General Biology Final Reviewer PDF

GENERAL BIOLOGY STUDENT’S ADVISORY BOARD PEER TUTORING PROGRAM 3. Storage Root - tap root has become greatly thickened, I. ROOTS accumulating reservoirs of h...

GENERAL BIOLOGY STUDENT’S ADVISORY BOARD PEER TUTORING PROGRAM 3. Storage Root - tap root has become greatly thickened, I. ROOTS accumulating reservoirs of high energy storage compounds (usually starch) Plants organ that function for anchorage and in absorption of water and minerals Developed by the formation of new cells within the actively 4. Adventitious Roots - roots that arise from anything other growing apical meristem of the root tip than the radicle EMBRYONIC ROOT A. ROOT TYPES 5. Aerial Roots - epiphytic plants (grow on another plant), particularly tropical members of the monocot families (ex 1. Fibrous Root (arise from radicle) - if the primary root soon Orchidaceae) withers and subsequent roots are diffused; the plant has a fibrous root system. 2. Taproot (arise from radicle) - if the primary root becomes dominant; and the plant is described as having a taproot 6. Haustoria - specialized structures of parasitic plants that system penetrate the tissues of host plants 7. Prop Roots - grows from the base of the stem and provides support to the plant STUDENTS’ ADVISORY BOARD. 1  1. Root Cap Initials 2. Protoderm 3. Ground Meristem 4. Procambium 5. Root Cap 8. Pneumatophores - specialized structures of plants growing in swamps or marshes; roots that grows upward from soil to air in order to obtain additional oxygen. Region of Elongation - cells become longer and wider 9. Buttress Roots - are enlarged horizontally spreading and often vertically thickened roots at the base of trees that aid in mechanical support; they are found in certain tropical or marsh/swamp tree species. Region of Maturation/ Differentiation - Root hairs develop as protuberances from epidermal cells - Increase the surface area for the absorption of water - Cuticle exists on root but on root hairs EXTERNAL ANATOMY Root Apical Meristem STUDENTS’ ADVISORY BOARD 2  MONOCOT ROOT CROSS SECTION DICOT ROOT CROSS SECTION Pericycle - gives rise to branch roots, which force their way out through the cortex and epidermis - Lateral roots arise from the pericycle of the steele Stele - central cylinder - Pericycle - Xylem - Phloem STUDENTS’ ADVISORY BOARD 3  Woody Dicot Absorption of materials - osmosis, imbibition, diffusion of solutes and active absorption Roots hairs -> cortex -> endodermis -> pericycle -> xylem Storage of food and water -> cortex of cells and roots, Young Dicot parenchyma of stele Growth in length -> root tips Roots give off waste products into the soil II. STEM External Morphology of the Stem Dicot and Monocot Stem Cross Section Monocot Monocot Vascular Bundle STUDENTS’ ADVISORY BOARD 4  STEM MODIFICATIONS TISSUE LAYER MONOCOT DICOT Epidermis Single layer with thick Single layer with thick SUB-AERIAL MODIFICATIONS cuticle, epidermal hair is cuticle, epidermal hair may Runner absent or may not be present Vascular Scattered (atactostele) Arrange in a ring (eustele) Bundle Bundle Sheath Present Absent Ground Tissue No differentiation except Differentiated into hypodermis hypodermis, cortex, endodermis, pericycle and pith Vascular Present Absent Bundle Cavity (Lacuna) Pericycle Absent Present These are special, narrow, green, horizontal or prostrate branches which develop at the base of erect shoots called PHLOEM XYLEM crowns. Roots, stem and leaves Roots, stem and leaves Many runners arise from each erect shoot. They spread in Occurrence different directions and bear new crowns above and tufts of Additional Forms vascular bundles Forms vascular bundles adventitious roots below at certain intervals. Functions with xylem with phloem and gives Each runner has one or more nodes. The nodes bear scale mechanical strength to plants due to presence of leaves and axillary buds lignified cells. e.g., Lawn grass (Cynodon dactylon) Elements Sieve tubes, companion Tracheids, vessel elements, Hydrocotyl (centella asiatica) cells, phloem xylem parenchyma, xylem Oxalis, etc. parenchyma, bast fibers, sclerenchyma intermediary cells Nature of Living tissue Non living tissue at maturity UNDERGROUND MODIFICATIONS Tissue Rhizome Movement Bidirectional Unidirectional (upward) Function Transportation of food Water and mineral transport and nutrients from leaves from roots to aerial parts of to store organs and the plant. growing parts of plants Structure Tubular with soft walled Tubular with hard walled cells cells Growth of rhizome takes place horizontally with the help of the lateral bud This type of rhizome is called sympodial rhizome E.g. ginger (zingiber officinale), turmeric (curcuma domestica), canna etc. In some plants, growth of rhizome occurs with the help of terminal bud These are called monopodial rhizomes E.g. Lotus pteris (a fern) etc. Corm Is a short, stout, fleshy, upright and thickened underground stem. STUDENTS’ ADVISORY BOARD 5  It bears many buds in the axils of scale leaves which develop into daughter corms III. LEAF At the bases or even from sides of stem adventitious roots - Leaves are the solar energy and CO2 collectors of plants. develop. - In some plants, leaves have become adapted for specialized Corm is a condensed form of rhizome growing vertically, functions E.g, Arbi (colocasia), zaminkand (amorphophallus etc.) Bulb It is a condensed; disc like underground stem, which itself does not store food material. The upper surface disc-like stem is slightly conical and bears centrally placed apical bud and many concentrically arranged overlapping scale leaves. Inner scale leaves or leaf bases store food and are thick and fleshy, while outer few scaly leaves remain thin and dry and are protective in function. PARTS OF A LEAF Lower surface of the disc-like stem produces adventitious roots. Tuber Tubers are actually the swollen ends or tips of special swollen underground branches, due to the storage of food (carbohydrate like starch) The tubers show nodes and internodes bear scale leaves with axillary buds, commonly called as eyes Under favorable conditions these eyes sprout and produce aerial shoots. Thus, tubers help in vegetative propagation. Tubers do not produce adventitious roots, thus they differ from rhizome e.g. potato (solanum tuberosum) General Leaf Form Leaves are the main photosynthetic organs of most p;ants Green stems are also photosynthetic While leaves vary extensively in form they generally consist of a flattened blade and a stalk, the petiole, which joins the leaf to a stem node. In the absence of petioles in grasses and many other monocots, the base of the leaf forms a sheath that envelops the stem. Most monocots have parallel major veins that run the length of the blade while dicot leaves have a multi branched network of major veins. STUDENTS’ ADVISORY BOARD 6  LEAF ARRANGEMENT ON THE STEM 1. Alternate - 1 leaf per node, with the second leaf being above - Monocots and dicots differ in the arrangement of veins, the the first but attached on the opposite side of the stem vascular tissue of leaves 2. Opposite - 2 leaves at a node, on opposite sides of the stem - Most dicots have branch-like veins and palmate leaf shape 3. Whorled - 3 or more leaves at node - Monocots have parallel leaf veins and longer slender blades INTERNAL STRUCTURE OF LEAVES - Plant taxonomists use leaf shape, spatial arrangement of leaves, and the pattern of veins to help identify and classify plants - Simple leaves have a single, undivided blade, while compound leaves have several leaflets attached to the petiole - A compound leaf has a bud where its petiole attaches to the stem, not at the base of the leaflets. VENATION (arrangement of veins in a leaf) 1. Pinnately-veined - main vein called midrib with secondary veins branching from it (e.g., elm) Cuticle - the outermost layer of both the upper and lower 2. Palmately-veined - veins radiate out of base of blade (e.g., surfaces of the leaf. It is clear and waxy to prevent water loss. maple) Epidermis - a layer of cells one cell thick that provides 3. Parallel - characteristics of many monocots (e.g., grasses, protection for the inner tissues. These cells are clear to allow cereal grains); veins are parallel to one another light to reach the photosynthetic tissues. 4. Dichotomous venation - no midrib or large veins; rather Mesophyll - between the epidermal layers. It contains individual veins have a tendency to fork evenly from the base palisade cells that are tall, tightly packed, and filled with of the blade to the opposite margin, creating a fan-shaped leaf chloroplasts for photosynthesis It also has spongy cells which are irregularly shaped, have large air spaces between them, and fewer chloroplasts. STUDENTS’ ADVISORY BOARD 7  Stomates - openings in the surface of the leaf and stems for Guard Cells gsa exchange. The lower surface of a leaf usually has more. - The rate of transpiration is regulated by the size of Water vapor also passes out through these holes. the opening of stomates. Guard cells - two of these special cells surround each - They are usually closed when there is too little water stomata and regulate the opening and closing of the stomata. available, temperature is low, or there is little light. Veins - contain the vascular tissue that is continuous with that - Most plants open their stomates during the day and in the stem. Xylem carries water and minerals upward. close them at night. Phloem carries dissolved food throughout the plant. TYPICAL DICOT LEAF CROSS-SECTION Stomatal Control - Almost all leaf transpiration results from diffusion of water vapor through the stomatal pore ➔ Waxy cuticle - Provide a low resistance pathway for diffusion of gasses across the epidermis and cuticle - Regulates water loss in plants and the rate of CO2 uptake ➔ Needed for sustained CO2 fixation during photosynthesis - When water is abundant: - Temporal regulation of stomata is used: ➔ Open during the day ➔ Closed at night - At night there is no photosynthesis, so no demand for CO2 inside the leaf TYPICAL MONOCOT LEAF CROSS-SECTION - Stomata closed to prevent water loss - Sunny day: demand for CO2 in leaf is high - stomata wide open - As there is plenty of water, plant trades water loss for photosynthetic products - When water is limited: - Stomata will open less or even remain closed even on a sunny morning ➔ Plant can avoid dehydration - Stomatal resistance can be controlled by opening and closing the stomatal pores. - Specialized cells: The Guard Cells Transpiration - Plants must supply water to all their tissues. It The C4 Carbon Leaf moves from the roots up to the stem to the leaves by - This is a biochemical pathway that prevents the capillary action. photorespiration - Most of the water plants take up is lost to the - C4 leaves have 2 chloroplasts containing cells atmosphere by evaporation. - Mesophyll cells - The evaporation of water vapor from plant surfaces - Bundle sheath (deep in the leaf so atmospheric is called transpiration. oxygen cannot diffuse easily to them) - Most takes place through stomates - Operation of the C4 cycle requires the coordinated effort of both cell types - No mesophyll cells is more than three cells away from a bundle sheath cells ➔ Many plasmodesmata for communication STUDENTS’ ADVISORY BOARD 8  FLOWER ENVELOPE OR PERIANTH MODIFIED LEAVES non-reproductive part of the flower Petal (Corolla) - the innermost whorl surrounding the flowers’ reproductive parts. It is usually bright colored to attract pollinators. Sepal (Calyx) - usually a green leaf-like structure that forms the outermost floral whorl; it protects the inner parts of the flower before it opens. FLORAL STALK Receptacle (Torus) - thickened part of a stem from which the flower grows Peduncle - a stalk supporting the flower VARIABLE FEATURES AND STRUCTURES OF FLOWERS 1. Color - day-blooming flowers are generally bright colored IV. FLOWER while night-blooming flowers are usually white, creamy or yellowish. - Are modified shoots adapted primarily for reproduction, which 2. Petals ultimately forms the fruit and seed. Gamopetalous Polypetalous Apetalous 3. Odor - flower with fragrant and stinky odor PARTS PRESENT 1. Complete flowers - flowers are said to be complete when the four main parts (petal, sepal, stamen and carpel) are present 2. Incomplete flowers - flowers are incomplete when one or more of the main parts are not present SEXUALITY Flowers with both stamen and carpel are called Perfect flowers. These flowers can also be called bisexual or hermaphrodite flowers, Flowers that have only either stamen or carpel are called Imperfect flowers. These flowers can also be called unisexual flowers. An imperfect flower with only the carpel or pistil is called Pistillate flower. One with the steam only is a staminate CARPEL (GYNOECIUM) flower. the female reproductive part of a flower. It is collectively Imperfect flower known as the Pistil ➔ Monoecious - both male and female flowers are - If a gynoecium has a single carpel, it is called found on the same plant Monocarpous or Unicarpellate Gynoecium ➔ Dioecious - are borne on separate plants - If it has multiple, distinct (free, unused) carpels, it is Apocarpous - If it has multiple fused carpels (connate), into a single structure, it is Syncarpous Stigma - slightly enlarged tip of the style on which pollen is deposited at pollination Style - a long and thin filament that serves as a passageway for pollen grains to move from the stigma to the ovary Ovary - a swollen basal part of a pistil which carries the ovule or eggs (yellow); where fertilized eggs develop STAMEN (ANDROECIUM) the male reproductive part of a flower Anther - where pollens are formed Filament - a stalk holding the pollen at its tip STUDENTS’ ADVISORY BOARD 9  NATURE OF FLOWERS NUMBER OF FLOWERS PARTS Flowers are regular when the members of each set of organs Monocot - flower parts are in 3’s or in multiple of 3’s (sepals, petals, stamen and carpels) are of the same size and Dicot - flower parts are in 4’s or 5’s or in multiple of 4’s or 5’s shape Flowers are irregular when some members of one or more sets of organs are different in size or shape or both Regular flower - members of each set of organs are of the same size and shape Irregular flower Papilionaceous ➔ Standard petal or Banner - outermost and the largest part of the flower ➔ Wings or Alae - two lateral parts ➔ Keels or Carinae - two innermost smallest petal SYMMETRY OF FLOWERS Caesalpinaceous Actinomorphic ➔ Wings - two upper lateral petals ➔ Radial symmetry ➔ Banner - innermost and smallest petal ➔ Flowers can be divided into 2 equal halves along ➔ Keel - two lower lateral petals any plane Zygomorphic Bilabiate ➔ Bilateral symmetry ➔ Divided into 2 equal halves only by a medial cut through the central axis OVARY POSITION Superior or Hypogynous The sepals and petals are attached below the ovary Orchidaceous ➔ Sepals - three outermost whorl ➔ Petals - two innermost whorl ➔ Lip or Labellum - also a petal but with different shape and size Half-Superior/Half-Inferior - the sepals and petals are attached at the side of the ovary FUSION OF FLOWERS Inferior or Epigynous - the sepals and petals are attached Connation - when like parts are fused or united above the ovary PLACENTATION The places where the ovules are attached in the ovary are known as the placentae. The arrangement of the placentae inside the ovary is called placentation. Adnation - when unlike parts are fused Axile - the placentae are found at the central axis of a compound ovary Parietal - the placentae are found on the wall of a compound ovary Marginal - the placentae are located on the wall of a single ovary. A single ovary has one chamber or locule Basal - the placentae with a single ovule is found more or less at the base of the ovary STUDENTS’ ADVISORY BOARD 10 Pollen Tube V. FRUITS - Matured and ripened ovaries INFLORESCENCE - Holds and protects the seeds until they mature Flower clusters are called inflorescence. These may differ in - Helps in dissemination or dispersal of the seeds the number of flowers borne, the sequences of flower - Does not apply to those that have edible portions, but also to maturation, the length of flower stalks, the number and those which are commonly referred to as vegetable arrangement of the floral branches or peduncles. Spike - an inflorescence has an elongated axis with sessile (without pedicel) florets Raceme - the elongated axis is unbranched. The flowers are provided with stalks or pedicles or equal lengths and are called pedicellate flowers. Panicle - the elongated axis is branched. Flowers are pedicellate, opening all at the same time. Corymb - it has a more or less flat convex top because of the pedicels bearing the outer, older flowers are longer than the younger flowers at the center. Umbel - the axis is short so that pedicellate flowers radiate from the apex of axis Cyme - this inflorescence is similar to a corymb except that the inner pedicelled flowers open first Spadix - a fleshy spike (spadix) bearing both male and female flowers, surrounded by a petaloid bract called the spathe. CLASSIFICATION OF FRUITS Catkin/Ament - this inflorescence is a special type of spike - As to the composition or number of flowers involved in their which is hanging or drooping. The flowers are usually formation (origin) unisexual. 1. Simple fruits - develops from one ovary Fascicle - the pedicelled or sessile flowers are crowded at 2. Aggregate fruit - develops from several ovaries of a single one side of the stem flower Head/Capitate - it is similar to umbel but the flowers are 3. Collective or multiple fruit - derived from several ovaries of sessile. Usually the flowers are of two kinds; the disc flower at several flowers or from the ovaries of a compact inflorescence the center and the ray flowers at the margin - As to structure, consistency and dehiscence (includes the state of the pericarp in the ripened fruit) 1. Fleshy - when the pericarp is soft, juicy (or pulpy) or succulent 2. Dry - when the pericarp is dry or papery upon maturity STUDENTS’ ADVISORY BOARD 11  SIMPLE-FLESHY-DRUPE-FIBROUS - Fibrous mesocarp and fleshy ovary. Seed enclosed within a stony endocarp (pit). Ex: coconut SIMPLE-FLESHY HESPERIDIUM - Derived from a single fleshy ovary. The entire pericarp is soft and fleshy SIMPLE-FLESHY-POME - Fleshy part derived mainly from torus. Ovary surrounded by fleshy hypanthium. Ex: apple and pear - Derived from a fleshy ovary enclosing several seeds and has thick leathery skin containing oil. Ex: calamansi and orange SIMPLE-DRY-DEHISCENT-FOLLICLE - Dry fruit derived from one carpel splitting along one seam. Ex: kalachuchi and star anise SIMPLE-DRY-DEHISCENT-LEGUME/POD - Dry fruit derived from one carpel splitting along two seams. Ex: chicharo and peanuts SIMPLE-FLESHY PEPO SIMPLE-DRY-DEHISCENT-SILIQUE - Derived from a fleshy ovary enclosing many seeds. Pepo has - Dry fruit derived from two or more carpel with persistent a hard, thick rind. Ex: cucumber and watermelon partition walls after splitting. Ex: narrowleaf bittercress and blue pod rockress SIMPLE-DRY-DEHISCENT-CAPSULE - Derived from two or more carpel splitting in one or four ways. Ex: jimson weed, calico flower, opium and twinberry SIMPLE-DRY-INDEHISCENT-GRAIN/CARYOPSIS - Rice anatomy SIMPLE-FLESHY-DRUPE-FLESHY - Fleshy mesocarp and ovary. Seed enclosed within a stony endocarp (pit). Ex: peach and mango STUDENTS’ ADVISORY BOARD 12 - Corn (zea mays) anatomy - Dispersal is important to: ➔ Avoid competition with parent and siblings ➔ Colonize new habitats ➔ Avoid pathogens and predators ➔ Minimize breeding - Methods of dispersal are often tied to certain habitats ➔ Wind - prairie/grasslands, mountains, forest trees, weedy areas ➔ External attachment to animals - forest plants relatively low to ground ➔ Ingestion by animals - forest plants ➔ Water - plants that grow in wetlands and along streams ➔ Ballistic - various; some parasitic plants, some forest plants, some weedy plants SIMPLE-DRY-INDEHISCENT-SAMARA/KEY - Seed separable from the fruit wall. Fruit with wings. Ex: VI. SEEDS mahogany and narra A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. SIMPLE-DRY-INDEHISCENT-NUT The formation of the seed completes the process of - Fruit without wings and with a very hard fruit wall and only has reproduction in seed plants. one seed. Ex: pili nut and cashew nut Seeds are advantageous for plants because: ➔ Maintain dormancy until better environmental SIMPLE-DRY-INDEHISCENT-ACHENE conditions arise - Seed without wings and with thin fruit wall. One seed is ➔ Afford protection to young plant at vulnerable attached to the ovary wall at one point. Ex: sunflower and developmental stage strawberry ➔ Contain adequate food supply until photosynthesis is possible SIMPLE-DRY-INDEHISCENT-SCHIZOCARP - Seed not coming out of fruit although united carpels split apart SEED STRUCTURE at maturity. Ex: little mallow and queen anne’s lace External - Seed coat (testa) - Hilum Embryo COMPOUND-AGGREGATE - Cotyledon - Many ovaries derived from a single flower - Epicotyl / hypocotyl - Plumule - Radicle Seed Coat ​ Aka the Testa The seed coat protects the embryo COMPOUND-MULTIPLE/COLLECTIVE Can be varying thicknesses, depending on the seed type - From several ovaries of several flowers of a compact inflorescence. Ex: pineapple Hilum Scar from the seed being attached to the parent plan SEED DISPERSAL - Plants often solicit the aid of animals, as well as abiotic forces such as wind, to accomplish both of these ➔ Insects - much less important for dispersal than pollination, but ants often involved in dispersal ➔ Birds, mammals, reptiles and even fish - much more important for dispersal than pollination ➔ Wind - important in both pollination and dispersal ➔ Water - minor importance in pollination, somewhat Embryo greater in dispersal The embryo is what forms the new plant once the opportune ➔ Self dispersal - just like some plants carry out self conditions are present pollination, some plants have much mechanisms or self dispersal STUDENTS’ ADVISORY BOARD 13 Cotyledon The cotyledon is the first leaf that germinates. It is filled with stored food that the plant uses before it beings photosynthesis Some plants have 1 cotyledon (monocot) and some have 2 cotyledons (dicot) Epicotyl/Hypocotyl The basis for the plant’s stem It is known as the epicotyl above the cotyledon and a hypocotyl below the cotyledon These grow upward in response to light Plumule The shoot tip with a pair of miniature Radicle The part of the seed where the root develops. STUDENTS’ ADVISORY BOARD 14