RBSE Class 11 Biology Notes Chapter 6 Anatomy of Flowering Plants

These comprehensive RBSE Class 11 Biology Notes Chapter 6 Anatomy of Flowering Plants will give a brief overview of all the concepts.

RBSE Class 11 Biology Chapter 6 Notes Anatomy of Flowering Plants

→ Anatomically, a plant is made of different kinds of tissues.

→ The plant tissues are broadly classified into meristematic (apical, lateral and intercalary) and permanent (simple and complex).

→ Assimilation of food and its storage, transportation of water, minerals and photosynthates, and mechanical support are the main functions of tissues.

→ There are three types of tissue systems - epidermal, ground and vascular.

→ The epidermal tissue systems are made of epidermal cells, stomata and the epidermal appendages.

→ The ground tissue system forms the main bulk of the plant. It is divided into three zones - cortex, pericycle and pith.

→ The vascular tissue system is formed by the xylem and phloem.

→ On the basis of presence of cambium, location of xylem and phloem, the vascular bundles are of different types.

 

→ The vascular bundles form the conducting tissue and translocate water, minerals and food material.

→ Monocotyledonous and dicotyledonous plants show marked variation in their internal structures. They differ in type, number and location of vascular bundles.

→ The secondary growth occurs in most of the dicotyledonous roots and stems and it increases the girth (diameter) of the organs by the activity of the vascular cambium and the cork cambium.

→ The wood is actually a secondary xylem.

→ There are different types of wood on the basis of their composition and time of production.

→ Air space: Intercellular gaps within the spongy mesophyll. These gaps are filled with gas that the plant uses (Carbon dioxide - CO₂) and gases that the plant is expelling (Oxygen - O₂, and water vapour).

→ Amphiphloic: Having phloem on both sides of the xylem.

→ Analogous, analogy: Opposite to homologous, correspondence in function between anatomical parts of different structure and origin; analogous: exhibit analogy (synonym: similar).
 
→ Anatomy: Study of internal structure of plants is called anatomy.

→ Apical meristem: Embryonic, totipotent tissue in the tips of the roots and shoots of plants.

→ Cambium: A lateral meristem that produces secondary growth.

→ Collenchyma: Tissue composed of unevenly thickened cell walls; collenchyma cells are flexible and support young parts of the plant without hindering growth; collenchyma cells are composed of cellulose.

→ Companion cell: A specialized cell of phloem, derived from the same parent cell as the closely associated sieve-tube element immediately adjacent to it; the nucleus of the companion cell supports both its own cell and the cell of its associated sieve-tube element.

→ Complex tissue: Tissue that consists of more than one types of cells e.g., phloem.

→ Cork: A plant tissue composed of cells whose walls are impregnated with suberin and are non- living at maturity; cork is produced by the cork cambium.

→ Cortex: A primary tissue composed mainly of parenchyma cells, which extends between the epidermis and the vascular tissue.

→ Cuticle: The'waxy, water-repelling layer on the outer surface of a leaf that helps keep it from dying out (and protect it from invading bacteria, insects, and fungi). The cuticle is secreted by the epidermis (including the guard cells) and is often thinner on the underside of leaves. The cuticle is generally thicker on plants that live in dry environments.

→ Cutin: The waxy .substance of which a cuticle is composed.

→ Dictyostele: A dissected siphonostele with two or more.overlaping leaf bases.

→ Ectophloic: Having phloem only on the outer side of the stele; compare to amphiphloic.

→ Endarch: A type of xylem maturation in which protoxylem is internal to metaxylem and development proceeds centrifugally (from the inside to out).

→ Epidermis: The protective, outer layer of cells on the surface of a leaf. The guard cells (and stoma) are part of the epidermis. The surface of many leaves is coated with a waxy cuticle which is secreted by the epidermis.

→ Exarch: A type of xylem maturation in which protoxylem is external to metaxylem and development proceeds centripetally (from the outside to in).

→ Fiber: A long-walled plant cell which is often dead at maturity; fibers impart elasticity, flexibility and tensile strength to plant structure.

→ Ground tissue: A tissue consisting mostly of parenchyma cells that makes up the bulk of a young plant.

→ Growth form: A general description of the type of growth exhibited by a plant such as herbaceous, shrubby (bush-like) and arborescent (tree-like).

→ Guard cell: One of a pair of kidney-shaped cells that surround a stoma (a pore in a leal). Guard cells change shape (as light and humidity change), causing the stoma to open and close.

→ Lamina: The blade of a leaf.

→ Leaf gap: A parenchyma filled interruption in a stem’s cylinder of vascular tissue immediately above the point at which a branch of vascular tissue (leaf trace) leading to a leaf occurs.

→ Meristem: Region of totipotent cells in which cell division and initiation of tissues and organs takes place; apical meristem, vascular cambium and cork cambium.

→ Mesarch: A type of xylem maturation in which the protoxylem is embedded in the metaxylem and development proceeds both centripetally (from the outside to in) and centrifugally (from the inside to out); compare to endarch and exarch.

→ Mesophyll: Parenchyma tissue between the upper and lower epidermis of a leaf.

→ Metaxylem: A type of primary xylem that differentiates and matures later than the protoxylem; generally metaxylem tracheids are longer than protoxylem.

→ Midrib: The central rib of a leaf - it is usually continuous with the petiole.

→ Palisade mesophyll: A layer of elongated cells located under the upper epidermis. These cells contain most of the leaf s chlorophyll, converting sunlight into usable chemical energy for the plant.

→ Parenchyma: the most common type of plant cell; thin-walled cells, varying in size, shape, and function. Phloem: A vascular tissue in land plants primarily responsible for the distribution of sugars and nutrients manufactured in the shoot.

→ Pith: The central parenchymatous tissue in a vascular plant axis.

→ Polystelic: Having more than one stele.
 
→ Primary growth: Growth in length, controlled by the apical meristem.

→ Protostele: A type of stele with a solid core of primary xylem.

→ Protoxylem: The first primary xylem to differentiate and mature usually before and during elongation of the axis; protoxylem cells are generally smaller in diameter than metaxylem.

→ Sclerenchyma: Tissue composed of thick-walled cells containing lignin for strength and support.

→ Sclereids: A short, irregular sclerenchyma cells with pits; sclereids function as tissue support.

→ Sclerenchyma: Tissue composed of cells with walls thickened with lignin; sclerenchyma tissue functions primarily in strengthening and support.

→ Secondary growth: Growth in width initiated and maintained by the vascular cambium and cork cambium.

→ Secondary xylem: Xylem produced by the vascular cambium.

→ Sieve cell: A phloem conducting cell type in all vascular plants except angiosperms.

→ Sieve element: Cell in the phloem tissue concerned with longitudinal conduction of food materials. In flowering plants, it is called as sieve-tube element.

→ Sieve plate: Area of the wall of a sieve tube element that contains several to many perforations that permits cytoplasmic connections between sieve tube cells.

→ Sieve tube: A series of sieve-tube elements arranged end to end and interconnected through sieve plates.

→ Siphonostele: A type of stele that consists of a ring of vascular tissue surrounding pith.

→ Spongy mesophyll: The layer below the palisade mesophyll; it has irregularly-shaped cells with many air spaces between the cells. These cells contain some chlorophyll. The spongy mesophyll cells communicate with the guard cells (stomata), causing them to open or close, depending on the concentration of gases.

→ Stele: The central vascular cylinder in stems and roots where the vascular tissue is located.

→ Stem: (Also called the axis) the main support of the plant.

→ Stoma: (Plural stomata) a pore (or opening) in a plant's leaves where water vapour and other gases leave and enter the plant. Stomata are formed by two guard cells that regulate the opening and closing of the pore. Generally, many more stomata are on the lower side of a leaf than on the upper.

→ Tracheid: A water conducting and supportive cell type of xylem composed of long, thin cells with tapered ends and walls hardened with lignin.

→ Transverse section: Cross section; a section perpendicular to the longitudinal axis of the plant organ.

→ Unifacial Vascular cambium: Having one “face”, i.e., a cambium that produces cells only on one side; a unifacial vascular cambium that produces only secondary xylem is found in some fossil non-seed plants.

→ Vascular bundle: A strand of tissue composed mostly of xylem and of phloem.

→ Vascular cambium: A lateral meristem that produces secondary vascular tissue in stems and roots.

→ Vascular tissue: Tissue composed of conducting cells, i. e., xylem and phloem.

→ Xylem: A vascular tissue in land plants primarily responsible for the distribution of water and minerals taken up by the roots; also the primary component of wood.