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Flashcards in lecture 11 Deck (28):
1

basic plant organs

-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

2

root system

-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

3

shoot system

-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

4

two types of buds

terminal buds
axillary buds

5

buds

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

6

3 modified root stems

horizontal stem (runner)
rhizomes
bulbs

7

horizontal stems

grows along the ground surface
-allows plant to reproduce asexually
ex) strawberry plant

8

rhizomes

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)

9

bulbs

underground shoots which contain swollen leaves for food storage

10

modified leaves

tendrils
spines

11

tendrils

the tips are coiled around a stem
-this helps the plant to climb such as in a grapevine

12

spines

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

13

three main plant tissues

-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

14

dermal tissue system

-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

15

vascular tissue

-composed of xylem and pholem tissues
-provides support and long distance transport

16

ground tissue

-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

ground tissue/ vascular tissue

-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

eudicots and monocots have different stem arrangements

-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

eudicot leaf tissue arrangement

-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

leaf vascular tissue

-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

unique plant structures

-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

five types of plant cells

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

23

parenchymal cells

-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

collenchyma cells

-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

sclernchyma cells

-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

water conducting cells

-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

food conducting cells

-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

summary of plant cell types

-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)