

The gradual spreading out of particles from an area of higher concentration to an area of lower concentration.

Concentration Gradient

The difference in the concentration of a substance between two regions; a larger gradient results in a faster rate of diffusion.

Osmosis

The net movement of water molecules across a partially permeable membrane from a more dilute solution to a more concentrated solution.

Partially Permeable Membrane

A membrane containing tiny holes that allows small molecules (such as water, glucose, and amino acids) to pass through, but blocks large molecules (such as starch and proteins).

Active Transport

The absorption or movement of substances against a concentration gradient (from lower to higher concentration), which requires energy from respiration.

Surface Area to Volume Ratio ($\text{SA} : \text{V}$)

A comparison showing how much surface area an organism has relative to its volume; larger organisms have smaller ratios compared to smaller organisms.

Exchange Surface Adaptations

Structural features that maximise diffusion: a thin membrane for short diffusion distance, large surface area, rich blood supply, and ventilation.

Alveoli

Microscopic air sacs in the lungs where gas exchange occurs; adapted with an enormous surface area (about $75\,\text{m}^2$ in humans), moist linings, thin walls, and good blood supply.

Villi

Millions of microscopic projections covering the inside wall of the small intestine that greatly increase the surface area for the absorption of digested food into the blood.

Stomata

Tiny pores covering the underside of a plant leaf that allow carbon dioxide to diffuse into the leaf, and oxygen and water vapour to diffuse out.

Guard Cells

Specialised cells flanking stomata that regulate their size and close them to prevent wilting if water is lost faster than the roots can replace it.

Gill Filaments

Thin plate structures that comprise fish gills, providing a high surface area for gas exchange between water and the bloodstream.

Lamellae (Fish Gills)

Tiny structures covering gill filaments that feature numerous blood capillaries, a thin surface layer of cells, and counter-current flow of water and blood to maximise gas exchange.