Structure and Life Process of a Plant.pptx

Structure and Life Process of a Plant.pptx

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  Structure and Life Process of aPlant Reward Bulay-og Gen Bio1 Instructor
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  PLANT TISSUES
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  Meristematic Tissues Characteristics o Composed ofactively dividing cells. o Cells are small, thin-walled, and have a large nucleus with dense cytoplasm. o Lack vacuoles. Functions o Responsible for the growth of the plant. o Found in regions where the plant grows, such as the tips of roots and shoots (apical meristems), the circumference of stems (lateral meristems), and at the base of leaves or internodes (intercalary meristems).
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  Permanent Tissues Permanent tissuesdevelop from meristematic tissues once the cells differentiate and specialize. They are divided into simple and complex tissues. •A. Simple Permanent Tissues 1. Parenchyma Characteristics  Made up of living cells with thin cell walls.  Cells are loosely packed with large intercellular spaces.  Contains large vacuoles. Functions  Provides support to the plant.  Stores nutrients and water.  Plays a role in photosynthesis (chlorenchyma) and buoyancy (aerenchyma). 2. Collenchyma Characteristics  Composed of living cells with unevenly thickened cell walls.  Cells are elongated and have little intercellular space. Functions  Provides flexibility and mechanical support to growing parts of the plant, such as young stems and leaves.  Helps in the structural integrity of the plant.
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  3. Sclerenchyma Characteristics  Madeup of dead cells at maturity.  Cells have very thick and lignified cell walls.  Two types: fibers (elongated) and sclereids (short, irregular). Functions  Provides strength and rigidity to the plant.  Found in hard parts such as seed coats, bark, and the gritty texture in some fruits.
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  B. Complex Permanent Tissues 1.Xylem Characteristics  Composed of various cell types including tracheids, vessels, xylem fibers, and xylem parenchyma.  Cells are mostly dead and hollow at maturity. Functions  Conducts water and dissolved minerals from roots to other parts of the plant.  Provides mechanical support due to lignified walls. 2. Phloem Characteristics  Composed of living cells including sieve tubes, companion cells, phloem fibers, and phloem parenchyma. Functions  Transports nutrients, particularly sugars produced during photosynthesis, from leaves to other parts of the plant.  Assists in the storage and redistribution of nutrients.
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  Xylem: Transportation of Water andMinerals Flow Direction: Upward, from roots to leaves. Process: 1. Water Uptake in Roots: Water and minerals are absorbed from the soil by the root hairs. 2. Transport Through Xylem:  Water moves from the root cortex to the xylem vessels.  The cohesion and adhesion properties of water molecules help them move upward through the xylem.  The process is driven by transpiration (water evaporation) from the leaves, creating a negative pressure that pulls water upward. • Water Reaches Leaves: The water is used in photosynthesis or lost through transpiration
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  Phloem: Transportation of Nutrients(Primarily Sugars) Flow Direction: Bidirectional, from leaves to other parts of the plant (can move upward or downward). Process: 1. Photosynthesis in Leaves: Leaves produce glucose through photosynthesis. 2. Loading into Phloem:  The glucose is converted into sucrose and actively loaded into the phloem sieve tubes. 3. Pressure Flow Mechanism:  The high concentration of sugars in the phloem causes water to move in from the xylem by osmosis, creating high pressure.  This pressure pushes the nutrient-rich sap through the phloem to areas of lower pressure (such as roots, fruits, or growing shoots). 4. Unloading: The sucrose is unloaded from the phloem into the target cells, where it is used for growth, storage, or energy.
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  3. Epidermal Tissue Characteristics o Formsthe outermost layer of the plant. o Cells are closely packed, with a waxy cuticle on their surface. o Specialized cells like guard cells and trichomes are part of this tissue. Functions o Protects the plant from water loss, pathogens, and mechanical injury. o Regulates gas exchange through stomata. o Absorbs water and nutrients in the roots.
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  4. Ground Tissue Characteristics oIncludes all tissues that are neither dermal nor vascular. o Composed mainly of parenchyma cells but also contains collenchyma and sclerenchyma cells. Functions o Provides support and storage. o Fills the interior of the plant and is involved in photosynthesis, storage, and secretion.
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  PLANT ORGANS
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  Roots - Roots arethe underground organs that anchor the plant and absorb water and nutrients from the soil. • Roots may perform other functions storage organ in beets, carrots, or sweet potatoes; hormone synthesis; aeration in aquatic plants; as an organ for plant propagation; and so on. Root branches die very often, which depends on the species and season of the year. Thus, plants need to produce new branches continuously, not only to increase the overall size of the root system, but also to maintain it in a steady state. Plant organs. Root. Atlas of Plant and Animal Histolo gy. (uvigo.es)
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  Aquatic Plants (roots) https://www.google.com/url?sa=i&url=https%3A%2F%2Fspectrumchart.blogspot.com%2F2017%2F02%2Fchart-393-aquatic-plants.html&psig=AOvVaw0EBp27L2Z2tWgxPgU_vIJn&ust=1725463562877000&source=images&cd=vfe&opi=89978449&ved=0CBcQjhxqFwoTCIjz6OeKp4gDF
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  Embryophyta or land plants
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  Taproot & FibrousRoot System Characteristics: A single, large primary root that grows directly downward with smaller lateral roots branching off. Examples: Carrots, dandelions, radishes. Function: Deep penetration into the soil for stability and accessing deep water sources. Characteristics: A dense network of thin, branching roots spreading out from the base of the stem. Examples: Grasses, wheat, rice. Function: Provides stability in shallow soil and efficiently absorbs surface water and nutrients.
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  Fibrous Root System -A fibrous root system is the opposite of a taproot system. - It is normally formed by thin, moderately branching roots developing from the stem. A fibrous root system is common in monocotyledonous plants and greeneries. The fibrous root system looks like a mat made from roots when the tree has reached complete development. https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.shutterstock.com%2Fsearch%2Frice-plant roots&psig=AOvVaw1XDD1Ouneu3sPDetaiQ0pN&ust=1725589006998000&source=images&cd=vfe&opi=89978449&ved=0CBcQjhxqFwoTCJ DThJLeqogDFQAAAAAdAAAAABAZ
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  Adventitious Roots Characteristics: Rootsthat grow from parts of the plant other than the primary root, such as stems or leaves. Examples: Prop roots in corn, aerial roots in orchids, and buttress roots in figs. Function: Support, anchorage, and sometimes specialized functions like aeration or storage
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  Stems - Stems arethe above-ground organs that support the plant and act as conduits for transporting water, nutrients, and photosynthates. The stem performs many important functions that help plants to grow and survive. Node: A node is a point on the stem from which leaves, buds, aerial roots, and branches arise. Internode: The space between the two successive nodes is called an internode. It is also known as the “internodal” area. It helps the plant to grow and keeps it erect. Apical Bud: Apical buds are found at the tip, or apex, of the stem, where primary growth of the plant or increasing the height occurs. It is also called the terminal bud. Axillary Bud: An axillary bud is usually found in the leaf axil, the area between the base of a leaf and the stem. Axillary buds give rise to a shoot that may be vegetative (branch) or reproductive (flowers). It is also called the lateral bud. Petiole: The thin stalk with which leaf is attached to the stem node is called a petiole. The petiole is commonly known as leaf stalk. A leaf with a petiole is called a petiolate leaf, whereas leaves without them are called sessile or stalkless.
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  TYPES OF THE STEM Basedon their adaptations, there are three types of stems: 1.Underground stem, 2.Aerial stem, 3.Sub- aerial stem.
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  1. Underground Stem •The stem that grows inside the soil is known as the underground stem. They produce aerial shoots annually. • Storage of food and perennation are the main functions of underground stems. These stems are also capable of vegetative propagation. They are of different types as follows: Rhizome: is a non-green underground stem with distinct nodes and internodes and dry, scaly leaves at the nodes. It grows horizontally or obliquely. Rhizomes store plant nutrition in the form of proteins and starches. Example: Ginger. Tuber: is a short and thickened underground stem that grows horizontally below the ground. It stores plant nutrition in the form of starch. Example: Potatoes. Bulb: is a short underground stem with internal buds surrounded by fleshy leaves or leaf bases that helps the plants survive adverse environmental conditions. Example: Onion. Corm: is a short, vertical, swollen underground stem of a plant-covered by thin sheathing leaf bases of dead leaves called scales. These dry leaf bases help protect the stem of the corm from harsh weather conditions and lack of moisture. Corm serves the functions of food storage, vegetative propagation, and perennation. E.g., Crocus
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  2. Sub-Aerial Stem Thestem, which partially remains below the ground and partially above the ground (i.e., in the air), is known as the subaerial stem. These stems are useful in the vegetative propagation of plants. E.g., Cynodon They are further divided into the following types: Runner: It is a creeper that runs horizontally along the surface of the soil. Runners have long internodes. The nodes have scale leaves, adventitious roots, and auxiliary buds. An underground runner is known as sobole. Example: Grass, Cynodon, Oxalis. Offset: These are shorter and thicker than the runner with a single internode. It originates from the leaf axis and grows horizontally. Offsets are often found in aquatic plants like water lettuce, water hyacinth, etc. Stolon: It grows above ground for some time and then bends towards the ground until it touches the ground. Stolon arises from the lower part of the main axis. Example: Jasmine, colocasia, etc. Sucker: The sucker stem is very similar to the stolon, but it grows obliquely upwards and gives rise to a new plant. Example: Garden chrysanthemum, strawberry, pineapple, mentha, etc.
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  3. Aerial Stem Thesestems are found above the ground and perform various functions like food storage, vegetative propagation, protection, climbing, etc. The aerial stem is further divided into the following types: Tendril: These types of stems are slender, spirally coiled, which help a plant to climb. Example: Passiflora, Grapevine etc. Bulbil: These are modified axillary buds which become fleshy and swollen due to the storage of food. They help in vegetative propagation to form a new plant. Example: Dioscorea. Thorn: These are hard, woody, and pointed structures that protect plants from grazing animals. It originates from the axillary or terminal bud. Example: roses, citrus, bougainvillea, duranta etc. Cladodes: These are non-fleshy and cylindrical that contain only one internode. Example: Asparagus, butcher’s broom. Phylloclade: These are green, fleshy, and flattened or cylindrical branches containing chlorophyll and photosynthesis. This modification is found in xerophytic plants and stores water. Example: Opuntia, Casuarina, etc.
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  Leaves -are the primary sitesof photosynthesis and gas exchange in most plants. Stomata (singular: stoma) are pores on the epidermis of leaves through which gas exchange takes place with the atmosphere.
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  Types of Leaves Simple Leaves Characteristics:A single, undivided blade attached to the stem by a petiole. Examples: Maple, oak, banana. Function: Photosynthesis, transpiration, and gas exchange.
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  Compound Leaves Characteristics: Aleaf divided into multiple leaflets, each attached to a central rachis. Examples: Rose, fern, neem. Function: Photosynthesis, increased surface area for light capture, and flexibility.
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  Modified Leaves 4.4: Modifiedleaves - Biology
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  Flowers - are thereproductive organs of angiosperms (flowering plants), responsible for seed production. A flower is the reproductive part of flowering plants. Flowers are also called the bloom or blossom of a plant. Flowers have petals. Inside the part of the flower that has petals are the parts which produce pollen and seeds.
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  Types of Flowers CompleteFlowers Characteristics: Contain all four major floral organs: sepals, petals, stamens, and carpels. Examples: Roses, lilies, sunflowers. Function: Facilitates sexual reproduction through pollination and fertilization.
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  Peduncle: The stalkof a flower. Receptacle: The part of a flower stalk where the parts of the flower are attached. Sepal: The outer parts of the flower (often green and leaf-like) that enclose a developing bud. Petal: The parts of a flower that are often conspicuously colored. Stamen: The pollen producing part of a flower, usually with a slender filament supporting the anther. Anther: The part of the stamen where pollen is produced. Pistil: The ovule producing part of a flower. The ovary often supports a long style, topped by a stigma. The mature ovary is a fruit, and the mature ovule is a seed. Stigma: The part of the pistil where pollen
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  Incomplete Flowers Characteristics - Lacking oneor more of the four major floral organs. Examples: Grasses (lacking petals), willows (separate male and female flowers). Cucumber, bottle gourd and papaya. Function: Adapted for specific pollination strategies or environmental conditions.
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  Inflorescences Characteristics: Clusters offlowers arranged on a stem. Examples: Sunflowers (head), wheat (spike), lupines (raceme). Function: Maximizes reproductive success by grouping flowers, attracting pollinators, or facilitating wind pollination. An inflorescence is categorized on the basis of the arrangement of flowers on a main axis (peduncle) and by the timing of its flowering (determinate and indeterminate).
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  Fruits - are matureovaries that protect seeds and aid in their dispersal.
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  Types of Fruits FleshyFruits  Characteristics: Soft, juicy tissues surrounding the seeds.  Examples: Apples, berries, tomatoes.  Function: Attract animals for seed dispersal. Dry Fruits  Characteristics: Hardened or papery tissues at maturity.  Types:  Dehiscent: Split open to release seeds (e.g., peas, poppies).  Indehiscent: Do not split open; seeds are dispersed with the fruit (e.g., nuts, grains).  Function: Protect seeds and facilitate various dispersal mechanisms (wind, water, animals).
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  Seeds - are thereproductive structures that develop from fertilized ovules.
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  Types of Seeds DicotyledonousSeeds (Dicots) Characteristics: Contain two cotyledons (seed leaves). Examples: Beans, peas, sunflowers. Function: Provides nutrients to the developing plant embryo and supports early growth. Monocotyledonous Seeds (Monocots) Characteristics: Contain a single cotyledon. Examples: Corn, wheat, rice. Function: Similar to dicots but with a single nutrient source
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  Water and Nutrient transportati on inPlants
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  Growth Responses andRegulation
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  Phototropism Phototropism is thegrowth response of a plant in reaction to light. Plants have specialized cells that can detect light, allowing them to grow towards or away from the light source. Key Characteristics: o Positive Phototropism: When a plant grows towards the light, such as a sunflower bending toward the sun. This is typically observed in stems and leaves. o Negative Phototropism: When a plant grows away from the light, which is less common but can occur in roots. o Mechanism: Plant hormones called auxins accumulate on the side of the plant that is shaded, causing cells on that side to elongate more than on the lighted side, which makes the plant bend toward the light.
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  Gravitropism (Geotropism) Gravitropism is thegrowth response of a plant to gravity. This helps plants orient their growth so that roots grow downward, and stems grow upward, ensuring proper development. o Positive Gravitropism: Roots growing downward into the soil, which helps anchor the plant and absorb water and nutrients. o Negative Gravitropism: Stems growing upward, away from the ground, which allows them to access light for photosynthesis. o Mechanism: Auxins play a role here as well. In roots, auxins inhibit growth on the lower side, causing the root to curve downward. In stems, auxins promote growth on the lower side, causing the stem to curve upward.
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  Thigmotropism Thigmotropism is thegrowth response of a plant to physical touch or contact with a solid object. This is commonly seen in climbing plants. o Positive Thigmotropism: Vines or tendrils grow towards and wrap around objects, such as the tendrils of a pea plant wrapping around a support. o Negative Thigmotropism: Growth away from a stimulus, though this is less common. o Mechanism: When a plant part comes into contact with an object, it triggers the production of auxins and ethylene, which leads to differential growth on the contact side, allowing the plant to bend or curl around the object.
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  Hydrotropism Hydrotropism is thegrowth response of a plant to moisture. This is particularly important for roots, as they grow towards areas of higher moisture concentration in the soil. o Positive Hydrotropism: Roots grow towards a water source, ensuring the plant can absorb sufficient water for its needs. o Mechanism: While the exact process is less understood compared to other tropisms, it involves a combination of hormonal signaling and cellular mechanisms that guide the roots towards moisture.
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  Chemotropism Chemotropism is thegrowth response of a plant to a chemical stimulus. This is important for processes like fertilization in flowering plants. o Positive Chemotropism: Growth towards a chemical stimulus, such as pollen tubes growing towards ovules during fertilization. o Negative Chemotropism: Growth away from a harmful chemical stimulus. o Mechanism: Chemical signals in the environment guide growth by influencing cellular processes, often involving receptors and signaling molecules.
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  Thermotropism Thermotropism is thegrowth response of a plant to changes in temperature. This helps plants adapt to temperature variations in their environment. o Positive Thermotropism: Growth towards a warmer environment, which can help optimize temperature conditions for processes like photosynthesis. o Negative Thermotropism: Growth away from heat, though this response is less commonly observed. o Mechanism: This response is mediated by temperature-sensitive enzymes and hormones that affect the direction and rate of growth based on temperature changes.
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  Nastic Movements Unlike tropisms, nasticmovements are non-directional responses to stimuli, meaning the movement does not depend on the direction of the stimulus. These are usually reversible and often triggered by changes in environmental conditions. o Photonasty: Response to changes in light intensity, such as flowers opening during the day and closing at night. o Thigmonasty: Response to touch, such as the rapid folding of the Mimosa pudica (sensitive plant) leaves when touched. o Nyctinasty: Sleep movements in plants, where leaves or flowers close at night, as seen in prayer plants. o Mechanism: These movements are often driven by changes in turgor pressure within plant cells, influenced by environmental factors like light, touch, or time of day.