topic 4

Question 1

wt is done to reduce the permbeabiloty in cell wals

Answer 1

suberin is added, lignin is part of the cell wall strucutre in wood

Question 2

describe the middle lamella

Answer 2

its the first layer, made of pectin. its flexible with the ceullose microfibrils. its called the primary cell walls

Question 3

describe the secondary cell wall

Answer 3

it builds up with the cellulose microfibirls laid densly at diff angles

Question 4

describe sturcutre of cellulose

Answer 4

made of long chains of glucose joined by glycosidic bonds.

Question 5

wt r microfibirls made of

Answer 5

long cellulose chain linked together by hydrogen bonds

Question 6

wt is plasmodesmata

Answer 6

channels of cytoplasm that pass between adjacent cell walls of plant cells that allows fast communication and exchange of substances between cells

Question 7

wt happens when the secondary thickening takes place

Answer 7

hemicelluloses and lignin r depostied in the cell wall, making it thicker

Question 8

wt happens when the secondary cell wall is laid down in sclenrenchyma

Answer 8

lignin gets deposited in the matrix to produce wood tissue or suberin to produce cork tissue, which makes the cell wall rigid and less permeable , an gets an empty lumen

Question 9

describe the struucutre of the plant cell vacuole

Answer 9

large and permnant struucture surrounded bya single membrane called tonoplast. its filled with an aq solution called cell sap.

Question 10

function of cell sap

Answer 10

it makes water to move either into or out of the cell down a water potential gradeient by osmosis which reulsts in the cytoplasm pressing against the cell wall and making it turgid, also helps

Question 11

name two subsatances that plant vaculoes store

Answer 11

proteins
hydrolytic enzymes, digestive enzymes

Question 12

describe strucutre of chlorplast

Answer 12

has a biconcave shape,suurounded by a chloroplast envelope and has a jelly material caled stroma. it contain chlorphyl in sacs called thylakoids

Question 13

3 functions of chlorplasts

Answer 13

is the site of photosynthesis
the ligh dependant reaction of photosynthesis takes place in the thylakoids which traps light
the light independant stage takes place in the stroma as it has the enzymes needed to catralyse the reactions

Question 14

describe 5 primary functions of plant stems

Answer 14

to hold th leaves in the best position for getting sunlight for photoysnthesis

to hold flowers for polination

moves the products of photosyntheis from photosynthesissig plant prts to non photosyntheiss parts

moves water from roots to leaves in the shoot apex

contains chlorphyl

Question 15

describe the 4 tissues and the layers in the stem

Answer 15

the outermost layer is the epdiermins. it protects the cells beneath it
most of the stem is made of packing tissue which consists of parenchyma
colenchyma hve thick walls to give support to the stem and flexibility
schlenchyma tissue is found around the vascular bundle in older steams, they hve stong secondry walls

Question 16

describe the fibres type of sclerenchyma

Answer 16

they r enlongated cells found in cylinders. the secongary cell walls r highly ligninfied.
the ligning deposits makes the fibres strong and flexible.
when the tissues int he stem grows, the fibres r stretched but there is no growth as they r ded cells

Question 17

descirbe the sclerids type in slenrenchyma

Answer 17

the secondary cell walls of these sclerenchyma cells r impreganted with lignin, so the cels r tough.
they r foudn in grps throuout the cortex of a stem

Question 18

wt is sclerenchyma

Answer 18

a modified parenchyma tissue. all sclenrenchyma cells hve strong seconfary wals made of cellulose microfibrils

Question 19

where is xylem and phloem found

Answer 19

in the vascular bundles , in stem roots and leaves

Question 20

descibe xylem including funcitons and flow direction

Answer 20

carries water and dissolved mineral ions from the roots to the photosynthetic parts of the plant. the movement of xylem is always upwards.

Question 21

descirbe phloem and flow direction

Answer 21

its a living tissue that trenasports dissovled produts of photosynthesis from teh elaves to where its needed for growth or storage.
the flow can go up and down

Question 22

wt is protoxylem

Answer 22

the firdst xylem the plant makes

Question 23

wt do u call the lignifid tissue in xylem

Answer 23

metaxylem

Question 24

wt is the result of the microfibirles in the walls of xylem vessel being arranged vertifcally in the stem

Answer 24

increases the stregnth of the tube and allows it to resist compression forces fromt eh weight of the plant.

Question 25

when is the amount of lignin increaseingly incorparted in to the cell walls

Answer 25

as the stem ages and the cels stop growing. so the cells beomes impermeable. the tossie becomes stronger but the contents of the cell die

Question 26

desckbe the proess of transporting water and mineral ions from the roots to the leaves and shoots

Answer 26

it goes thru the transpiration stream water moves out of the xylem into the surroudign cells thru specialised pits. the lignified xylem vessles r strong and supports the plant.

Question 27

wt do u call the process the phloem uses to transport materialsboth up and down the stem

Answer 27

transloction

Question 28

descibe the structure of phloem (4)

Answer 28

has Long, hollow cells with no nucleus to allow efficient flow of sap. End walls form sieve plates with small openings to enable movement between cells. also had companion cells that has a dense cytoplasm, many mitochondria, and a nucleus. Provide ATP for active loading of sucrose into sieve tube elemen

Question 29

function of phloem

Answer 29

Phloem transports sucrose and amino acids from sources to sinks Uses mass flow hypothesis

Question 30

4 reasons why plantrs need water

Answer 30

photosynthesis support by turgidity transport-mineral ions r dissolved in water and transported as a coolent-water is evaporated from plant tissues and heat is absorbed

Question 31

wt r root hairs and wt do they do

Answer 31

root hair r extensions of the epiderma cells in the root and they increase the surfae area need for absorption of water and minera ions

Question 32

descirbe the 3 alternate routes water takes when it moves up the root xylem

Answer 32

appolplast pathway-water moves from cell wall to cell wall thru diffusion symplast pathway-water moves from the cytoplasm to cytoplasm thru osmosis vacuolar pathway-water moves from vacuole to vacuole by osmosis

Question 33

wt is nitrogen needed for in plant cells, wt r the forms it is uptaken in, and wt r the defincency symptoms

Answer 33

NO3- NH4+ its needed for the synthesis of proteins, nucleic acids chlorphyl and hormones and DNA the deficnecy symtpooms r, the leaves turn yellow and stunted growth

Question 34

wt is calcium needed for in plant cells, wt r the forms it is uptaken in, and wt r the defincency symptoms

Answer 34

Ca2+ needed for formation of middle lamela. and to form Ca pectate deficnecy symptons r, the growing point die back and the leaves become yellow

Question 35

wt is magnesium needed for in plant cells, wt r the forms it is uptaken in, and wt r the defincency symptoms

Answer 35

Mg2+ needed for the formation of chlorophyl defincecny synpotoms r , yellow areas, growth slows down

Question 36

wt is potrasium needed for in plant cells, wt r the forms it is uptaken in, and wt r the defincency symptoms

Answer 36

PO43- needed for the synthesis of nucleic acids, ATP and some proteins deficency sympotoms r, dark green leaves with purple veins, stunted growth

Answer 37

.

Question 38

name 4 plant fibres

Answer 38

hemo, jute, manila, flax

Question 39

wt r fibres made of

Answer 39

long slcengryma cells and xylem tissues

Question 40

how a fibres produced

Answer 40

its relied on natural decomposers to break down the material around the fibres, it called retting

Question 41

wt is wood

Answer 41

a composite material made of lignified cellulose fibres embedded in hemicelluloses and lignin

Question 42

wt r cellulose based plastics

Answer 42

made of wood pulp. used to make plastic wrap

Question 43

wt r thermoplastic starch

Answer 43

the best known bioplastic. made from starch thats extracted from potatoes . used to make drugs, as it absorbs water and is readily digested

Question 44

wt is sustainabiloty

Answer 44

using materials which can be replaced in manufacturing process. renewable

Question 45

wt r synthetic fibres made of

Answer 45

chemicals derived from crude oil

Question 46

wt is paper made of

Answer 46

cellulose fibres obtained from wood

Question 47

wts the main advatange of cotton that allows it to be easiy extracted

Answer 47

its produced in the form of almost oure fibres packed around the seeds, so they can be easily extracted with no other chemical or treatment

Question 48

y r cotton fibres easier to use than the fibres fro plants such as jute and hemp

Answer 48

cotton fibre r produced in the form of almost pure fibres packed around the seed. they arent embedded in a matrix of hemicellulosed and ligning. so no prior cheimcal or treatment is needed. in jute and hemp, the fibres r embedded in a tough lignified matrix

Question 49

3 adv of synthetic fibres

Answer 49

cheap very hard wearing did not crease

Question 50

2 disadv of syntheic fibres

Answer 50

didnt absorb liquids so didnt absorb sweat raw materials used to mae synthetic fibres like crude oil got expensive

Question 51

define bioplastics

Answer 51

plastics r synthetic polymers produced from oil based products

Question 52

probs of using synthetic plastics

Answer 52

crude oil is non renewable non biodegradable so pollutes

Question 53

adv of using bioplastics

Answer 53

biological polymers like starch and cellulose r renewable resouces can be grown easily biodegradle cu natural decomposers r there like fungi and bacteria

Question 54

give a social/ethical issue of using bioplastics

Answer 54

use of crops as maize,wheat, sugar beet for bioplastics and biofuels r debatlble instead of being used as food

Question 55

why is it more advantagoues to burn bioplastics when their useful life is over rather than allowing them to undergo natural deocmpostion

Answer 55

when bioplastics r broken down by decomposers the may produce methane which is a greenhouse gas when burnt they release CO2 during burning, energy is released and this energy can be used to generate electricty etc

Question 56

describe polylactic acid (PLA)

Answer 56

similar properties to polyethene biodigradable produced from maize and sugar cane

Question 57

descirbe poly-3-hydroxybutyrate (PHB)

Answer 57

a stiff biopolymer used to make ropes and car parts produced from sugar cane