Year 10 Biology: Cell Biology, Microscopy, and Levels of Organisation

Comprehensive vocabulary flashcards covering cell theory, microscope components, plant and animal cell structures, bacterial organelles, specialized cell adaptations, biological levels of organisation, and magnification calculations.

Cell

The fundamental structural and functional unit of all living organisms.

Robert Hooke

The 17th-century scientist who examined cork tissue under an early microscope and coined the term cell.

Cell Theory

The unifying biological principle stating that all living things are composed of cells, cells are the smallest functional units of life, and all cells arise from preexisting cells by division.

Eyepiece (Ocular Lens)

The top lens of a microscope through which an observer looks, typically offering a magnification power of $10\times$ or $15\times$.

Objective Lenses

The primary magnification lenses mounted on a rotating nosepiece, commonly providing magnification levels of $4\times$, $10\times$, $40\times$, and $100\times$ (oil immersion).

Nosepiece (Revolving Turret)

The rotating mechanism on a microscope that holds the objective lenses and allows the user to switch between magnifications.

Condenser

A lens system mounted below the microscope stage that concentrates and focuses light from the illuminator onto the specimen to improve contrast and clarity.

Iris Diaphragm

An adjustable shutter situated beneath the stage that regulates the amount and aperture of light reaching the specimen.

Coarse Adjustment Knob

A control dial that moves the stage or body tube in large increments to achieve approximate or rough focus, primarily used with lower magnification objectives.

Fine Adjustment Knob

A control knob that moves the stage or body tube in small increments to bring a specimen into crisp, sharp focus, particularly under high power.

Mechanical Stage

A movable flat platform fitted with clips and control knobs allowing precise positioning of a microscope slide along both the $X$ and $Y$ axes.

Nucleus

A membrane-bound organelle containing genetic material ($\text{DNA}$) that regulates the chemical activities and reproduction of eukaryotic cells.

Cytoplasm

A gel-like cellular fluid composed of water and dissolved solutes that supports internal cell structures and serves as the site for metabolic processes, including anaerobic respiration.

Cell Membrane

A selectively permeable boundary enclosing cellular contents that regulates the passage of substances into and out of the cell.

Ribosome

A tiny non-membrane-bound structure located freely within the cytoplasm or bound to the endoplasmic reticulum that serves as the site of protein synthesis.

Mitochondria

Organelles found in the cytoplasm that serve as the site of aerobic respiration, releasing energy to fuel cellular reactions; cells with higher metabolic rates contain significantly greater numbers.

Cell Wall (Plant)

A rigid outer layer surrounding the cell membrane in plant cells, made of cellulose (a polymer of glucose), which provides mechanical strength and maintains cell shape.

Chloroplast

An organelle found in green plant cells containing chlorophyll pigments to absorb light energy and enzymes needed for photosynthesis.

Permanent Vacuole

A membrane-bound compartment in plant cells filled with cell sap (a solution of dissolved sugars and salts in water) that provides structural turgor support and stores materials.

Peptidoglycan

The structural macromolecule composing the cell wall of bacteria, structurally distinct from plant cellulose.

Plasmid

A small, circular ring of $\text{DNA}$ floating in the bacterial cytoplasm carrying accessory genes not present in the main chromosomal loop.

Flagellum

A long, thin, whip-like appendage on some bacteria and specialized cells that provides motility.

Lactobacillus

A rod-shaped bacterial species used commercially in the manufacturing of yoghurt from milk.

Pneumococcus

A spherical, pathogenic bacterial species responsible for causing pneumonia.

Rough Endoplasmic Reticulum (R.E.R.)

An internal membrane network within eukaryotic cells studded with ribosomes, visible under an electron microscope and involved in protein synthesis and transport.

Vesicle

A small circular membrane-bound sac that transports materials throughout the cytoplasm.

Differentiation

The developmental process by which unspecialized cells acquire distinct structural adaptations and functions under the control of nuclear genes.

Ciliated Cell

A specialized animal epithelial cell with hair-like extensions (cilia) that beat rhythmically to move mucus and trapped dust particles upward along the trachea and bronchi.

Nerve Cell (Neuron)

A specialized cell adapted for rapid conduction of electrical impulses across the body, featuring an elongated axon, branched dendrites, and an insulating myelin sheath.

Myelin Sheath

A fatty insulating layer formed from Schwann cells that covers the axon of a neuron to accelerate the transmission of electrical impulses.

Red Blood Cell (Erythrocyte)

A specialized blood cell characterized by a biconcave disc shape, absence of a nucleus, and high concentrations of haemoglobin for efficient oxygen diffusion and transport.

Acrosome

A cap-like structure at the anterior tip of a sperm cell head containing digestive enzymes required to penetrate the outer layer of an ovum during fertilisation.

Egg Cell (Ovum)

A female gamete possessing a large volume of nutrient-rich cytoplasm for early embryo development, a haploid nucleus, and a cell membrane that hardens post-fertilisation to block additional sperm.

Root Hair Cell

A specialized epidermal cell of plant roots featuring an elongated projection that increases surface area for maximum absorption of water and mineral ions, lacking chloroplasts.

Xylem Vessel

A non-living transport tube formed from joined hollow cells lacking end walls, reinforced with lignin to support plants and conduct a continuous water column.

Lignin

A rigid polymer deposited in the walls of xylem vessels that waterproofs them and provides mechanical support to the plant.

Palisade Mesophyll Cell

A columnar plant cell situated near the upper epidermis of leaves packed with numerous chloroplasts to maximize the absorption of sunlight for photosynthesis.

Tissue

An aggregate of similarly structured cells working cooperatively to perform a specific common biological function.

Organ

A distinct biological structure formed from different types of tissues cooperating to execute specific physiological functions.

Organ System

A group of interconnected organs with related functions working together to carry out major bodily processes.

Magnification Formula

The calculation expressing microscope power: $\text{Magnification} = \frac{\text{Image size}}{\text{Actual size}}$, where image and actual sizes share identical metric units and magnification carries no units.

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

A microscopic unit of linear measurement equal to $0.001\,\text{mm}$ ($10^{-3}\,\text{mm}$), meaning $1\,\text{mm} = 1000\,\mu\text{m}$ and $1\,\text{cm} = 10\,000\,\mu\text{m}$.