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Key Experiments Flashcards

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1
Q

Design an experiment investigating the effect of light intensity on photosynthesis

A

C- Changing whether there is light or no light
O- Same species, age and size of plant
R- Repeat experiment several times to ensure reliable results
M1- Observe the color change of leaf when iodine is applied
M2- After 1 day
S- Same room temperature

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2
Q

What are the safety precautions of the testing a leaf for starch and the requirements of light for photosynthesis experiment?

A

-Bunsen burner should be turned off before using ethanol IT IS FLAMMABLE
-Safest way to heat ethanol is in an electrical water bath

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3
Q

Explain the results of testing a leaf for starch and the requirements of light for photosynthesis

A

-Green leaf- the entire leaf turns blue to black (as photosynthesis is occurring in all areas of the leaf
-Area of leaf covered with Aluminium foil- remains orange to brown (didn’t receive any sunlight so couldn’t photosynthesize) (The area exposed to light turns blue to black)
-Shows light is necessary for photosynthesis and the production of starch

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4
Q

What is the method for testing a leaf for starch and the requirements of light?

A

1.DROP THE LEAF IN BOILING WATER- kills tissue & breaks down the cell walls
2.TRANSFER THE LEAF INTO HOT ETHANOL IN A BOILING TUBE FOR 5-10 MINS- removes chlorophyll so colour changes from iodine can be seen more clearly
3.RINSE THE LEAF IN COLD WATER- to soften the leaf tissue after being in ethanol
4.SPREAD THE LEAF OUT ON A WHITE TILE AND COVER IT WITH IODINE SOLUTION

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5
Q

Investigate food samples for the presence of glucose

A

-Benedict’s solution- test for reducing sugars (glucose)
1. Add Benedict’s solution to a sample of food (in solution)
2. Place in water bath at 80*c for 5 minutes
3. If glucose is present- blue to brick red
-green, yellow, orange is still a positive result but will have a lower concentration of sugar

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6
Q

Investigate food samples for the presence of starch

A

-Iodine- test for starch
1. Add a few drops of orange iodine solution to the sample on a spotting
2. If starch is present- blue/black colour

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7
Q

Investigate food samples for the presence of protein

A

-Biuret’s- test for protein
1. Add 2cm3 water to a food sample and shake (if not already liquid)
2. If protein is present- blue to violet/purple

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8
Q

Investigate food samples for the presence of lipids

A

-Emulsion- test for lipids
1. The food sample is placed in a test tube
2. Add a small volume of ethanol and shake to dissolve any liquid in the alcohol.
3. Add an equal volume of water
4. If lipids are present- cloudy white colour

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9
Q

Design an experiment investigating how enzyme activity can be affected by changes in temperature

A

C - Changing the temperature in each repeat
O - Not relevant, no organisms
R - Repeat experiment several times to ensure reliable results
M1 - Measure the time taken
M2 - for the iodine to stop turning black
S - Same concentration and volume of starch solution, iodine and amylase used in the investigation

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10
Q

Explain the results of investigating the effect of temperature on enzyme activity

A

-Amylase is an enzyme which breaks down starch
-The quicker the reaction is completed, the faster the enzyme is working

-Optimum temperature- the iodine stopped turning blue-black the fastest (because the enzyme is working at its fastest rate and has digested all the starch)

-Colder temperatures (below optimum), the iodine took a longer time to stop turning blue-black
(because the amylase enzyme is working slowly due to low kinetic energy and few collisions between the amylase and the starch)

-Hotter temperatures (above optimum) the iodine turned blue-black throughout the whole investigation (because the amylase enzyme has become denatured and so can no longer bind with the starch or break it down)

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11
Q

What is the method for investigating how enzyme activity can be affected by changes in temperature?

A

1.Add 5cm3 starch solution to a test tube & heat to a set temperature using beaker of water with a Bunsen burner
2.Add a drop of Iodine to each of the wells of a spotting tile
3.Use a syringe to add 2cm3 amylase to the starch solution & mix well
4.Every minute, transfer a droplet of solution to a new well of iodine solution (which should turn blue-black)
5.Repeat this transfer process until the iodine solution stops turning blue-black (this means the amylase has broken down all the starch)
6.Record the time taken for the reaction to be completed
7.Repeat the investigation for a range of temperatures (from 20°C to 60°C)

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12
Q

What is the method for investigating the effect on temperature on diffusion in beetroot? (investigating diffusion using living and non-living systems)

A

1.Using a knife, cut 2 equally-sized cubes of beetroot (or a cork borer)
2.Rinse the beetroot pieces
-To remove any pigment released during cutting
3.Put 5 cm3 of water into 2 test tubes labelled A and B
4.Keep test tube A at room temperature and transfer test tube B to a hot water bath at 90℃
5.Leave the test tubes for 2 minutes, then add a piece of beetroot into each test tube
6.After 10 minutes, observe the colour of the liquid in both test tubes

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13
Q

Design an experiment investigating diffusion using living and non-living systems

A

C - Changing the temperature of the environment
O - Cubes taken from same beetroot or beetroot of the same age
R - Repeat experiment several times to ensure reliable results
M1 - Observe the colour change of the liquid
M2 - after 10 minutes
S - Same volume of water used
Same dimensions of beetroot cubes
Each cube must be blotted before it is weighed each time

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14
Q

What are the results for investigating the effect of temperature on diffusion in beetroot?

A

-The higher temperature, more of the pigment has leaked out of the beetroot

-The cell membrane of the beetroot cells has become damaged so more pigment can leak out
-At higher temperatures, particles have more kinetic energy, this results in the faster movement of particles compared to when they have less energy

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15
Q

What are the limitations for investigating the effect of temperature on diffusion in beetroot?

A

-Beetroot size and shape variation affects tissue quantity.
Solution: Precisely cut beetroot, repeat for accuracy.
-Beetroot pigment concentrations vary.
Solution: Repeat with different beetroot parts, calculate mean.
-Testing a wider temperature range enhances reliability.
Solution: Use 5 test tubes at various temperatures.
-Subjective color observation complicates comparison.
Solution: Employ a colorimeter for objective measurement.

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16
Q

What is the method for investigating osmosis in cells?

A

1.Prepare a range of sucrose (sugar) solutions ranging from 0 Mol/dm3 (distilled water) to 1 mol/dm3
2.Set up 6 labelled test tubes with 10cm3 of each of the sucrose solutions
3.Using the knife, cork borer and ruler, cut 6 equally-sized cylinders of potato
4.Blot each one with a paper towel and weigh on the balance
5.Put 1 piece into each concentration of sucrose solution
6.After 4 hours, remove them, blot with paper towels and reweigh them

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17
Q

What are the limitations of investigating osmosis in cells?

A

-Variations in potato cylinder sizes may compromise result reliability.
Solution: Repeat the investigation with multiple potato cylinders for each sucrose concentration. This helps identify and discard any anomalous results when calculating the mean.

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18
Q

Design an experiment investigating osmosis in cells (potato cells)

A

C - Changing the concentration of sucrose solution
O - Potato cylinders taken from the same potato or potatoes of the same age
R - Repeat experiment several times to ensure reliable results
M1 - Measure the change in mass of the potato cylinders
M2 - after 4 hours
S - sucrose used
Same dimensions of potato cylinders
Each cube must be blotted before it is weighed each time

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19
Q

What are the results for investigating osmosis in potato cells?

A

-Potato in distilled water gains most mass due to high water potential gradient from water to cells.
-Water moves into potato cells via osmosis, increasing turgor pressure and making them turgid, resulting in firm potato cylinders.
-Highest sucrose concentration causes most mass loss in potato due to greater concentration gradient: potato cells (higher water potential) to sucrose solution (lower water potential).
-Water moves out via osmosis, making cells flaccid, causing cylinder to feel floppy.
-Cells from this potato cylinder might show plasmolysis under the microscope, indicating the cell membrane has pulled away from the cell wall.

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20
Q

What is the method for investigating the need for carbon dioxide in photosynthesis?

A

1.Destarch plant in dark cupboard for 24 hours.
2.Ensures existing leaf starch won’t affect results.
3.Enclose one leaf with potassium hydroxide to absorb CO2.
4.Enclose another leaf with no potassium hydroxide for control.
5.Expose plant to bright light for several hours.
6.Test both leaves for starch using iodine solution.
7.Boil leaf, transfer to hot ethanol for 5-10 mins.
8.Rinse leaf in cold water, spread on white tile.
9.over leaf with iodine solution for observation.

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21
Q

Explain the results of investigating the need for carbon dioxide in photosynthesis

A
  • Leaf in flask with potassium hydroxide stays orange-brown, unable to photosynthesize without carbon dioxide.
  • Leaf in flask without potassium hydroxide turns blue-black, having all requirements for photosynthesis.
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22
Q

Design an experiment investigating the need for carbon dioxide in photosynthesis

A

C - Changing whether there is carbon dioxide or no carbon dioxide
O - leaves will be taken from the same plant or same species, age and size of plant
R -
M1 - Observe the colour change of the leaf when iodine is applied
M2 - after 1 day
S - Same room temperature
Same light intensity

23
Q

What is the method for investigating the need for chlorophyll in photosynthesis?

A
  • Boil leaf to kill tissue and break cell walls.
  • Transfer to hot ethanol for 5-10 mins to remove chlorophyll.
  • Rinse in cold water to soften tissue.
  • Spread on white tile and cover with iodine solution for color changes.
24
Q

Explain the results of investigating the need for chlorophyll in photosynthesis

A
  • White leaf areas lack chlorophyll; only chlorophyll-containing areas stain blue-black.
  • Non-chlorophyll areas stay orange-brown due to lack of photosynthesis and starch storage.
25
Q

What are the safety precautions of investigating the need for chlorophyll in photosynthesis?

A
  • Exercise caution with ethanol due to its flammability.
    • Turn off Bunsen burner during ethanol use.
  • Prefer electric water bath for heating ethanol over open flame with a beaker.
26
Q

Design an experiment investigating the need for chlorophyll in photosynthesis

A

C - Changing whether there is chlorophyll or no chlorophyll
O - leaves will be taken from the same plant or same species, age and size of the plant
R - Repeat investigation several times to ensure reliable results
M1 - Observe the colour change of the leaf when iodine is applied
M2 - after 1 day
S - Same room temperature
Same light intensity

27
Q

Design an experiment investigating the energy content in a food sample

A

Change - the type of food in the sample
Organisms - not relevant/no organism used
Repeat - Repeat investigation several times to ensure reliable results
Measurement 1 - the change in temperature of the water
Measurement 2 - the mass of the food will be measured after the food sample has burned out
Same - Same volume of water used
Same distance between the food sample and the boiling tube during burning
The food will also be relit every time it goes out until it no longer lights

28
Q

What are the limitations of investigating the energy content in a food sample?

A
  • Incomplete burning of food sample occurs.
    Solution: Relight until fully burned.
  • Heat energy loss to surroundings affects accuracy.
    Solution: Ensure consistent procedure to compare results.
29
Q

What is the method for investigating the energy content in a food sample?

A

1.Measure 25cm³ of water into boiling tube using measuring cylinder.
2.Record initial water temperature with thermometer.
3.Weigh food sample before burning.
4.Ignite food sample with Bunsen burner, holding 2cm from tube until fully burned.
5.Record final water temperature.
6.Weigh remaining food after cooling, record.
7.Repeat steps for various food samples (popcorn, nuts, crisps).

30
Q

Explain the results of investigating the energy content in a food sample

A
  • Higher water temperature indicates more energy in sample.
  • Calculate energy in food sample using formula:
    • Energy transferred (J) = (mass of water (g) x 4.2 x temperature increase (°C)) ÷ (mass of food (g))
31
Q

What is the method for investigating the evolution of carbon dioxide from respiring seeds or other suitable living organisms?

A

-Measure out 10 cm3 of hydrogencarbonate indicator into 3 boiling tubes
-Put in a layer of cotton wool
-Place 10 germinating seeds in tube A
-Place 10 boiled/dead seeds in tube B
-Place 10 glass beads in tube C
-Seal each tube with a rubber bung
-After 3 hours, observe the colour of the indicator

32
Q

Explain the results for investigating the evolution of carbon dioxide from respiring seeds or other suitable living organisms

A

-Tube A- turns yellow as the seeds are respiring and producing carbon dioxide
-Tube B- remains orange as the dead seeds produce no carbon dioxide
-Tube C- remains orange as there is no living material in there

33
Q

What is the method for investigating the evolution of heat from respiring seeds or other suitable living organisms?

A

Set up:
-Flask A with the dead seeds
-Flask B with the germinating seeds
-Make sure the cotton wool is plugging the top of each flask
-Hold the thermometer in place with the cotton wool
-Invert the flask
-Record the initial temperature
-After 4 days, record the final temperature

34
Q

Explain the results for investigating the evolution of heat from respiring seeds or other suitable living organisms

A
  • Thermometer in Flask B (with germinating seeds) should show a temperature increase.
  • Flask A (without seeds) should remain at room temperature.
    • Seeds in Flask B are respiring, producing heat energy.
  • Indicates respiration as an exothermic reaction.
  • Seeds in Flask A (dead) do not respire, temperature stays constant.
35
Q

Design an experiment the volution of carbon dioxide from respiring seeds or other suitable living organisms

A

Change - the content of the boiling tube (germinating seeds, dead seeds or glass beads)
Organisms - seeds used should all be of the same age, size and species
Repeat - Repeat investigation several times to ensure reliable results
Measurement 1 - Observe the change in the hydrogen carbonate indicator
Measurement 2 - after 3 hours
Same - Same volume of hydrogen carbonate indicator
Same number of seeds/beads
Same temperature of the environment

36
Q

Design an experiment the evolution of heat from respiring seeds or other suitable living organisms

A

Change - the content of the flasks (germinating seeds or dead seeds)
Organisms - seeds used should all be of the same age, size and species
Repeat - Repeat investigation several times to ensure reliable results
Measurement 1 - Observe change in the temperature on the thermometer
Measurement 2 - after 4 days
Same - Same number of seeds
Same starting temperature of the flasks
Same material and size of the flasks

37
Q

Hydrogencarbonate indicator

A
  • Hydrogencarbonate indicator changes color based on CO2 levels.
  • Orange in atmospheric CO2.
  • Turns yellow in high CO2, absorbs CO2.
  • Turns purple in low CO2, loses CO2.
38
Q

What is the method for investigating the effect of exercise on breathing?

A

1.Measure resting breathing rate for student A by counting breaths for 15 seconds and multiplying by 4; repeat for accuracy and calculate average.
2.Student A exercises for a minimum of 4 minutes.
3.Post-exercise, count breaths for 15 seconds and multiply by 4 to determine breathing rate per minute.
4.Compare post-exercise breathing rate to resting rate to assess change.
5.Repeat post-exercise breathing rate measurement every minute for 5 minutes.
6.Repeat entire process for student B.
7.After a rest period, repeat investigation for both students.

39
Q

What are the results for investigating the effect of exercise on breathing?

A

Frequency of breathing increases when exercising:
-because muscles are working harder and aerobically respiring more and they need more oxygen to be delivered to them (and carbon dioxide removed) to keep up with the energy demand
-cannot meet the energy demand they will also respire anaerobically, producing lactic acid

After exercise has finished, the breathing rate remained elevated for a period of time:
-because the lactic acid that has built up in muscles needs to be removed as it lowers the pH of cells and can denature enzymes catalysing cell reactions
-can only be removed by combining it with oxygen - this is known as ‘repaying the oxygen debt’
-can be tested by seeing how long it takes after exercise for the breathing rate to return to normal
The longer it takes, the more lactic acid produced during exercise and the greater the oxygen debt that needs to be repaid

40
Q

What are the limitations of investigating the effect of exercise on breathing?

A

Difficulty controlling variables:
- Ensure students are similar in size, fitness, age, and gender
- Provide each with the same meal before exercise

Challenges in replicating activity:
- Use exercise types with easier intensity control (e.g., treadmill running, cycling with specific power output)

Variability and quick changes in breathing rate:
- Start counting immediately when the time interval begins
- Measure for a short duration (e.g., 15 seconds) and multiply to calculate breaths per minute

Potential fatigue during investigation:
- Allow significant rest breaks between exercises
- Avoid prolonged periods of exercise

41
Q

Design an experiment investigating the effect of exercise and release of carbon dioxide on breathing

A

Change - whether the student has exercised or not
Organisms - students should be of the same age, gender, size and general fitness
Repeat - Repeat investigation several times to ensure reliable results
Measurement 1 - the change in breathing rate
Measurement 2 - immediately after exercise & each minute for the subsequent 5 minutes
Same - Same type of exercise carried out
Same temperature of the environment
Same food intake of the students prior to the investigation

42
Q

Explain the results of investigating the population size of an organism in two different areas using quadrats

A

-Once the results have been collected and the averages calculated, we can compare the abundance of the study species in each survey area
-Species abundance is likely to be influenced by biotic factors such as:
Competition:
–> Predator-prey relationships, Interactions with other organisms within the food chain or food web
-The abundance will also be influenced by abiotic factors such as:
–>Light intensity, Mineral availability, Water availability, pH, Temperature, Salinity

43
Q

Design an experiment investigating the population size of an organism in two different areas using quadrats

A

C - changing the study area where we are collecting the data
O - count the same species of organism in each quadrat
R - Repeat experiment several times to ensure reliable results
M1 - count the number of the designated study species found across all quadrats
M2 - this isn’t really relevant in this scenario
S - Same size of the quadrat
control the random way that quadrats are placed on the ground
control the day that the results were collected

44
Q

What are the limitations for investigating the population size of an organism in two different areas using quadrats?

A
  • Difficulty in counting individual organisms in a quadrat due to coverage by other species
    Solution: Use a pencil or stick to gently move leaves aside for better visibility
  • Identifying species may pose challenges
    Solution: Utilize a species key for accurate identification
45
Q

What is the method for investigating the population size of an organism in two different areas using quadrats?

A

1.Lay out 10cm tape measures in your first area- right angles to eachother. This will be your grid
2.Use a calculator to work out random coordinates or use a random number generator.
3.Walk to the position of the first set of coordinates. Placing the quadrat on the ground uniformly
4.Count the number of individuals of that 1 species
5.Repeat 10 times and you calculate a mean
6. Mean no in your quadrat (per m^2 if comparing 2 sites) for entire field: area of field/area of quadrant x mean

46
Q

What is the method for investigating the distribution of organisms in their habitats and measure biodiversity using quadrats?

A

1.Use 2 tape measures to lay out your first survey area (e.g. 10m X 10m)
2.Use a random number generator to create a set of coordinates to place your first quadrat:
E.g. for coordinates 4,5, you would place your quadrat 4m along on the x-axis and 5m along on the y-axis
3.Count the number of different species found within that quadrat
4.Repeat this process until you have collected the data for 10 quadrats
5.Repeat these steps for the second survey area

47
Q

Explain the results of investigating the distribution of organisms in their habitats and measure biodiversity using quadrats

A

-The simplest indicator of biodiversity in this investigation is simply to compare the number of different species found in each survey area
-A higher level of biodiversity would be indicated by a larger number of different species found in that area
-However, this measurement of biodiversity is very simplistic as it doesn’t tell us about the distribution or population size in either survey area
-As with species abundance, the biodiversity is likely to be influenced by biotic factors such as:
–>Competition, Predator-prey relationships, Interactions with other organisms within the food chain or food web
–>Biodiversity will also be influenced by abiotic factors such as:
Light intensity,Mineral availability,Water availability, pH, Temperature, Salinity

48
Q

What are the limitations for investigating the distribution of organisms in their habitats and measure biodiversity using quadrats?

A
  • Difficulty in counting organisms in a quadrat due to coverage by other species
    –>Solution: Use a pencil or stick to move leaves aside for thorough inspection
  • Challenges in species identification or differentiation
    –>Solution: Utilize a species key for accurate identification
49
Q

Design an experiment investigating the distribution of organisms in their habitats and measure biodiversity using quadrats

A

C - changing the study area where we are collecting the data
O - count plant species each time (not animal, fungi etc)
R - Repeat investigation to ensure reliable results
M1 -count the number of different plant species found across all quadrats
M2 - this isn’t really relevant in this scenario
S - Same size of quadrat
Control the random way that the quadrats are placed on the ground
Control the day that the results were collected

50
Q

What is the method for investigating the role of anaerobic respiration by yeast in different conditions?

A

1.Combine yeast with sugar solution in a boiling tube to supply glucose for anaerobic respiration.
2.Add oil layer to prevent oxygen entry, inhibiting aerobic respiration in yeast.
3.Connect the boiling tube to another filled with limewater using a capillary tube.
4.- Submerge the yeast and sugar solution in a water bath at a fixed temperature and count bubbles over a set duration (e.g., 2 minutes).
- Measure carbon dioxide production rate to assess anaerobic respiration, i.e., fermentation rate.
5.Change the temperature of the water bath and repeat

51
Q

Explain the results of investigating the role of anaerobic respiration by yeast in different conditions?

A

-Compare results at different temperatures to find out at which temperature yeast respires fastest
-Higher temperatures increase enzyme activity in yeast, leading to more carbon dioxide bubbles.
-As enzyme activity increases, anaerobic respiration rate rises.
-At high temperatures, enzymes denature, slowing and eventually halting carbon dioxide production.

52
Q

Design an experiment investigating the role of anaerobic respiration by yeast in different conditions

A

C – changing the temperature in each repeat
O – same type (species) of yeast
R – repeat the investigation several times at each temperature to ensure reliable results
M1 – Measure the number of bubbles (of carbon dioxide) produced
M2 – in a set time period (e.g. 2 minutes)
S – Same concentration of sugar solution
Same volume of sugar solution
Same pH of sugar solution
Same mass of yeast added

53
Q

Design an experiment investigating factors affecting rate if diffusion and osmosis (agar cubes)

A

C- The SA:Vol ratio of agar cube
O- Same agar jelly
R- Repeat 3 times for each sliced cube
M1- The length of agar colourless
M2- Over 2 minutes
S1- Same room temperature
S2- Same vol + conc of acid the sugar is placed in

54
Q

Explain the results of investigating the factors affecting rate of diffusion + osmosis (potato)

A

-Osmosis will occur until the WP of the tissue + solution are same, causing a mass change
-If the solution has a high water conc, water will move into the potato chip + mass will increase
-If the solution has a lower water conc, water will move out of the potato chip + mass will decrease
-If there is no change in mass, the conc of solution is the same as the conc of cytoplasm.

Biology (17 decks)

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