IGCSE Biology: Cells, Classification, Nutrition, and Organ Systems

Comprehensive vocabulary flashcards covering IGCSE Biology topics including characteristics of life, classification, microscopy, cytology, specialised cells, human nutrition, digestive enzymes, plant anatomy, and photosynthesis.

Movement

An action by an organism or part of an organism causing a change of position or place, defined as the ability to change position by themselves.

Respiration

The chemical reactions in cells that break down nutrient molecules and release energy for metabolism.

Sensitivity

The ability of an organism to detect and respond to changes in the internal or external environment.

Growth

A permanent increase in size and dry mass by an increase in cell number, cell size, or both.

Reproduction

The biological processes that make more of the same kind of organism, creating offspring or new individuals.

Excretion

The removal of the waste products of metabolism, toxic materials, and substances in excess of requirements from the bodies of living organisms.

Nutrition

The taking in and using of food and nutrient materials for energy, growth, and development.

Dichotomous Key

A biological identification tool consisting of a series of paired statements or 'yes'/'no' choices based on identifiable physical features used to classify and identify organisms.

Species

A group of organisms that can reproduce together to produce fertile offspring.

Binomial System

An internationally agreed naming system where an organism's scientific name consists of two parts: a capitalized Genus and a lowercase species.

Prokaryotes

Unicellular organisms that lack a distinct membrane-bound nucleus (having circular DNA free in the cytoplasm), lack mitochondria or chloroplasts, and possess a cell wall.

Protoctists

A kingdom of mostly unicellular (with some multicellular examples like kelp) eukaryotic organisms containing a nucleus, including amoeba, protozoa, and algae.

Fungi

Mostly multicellular eukaryotic organisms (with unicellular yeast) that have cell walls, lack chloroplasts, and feed by saprotrophic or parasitic absorption via hyphae.

Arthropods

Invertebrates characterized by having jointed legs, segmented bodies, and a hard exoskeleton, classified into insects, arachnids, crustaceans, and myriapods.

Monocotyledons

Flowering plants characterized by possessing $1$ cotyledon in the seed, parallel leaf veins, fibrous roots, and floral parts grouped in multiples of $3$.

Dicotyledons

Flowering plants characterized by possessing $2$ cotyledons in the seed, reticulate/branched leaf veins, taproots, and floral parts in multiples of $4$ or $5$.

Compound Light Microscope

An optical laboratory tool consisting of an eyepiece lens, body tube, turret with objective lenses, stage, light source or mirror, and coarse/fine focusing knobs.

Total Magnification

The complete magnification power of a light microscope calculated using the formula: $\text{Total magnification} = \text{Eyepiece lens} \times \text{Objective lens}$.

Biological Magnification Formula

The equation used to determine magnification from an image and actual object: $\text{Magnification } (M) = \frac{\text{Image Size } (I)}{\text{Actual Size } (A)}$.

Staining

The process of adding chemical solutions (such as iodine or methylene blue) to a specimen slide to improve contrast, highlight specific cell components, and make structures more visible.

Cell Membrane

A selectively permeable boundary present in all cells that controls the entry and exit of substances.

Nucleus

A structure found in plant and animal cells that contains genetic material (DNA) and controls cellular activities.

Cytoplasm

A jelly-like fluid found in all cells that contains organelles and serves as the primary site of metabolic and chemical reactions.

Cell Wall

A fully permeable outer layer providing structural support, composed of cellulose in plant cells and peptidoglycan in bacterial cells.

Chloroplasts

Organelles found in the green parts of plant cells that contain chlorophyll to absorb light energy for photosynthesis.

Mitochondria

Organelles present in plant and animal cells that act as the site of aerobic respiration to release energy.

Permanent Vacuole

A large central organelle in plant cells that stores cell sap (water and dissolved nutrients) and maintains cell turgidity.

Ribosomes

Small structures present in all cells that serve as the site of protein synthesis.

Plasmids

Small, circular loops of non-genomic DNA found in bacteria that confer extra phenotypic traits, such as antibiotic resistance.

Bacterial Cell

A prokaryotic cell lacking a nucleus, containing a peptidoglycan cell wall, cell membrane, cytoplasm, ribosomes, plasmids, and a circular loop of free-floating DNA.

Tissue

A group of cells with similar structures working together to perform a shared biological function.

Organ

A distinct biological structure made up of a group of tissues working together to carry out specific functions.

Organ System

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

Formed Elements of Blood

The cellular components of blood including red blood cells (erythrocytes) for oxygen transport, white blood cells (leucocytes) for immune defense, and platelets (thrombocytes).

Ciliated Epithelium

Specialized lining cells found in the throat and airways that possess surface cilia to sweep mucus, dust, and trapped dirt back up the airway.

Root Hair Cell

A specialized plant cell found in roots with a long, thin projection adapted to absorb water and mineral ions from the soil.

Palisade Mesophyll Cell

A specialized plant cell situated on the upper surface of leaves, packed with numerous chloroplasts to maximize photosynthesis.

Neurone

A specialized animal cell with dendrites, an axon, and a myelin sheath that conducts electrical impulses throughout the body to the brain.

Balanced Diet

An intake of food containing all essential nutrients in the correct proportions to maintain good health, proper body function, growth, repair, and energy.

Kwashiorkor

A malnutrition condition caused specifically by a severe dietary deficiency of protein.

Scurvy

A nutritional deficiency disorder resulting from an insufficient intake of Vitamin C.

Iodine Test

A biochemical test where iodine solution turns blue-black in the presence of starch.

Benedict's Test

A biochemical test for reducing sugars where a crushed sample is heated with Benedict's solution until boiling, turning orange/red upon a positive result.

Biuret Test

A biochemical test using sodium hydroxide and copper sulphate that turns purple in the presence of protein.

Ingestion

The process of taking food into the body through the mouth.

Peristalsis

The wave-like muscular contractions of the esophagus and digestive tract walls that push food downward to the stomach.

Chemical Digestion

The breakdown of large, insoluble food molecules into small, soluble molecules through the action of enzymes such as protease, amylase, and lipase.

Photosynthesis

The process by which green plants synthesize glucose and oxygen from carbon dioxide and water using light energy captured by chlorophyll: $\text{Carbon dioxide} + \text{Water} \rightarrow \text{Glucose} + \text{Oxygen}$.

Parts of a Leaf

The macro-anatomical components of a plant leaf, comprising the lamina (blade), apex, margin, veins, central midrib, petiole, and stipule.

Internal Leaf Structure

The micro-anatomical layers of a leaf comprising the waxy cuticle, upper epidermis, palisade mesophyll, spongy mesophyll with air spaces, vascular bundles (xylem and phloem), and lower epidermis with stoma and guard cells.