General Biology: Scientific Method, Cytology, Classification, and Cellular Physiology

Comprehensive practice flashcards covering the scientific method, the characteristics and organization of living things, five-kingdom taxonomic classification, cellular structure and organelles, and cellular biophysical transport processes.

Biology

A branch of science involving the study of living things, derived from the Greek words "BIOS" (meaning life) and "LOGOS" (meaning to study).

Botany

The branch of biology concerned with the study of plants.

Zoology

The branch of biology concerned with the study of animals.

Hypothesis

A scientific or intelligent guess formulated by a scientist in order to account for an observed natural phenomenon.

Theory

A tested hypothesis that has been repeatedly proven correct within the limits of available evidence.

Principle or Law

A scientific theory that has been tested extensively and proven true through consistent positive results from independent experiments.

Klinostat (Clinostat)

A slowly rotating turntable used in plant experiments to expose all sides of a shoot equally to light or other external stimuli.

Controlled Experiment

An experiment designed to eliminate bias by keeping all factors constant except the single factor being tested (the variable).

Respiration

The oxidative breakdown of complex food substances (such as glucose) in cells to release energy for vital life activities.

Irritability (Sensitivity)

The capacity of living organisms to perceive and respond to external stimuli (e.g., heat, light, sound) or internal stimuli (e.g., hunger, thirst, pain) for survival.

Growth

An irreversible increase in size or dry weight resulting from the synthesis of new body materials, cell multiplication, cell enlargement, and differentiation.

Excretion

The biological process of removing waste products of metabolism from inside the body.

Virion

An infectious viral particle consisting of an outer protein shell and an inner nucleic acid core containing either RNA or DNA, but never both.

Bacteriophage

A virus that infects and replicates within bacterial cells, typically consisting of a head, DNA, neck, collar, sheath, base plate, and tail fibers.

Cell (Level of Organization)

The fundamental structural and functional unit of life, defined as a microscopic mass of protoplasm enclosing a nucleus and bounded by a membrane or wall.

Tissue

A group of similar cells working together to carry out a particular, specialized function.

Organ

A distinct structure composed of a group of similar tissues coordinated to perform a specific function.

System

A group of coordinated organs working together to perform a major bodily function.

Kingdom Monera

The kingdom of single-celled prokaryotic organisms (such as bacteria and blue-green anabaena) whose cells lack a nuclear membrane and most organelles except ribosomes.

Kingdom Protista

The kingdom of unicellular eukaryotic organisms with definite nuclei, mostly aquatic, divided into animal-like Protozoa and plant-like Protophyta.

Kingdom Fungi

Non-green, non-photosynthetic organisms with rigid cell walls of chitin and polysaccharides, reproducing via spores and typically forming saprophytic or parasitic mycelia.

Hyphae

The individual fine, branching filaments that make up the vegetative body of multicellular fungi.

Mycelium

The collective mass or network formed by interwoven hyphae in multicellular fungi.

Phylum Thallophyta (Algae)

Simple aquatic photosynthetic plants that lack vascular tissues and true roots, stems, or leaves, exhibiting alternation of generations.

Phylum Bryophyta

Multicellular, non-vascular terrestrial plants living in moist habitats that lack true roots, stems, and leaves and possess chlorophyll as their sole photosynthetic pigment.

Phylum Tracheophyta

The largest group of plants, comprising green, multicellular vascular plants with tissues for conducting food and water and true roots, stems, and leaves.

Pteridophyta (Ferns)

Spore-bearing vascular plants characterized by horizontal underground stems called rhizomes, sori for asexual reproduction, and prothalli for sexual reproduction.

Gymnosperms

Non-flowering seed plants whose seeds are borne naked in cones rather than enclosed within fruits (e.g., conifers, cycads, and ginkgoes).

Angiosperms

The largest group in the plant kingdom, consisting of flowering plants that produce seeds enclosed within fruits and utilize specialized pollination and fertilization mechanisms.

Monocotyledonous Plants

Angiosperms whose seeds contain one cotyledon, featuring fibrous roots, parallel leaf venation, scattered stem vascular bundles, and hypogeal germination without secondary growth.

Dicotyledonous Plants

Angiosperms whose seeds contain two cotyledons, characterized by taproots, net-veined leaves, secondary growth, and epigeal germination.

Phylum Porifera

Primitive aquatic multicellular animals (colonies of cells) lacking true tissues and nervous systems, commonly known as sponges.

Phylum Coelenterata (Cnidaria)

Aquatic animals with two-layered bodies surrounding a central enteron cavity, tentacles armed with stinging nematocysts, and a mouth but no anus.

Phylum Platyhelminthes

Flatworms with soft, flattened, unsegmented, bilaterally symmetrical bodies lacking a coelom and possessing an incomplete digestive tract with no anus.

Phylum Nematoda

Roundworms characterized by thread-like, cylindrical, unsegmented bodies without a body cavity, but with a complete alimentary canal having both mouth and anus.

Phylum Annelida

Segmented worms with long, cylindrical bodies, a true coelomic body cavity, and non-jointed locomotory setae (e.g., earthworms and leeches).

Phylum Arthropoda

The largest animal phylum, characterized by segmented bodies, jointed appendages, bilateral symmetry, and an exoskeleton composed of chitin.

Mycoplasma

A genus of bacteria recognized as the smallest single cell among living organisms.

Amoeba proteus

A free-living, shapeless unicellular protist that moves and engulfs food by extending and retracting pseudopodia.

Paramecium caudatum

A slipper-shaped ciliated protist containing a blunt anterior end, pointed posterior end, two contractile vacuoles, a mega nucleus, and a micro nucleus.

Euglena viridis

A unicellular protist displaying both plant-like traits (chloroplasts, paramylum granules) and animal-like traits (flagellum, eyespot, gullet, flexible pellicle).

Chlamydomonas reinhardtii

A unicellular biflagellate green alga, often called green yeast, with a cup-shaped chloroplast, pyrenoid, eyespot, and hemicellulose cell wall.

Volvox

A spherical colonial organism made of numerous flagellated cells connected by cytoplasmic strands, exhibiting physiological interdependence and division of labor.

Spirogyra

A multicellular filamentous green alga with unbranched cylindrical cells joined end to end, featuring spiral chloroplasts, pyrenoids, and a pectin-rich slippery outer wall.

Cell Theory

The biological principle establishing that all living things consist of cells, the cell is the basic structural and functional unit of life, and all cells arise from pre-existing cells.

Protoplasm

The entire living substance of a cell (cytoplasm and nucleus), originally designated as "sarcode" by Felix Dujardin in 1835 and renamed protoplasm by Purkinje in 1839.

Rough Endoplasmic Reticulum

A network of cytoplasmic canals studded with ribosomes that aids in the synthesis, packaging, and intracellular transport of proteins and enzymes.

Smooth Endoplasmic Reticulum

A network of endoplasmic tubules lacking ribosomes that synthesizes lipids and steroids, packages materials, and detoxifies drugs like codeine and morphine in the liver.

Ribosomes

Dense, rounded cellular organelles composed largely of ribonucleic acid (RNA) that serve as the direct sites of protein synthesis.

Mitochondria

Double-membraned, rod- or sausage-shaped organelles known as the "powerhouse of the cell," responsible for cellular respiration and oxidative phosphorylation of ADP to ATP.

Lysosomes

Membrane-bound spherical sacs containing digestive enzymes used to break down cellular debris, destroy degenerating tissues, and digest invading bacteria.

Golgi Apparatus

A stack of flattened tubular sacs that distributes synthesized proteins, produces lysosomes, and assists in generating endoplasmic reticulum membranes and plant cell walls.

Centriole

An organelle present primarily in animal cells that provides spindle fibers during cell division and aids in the formation of cilia and flagella.

Tonoplast

The semi-permeable membrane that bounds the central vacuole in a plant cell, enclosing the water, mineral salts, sugars, and pigments of the cell sap.

Diffusion

The random movement of gas or liquid molecules from a region of higher concentration to a region of lower concentration until an even distribution is achieved.

Osmosis

The net movement of water molecules from a region of low solute concentration (higher water potential) to a region of high solute concentration across a semi-permeable membrane.

Osmotic Pressure

The pressure developed in a concentrated solution when water diffuses into it across a semi-permeable membrane, or the pressure required to halt such water diffusion.

Yam Cavity Experiment

An experimental demonstration of osmosis where a peeled yam tuber cavity containing strong salt solution draws water from an external trough across living yam cells.

Haemolysis

The swelling and eventual bursting of red blood cells caused by excessive endosmosis when placed in a hypotonic medium.

Crenation

The shrinking and wrinkling of red blood cells caused by exosmosis of water when placed in a hypertonic solution.

Plasmolysis

The shrinkage of the central vacuole and pulling away of the cytoplasmic lining from the cell wall when a plant cell is placed in a hypertonic solution.

Turgidity

The firm, swollen state of a plant cell resulting from water entering the vacuole via endosmosis, causing the distended cytoplasm to press against the rigid cell wall.

Flaccidity

The limp, wilted condition that arises in plant tissues when the rate of water loss through transpiration exceeds the rate of water absorption by the roots.

Active Transport

The process by which molecules or ions are transported across a semi-permeable living cell membrane against a concentration gradient, requiring metabolic energy in the form of ATP.