bio edexcel unit 3b notes

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Acover slipcover slipis a thin square of glass that you put over a specimen on a microscope slide. The cover slip stops the specimen from drying out, and squishes it so that light can get though it easier

antibacterial antibacterial

improvements-improvements-weigh fixed / known amount plant ; 2. measured/known volume of ethanol / known concentration of ethanol ;

3. shake / leave for known / stated time ; 4. standardised crushing method ;

5. separation / filtration /eq ;

6. use same part of plant / same strain / variety of the plant ;

measurement:

measurement:1. graph paper tracing / {mean / average} diameter / eq ;

2. count squares / calculate area / eq ; 3. subtract area of {well / paper} / eq

Enzymes-risk

risk1. respiration / breathing problems / eq ; 2. use coated enzymes / eq / wear mask ; 3. possible skin reaction to enzyme /eq ; 4. wear gloves / wash with copious water / wash bench down / dry up spills ;

5. getting enzyme into blood through cut ; 6. wear plaster / gloves ;

7. high level of alkali damages skin / eyes ; 8. gloves / goggles as appropriate ;

9. reference to enzyme damage to eyes ; 10. wear goggles / eq

reliability of graph:

reliability of graph:reference to wide range / variability of data ; 2. greater reliability for data at {1% / 4% / 5%} /

eq ;

3. reference to more data needed for 1.5% to allow better assessment of reliability ; 4. reference to outliers / anomalies ;

economic implications:

economic implications:reference to (idea of) best concentration to use (ignore value) ;

2. reference to no improvement above this concentration ;

3. enzyme costs money ;

4. reference to reduced cost effectiveness at higher concentrations ;

conservation: conservation: bias:

bias:check for any bias of sponsor (e.g. funding source) ;

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2. check for credentials of contributor ;

3. reference to cross check with another source ;

4. reference to evidence of peer reviewing ;

issues:

issues:1. Economic ;

2. about possible uses of money in conservation of different types / eq ; ethical, lines 47-48 ; 2. ethics of keeping animals in zoos ;

3. cage environment ; 4. ethical, lines 38-39 ; 5. ethics of hunting animals ; 6. (wrong if) for ornaments, dubious medications, trophies etc / might lead to extinction ;

7. social, lines 49-54 ;

8. part of this (social) is education ; 9. teaching, awareness ;

10. environmental, lines 30-31 ;

11. correct reference to appropriate habitat ;

12. as only place organisms can properly exist

vitamin c

controlled variable:

heating time / eq ; 2. cooling time / eq ; 3. concentration of DCPIP / eq

How controlled:

named variable e.g. volume DCPIP / {/type / source / age / eq} of orange juice ;

2. means of controlled described e.g. {suitable measuring device named / use same orange / orange juice carton} ;

reliability:

idea that {SD / range} measures reliability / eq ;

2. SDs low / eq, therefore reliability high / eq OR replicated results similar at each temperature / eq ;

3. SDs differ at various temps, therefore so does reliability ; 4. 20, 23 and 50 (any 2) same reliability ;

5. and more reliable than 40/30 / eq ; 6. 30 least reliable / eq ;

7. comment on anomalous data / eq ;

Validity:

both (sets of data) show loss on heating / eq ;

2. all the vegetables show similar loss which is less than hers/eq ; 3. credit comparative manipulation of data to support

Validity of product:

cooking temp / eq ; 2. cooking time / eq ; 3. cooking method / eq ;

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4. source of fruit or vegetable / eq ;

5. comment on juice compared with whole extract ;

genetic testing:

usefulness of evidence

(Using source A) this would not support the statement / eq ;

2. (Using source A) (because) it’s a survey of the general population / there is no evidence from religious groups / eq ;

3. (Using Souce B) don’t know what % is therefore not much use / eq ;

4. If makes an assumption about what it is a percentage of, credit correct conclusion from that assumption ;

5. (Using source B) only considers one religious group / catholics / eq ;

(Using source B) catholics compared with non-catholics, who still might be religious people / eq ;

7. (Using source B) there is {no / little} difference between the two groups / eq ; 8. (Using sources A and B) there is {no / little} difference between general population, Catholics, non-Catholics / eq ;

9. use of comparative figures ;

10. We have no idea of sample size in either study/ We have no idea of variability of estimates/ We cannot say anything about reliability / eq ;

relevancy: relevancy:

Appropriate type of chart / graph ; 2. detail of chart / graph ;

3. relevant information select

economic issues:

increase cost in short term /eq ;

2. because money spent on trialling stem cell therapies / eq ; 3. reduce the cost in long term / eq ;

4. because benefits easily come by / eq ; 5. so other (expensive) research not needed /

mineral deficiency: mineral deficiency:

controlled/ how its controlled: controlled/ how its controlled:

the deficient mineral / solution(s) eq ; (reject nutrients), seed mass

light intensity / wavelength ; 2. light bank / eq / use same bulb ; 3. temperature ;

4. environment chamber / some sensible suggestion about the lab / room /sensible use water bath ;

5. carbon dioxide level / eq ;

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7. humidity / eq ;

8. reference to enclosed chamber ; 9. wind speed ;

10.reference to {enclosed chamber / fan} ; 11.{source / variety / age / ref genes} of seed / eq ;

12.from same packet / (parent) plant / eq ; 13.pH (of mineral solution) ;

14.Use buffer ;

15.Same concentration ((I) amount / volume) of all other minerals / minerals not omitted ; 16. Use same concentration as in complete solution each time ;

how to calculate or get dry mass:

remove water by placing in oven for sensible time (24 hours or so / at sensible temp (100°C or so) / eq ;

2. until constant mass idea ; NOTE (I) Filter paper, evaporation

tensile strength:

cross sectional area of fibre / eq ;variable that must be measured to convert the breaking force (N)

into tensile strength (Pa)

controlled and how controlled: controlled and how controlled:

length of fibre ;

2. suitable measuring device so all the same ;

3. cross-sectional area / diameter / radius / thickness of fibre ; 4. select after measuring with micrometer / eq;

5. humidity ;

6. chamber with suitable solution, which could just be water, to keep them all the same ; 7. temperature ;

8. {chamber / water bath} kept at {stated / fixed} temperature ; 9. soaking time ;

10. use of stopclock for {stated / same} time ; 11. nature of fibre / eq ;

12. same {species / plant /

location in plant/ age

how reference should be improved: how reference should be improved:

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dates / times websites accessed ; 2. specific detail of website {e.g. hyperlinks to websites / url / eq / author} / eq ;

3. reference to addition of suitable non-web resource ;

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heart beat: heart beat:

idea of (transparent / eq) so heart visible ; 2. {easily obtainable / cheap / abundant} / eq ;

3. idea that Daphnia {well studied / model organism} ;

4. Daphnia are easy to manipulate / eq

ethics: {simple nervous system / invertebrate} so reduced awareness of pain /eq ;

2. (transparent so) no need for dissection /eq ; 3. abundant in nature so no threat to it or its dependent species (food chains) / eq ;

4. bred for fish food will thus die anyway / eq ; 5. may be clones therefore no loss of genetic variation / eq ;

6. animal welfare argument e.g. cannot give consent / may feel pain / eq

temp:

idea that lactic acid concentration is only variable / to avoid changes in heart rate due to temperature changes (rather than [lactate]) ;

2. high enough to ensure good level of activity / not denature enzymes / habitat temperature of Daphnia / easy to maintain 25 ° C / eq ;

controlled variable:

controlled variable: some feature of Daphnia (age / size /sex / eq) ;

2. measure/ref to source of fleas / reference to some feature to assess sex (e.g. brood

chamber) ;

3. reference to {pre-treatment / acclimatisation / recovery time / eq} ;

4. detail of {pre-treatment / acclimatisation / recovery time / eq} given ;

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low ph results and validity of evidence and that graph in:

low ph results and validity of evidence and that graph in:increase in lactic acid concentration causes fall

in heart rate / eq ;

2. low pH has an effect on enzymes / slows down / inhibits muscle contraction

Idea that more lactic acid lowers pH

2. these data show that lowering pH depresses heart rate in rats as in Daphnia / eq ;

3. published in peer-reviewed journal therefore validity is likely to be good ;

4. but rat is vertebrate / (many) differences (in physiology) between rat andDaphnia / eq ; 5. rat heart is isolated, Daphnia whole organism / eq ;

cell membrane: cell membrane:

why equal sized cylinders of beetroot:

why equal sized cylinders of beetroot:same {amount / volume /eq} of pigment / same face area / number of cells on surface / e

colorimeter:

colorimeter:Then anytwotwofro

• shake before measurement • use of appropriate colour filter • zeroing against blank

• clean cuvettes • wiping cuvettes

• transparent sideREJECTREJECTsmooth side • measure absorbance / transmission • enough liquid to allow light go through

how variable could be controlled:

volume of water (in the boiling tube) ;

2. suitable method e.g. measuring cylinder, pipette / eq ; 3. reference to rinsing ;

4. until clear / for fixed time for all ;

5. similar {variety / density / eq} of beetroot ;

6. method to ensure same variety e.g. same beetroot ; 7. pre-treatment e.g. storage ;

8. detail of above ;

9. (use same) part of beetroot / eq ; 10. detail e.g. cut from middle, peeling ;

how temperature affected:

freezing / condensation effect at low temperature explained ;

2. correct reference to effect of temperature on membrane permeability ; 3. correct reference to effect of temperature on membrane component ;

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4. {all / as much} pigment as possible gone at 60 °C / idea of high temperature destroys pigment / eq ;

Ethical implication gene testing:

Ethical implication gene testing:For example:

• invasive procedure

• elimination / disposal / storage of unused embryos / right to life • eugenics / designer babies / discrimination

• who should have access • high cost

(false positive

• distress - abortion not justified

• distress - worry about baby / not having children when not a problem • distress – about abortion that was not needed

(false negatives)

• shock of diseased baby born • false confidence

right to know or not: right to know or not: Diagram A

Diagram A

1. most people have definite opinions ({few / only 2%} not sure, no response % low) ; 2. the idea that {a majority / most} think somebody has a right to know /eq ;

Diagram B Diagram B

3. more think that medical practitioners should know than think commercial insurers should

ACCEPT

ACCEPTconverse ;

4. more people are unsure / no response / eq about medical practitioners knowing than about commercial insurers ;

5. anywhere within lines 55 and 65 ;

what u would look more

what u would look more for reliability of evidence:for reliability of evidence:Credit anytwotwoappropriate questions ;;

For example

• what research is being done on treatments for TSD • what is gene therapy

• what progress on gene therapy (in relation to named diseases) • is it available

internet search engine / scientific journals / gazines / reference to specialist library / erence to relevant experts / eq ma ref

tissue culture tissue culture:

how growth controlled:

how growth controlled: idea of concentration of {mineral salt / auxin / cytokinin

/ eq} ;

2. reference to same {mass / eq} of chemical ;

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of {water / medium / eq } ; OR

1. temperature (of incubation) ; 2. water bath / incubator / eq ; 3. sensible temperature value e.g.15-30oC ;

OR 1. light ;

2. idea of same light source e.g. light bulb ;

3. idea of how same intensity / wavelength obtained e.g same distance, same wattage, same filter ;

OR 1. pH ;

2. use a buffer / eq ; 3. idea of buffer content or appropriate pH e.g. 6 to 8 ; OR

1. humidity / eq ;

2. idea of closed container used idea of reduces evaporation

Reliability:

Reliability: idea that SD indicates reliability ;

2. idea of that (all) these results are reliable ;

3. idea that a small SD means better reliability ;

4. idea that SDs do not overlap advan and disadvan of gm crops:

advan and disadvan of gm crops:Maximum of threethree from the following 1. idea of crops resistant to (disease

/ pests / insects / eq} ;

2. idea of survive adverse abiotic factors e.g. drought, weather ;

3. less use of chemicals e.g. agrochemicals, pesticides, insecticides

;

4. saves money ;

5. idea of reducing soil erosion / eq ;

6. idea of bigger yields ; 7. improved nutritional value ; 8. might help with food shortage / reduce famine/ make

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LEDCs more {self sufficient /

economically stable};DisadvantagesDisadvantages Maximum of threethree from the following 9. escape of (resistant / eq) genes / alleles ;

10.expense (especially to LEDC farmers) of seeds ;

11.loss of beneficial insects / birds / eq ;

12. idea of damage due to increased use of glyphosphate ;

environmental implications of gm crops

environmental implications of gm cropsreduce agro-chemical use / eq ; 2. idea of reduced impact on

environment described e.g. nontarget organisms survive, less

pesticide in food chains ;

3. idea of use of GM reduces need for{cleansing soil / fallow fields} ;

4. idea of reduces {erosion / loss} of soil (when fields fallow);

5. idea of escape of {GM/ resistant / eq} genes into wild population ;

6. idea of consequences on organisms in the ecosystem ; 7. idea of toxin present in GM crop gets into food chain;

8. effect on food chain described e.g. loss of beneficial insects / detail (ladybirds /lacewings / birds) ;

heart rate: heart rate:

why daphnia:simple nervous system / invertebrate; reduced awareness of pain/eq.;

or or

transparent;

heart visible without need for dissection/eq.; or

or

abundant in nature;

no threat to it or its dependent species (food chains); or

or

bred for fish food; will thus die anyway;

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or or

may be clones;

therefore no loss of genetic variation max temp min temp:

max temp min temp:lower temp leads to inactivity /freezing; higher temp leads to enzyme denaturation

reliability:controlling temperature/eq improvement:accuracy;

the graphs interpretation

the graphs interpretation: reference to kinetic effects on enzymes and the substrate; increase rate of respiration increases oxygen demand/increased rate of

reaction increases heart muscle activity/eq; Above 30°C enzymes/proteins begin to denature;

Reduced heart rate because of heart made of protein/eq; Daphnia become exhausted;

ethics of drug:

ethics of drug: ethical; ethics of drug trials discussed (informed consent); social; implications of drug trials discussed (payment / encourages less well off volunteers (students etc.) ;

economics; comment on high costs / long time

how to make better data to be published:discussion of use of sub-headings; suggestion for 1 or 2 such sub-headings;

suggestion for at least one visual aid; detail of visual aid; flow charts

Explain how a respirometer you have used is designed to overcome this problem and describe how it could be used to measure the volume of

oxygen taken up by respiring tissue in a human-carbon dioxide is absorbed in the apparatus / eq ; named absorber (e.g. sodium hydroxide/potassium hydroxide/soda lime) ;

therefore there will be a decrease in volume/pressure which can be measured / eq ;

Explain how temperature was controlled when using your respirometer.: use of water bath /eq ; allow to equilibrate before sealing apparatus ;

suitable named temperature (20 –40°C) [Reject room temperature

Describe the measurements you would take when using a respirometer and any calculations necessary to determine the raterate of oxygen uptake in a

sample of respiring tissue-measure movement of liquid in capillary/manometer/U tube ; in a fixed time ;

measure diameter/radius of tube ;

volume =πr 2l (l = distance moved by liquid in tube / eq) ;