Topic 4

Question 1

what did Wilhelm wuthering come up with?

Answer 1

found that active ingredient in foxglove was digitalis. through trial an error found doasge was important.

Question 2

what are the three steps in modern clinical trials?

Answer 2

1) preclinical testing: when the drug is tested on isolated cells or tissues to see if it is effective
pre-clinical test 1) tried on small population of people to see if it can be metabolised and excreted properly so if tiss safe to use
clinal test 2) tried on group of people with condition to see if it’s effective
3) tried on large sample of people double-blind trial as some receive a placebo and actual drug. placebo is an inactive dummy

Question 3

what are the conditions required for bacteria to grow?

Answer 3

optimum temperature and ph as well as plenty of nutrients. reproduce in a process known as binary fission asexually.

Question 4

what is contamination?

Answer 4

you want to prevent contamination of the sample from outside microorganisms. this is important so you can get reliable and repeatable data.

Question 5

what are aseptic techniques?

Answer 5

techniques to prevent contamination from pathogens.
disinfect work surfaces
use sterile equipment
flame any equipment and use bunsen burners close windows to reduce draughts

Question 6

describe the antimicrobial practical?

Answer 6

IV: garlic and mint
DV: zone of inhibition
pestle and mortar used to crush mint and garlic, ethanol added, sterile pipette used to add solution onto paper discs. ethanol extracts antimicrobial properties. Put into an agar petri dish. left to incubate.
CONTROL: water and paper discs
cv: same volume of plant material on each disc, the same size of each disc
larger the zone the more it prevents bacterial growth

Question 7

what is zone fo inhibition?

Answer 7

the area that inhibits bacterial growth or binary fission so clear zone where bacteria does not reproduce

Question 8

what does deplete mean

Answer 8

to reduce something in amount or size

Question 9

what is sustainability?

Answer 9

using resources in a way that doesn’t deplete them and they can remain for future generations

Question 10

structure of cellulose microfibril?

Answer 10

plant fibers are made up of cellulose fibres. cellulose microfibrils in cell wall have a net-like arrangement, and matrix of hemicellulose and pectin, which are short polysachharides bind both to each other and cellulose to hold cellulose mircofibril together. Pectin is found in middle lamella the region found between the cells of adjacent cells. holding them together

Question 11

what are plant fibres?

Answer 11

they are made of cellulose microfibrils and are therefore strong. sustainable as they can be regrown and secondary thickening of plant fibres make them stronger. can be used for ropes and fabrics.

Question 12

what is starch used for?

Answer 12

unused energy in plants is stored as starch. starch composed of glucose molecules in a polysaccharide chain. used to make bioethanols or biofuels which are fuels. fuels used instead of burning fossil fuels. can be extracted from crops which can be regrown. used for vehicle fuels.

Question 13

what is the structure of cellulose?

Answer 13

polysaccharide chain of beta glucose molecules held together by 1-4 glycosidic bonds and is unbranched. ins

Question 14

how can you measure the tensile strength of fibre?

Answer 14

IV: source and type of fibre
DV: how many masses can be held
CV: size off fibre and size of each mass plant soaked in a
bucket of water so fibres can be easily extracted ( retting )
2 clamps stand used
same age of fibre should be used as well as same length. the number of weights held determines the strength

Question 15

describe investigation to test plant mineral deficiencies

Answer 15

IV: minerals present
CV: physical characteristics of the plant
several tubes one containing all minerals and one lacking all or some minerals.
observe growth and deficiency
use Mexican hat plantlets

Question 16

how does magnesium ion nitrate ion and calcium ion affect the plant?

Answer 16

magnesium ions are needed for production of chlorophyll for photosynthesis, so stunt in growth and leaves appear yellow
nitrate needed for the production of protein enzymes and DNA
calcium ions needed for plant growth and forms calcium pectate which ensures stability in plant, so distorted growth of cell walls.

Question 17

what is genetic drift?

Answer 17

some alleles are not passed due to chance which causes a change in allele frequency and reduces genetic variation

Question 18

how do zoos maintain genetic diversity?

Answer 18

captive breeding programmes help endangered species. Involves breeding animals in controlled environments, species that are extinct or endangered in the wild can be bred and introduced back into the wild to help increase their numbers.

Question 19

what are the drawbacks of captive breeding programmes?

Answer 19

• Animals find it harder to breed in the natural environment and cant reproduce as successfully in captivity
• wrong to keep animals in captivity
• conservation of natural habitat required
• introduced can bring new diseases to habitat harming other organisms
• problems finding food or communicating with wild species

Question 20

benefits of captive breeding programmes?

Answer 20

Maintains genetic variation
studbooks ensure which individuals should be bred
- individuals who breed poorly in captivity must be encouraged more and those who breed well should be limited.
could help organisms that rely on these plants or animals for food

Question 21

what are seedbanks used for?

Answer 21

to store seeds from plants that are endangered
cool and dry conditions
seeds are tested for viability

Question 22

what do both seedbanks and zoos do?

Answer 22

help conserve genetic diversity

Question 23

how do seedbanks and zoos contribute to scientific research?

Answer 23

seedbanks used to grow endangered plants for medical research rather than removing them from endangered species.

Question 24

benefits of seedbanks?

Answer 24

cheaper to store seeds as require less space than grown plants
less labour work only need cool and dry conditions
plants need conditions from the original habitat

Question 25

drawbacks of seedbanks

Answer 25

testing seeds for viability is time-consuming and can be expensive
expensive to store all types of seed
difficult to collect seeds from some plants as they grow in remote locations

Question 26

where is plasmodesmata found and what is its function?

Answer 26

narrow fluid filled channels which cross the cell wall making the cytoplasm of one cell continuous with the other. can be found in regions of one layer of cellulose known as pits.

Question 27

what are the 3 types of tissue found in plant?

Answer 27

vascular tissue ( xylem and phloem) involved in transport surrounded by the ground tissue (schelerenchyma cells for support of vascular bundle) which contains cells for photosynthesis and the epidermis which is single layer covering the plants

Question 28

what are schelernchyma cells?

Answer 28

dead cells cause fo lignification, no pits, that have heavily thickened secondary walls containing lignin. they are holllow, strong walls supporting tissue. thick lingified walls making them strong and water proof

Question 29

describe structure of xylem?

Answer 29

produces polymer lignin to make xylem vessels waterproof and restrict amount of solutes and water. tonoplast ( membrane of vacuole) breaks down, vacuole contents such as enzymes are released, digesting organelles, such as cytoplasm and cell surface membrane ( autolysis) and there are dead organelles. these cause dead end walls in xylem making them hollow tubes with no end walls and lignified cellulose cell walls , forming long tubes, continuous from roots to plants.

Question 30

what is function of xylem

Answer 30

transport water and inorganic ions such as magnesium calcium and nitrate up the plant

Question 31

describe the transpiration stream

Answer 31

water is evaporated by cells in substomatal cavities (transpiration)
water is drawn up xylem vessel by capillary action
cohesion surface tension
cohesive nature of water allows hydrogen bonding forming continuous column in xylem
adhesive nature allows hydrogen bonds to form between between water and hydrophobic cell wall.

Question 32

why is ice less dense than water?

Answer 32

hydrogen bonding is further apart in ice than in liquid water , making ice less dense than liquid water.

Question 33

how do the thermal properties of water help plants survive?

Answer 33

large input of energy required to raise temperature of water, so heats and cools slowly enabling organisms to maintain a fairly steady temperature.

Question 34

what is a mass trasnoirt system?

Answer 34

In biology a mass transport system is an arrangement of physical structures by which materials are moved in the form of a fluid containing particles of those materials travelling in one direction