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Bio MC > Prac > Flashcards

Prac Flashcards

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Biology 101 flashcards
1
Q

Testing for fat

a

A

add ethanol then water, shake

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2
Q

Describe a control experiment involving enzymes.

A

boiled pectinase, denatured pectinase

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3
Q

Reagent for CO2?

a

A

Limewater

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4
Q

Hazards

a

A

breakage of glass equipment

pectinase, gloves and goggles (handle carefully)

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5
Q

Kept constant in human experiment?

a

A

environment, age, sex of participants

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6
Q

Agar jelly conclusions (monkey)

a

A

huddling reduces heat loss, as time increases temperature falls

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7
Q

Kept constant in insulation investigation?

A

size and kind of test tubes, all placed in a beaker, same time intervals

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8
Q

Errors

a

A

no repeat, volume vary, temp at start, bands for insulation, band tightness, dough not flat/uneven

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9
Q

Improvement to method?

a

A

repeat investigation twice more, (things to fix errors), use clean rod, no 10-minute cut-off

foam is uneven, measure volume of gas produced

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10
Q

Things to mention in experiment with enzymes and disappearance.

a

A

Method: white tile, buffer colorimeter, maintaining temperature using water bath

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11
Q

Why a large number sampled?

a

A

To get a representative sample. To avoid bias. To identify anomalies.

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12
Q

Why temp of water bath change not significant error?

a

A

would effect the tubes equally

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13
Q

(Agar jelly) Control experiment?

a

A

use water instead of acid, only add water to agar jelly

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14
Q

Kept constant in plant growth experiment?

A

plant species, number of leaves, humidity, soil type, water supplied, time, wind-speed

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15
Q

(Vit C) Reason for wrapping beaker in foil?

A

Insulation, decrease heat loss, maintain temperature

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16
Q

Explain why it is important to rinse the outside of the dialysis tubing.

A

to ensure no starch is left

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17
Q

Why repeating two more times is an improvement to method?

A

identify any anomalies

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18
Q

Explain why it is important to take measurements from the same place

A

so differences between measurements can be compared accurately

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19
Q

Conclusion of dialysis tubing experiment.

A

osmosis allows water to move across a semi-permeable membrane down a concentration gradient

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20
Q

Explain why percentage change in mass is more useful than change in mass.

A

Allows comparison, as initial masses were different

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21
Q

Results not the same. Did not wash syringe.

A

contamination of new substance

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22
Q

Explain why it is important to stir the yeast suspension.

A

ensures yeast cells are uniformly distributed

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23
Q

Improving an investigation including color change.

A

place a white card behind the test tube to identify color change easily

24
Q

Compare the volumes produced at 20 degrees and 30 degrees

A

COICC

25
Q

Temp was a source of error. Give improvement.

A

bunsen burner to heat and thermometer to monitor

water bath

26
Q

Test tubes were covered in foil. Predict and explain the effect.

A

If room temp was lower, temp of test tube would be lower. More heat loss.

27
Q

Obtain a more accurate value for optimum pH.

A

use a set of pH values with shorter intervals between pH 7 and pH 9

28
Q

Describe variables that scientists should have considered when selecting women.

A

age, calcium intake from their diets and their health status

29
Q

State one way this study is not representative of the population.

A

only women, not done on people younger than 50

30
Q

“More women were losing bone mass than gaining” Why this may not be correct?

A

the number of women in each category is unknown

31
Q

(Experiment of potatoes, dye and light) Independent, dependent and kept constant?

A

potato sa
percentage of light absorbed
type of dye and length of times

32
Q

Independent variable for agar jelly?

A

size of blocks

33
Q

(Effect of temperature on osmosis in plant tissue) What is the dependent variable?

A

volume/mass of tissue before and after immersion

measuring volume of water before and after immersion

34
Q

Describe the relationship between pulse rate and time after exercise

A

biggest decrease..
return to pre-exercise pulse rate at 2 mins

35
Q

(Potato cylinders and diffusion) Suggest improvements to the method used.

A

-measure mass instead of length
-more intermediate concentrations
-extend the range of concentrations used
-repeat 2 more times
-same temp
-dry before measuring

36
Q

State one safety precaution that the students would take when evaporating
substances
containing ethanol.

A

not using a bunsen burner or water bath

37
Q

Suggest why repeating the procedure several times would improve the investigation

A

anomalous result identified

38
Q

Suggest why some named factors were same for all experiment?

A

so the results are comparable

39
Q

How to maintain temperature of water bath?

A
  1. use thermostatically controlled water-baths ;
  2. use a Bunsen burner AND thermometer (method outlined) / use a Bunsen
    burner and monitor the temperature ;
  3. top up with, hot water / cold water / ice, and monitor /use a thermometer ;
  4. insulate the container / AW ;
40
Q

How to decrease humidity around plant?

A

dehumidifier

41
Q

How to increase humidity around plant?

A

bowls of hot water around apparatus / place in plastic bag

42
Q

Error and improvement for any experiment involving indicators.

A

Error → Judgement of endpoint is subjective and qualitive
Improvement → Compare to a colorimeter

43
Q

Error and improvement for any experiment involving drops of a liquid.

A

Error → Volume of drops size is inconsistent or unknown or different
Improvement → Use syringe/ burette/ graduated pipette to measure volume

44
Q

Error and improvement for any experiment involving shaking or stirring a liquid.

A

Error → different degree of, shaking / mixing / stirring
Improvement → shake at a fixed speed or use a (mechanical) stirrer
Error → different time of, mixing or shaking
Improvement → shake or stir, for a fixed time ;

45
Q

Error and improvement for any experiment involving hot or cold water.

A

Error → temperature of the water not controlled / temperature changes
Improvement → thermostatically controlled water-bath / insulation / Bunsen burner

46
Q

Error and improvement for any experiment involving unknown volume of a liquid.

A

Error → volume of starch not measured
Improvement → measuring cylinder

47
Q

Explain why a control group was used in this investigation

A

to show that the beetroot causes the effect

48
Q

Describe suitable apparatus that could be used to collect and measure the volume of carbon dioxide produced.

A

gas syringe

upturned measuring cylinder with delivery tube

49
Q

Carbon dioxide gas was bubbled through hydrogencarbonate indicator solution.
The indicator was red before the gas was bubbled through.
State the colour change that would occur.

A

Red to Yellow

50
Q

DCPIP colour change.

A

blue to colourless

51
Q

What is the dependant and independant variable in determining the rate of breakdown?

A

dependant- temperature
independant- time taken for the negative result for starch

52
Q

Method basics.

A

-maintaining 2 temp, thermostat and water bath
-iodine test
- pH
- buffer

53
Q

Method relating to plants.

A
  • medium for keeping moist
  • variety of tomato seed
  • soil type
  • pH
  • cut sections of stalk to see distance moved by dye
54
Q

Method relating to general preparation.

A

cutting
measuring

55
Q

Method methods..

A

method of measuring gas
method to check end-point

Bio MC (10 decks)

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