AQA Biology GCSE Topic 1: Cell Biology - Vocabulary Flashcards

Vocabulary flashcards covering key terms and definitions from the notes on Cell Biology.

Eukaryote

A cell that has a nucleus and membrane-bound organelles; examples include animal and plant cells.

Prokaryote

A simple cell without a nucleus; bacteria have circular DNA and plasmids and are smaller.

Organelle

A specialised subcellular structure with its own function inside a cell.

Cell membrane

The phospholipid bilayer that controls what enters and leaves the cell.

Cytoplasm

The jelly-like interior where chemical reactions occur and organelles are located.

Nucleus

The organelle that contains the cell’s DNA and is surrounded by a membrane.

DNA

The molecule that carries genetic information for making proteins.

Chromosome

A long DNA molecule that carries many genes; humans have 23 pairs.

Gene

A short section of DNA that codes for a protein and determines a feature.

Plasmid

Small circular DNA separate from the bacterial chromosome in bacteria.

Bacterial DNA (single circular strand)

The main circular chromosome of bacteria that contains essential genes.

Cell wall (plants/bacteria)

Rigid layer that supports the cell; in plants made of cellulose.

Cellulose

A carbohydrate that strengthens plant cell walls.

Mitochondrion

Organelle where aerobic respiration occurs; provides energy (ATP).

Ribosome

Organelle where protein synthesis happens; found on rough endoplasmic reticulum.

Chloroplast

Organelle where photosynthesis occurs; contains chlorophyll.

Chlorophyll

Green pigment that captures light energy for photosynthesis.

Permanent vacuole

Large vacuole in plant cells containing cell sap and helping rigidity.

Nucleus (structure/function)

Contains DNA; enclosed by a nuclear membrane.

Cell membrane (function)

Controls what enters and leaves the cell.

Mitochondria (function)

Powerhouse of the cell; site of energy production through respiration.

Chloroplasts (function)

Sites of photosynthesis in plant cells; contain chlorophyll.

Ribosomes (function)

Sites of protein synthesis; essential for building proteins.

Vacuole (plant cell)

Stores cell sap and helps maintain turgor pressure.

Cell wall (function)

Provides structural support and protection; made of cellulose in plants.

Sperm cell

Male gamete specialized to deliver DNA to the egg; streamlined head, long tail, mitochondria, acrosome.

Nerve cell (neuron)

Transmits electrical impulses; long axon and dendrites for connections.

Muscle cell

Specialised to contract; contains actin and myosin and many mitochondria.

Root hair cell

Cell in roots with a large surface area for water and mineral uptake.

Xylem cell

Water and mineral transport tubes; dead, hollow, lignified cells.

Phloem cell

Transport sugars and nutrients; contains sieve plates and companion cells.

Lignin

Rigid compound deposited in xylem walls to withstand pressure.

Sieve plates

Breaks in phloem cell walls that allow movement of substances between cells.

Companion cell

Provides energy to phloem sieve elements for loading and transport.

Meristem

Plant stem cells found at tips; can differentiate into various plant cells.

Embryonic stem cell

Pluripotent stem cells from the embryo that can become any cell type.

Adult stem cell

Stem cells found in tissues (e.g., bone marrow) with limited differentiation.

Therapeutic cloning

Creating embryos to harvest embryonic stem cells with the same genes as the patient.

Mitosis

Nuclear division producing two genetically identical nuclei; part of the cell cycle.

Interphase

Stage of the cell cycle when the cell grows and DNA is replicated.

Cytokinesis

Division of the cytoplasm; results in two separate daughter cells.

Cell cycle

Series of stages including growth, DNA replication, and division; mitosis is part of it.

Diffusion

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

Gas exchange

Movement of gases (O2 in, CO2 out) across respiratory surfaces by diffusion.

Alveoli

Tiny air sacs in the lungs with a large surface area for gas exchange.

Villi

Small projections in the small intestine that increase surface area for absorption.

Gills (lamellae)

Gas exchange sites in fish where water diffuses oxygen into blood.

Guard cells

Specialised cells that regulate stomatal openings in leaves.

Stomata

Pores on the leaf surface allowing gas exchange; opened by guard cells.

Osmosis

Movement of water across a partially permeable membrane from high to low water potential.

Isotonic

Solution with the same water potential as the cell, no net water movement.

Hypertonic

External solution has higher solute concentration; water leaves the cell.

Hypotonic

External solution has lower solute concentration; water enters the cell.

Turgor

Internal pressure in plant cells from water uptake that keeps leaves stiff.

Plasmolysis

Cell membrane pulls away from the cell wall when cells lose water in hypertonic solutions.

Potato osmosis experiment

Measuring potato mass change after soaking in sugar solutions to infer water potential differences.

Active transport

Movement of substances against the concentration gradient requiring energy.

Root hair active transport

Uptake of mineral ions from soil into root hairs using energy.

Gut active transport

Absorption of glucose and amino acids from the gut into the bloodstream against the gradient.

Binary fission

Asexual bacterial reproduction where one cell divides into two identical cells.

Zone of inhibition

Clear area around an antibiotic disc on an agar plate indicating bacterial death.

Autoclave

Sterilizing device using steam under pressure to kill microorganisms.

Inoculating loop

Sterilized tool used to transfer microorganisms in culture procedures.

Petri dish

Shallow dish containing agar used to culture microorganisms.

Agar

Gelatinous medium used as a culture substrate for microorganisms.

Colony

A visible group of microorganisms growing on a culture surface.

Prefixes (centi, milli, micro, nano)

Small unit prefixes: centi (0.01), milli (0.001), micro (0.000001), nano (0.000000001).

Magnification

Product of the magnifications of the eyepiece and objective lenses.

Resolution (resolving power)

Ability to distinguish two close points as separate; higher RP means better detail.

SEM

Scanning electron microscope; produces 3D images with up to high magnification.

TEM

Transmission electron microscope; produces 2D images with very high resolution.

Size of object formula

Size of object = size of image / magnification (units must match).