4.4

Question 1

what are three principles plants use to build tall structures?

Answer 1

1) produce strong cell walls out of cellulose
2) build columns and cells from specialised cells
3) strengthen cells with lignin

Question 2

what is plarenchyma?

Answer 2

a type of plant tissue found throughout the plant which fills spaces between more specialised tissues

Question 3

what is cellulose made from?

Answer 3

beta glucose units

Question 4

what is the bond between the glucose molecules in cellulose?

Answer 4

1,4 glycosidic bond

Question 5

how are microfibrils formed?

Answer 5

hydrogen bonds form between the OH groups in neighbouring cellulose chains

Question 6

what is the glue that holds the microfibrils together?

Answer 6

branched polysaccharides called hemicelluloses and pectins

Question 7

where else are pectins found?

Answer 7

in the middle lamella (the region between the cell walls of adjacent cells)

Question 8

what are the plasmadesmata?

Answer 8

narrow fluid filled channels that cross the cell walls

Question 9

what do xylem vessels transport?

Answer 9

water and minerals

Question 10

what do phloem sieve tubes transport?

Answer 10

organic solutes

Question 11

from the inside to the outside of the vascular bundle, what are the three elements?

Answer 11

xylem, phloem and sclerenchyma fibres

Question 12

what does lignin to in the xylem vessels?

Answer 12

it impregnates the cell wall and the entry of water and solutes into them is restricted

Question 13

what happens during autolysis?

Answer 13

the cell organelles, cytoplasm and cell surface membrane are broken down by the action of enzymes and are lost leaving dead empty cells that form a tube

Question 14

what happens in the xylem?

Answer 14

transpiration

Question 15

what happens in the phloem?

Answer 15

translocation

Question 16

what three cells surround the phloem sieve tubes?

Answer 16

transfer cells, companion cells and phloem plarenchyma cells

Question 17

what are the processes that extract plant fibres called?

Answer 17

retting

Question 18

how to bacteria produce and what happens?

Answer 18

binary fusion: the circular dna replicates and new cell content is synthesised before the new cell wall forms to divide the cell into two roughly equal halves

Question 19

what three conditions are needed for successful bacterial growth?

Answer 19

sufficient nutrients, optimum temperature and no build up of toxic waste products

Question 20

who did the first drug trial investigating digitalis?

Answer 20

william withering

Question 21

what two things did withering do in his trial?

Answer 21

tested unhealthy patients to record side effects and discover the correct dosage

Question 22

what does pre-clinical testing involve?

Answer 22

laboratory studies are carried out on isolated cells and tissue cultures to assess safety and determine whether the compound is effective

Question 23

what does the clinical trials phase 1 involve?

Answer 23

healthy volunteers are given different doses of which the side effects are monitored

Question 24

what does the clinical trials phase 2 involve?

Answer 24

small groups of patient volunteers are treated to look at the drugs effectiveness

Question 25

what does the clinical trials phase 3 involve?

Answer 25

two large groups of patients are split into two, half are given the drug and the rest a placebo (double blind randomised controlled trial)