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Unit 4-Plant Structure And Physiology
Transcript of Unit 4-Plant Structure And Physiology
Mosses: A member of the kingdom plantae that lacks a vascular system
Since mosses have no vascular system to transport water through the plant or waterproofing systems to prevent tissue water from evaporating, they must have a damp environment to grow, and a surrounding of liquid water to reproduce. Since mosses are autotrophic they require enough sunlight to conduct photosynthesis. Unit 4- Plant Structure and Physiology Section 4.8 Roots and Stems Section 4. 15 Control of plants Development Leaves: Their green colour is the major site where photosynthesis occurs. A green pigment that captures light energy used in photosynthesis.
Two types of leaves;
Simple leaf: A leaf that is not divided into leaflets.
Complex leaf: A leaf that is divided into two or more leaflets. 2) Ferns: A member of the kingdom plantae that lacks a vascular system and does not produce seeds.
Fern species live in a wide variety of habitats, from remote mountain elevations, to dry desert rock faces, to bodies of water or in open fields. but ferns generally prefer warm and moist environments. 3) Moss relative
Bryophyte:A member of a large group of seedless green plants including the mosses, liverworts, and hornworts.
Bryophytes lack the specialized tissues xylem and phloem that circulate water and dissolved nutrients in the vascular plants. instead they have rhizoids, which are small rootlike structures that absorb water like a sponge, Since they have no vascular system, they depend on osmosis, diffusion, and active transport to move water and nutrients between cells.
The Bryophytes generally live on land but are mostly found in moist environments, for they have free-swimming sperm that require water for transport. 1)Gymnosperms: A member of the kingdom plantae that has a vascular system, and produces seeds. Two spore types, microspores and megaspores, are typically produced in pollen cones or ovulate cones, respectively. Gametophytes, as with all heterosporous plants, develop within the spore wall. 2)Agiosperms(flowering plants):A member of the kingdom plantae that has a vascular system and produces enclosed seeds within flowers fertilization: a process in which two sperm cells fertilize cells in the ovary. This process begins when a pollen grain adheres to the stigma of the pistil (female reproductive structure), germinates, and grows a long pollen tube. While this pollen tube is growing... LIFE CYCLE 3) Monocots and Dicots
Monocots: An angiosperm that produces seeds containing embryos with one cotyledon.
Dicots: An angiosperm that produces seeds containing embryos with two cotyledon Section 4.5 Vascular plant structure 1) Vascular plants re made up of 4 types of tissues:
*Meristematic Tissue: Plant tissue composed of cells that are able to divide repeatedly by mitosis. This tissue gives rise.
*Dermal Tissue: Cells specialized for covering the outer surfaces of leaves,stems and roots.
*Ground Tissue: The internal non vascular tissues of a plant. They perform many functions, such as photosynthesis and food storage.
*Vascular Tissue: Tissue composed of cells specialized in transporting water and other substances among cells. Section 4.6 Plant Development Xylem PHYLOEM Carries out cell division for plant groth Gives rise to all other tissue and cell tpes Produces a waxy cuticle to limi water loss Has a microscopic hairs on root dermal cells to increase water and mineral absorption Protects the plant from elements and herbivores Carries out photosynthesis Stores nutrients Transports water and minerals up from the roots Transports sugars and other nutrients from the leaves Vascular plants especially Gymnospermas and Angiosperms, dominate almost all terrestrial environments. They are the worlds most important land plants. ( food, wood, paper, clothing, midicines)
Plants are multicellular organisms, made up of different kinds of cells. These cells are organized into the tissues, which form the grgans of the plant body. Shoot: Above ground portions such as (leaf, stem)
Root: Portion of the plant that grows downwards and absorbs minerals, water from the soil.
Terminal Bud: The growing tip of a shoot.
Axillary Bud: A bud that will form a side branch from a stem.
Leaf Blade: The wide portion of a leafe
Leaf Petiole: A stalk that supports a leaf and attaches it to a stem.
Root Tip: The central, often largest portion of the oot.
Secondary Root: A branching root arising from the primary root. Life cycle of Plant (Zygote)
:the initial cell formed when two gamete cells are joined by means of sexual reproduction. In multicellular organisms, it is the earliest developmental stage of the embryo. Zygotes are usually produced by a fertilization event between female gamete and male gamete Life cycle of Plant (Spore)
: a reproductive structure, of which plants adapt for surviving inextended periods of time in unfavorable conditions. Once conditions are favorable, the spore can develop into a new organism using mitotic division, producing a multicellular gametophyte, Plant development(growth)
Apical meristems: A meristem located at any growing tip of shoots or roots, which contributes to increases in the length of plant tissues.
Lateral meristems: A meristem located within a root that contributes to increases in the diameter of plant tissues. Differentiation: The process of a specialized cell becoming a more specialized cell type. Differentiation occurs many times during the development of a multicellular organism as the organism changes from a simple zygote to a complex system of tissues and cell types.
Primary Growth: All growth of apical meristems and first-year growth of lateral meristems
Secondary Growth: All growth from lateral meristems occuring after the first year Section 4.10 Leaves Section 4.12 Seeds and Fruits Roots: All vascular plants have a form of a root or shoot. Roots are used to provived support for a plant. They are also used to transport food, water, and nutrients to the plant. Some rots are even edible, such as carrots and potatoes. There are two types of roots: 1) Taproots: One large root with side branches.
2) Fibrous roots: Many small roots that grow out from the bottom of the plant. Stems: Provide support for the parts of the plant that are above the ground. They are also capable of transporting and storing food and water. Stems of Herbaceous plants are typically soft and easily bent therefore they dont grow to be very tall. Stems of woody plants are very ard and dont bend easily such as large trees. Leaf Structure
: Epidermal is one-cell layer that covers the upper and lower surfaces of the leaf blade. This produces a waxy cuticle that protects the leaf. Most cells in a leaf are mesophyll cells, which are cells that are rich in chloroplast. Beneath the upper epidermis, mesophyll cells are packed tightly into a layer one or two cells thick(palisade mesophyll). This area of the leaf is known as the spongy mesophyll. This is where gas exchange occurs, leaf viens run thrigh the mesophyll layers and conduct water and minerals to the leaves and carry away the products og photosynthesis.
Leaf Adaptations(Shade Plants)
: Theses plants typically posses leaves that are thinner, broader, and greener. As a result, shade plants are more efficient at harvesting light, even in the lowest intensities.
is a process similar to evaporation. It is the loss of water vapor from parts of plants especially in leaves but also in stems, flowers and roots. Leaf surfaces are dotted with openings which are called Stoma, and in most plants they are more many. The stoma are bordered by guard cells that open and close the pore. Leaf transpiration occurs through the opening of the stomata to allow the diffusion of carbon dioxide gas from the air for photosynthesis. Transpiration also cools plants, changes osmotic pressure of cells, and enables mass flow of mineral nutrients and water from roots to shoots.
The rate of transpiration is also influenced by the evaporative demand of the atmosphere surrounding the leaf such as humidity, temperature, wind and low or high sunlight. Humans consume almost no gymnosperms, moss, or fern plant material. Most of the species we use for food are angiosperms(flowering plants), and the plant structures most commonly used are the seed or fruit plant.
The three most important food plants are the angiosperms wheat, rice, and corn. The edible portions of theses monocots plants are the seeds. The seeds of dicot species are rich in protein, carbohydrates, or fats and fibre. And seeds can be stored for long period of times.Fruit is a structure that develops within the ovary of a pollinated angiosperm. Therefore develop within a flower and usually contain seeds, But there not always sweet.Example(tomatoes, zucchini) Seed dispersal helps plants to spread into new environments. Fruits take many different forms to help in the seed dispersal. Maple keys are an example. Pollination and Fruit production:
Fertilization of the egg cell of a flowering plant requires pollination, the transfer of pollen grains to the stigma of a flower. Most angiosperm will not produce fruit until the flowers have been pollinated. The greater the percentage of pollinated flowers the greater the fruit production from each plant.
Many plants are pollinated by wind, whereas other plants are pollinated by birds and insects. The most important pollinator of our food crops is the honeybees. They pollinate 85% Ontario's apple trees. Greenhouses
Allow people to grow fruits and vegetables to grow all year long. Plant growth Regulators:
Plant growth regulators are a group of of chemicals that affect the rate of division of plant cells. These chemicals are known as plant hormones. Plant hormones can be grouped into 2 categories Growth Promoters:
1) Gibberellins: Promote cell division and cell elongation(makes fruits bigger)
2) Cytokins: Encourgr cell division and leaf growth
3) Auxins: Promote the length of cells Growth Inhibitors:
1) Abscisis Acid: Inhibits growth by forcing seeds to enter dormancy(state of sleep)
2) Ethylene: Inhibits growth by promoting flowers death and leaf and fruit loss. plant movement:
Plant movement occurs in response to environmental stimuli: these plants movement are called (Tropisms). Movement towards a stimulus is known as (Positive tropism). Where movent away from stimulus is known as Negative Tropism. There are five types of Tropism. Tropism Growth Photoropism
Thigmotropism growth in response to light
Growth in response to gravity
Growth in response to chemicals
Growth in response to water
Growth in response to touch Section 4.19 Pest management The most commonly used pesticides are herbicides, fungicides, and insecticides. Some are broad-spectrum pesticides, killing a large variety of species, while others may be selective pesticides, killing more limited range of species. Pesticides and Safety:
All pesticides used in Canada are regulated under the federal pest Control Products(PCP) Act and in Ontario, under the Pesticides Act. Theses regulations are to protect human health and natural environments as well as the animals who live their. The legislation covers Transportation, storage, and disposal of pesticides.
Alternative Methods of Pest Control
* Integrated pest management (IPM): A pest-management strategy that uses a combination of careful monitoring, natural biological controls, and limit applications of synthetic pesticides. Example( Ladybugs used to kill aphids, plus the ladybug doesn't harm the plant in any way.)
* Genetically modified organism(GMO): An organism in which the genetic material has been modified to suit human purposes, often by the introduction of genes from other species.Example( BT corn: this gene enables the corn plant to manufacture a natural insecticide. BT toxin, which is fatal to the larvae of moths and butterfly's but not humans. And there is no need to spray the corn crops with external insecticides.