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Bio MC > Prac > Flashcards

Prac Flashcards

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Biology 101 flashcards
1
Q

Testing for fat

A

add ethanol the water, shake

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2
Q

(Juice and pectinase) Control experiment?

A

boiled pectinase, denatured pectinase

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3
Q

(dough) Error with method measuring independent variable

A

Dough was not flat

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4
Q

Reagent for CO2?

A

Limewater

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5
Q

Hazards

A

Heating the reagent, burning your hands, damaging skin, gloves and goggles

hot water runs risk of burning, gloves and goggles, stand up during practical

burning hand in acid, wear gloves and goggles

breakage of glass equipment

pectinase, gloves and goggles

chopping, cutting away from body

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6
Q

Kept constant in human experiment?

A

environment, age, sex of participants

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7
Q

Agar jelly conclusions (monkey)

A

huddling reduces heat loss, as time increases temperature falls

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8
Q

Kept constant in agar jelly investigation? (monkey)

A

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

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9
Q

Agar jelly error
(monkey)

A

volume vary, temp at start, bands for insulation, band tightness

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10
Q

Improvement to method?

A

repeat twice more, (things to fix errors)

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11
Q

Things to mention in experiment with enzymes and disappearance.

A

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

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12
Q

Why a large number sampled?

A

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

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13
Q

Why temp of water bath change not significant error?

A

would effect the tubes equally

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14
Q

(Agar jelly) Control experiment?

A

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

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15
Q

Kept constant in plant growth experiment?

A

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

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16
Q

(Vit C) Reason for wrapping beaker in foil?

A

Insulation, decrease heat loss, maintain temperature

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17
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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18
Q

Why repeating two more times is an improvement to method?

A

identify any anomalies

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19
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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20
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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21
Q

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

A

Allows comparison, as initial masses were different

22
Q

Results not the same. Did not wash syringe.

A

contamination of new substance

23
Q

Explain why it is important to stir the yeast suspension.

A

ensures yeast cells are uniformly distributed

24
Q

Improving an investigation including color change.

A

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

25
Q

Compare the volumes produced at 20 degrees and 30 degrees

A

COICC

26
Q

Temp was a source of error. Give improvement.

A

bunsen burner to heat and thermometer to monitor

water bath

27
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.

28
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

29
Q

Describe variables that scientists should have considered when selecting women.

A

calcium intake from their diets and their health status

30
Q

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

A

only women, not done on people younger than 50

31
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

32
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

33
Q

Independent variable for agar jelly?

A

size of blocks

34
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

35
Q

Describe the relationship between pulse rate and time after exercise

A

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

36
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
-warmer solutions to speed up diffusion

37
Q

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

A

not using a bunsen burner or water bath

38
Q

Suggest why repeating the procedure several times would improve the investigation

A

anomalous result identified

39
Q

Suggest why some named factors were same for all experiment?

A

so the results are comparable

40
Q

Source of error for an experiment?

A

no repeat

41
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 ;
42
Q

How to decrease humidity around plant?

A

dehumidifier

43
Q

How to increase humidity around plant?

A

bowls of hot water around apparatus / place in plastic bag

44
Q

Error and improvement for any experiment involving indicators.

A

Error → Judgement of endpoint is subjective and qualitive
Improvement → Compare to a standard colour chart or colorimeter

45
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

46
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 ;

47
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

48
Q

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

A

Error → volume of starch not measured
Improvement → measuring cylinder

49
Q

Explain why a control group was used in this investigation

A

to show that the beetroot causes the effect

50
Q

When suggesting improvement regarding drops of some liquid say:

A

measure volume instead of drops

Bio MC (7 decks)

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