Concise Biology Class IX: Cell, Tissues, Flower, Pollination, Seeds, and Respiration

Vocabulary flashcards covering fundamental definitions, organelles, plant and animal tissues, floral anatomy, pollination, seed germination, and cellular respiration based on the ICSE Concise Biology textbook chapters.

Cell

The fundamental structural and functional unit of all living beings.

Cell Theory

The biological principle proposed by Matthias Schleiden and Theodor Schwann in 1839, with Rudolf Virchow's addition in 1858, stating that the cell is the smallest unit of structure and function of all living things, and all cells arise from pre-existing cells.

Organelles

Living parts of a cell that have a definite shape, structure, and specific function, performing roles within the cell analogous to organs in an organism.

Plasma Membrane

The living, thin, flexible, selectively permeable outer boundary of a cell composed of lipoproteins that regulates the entry and exit of solutes and ions.

Cell Wall

A non-living, rigid, freely permeable outer layer found only in plant cells, composed mainly of cellulose, that gives shape and rigidity to the cell.

Protoplasm

The total living substance of a cell, comprising both the cytoplasm and the nucleus.

Endoplasmic Reticulum

An irregular network of double membranes distributed over the cytoplasm, connected to the cell membrane on the outside and the nuclear membrane on the inside, serving as a supporting framework and pathway for material distribution.

Mitochondria

Spherical or rod-shaped double-walled organelles with inner folds called cristae that act as the cellular respiration sites releasing energy stored in the form of $38\,\text{ATP}$ per mole of glucose.

Ribosomes

Numerous small, single-walled dense granules composed mainly of RNA scattered in the cytoplasm or attached to the endoplasmic reticulum, serving as the main sites for protein synthesis.

Golgi Apparatus

Cell organelles consisting of stacks of flattened membrane sacs called cisternae, associated with vesicles and vacuoles, that function in the synthesis, packaging, and transport of cell secretions such as enzymes and hormones.

Dictyosomes

The specific term used for Golgi complexes in plant cells, which usually contain smaller and more scattered groups of cisternae and vesicles.

Lysosomes

Small membranous sacs containing about 40 different types of digestive enzymes that destroy foreign substances and rapidly dissolve damaged cellular organelles, commonly termed "suicide bags."

Centrosome

An organelle found only in animal cells, containing two centrioles surrounded by radiating microfilaments forming an aster during cell division, which initiates and regulates cell division.

Leucoplasts

Colourless plant plastids devoid of pigments that function primarily to store starch, as seen abundantly in potato cells.

Chromoplasts

Yellow, orange, or red plant plastids containing pigments such as xanthophyll and carotene that impart bright colours to flower petals and fruits to aid in pollination and seed dispersal.

Chloroplasts

Green-coloured plant plastids containing chlorophyll and disc-like thylakoids that trap solar energy and absorb carbon dioxide for the manufacture of food during photosynthesis.

Tonoplast

The membrane covering a vacuole in plant cells.

Stem Cells

Undifferentiated cells in the embryo or adult capable of undergoing unlimited divisions and giving rise to one or several specialized cell types.

Tissue

A group of similar cells performing a specific function.

Meristematic Tissue

Plant tissue composed of small, thin-walled, tightly packed, actively dividing cells with large nuclei and almost no vacuoles, found at growing points such as tips of roots, stems, and cambium.

Parenchyma

A type of simple permanent supporting plant tissue composed of large, thin-walled, living cells with a single large vacuole, located in soft plant parts like cortex and pith to store food and provide temporary support.

Chlorenchyma

Parenchymatous leaf cells containing chloroplasts that enable the plant to produce food through photosynthesis.

Collenchyma

Simple permanent supporting plant tissue made of elongated living cells with cell wall thickenings at the corners, providing mechanical support to leaf stalks and young stems.

Sclerenchyma

Simple permanent supporting plant tissue made of long, narrow, dead cells with heavily lignified, thick walls, providing structural strength to stems and leaf veins.

Xylem

Complex vascular plant tissue consisting of tracheids, vessels, xylem parenchyma, and xylem fibres, responsible for the upward conduction of water and dissolved minerals from roots.

Phloem

Complex vascular plant tissue consisting of sieve tubes, companion cells, phloem parenchyma, and phloem fibres, responsible for transporting manufactured organic food from leaves to other plant parts.

Epithelial Tissue

A thin, continuous, protective sheet of tightly fitted cells covering the outer body surface and lining internal body cavities and blood vessels.

Squamous Epithelium

Epithelial tissue composed of thin, flat cells with prominent nuclei, lining the mouth, nasal cavities, blood vessels, and lymph vessels to protect underlying structures from injury and drying up.

Ciliated Columnar Epithelium

Columnar epithelial tissue bearing thread-like protoplasmic projections called cilia at their free ends, which lash constantly to move materials, as seen in the lining of the trachea.

Tendons

Bundles of fibrous connective tissue that connect muscle to bone.

Ligaments

Bundles of fibrous connective tissue that connect bone to bone and hold them in position.

Neuron

A specialized nerve cell consisting of a cell body (cyton or perikaryon), dendrites, and a long axon that perceives stimuli and conducts nerve impulses.

Flower

A specialized shoot in flowering plants in which leaves are modified into floral structures to perform sexual reproduction.

Perianth

The non-essential floral structures formed when sepals and petals look very similar and cannot be visually distinguished, with individual members called tepals.

Monadelphous Stamens

Stamens whose filaments are united into a single group or bundle while their anthers remain free, as seen in China rose and cotton.

Diadelphous Stamens

Stamens whose filaments are united into two distinct bundles, as seen in pea flowers.

Polyadelphous Stamens

Stamens whose filaments are united into several distinct groups or bundles, as seen in Bombax.

Monoecious Plants

Plants in which separate male and female unisexual flowers grow on the exact same individual plant, such as maize and cucumber.

Dioecious Plants

Plants in which male (staminate) and female (pistillate) unisexual flowers grow on separate individual plants, such as palm and papaya.

Inflorescence

The mode or manner of arrangement of flowers on the axis of a plant.

Placentation

The manner in which ovules are attached to the wall of the ovary via the placenta.

Autogamy

The transfer of pollen grains from the anther to the stigma of the exact same flower.

The transfer of pollen grains from the anther of one flower to the stigma of another flower borne on the same individual plant.

Allogamy

The transfer of pollen grains from the anther of a flower on one plant to the stigma of a flower on another plant of the same species.

Cleistogamous Flowers

Small bisexual flowers that never open even at maturity, keeping their anthers and stigma hidden to enforce self-pollination without external agents.

Chasmogamous Flowers

Large flowers with open petals and exposed reproductive structures that require external pollinating agents for cross-pollination.

Protandry

A dichogamous condition in which the anthers of a flower mature earlier than its stigma to prevent self-pollination.

Protogyny

A dichogamous condition in which the stigma of a flower matures earlier than its anthers to prevent self-pollination.

Herkogamy

A condition in which mechanical or physical barriers prevent a flower's pollen from reaching its own stigma.

Heterostyly

A condition in which stigma and anthers grow at different heights in flowers of the same species, favoring cross-pollination.

Entomophilous Flowers

Flowers adapted for insect pollination, typically characterized by large brightly coloured petals, scent, nectar, and sticky or spiny pollen grains.

Anemophilous Flowers

Flowers adapted for wind pollination, characterized by small size, dull colour, absence of scent or nectar, light smooth pollen, versatile anthers, and feathery hanging stigmas.

Hydrophilous Flowers

Flowers adapted for water pollination, found exclusively in aquatic plants like Vallisneria.

Emasculation

The process of removing anthers from young flowers in artificial pollination before they mature.

Double Fertilization

A fertilization process unique to flowering plants in which one sperm nucleus fuses with the egg nucleus to form a zygote, and the second sperm nucleus fuses with two polar nuclei to form the primary endosperm nucleus.

Triple Fusion

The fusion of three nuclei—one sperm nucleus and two polar nuclei—inside the central cell of the embryo sac to produce the triploid endosperm nucleus.

Fruit

The enlarged, ripened ovary whose ovarian wall forms the pericarp that encloses the seeds.

Seed

The ripened ovule containing a dormant embryo capable of developing into a new plant under favorable conditions.

Grain

A single-seeded fruit in which the fruit wall (pericarp) and the seed coat (testa) are completely fused together, as in maize and wheat.

Scutellum

The single cotyledon present in the embryo of a monocotyledonous seed or grain like maize.

Coleorhiza

The protective sheath enclosing the radicle in a monocot seed.

Coleoptile

The protective sheath enclosing the plumule in a monocot seed.

Germination

The process of formation of a seedling developed from the dormant embryo when exposed to essential conditions such as water, suitable temperature, and oxygen.

Hypogeal Germination

A type of seed germination in which the epicotyl elongates faster than the hypocotyl, keeping the cotyledons underground.

Epigeal Germination

A type of seed germination in which the hypocotyl elongates rapidly and arches, pushing the cotyledons above the ground.

Vivipary

A specialized mode of seed germination occurring in mangrove plants like Rhizophora, where the seed germinates inside the fruit while still attached to the parent plant.

Aerobic Respiration

The complete oxidation of glucose in the presence of free oxygen into carbon dioxide and water, releasing energy as represented by $C_6H_{12}O_6 + 6O_2 \xrightarrow{\text{enzyme}} 6CO_2 + 6H_2O + 38\,\text{ATP}$.

Anaerobic Respiration

The incomplete breakdown of glucose in the absence of oxygen into ethanol and carbon dioxide, releasing a smaller amount of energy as represented by $C_6H_{12}O_6 \xrightarrow{\text{enzyme}} 2C_2H_5OH + 2CO_2 + 2\,\text{ATP}$.

Glycolysis

The initial cytoplasm-based phase of cellular respiration in which a glucose molecule is broken down into pyruvate.

Krebs Cycle

The second phase of aerobic respiration occurring inside the mitochondria, where pyruvate is oxidized to release carbon dioxide, water, and ATP.