topic 4A

Question 1

what is cell wall

Answer 1

a freely permeable wall around plant cells, made mainly of cellulose.

Question 2

define suberin and lignin

Answer 2

suberin = a waterproof chemical
lignin = a durable, waterproof polymer that serves as a “backbone” for plants, providing structure and support

Question 3

what is the middle lamella

Answer 3

contains calcium pectate, pectin, and the calcium pectate strengthens the adhesive property, pectin is sticky and allows for cell - cell adhesion by forming a gel-matrix

Question 4

define pectine

Answer 4

a polysaccharide that holds cell walls of neighbouring plant
cells together and is part of the structure of the primary cell wall

Question 5

primary cell wall

Answer 5

the first very flexible plant cell walls to form, with
all the cellulose microfibrils orientated in a similar direction ( made pectin ALONE, cellulose microfibrils and hemicellulose )

Question 6

secondary cell wall

Answer 6

the older plant cell wall in which the cellulose
microfibrils have built up at different angles to each other making the
cell wall more rigid.
( made of cellulose, hemicellulose and lignin- for turgidity )

Question 7

hemicellulose

Answer 7

polysaccharides containing many different sugar monomers,

Question 8

difference between cellulose and hemicellulose

Answer 8

• hemicellulose is made of multiple monomers like ( lactose, xylose)
• branched and short chain
• cellulose is made of beta-glucose
• long, unbranched chain

Question 9

plant fibers

Answer 9

long cells with cellulose cell walls that have been heavily
lignified so they are rigid and very strong

Question 10

composed material

Answer 10

a material made of two or more materials which
combined together make a composite with different properties from
either of the constituent materials

Question 11

define turgid and flaccid

Answer 11

turgid = swollen
flaccid = floppy, soft

Question 12

meaning of plasmodesmata

Answer 12

a narrow threat of cytoplasm that connect the cytoplasm of neighbouring plant cell. allows cytoplasmic exchange between 2 cells freely through passive diffusion.

Question 13

define symplast

Answer 13

all of the material (cytoplasm, vacuole, etc.) contained
within the surface membrane of a plant cell

Question 14

meaning of pits

Answer 14

there in region f te cell wall where there no lignin, they are used to transport dissolved ions and water between substances by diffusion, short distance.

Question 15

role of tonoplast

Answer 15

the specialised membrane that surrounds the permanent
vacuole in plant cells and controls movements of substances into and
out of the cell sap

Question 16

role of cell sap

Answer 16

he aqueous solution that fills the permanent vacuole

Question 17

role of chloroplast

Answer 17

rganelles adapted to carry out photosynthesis,
containing the green pigment chlorophyll

Question 18

role of chlorophyll

Answer 18

the green pigment that is largely responsible for
trapping the energy from light, making it available for the plant to
use in photosynthesis

Question 19

role of amyloplast

Answer 19

plant organelles that store starch

Question 20

role of RER

Answer 20

has tons of ribosomes for protein synthesis

Question 21

role of SER

Answer 21

synthesis lipids

Question 22

parenchyma

Answer 22

unspecialised cell that can differentiate for storage purposes or photosynthesis, can also differentiate into collenchyma and sclerenchyma cells.
- structure is thin and flexible [ primary cell wall ] made of cellulose and hemicellulose and calcium pectate.
- living cells, at maturity.

Question 23

collenchyma

Answer 23

shape: elongated, unevenly thick, non-lignified walls.
- contains: cellulose, pectin rich and has hemicellulose, no secondary cell wall, has minimal intercellular spaces. ( thick primary cell walls don’t go through lignification )

Question 24

sclerenchyma

Answer 24

plant cells that have very thick lignified cell walls and
an empty lumen with no living contents , provides mechanical stress and provides rigidity

Question 25

sclereids

Answer 25

sclerenchyma cells that are completely impregnated with lignin

Question 26

xylem

Answer 26

a transporting vessel made from dead cells, so dignified and water proofed, one way, transports water and mineral ions.

Question 27

phloem

Answer 27

made from living cells, so no lignification. 2 way and transports glucose, sugars, and food.

Question 28

vascular bundel

Answer 28

part of the transport system of a plant, with phloem on the outside and xylem on the inside - often with strengthening sclerenchyma

Question 29

cambium

Answer 29

the layer of unspecialised plant cells that divide to form both the xylem and the phloem

Question 30

protaoxylem

Answer 30

the first xylem the plant makes; it can stretch and grow because the walls are not fully lignified

Question 31

metaxylem

Answer 31

consists of mature xylem vessels made of lignified tissue

Question 32

transportation stream

Answer 32

the movement of water up from the soil through the root hair cells, across the root to the xylem, then up the xylem, across the leaf until it is lost by evaporation from the leaf cells and diffuses out of the stomata down a concentration gradient

Question 33

translocation

Answer 33

the active movement of substances around a plant in the phloem

Question 34

sieve plates

Answer 34

the perforated walls between phloem cells that allow the phloem sap to flow allow food to be dissolved and ditributed to the plant by dissusion

Question 35

companion cells

Answer 35

very active cells closely associated with the sieve tube elements that supply the phloem vessels with everything they need and actively load sucrose into the phloem

Question 36

tensile strength

Answer 36

he resistance of a material to breaking under tension

Question 37

carbon neutral

Answer 37

a process where no net carbon is released into the atmosphere

Question 38

bioplastic

Answer 38

plastics based on biological polymers

Question 39

binary fission

Answer 39

asexual reproduction in bacteria in which the bacteria split in half

Question 40

culture

Answer 40

growing microorganisms in the laboratory, providing them with the nutrients, oxygen, pH and temperature they need to produce large numbers so they can be observed and measured

Question 41

septic technique

Answer 41

method of carrying out a procedure to prevent contamination by unwanted microorganisms

Question 42

aspirin

Answer 42

a widely used drug which relieves pain and reduces blood clotting and inflammation

Question 43

testing new drugs

Answer 43

1. safe 2. stable 3. effective 4. can be made in large scale 5. can enter and exit the body easily.

Question 44

clinical trials

Answer 44

stages - preclinical stage - 3 stages of clinical trials - licensing phase 1 - phase 2 phase 3

Question 45

pre- clinical trials

Answer 45

Computer models to simulate the metabolic pathways Tested on cells culturing, tissues cultures and whole organs in the lab. efficacy and toxicity are tested this stage. the developed drug is tested on live animals to see the effect inna whole organism.