AQA GCSE Biology: Cell Biology

Comprehensive vocabulary flashcards covering AQA GCSE Biology: Cell Biology topics including cell structures, specialised cells, microscopy, bacterial growth, cell division, and transport mechanisms.

Eukaryotic cells

Plant and animal cells that contain a cell membrane, cytoplasm, and genetic material enclosed in a nucleus.

Prokaryotic cells

Bacterial cells that are much smaller than eukaryotic cells, featuring a cytoplasm and cell membrane surrounded by a cell wall, with genetic material in a single DNA loop and potentially one or more plasmids.

Millimetre (mm)

A unit of measurement equal to a thousandth of a metre ($10^{-3}\,m$).

Micrometre ($\mu\text{m}$)

A unit of measurement equal to a millionth of a metre ($10^{-6}\,m$).

Nanometre (nm)

A unit of measurement equal to a billionth of a metre ($10^{-9}\,m$).

Nucleus

A sub-cellular structure that contains genetic information and controls the cell's activities.

Cell membrane

The structure that controls the passage of substances, such as glucose and ions, in and out of the cell.

Cytoplasm

The part of the cell where most chemical reactions take place.

Ribosomes

The sub-cellular structures where protein synthesis occurs.

Mitochondria

The sub-cellular structures where aerobic respiration takes place.

Chloroplasts

Organelles in plant cells where photosynthesis occurs containing chlorophyll.

Plasmids

Small rings of DNA in bacterial cells that code for specific features such as antibiotic resistance.

Permanent vacuole

A structure found in plant cells filled with cell sap.

Cell wall

A structure made of cellulose that strengthens plant and algal cells.

Sperm cells

Cells adapted for reproduction with a long tail, middle section with lots of mitochondria for energy, an acrosome for breaking down egg layers, and a large nucleus.

Nerve cells

Cells adapted for transmitting messages with a long axon, dendrites for connections, and nerve endings with mitochondria for transmitter chemicals.

Muscle cells

Cells adapted for movement containing many mitochondria, stored glycogen, and special proteins that slide to cause contraction.

Root hair cells

Plant cells adapted for absorbing minerals and water with an increased surface area, large permanent vacuole, and many mitochondria for active transport.

Xylem cells

Cells adapted to carry water and mineral ions from roots, coated in lignin which kills and waterproofs them, forming hollow tubes.

Phloem cells

Cells adapted to transport sugar (translocation) with sieve plates and supported by companion cells containing mitochondria.

Cell differentiation

The process by which a cell becomes specialised for a particular function by acquiring different sub-cellular structures.

Light microscopes

Instruments that use a beam of light and lenses to form an image, magnifying up to around 2000 times.

Electron microscopes

Instruments invented in the 1930s that use beams of electrons to form images with up to 2,000,000 times magnification and higher resolving power.

Resolution

The ability to distinguish between two points.

Magnification formula

$$\text{Magnification} = \frac{\text{size of image}}{\text{size of real object}}$$

Binary fission

The simple cell division process by which bacteria multiply.

Aseptic technique

Methods used to prepare uncontaminated cultures, including sterilising equipment and media to prevent the growth of unwanted microorganisms.

Zone of inhibition

A clear area of agar gel indicating where bacteria have been killed by a disinfectant or antibiotic.

Bacterial populations equation

$$\text{Bacteria at end of growth period} = \text{Beginning quantity} \times 2^{\text{number of divisions}}$$

Chromosome

A structure made of DNA molecules found in the nucleus; body cells normally contain them in pairs.

Cell cycle

The three-stage process consisting of interphase, cell division (mitosis), and cytokinesis.

Interphase

The longest part of the cell cycle where the cell grows, functions, and doubles its genetic material.

Cytokinesis

The stage of the cell cycle when the cell cytoplasm divides to form daughter cells.

Mitosis

The part of the cell cycle where one set of chromosomes is pulled to each end of the cell and the nucleus divides.

Diffusion

The spreading out of particles resulting in a net movement from an area of higher concentration to an area of lower concentration.

Osmosis

The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

Isotonic

When the external concentration of solutes is the same as the internal concentration.

Hypertonic

When the external concentration of solutes is greater than the internal concentration.

Hypotonic

When the external concentration of solutes is lower than the internal concentration.

Crenation

The process occurring when an animal cell is placed in a hypertonic solution and water travels out by osmosis.

Lysis

The bursting of an animal cell when placed in a hypotonic solution due to water entering via osmosis.

Plasmolysed (Flaccid)

The condition of a plant cell placed in a hypertonic solution where the cell membrane pulls away from the cell wall.

Turgid

The swollen state of a plant cell when placed in a hypotonic solution.

Active transport

The movement of substances from a dilute solution to a more concentrated solution (against a concentration gradient), requiring energy from respiration.