lecture 11 Flashcards

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1
Q

basic plant organs

A
  • the plant body contains three basic organs:
  • roots, stems, and leaves
  • each of these organs are composed of different tissues
  • the organ structure correlates nicely with function
  • plants must draw water and minerals from soil and water and CO2 from the environment
  • plant root and plant shoot cannot survive without one another
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2
Q

root system

A
  • anchors the plant in soil
  • absorbs ad transports minerals and water
  • stores food
  • near the root tips there is an abundance of root hairs
  • increases surface area
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3
Q

shoot system

A
  • made of stems and leaves
  • also reproductive structures such as flowers
  • stems: generally above ground
  • support leaves and flowers
  • nodes: point at which leaves are attached
  • internodes: portions of the stem between the nodes
  • leaves: main photosynthetic organs
  • composed of a flattened blade and a stalk called a petiole which joins the leaf to the node of the stem
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4
Q

two types of buds

A

terminal buds

axillary buds

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5
Q

buds

A

terminal buds: at the apex tip of the growing stem
-has developing leaves and a compact series pf nodes and internodes
axillary buds: these are within the angle between the leaf and the stem
-usually dormant
-hormones produced by the terminal buds inhibit their growth-this is called apical dominance
-concentrating resources toward growing taller increases the plants exposure to sunlight, important when vegetation is dense
-under some conditions the axillary buds begin to grow and removing the terminal bud often stimulates the growth of the axillary bud

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6
Q

3 modified root stems

A

horizontal stem (runner)
rhizomes
bulbs

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7
Q

horizontal stems

A

grows along the ground surface

  • allows plant to reproduce asexually
    ex) strawberry plant
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8
Q

rhizomes

A

horizontal stems that grow either right below or along the surface of the soil

  • they store food and may also spread and form new plants
  • potato plants have rhizomes which end in enlarged structures called tubers which are specialized for storage (the potato)
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9
Q

bulbs

A

underground shoots which contain swollen leaves for food storage

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10
Q

modified leaves

A

tendrils

spines

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11
Q

tendrils

A

the tips are coiled around a stem

-this helps the plant to climb such as in a grapevine

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12
Q

spines

A

spines of a cactus are a modified leaf that protects against being eaten by animals

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13
Q

three main plant tissues

A

-tissue: group of cells with common structure, function or both
tissue system: composed of one or more functional units within a plant
-the plant root system, stem and leaf are all made of three tissue systems:
1. dermal tissue
2. vascular tissue
3. ground tissue
-three tissue systems have different arrangements in different organs

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14
Q

dermal tissue system

A
  • forms an outer protective covering
  • first line of defense against physical damage and infectious organisms
  • consists of:
  • epidermis: single layer of tightly packed cells
  • cuticle: waxy outer covering atop the epidermis, protects against waste loss
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15
Q

vascular tissue

A
  • composed of xylem and pholem tissues

- provides support and long distance transport

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16
Q

ground tissue

A
  • not dermal or vascular
  • accounts for the bulk of a young plant
  • fills the space between the vascular tissue and the epidermis
  • ground tissue internal to the vascular tissue is the pith
  • ground tissue external to the vascular tissue is the cortex
  • this system functions in support, storage and photosynthesis
  • endodermis: is the inner layer of the cortex
  • a cylinder that is one cell layer thick
  • a selective barrier that determines which materials can pass between the rest of the cortex and the vascular tissue
17
Q

ground tissue/ vascular tissue

A

-water and minerals absorbed from the soil enter through the epidermis
-vascular cylinder: vascular tissue in the center of the root
xylem cells: of dicot radiate from the center like spokes of a wheel
-ring of xylem cells found in root of monocot
-phloem cells of dicot fill the wedges between the spokes
-ring of pholem cells found in root of monocot
-the region between the vascular cylinder and the epidermis consists entirely of cortex
-the cortex cells store food and starch and take up minerals that have entered the root via the epidermis

18
Q

eudicots and monocots have different stem arrangements

A
  • both have vascular tissues arranged in vascular bundles
  • monocot stem has vascular bundles scattered throughout the ground tissues
  • eudicot stem has vascular bundles arranged in a ring
  • unlike root a eudicot stem has both a cortex region and a pith region
  • cortex fills the region between the vascular ring and the epidermis
  • pith fills the center of the stem and is often vital for food storage
  • monocot stems are not divided into pith and cortex
19
Q

eudicot leaf tissue arrangement

A
  • pores called stomata interrupt the epidermis
  • these allow Co2, exchange between the air and the photosynthetic cells within the leaf
  • each of the stoma is boarded by two guard cells which regulate the size of the stromata opening
  • ground tissue of the leaf is called mesophyll and is sandwiched between the upper and lower epidermis
  • consists predominately of photosyntheic parenchymal cells
  • chloroplasts are located within these cells
  • cells of the lower mesophyll are loosely arranged with air spaces allowing O2 and CO2 to circulate
20
Q

leaf vascular tissue

A
  • eudicots and monocots have vascular tissue is the leaf made up of a network of veins
  • each vein has a vascular bundle composed of xylem and phloem
  • the xylem and phloem arw in close contact with the lead photosynthetic organs
  • this ensures that photosynthetic tissues are supplied with water and mineral nutrients from the soil and that the sugars made by photosynthesis are transported to the rest of the plant
  • the vascular structure also behaves as a skeleton, maintaining the leaf shape
21
Q

unique plant structures

A
  • three structures distinguish plants from other eukaryotes
  • chloroplasts: the site of photosynethesis
  • a central vacuole: contains fluid to help maintain the cell shape
  • a cell wall made from cellulose, a carbohydrate which surrounds the plasma membrane
  • many plant cells have two cell walls
  • the first is called the primary cell wall and is laid down first
  • a more rigid secondary cell wall is laid down second between the plasma membrane and the primary cell wall
  • the middle lamella is sticky layer that holds the primary cell walls of adjacent cells together
  • pits are regions where the cell wall is relatively thin allow the migration of water between adjacent cells
  • plasmodesmata are channels of communication and circulation between adjacent plant cells
22
Q

five types of plant cells

A
  1. parenchymal cells
  2. collenchyma cells
  3. sclerenchyma cells
  4. water-conducting cells
  5. food conducting cells
23
Q

parenchymal cells

A
  • most abundant cell type
  • have only primary cell walls which are thin and flexible
  • preform most metabolic plant function
  • photosynthesis
  • aerobic respiration
  • food storage
  • most can divide and differentiate into other types of plant cells
24
Q

collenchyma cells

A
  • also do not have secondary cell walls
  • have unsually thickened primary cell walls
  • provide flexible support in parts of the plant that are still growing
  • young stems and petioles often have collenchyma cells just below their surface
  • these cells remian alive and elongate as stems and leaves grow
25
Q

sclernchyma cells

A
  • have thick secondary walls
  • strengthened with lignin the primary component of wood
  • mature cells cannot elongate and thus are found in regions of the plant that have stopped growing
  • most are dead at maturity
  • these cells form a rigid cell skeleton to support the plant
  • there are two types of cells: fibers and sclerids
    1. fibers: are long and slender and often arranged in bundles
    2. sclereids: shorter than fiber cells, have thick irregular and very hard secondary walls
  • cells responsible for hardness of nutshells
26
Q

water conducting cells

A

-two types in angiosperms: tracheids and vessel elements
-both types have rigid, lignin containing secondary cell walls
-tracheids: long, thin cells with tapered ends
vessel elements: wider, shorter, and less tapered
-chains of both these cell types form tubers by over lapping their end
-carries water from the roots to the stems and leaves as part of the xylem tissue
-these tubers are hollow and the cells dead when they are mature-only thier cell walls remain
-rigid, thick walla allow these cells to function in support

27
Q

food conducting cells

A
  • sleve-tube members are arranged end to end like xylem forming tubes
  • remian alive at maturity but lose most organelles ( not nucleus and ribosomes)
  • allows more room for the transport of materials
  • end walls have sleeve plates containing pores that allow fluid to flow from cell to cell
  • companion cells are alongside each sleeve-tube cell (at least one) connected by plasmodesmata and function to supply the cell with proteins
28
Q

summary of plant cell types

A
  • plant cells are grouped into tissues:
  • xylem tissue functions to transport water and dissolved minerals upward from the root
  • phloem contains sieve-tube members that transport sugars from leaves/storage tissues to other parts of the plant
  • the vascular tissue system, the dermal and ground tissue systems make up each plant organ (leaf, root, ect)