Year 7 Cells and Classification AT3 Prep Science MHS

A vocabulary set covering key terms from the 7.3 Cells and Classification notes, including living things, classification, taxonomy, cell theory, organelles, energy processes, and Indigenous classification concepts.

Living things

Organisms that display Characteristics of Life and can be distinguished from non-living things.

Characteristics of Life

The shared processes that define life: Movement, Responses to Stimuli, Respiration, Assimilation, Growth, Reproduction, Excretion.

Movement

The ability of living things to move or change position, either visibly (animals) or less obviously (plants).

Responses to Stimuli

Detecting and responding to changes in the surroundings.

Respiration

Producing energy through chemical processes to supply the organism.

Assimilation

Absorption of nutrients to support growth and repair of the body.

Growth

Increase in body mass by cell multiplication.

Reproduction

Production of offspring by sexual or asexual processes.

Excretion

Removal of waste materials produced during metabolism.

Classification

The process of grouping similar things together based on common features.

Taxonomy

The science of identifying, describing, naming, and classifying organisms into hierarchical groups.

Binomial nomenclature

Scientific naming of species using genus and species names (genus capitalised; species lowercase; Italicised or underlined).

Linnaean system

The internationally recognised taxonomic system based on binomial nomenclature and hierarchical classification.

Five Kingdom Classification System

Early framework dividing life into Monera, Protista, Fungi, Plantae, and Animalia (later expanded by domains).

Prokaryote

Organism lacking a defined nucleus and membrane-bound organelles (e.g., bacteria, archaea).

Eukaryote

Cell or organism with a defined nucleus and membrane-bound organelles (multicellular or unicellular).

Kingdoms (Monera, Protista, Fungi, Plantae, Animalia)

Initial Linnaean grouping of life into five kingdoms before domains were added.

Domain

A higher taxonomic rank above kingdoms (Archaea, Bacteria, Eukarya).

Species

A group of organisms with the same evolutionary history, capable of interbreeding to produce viable offspring; share chromosome number and genetic similarities.

Subspecies

A distinct population within a species with characteristic differences, but not enough to be a separate species.

Hybrids

Offspring resulting from the cross-breeding of two different or closely related species; often sterile (exceptions exist).

Dichotomous key

A tool that uses paired statements to identify organisms by progressively narrowing options.

Adaptations

Ways organisms cope with environmental stresses to survive: structural, behavioural, and physiological.

Structural adaptation

Physical features of an organism (e.g., body parts, coloration) that aid survival.

Behavioural adaptation

Actions or behaviors that help an organism survive in its environment.

Physiological adaptation

Internal bodily processes that enhance survival (e.g., venom production, temperature regulation).

Cell

The basic unit of life; all living things are composed of one or more cells.

Tissue

A group of similar cells that work together to perform a specific function.

Organ

A structure made of two or more tissues that carries out a specific function.

System

A group of organs that work together to perform a broader task in the organism.

Organelles

Specialised structures within a cell that perform specific functions (e.g., nucleus, mitochondria).

Cell membrane

Thin, tough boundary that surrounds the cell; controls movement of substances in and out.

Cytoplasm

The cell contents outside the nucleus; site of many chemical reactions; contained in cytosol.

Nucleus

Control centre storing genetic material and coordinating cellular activities.

Mitochondria

Powerhouse of the cell; site of cellular respiration producing ATP.

Chloroplasts

Organelles in plants where photosynthesis occurs; contain chlorophyll.

Vacuole

Storage and waste disposal organelle; largest in plant cells.

Cell wall

Rigid layer outside the cell membrane in plants; made of cellulose; provides support.

Endoplasmic reticulum

Network of membranes; rough has ribosomes (protein synthesis); smooth lacks ribosomes (lipid synthesis and transport).

Golgi apparatus

Modifies, sorts, and packages substances for transport within or outside the cell.

Ribosome

Site of protein synthesis; can be free-floating or attached to ER.

Plant cell

Cell type characterized by cell wall, vacuole, and chloroplasts in addition to standard organelles.

Animal cell

Cell type lacking cell wall and chloroplasts; typically contains nucleus, membrane, cytoplasm, mitochondria.

Photosynthesis

Process by which green plants convert sunlight into glucose in chloroplasts.

Chlorophyll

Green pigment in chloroplasts that absorbs light for photosynthesis.

Cellular respiration

Process that releases energy (ATP) by breaking down glucose, mainly in mitochondria.

ATP

Adenosine triphosphate; the energy currency produced by cellular respiration.

Cristae

Folded inner membranes of mitochondria where ATP production occurs.

Indigenous classification systems

Diverse binary and hierarchical ways First Nations Australians classify plants and animals based on uses, forms, and functions (e.g., edible/non-edible; totemic/non-totemic).

MRS GREN

Movement; Respiration; Sensitivity (Responses to stimuli); Growth; Reproduction; Excretion; Nutrition/Assimilation.

Taxonomic hierarchy

Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species (from most general to most specific).

Taxonomic mnemonic

"Dear King Philip Came Over For Good Soup" = Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Magnification

The factor by which an image is enlarged; total magnification = objective lens × eyepiece lens.

Resolution

The ability of a microscope to distinguish two very close points as separate; higher resolution shows finer detail.

Light microscope

A microscope that uses visible light and lenses to magnify specimens; suitable for viewing living cells and stained slides at moderate magnification.

Electron microscope

A microscope that uses electron beams for much higher magnification and resolution to view ultrastructure; typically requires dead, specially prepared specimens.

Preparing microscope slides

Place a very thin specimen on the slide, add a drop of water or stain if needed, carefully lower a cover slip to avoid air bubbles, and label the slide.

Scientific drawings for microscopes

Pencil drawing with clear labels, no shading, correct proportions, a scale or magnification, and a descriptive title.

Cell theory

(1) All living things are composed of one or more cells; (2) Cells are the basic units of structure and function in organisms; (3) All cells come from pre-existing cells.

Unicellular organism

An organism made of a single cell that carries out all life processes (e.g., many bacteria, some protists).

Multicellular organism

An organism made of many specialised cells that form tissues, organs and systems to carry out life processes.

Red blood cell (RBC)

Transports oxygen using haemoglobin; biconcave shape increases surface area for gas exchange and it lacks a nucleus to maximise oxygen-carrying capacity.

Sperm cell (example)

The male gamete; small with a flagellum (tail) for movement, many mitochondria for energy, and an acrosome containing enzymes to penetrate the egg.

Nerve cell (neuron)

A specialised cell for transmitting electrical impulses; typically has dendrites to receive signals and a long axon to transmit them.

Guard cell

One of a paired cell around a stomatal pore; changes shape to open or close the stoma, controlling gas exchange and water loss in leaves.

Root hair cell

An elongated epidermal cell on plant roots that increases surface area for absorption of water and minerals from the soil.

Hierarchy in living organisms

The levels of biological organisation: Cell → Tissue → Organ → Organ system → Organism.

Dichotomous key

A tool for identifying organisms that uses a series of paired, mutually exclusive choices based on observable features to narrow down to a single identification.

Designing a dichotomous key

Create clear, observable, mutually exclusive paired statements at each step so each branch leads logically to a single organism or group.

Prokaryotic cell

A unicellular organism without a nucleus or membrane-bound organelles; DNA is free in the cytoplasm (e.g., bacteria).

Eukaryotic cell

A cell that contains a nucleus and membrane-bound organelles; found in animals, plants, fungi, and protists.

Specialised cell

A cell that has a particular structure and function suited to its role (e.g., red blood cell, neuron, root hair cell).

Cell specialisation

The process by which cells develop specific structures and functions to perform particular tasks in multicellular organisms.

Photosynthesis word equation

carbon dioxide + water → glucose + oxygen (in the presence of sunlight and chlorophyll).

Cellular respiration word equation

glucose + oxygen → carbon dioxide + water + energy (ATP).

Adaptive features

Physical or behavioural traits that improve an organism’s chances of survival and reproduction in its environment.

Eyepiece (ocular lens)

The lens you look through; contains the ocular lens and contributes to total magnification.

Objective lens

Lens near the specimen; microscopes have multiple objectives (e.g., 4x, 10x, 40x) that determine most of the magnification.

Revolving nosepiece

The rotating part that holds objective lenses and lets you switch magnification quickly.

Stage

The flat platform where the slide is placed for viewing.

Stage clips

Metal clips that hold the slide in place on the stage.

Diaphragm (iris)

Controls the amount of light reaching the specimen and affects contrast.

Condenser

Focuses light onto the specimen to improve image brightness and resolution.

Coarse adjustment knob

Large focus knob used to make big changes in stage position for rough focusing (use on low power only).

Fine adjustment knob

Small focus knob used for precise focusing at medium/high power.

Light source (lamp)

Provides the illumination that passes through the specimen (adjust brightness as needed).

Arm

The support structure used to carry the microscope (also where you hold it).

Base

The bottom support of the microscope containing the light source and electronics.

Field of view (FOV)

The circular area visible through the eyepiece; diameter used to estimate specimen size.

Measuring FOV with a mini-grid

Place mini-grid slide, count number of 1 mm squares across FOV, multiply to get FOV diameter in mm then convert to µm.

Scale bar calculation (steps)

1) Measure FOV diameter (µm). 2) Draw FOV circle and measure its diameter on paper (cm). 3) Scale = actual µm ÷ measured cm → record as 1 cm : x µm.

Unit conversions (quick)

1 mm = 1000 µm; 1 cm = 10 mm = 10,000 µm. (Use these when converting FOV and scale bars.)

Wet mount preparation (steps)

Place thin specimen on slide, add one drop of water, lower coverslip at 45° to avoid bubbles, remove excess liquid, label slide.

Preparing a stained slide (onion example)

Place specimen on slide, add a drop of stain (methylene blue or iodine), wait briefly, lower coverslip carefully, remove excess stain, observe under microscope.

Purpose of staining

Stains increase contrast, highlight specific structures (e.g., nucleus), and make transparent parts visible for observation.

Methylene blue

A common stain that highlights nuclei in animal cells and some plant tissues.

Iodine

A stain that highlights starch and improves contrast in plant cell structures.

Unstained vs stained observation

Unstained specimens may be clearer for living movement but low contrast; stained specimens show structures more clearly but usually require fixed/dead samples.

Mini-grid usage

A 1 cm mini-grid contains 1 mm squares; count squares across FOV to estimate diameter (use 0.1 mm sub-squares for finer measures).

Estimating specimen size from FOV

If specimen fills half the FOV, specimen size ≈ 0.5 × FOV diameter (convert units appropriately).