RP 1-6 Flashcards

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1
Q

What is the aim of RP1?

A

Factor affecting the rate if enzyme controlled reactions

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2
Q

What are the control variables in RP1?

A

Controlling all other factors that don’t include the one you are investigating
- Temperature, pH, Enzyme concentration, substrate concentration, conc of inhibitors

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3
Q

In RP1, a student controlled the temperature. State two other variables that the should have controlled

A

Concentration of amylase and pH

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4
Q

Describe how the temperature could have been monitored - RP1

A

The use of a thermometer in a water bath and check the temperature every 10 minutes to make sure it remains constant

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5
Q

The student maintained the temperature at 30 degrees, why may it be faster at 40 degrees - RP1

A

The starch and amylase have more kinetic energy at higher temperatures so there are more successful collisions and so more E-S complexes will be formed

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6
Q

The student took samples until the blue-black colour no longer appeared. How would the student ensure it remained consistent - RP1

A

She could have compared the colour of each sample to the colour of the reaction mixture that has gone to completion and been tested with iodine solution

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7
Q

The student concluded that the optimum ph was 5, explain why this may not be valid? - RP1

A

The student needs to repeat the experiment using smaller intermediary values. This may include pH 4 to pH 6

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8
Q

What is the aim of RP2?

A

Preparing and observing a root tip squash

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9
Q

How do you calculate the mitotic index?

A

Number of cells undergoing mitosis/Total number of cells

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10
Q

What are the control variables - RP2

A
  • The same root tip being use
  • The same age root tip
  • The same length of root tip
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11
Q

How to use a microscope - RP2

A
  • Select the smallest objective lens
  • Place your slide on the stage
  • Use the coarse focus to either raise the stage or lower the lense
  • Look through the eyepiece lens
    Adjust with fine focus
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12
Q

How to calibrate the eyepiece graticule?

A
  • Place a stage micrometer on the stage of a microscope
  • Align the scales of the eyepiece graticule and determine how many eyepiece graticules go into one stage micrometre
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13
Q

Explain why the student added a drop of stain - RP2

A

The stain binds to the chromosomes, so the become visible

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14
Q

Explain why the cover slip was pressed down firmly - RP2

A

To squash the root tip into a thin layer so that the light could pass through the sample

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15
Q

Explain why the student handled the hydrochloric acid with caution - RP2

A

Highly concentrated which can be highly corrosive

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16
Q

What is the aim of RP3?

A

Using a calibration curve to estimate the water potential

17
Q

What are the control variables - RP3?

A
  • Temperature
  • Source of the plant tissue
  • Size and shape of the plant tissue
  • Batch of stock solution
  • Length of time the plant tissue is immersed in the solution
18
Q

Suggest why the student removed the ‘skin’ of the potato? - Rp3

A

The skin is a different tissue from the rest of the potato and so has a different water potential

19
Q

Why did the student use potato chips from the same potato? - RP3

A

If the potato chips are from the same potato, all the cells will have the same water potential

20
Q

Suggest why the student processed her data to find the percentage change in mass - RP3?

A

The initial mass of the potato chips was different, so working out the percentage change would allow her to make a valid comparison

21
Q

Explain how the student could use her processed data to find the water potential - RP3

A
  1. Plot a graph with concentration on the x-axis and percentage change in mass on the y-axis
  2. Find concentration where curve crosses the x-axis / where percentage change is zero
  3. Use (another) resource to find water potential of sucrose concentration (where curve crosses x-axis)
22
Q

What is the aim of RP4?

A

Factors affecting the membrane permeability

23
Q

What are the control variables in RP4?

A
  • Source of the plant
  • Time in the solution
  • Size and shape of the plant tissue
24
Q

What are the 2 measures to determine the permeability of a membrane?

A
  • Producing colour standards
  • Colorimeter
25
Q

Suggest how the increase in temperature of the water caused the release of the red pigment

A
  1. Proteins in membrane will denature
  2. Phospholipid are damaged or melt
26
Q

Why did the student put the beetroot in distilled water after cutting them? RP4

A
  • This is so that the pigment from the beetroot is released into the distilled water due to the effect of temperature changing the permeability
27
Q

Why were the test tubes of distilled water left in the water bath for 5 minutes before adding the beetroot - RP4

A

Allows the water to equilibrate

28
Q

Why did the student shake the test tubes every 5 minutes? - RP4

A
  • This is to maintain the diffusion gradient for the pigment to pass out of the cells and into the distilled water
29
Q

Why did the student use fresh beetroot instead of cooked beetroot? - RP4

A

Cooking would involve the beetroot to be heated to high temperatures that would denature the proteins in the plasma membrane and allow the pigment to leak out

30
Q

What is the aim for RP5?

A

Dissection of an organ or system from an animal orplant

31
Q

What are rules of biological drawing? - RP5

A
  • Use a sharp pencil
  • Do not shade or use colour
  • Do not sketch
  • Label the structures
32
Q

What are some safety precautions when dissecting an organ?

A
  • Disinfect surfaces before and after
  • Wear gloves/apron
  • Scalpel should be faced down when carried and not near the edges of the table
33
Q

Describe how a student could prepare a piece of lower epidermis to observe on an optical microscope?

A
  • Take a clean glass slide and add one drop of water to the centre
  • Peel off the lower epidermis which is a thin as it is a single layer of cells
  • Place the cover slide at a 45degree angle and gently lower using a mounted needle
34
Q

What is the aim of RP6?

A

Using aseptic techniques to investigate the effect of antimicrobials

35
Q

What are the examples of aseptic techniques? - RP6

A
  • Disinfecting work surfaces
  • Wearing gloves and goggles
  • Having a lit bunsen burner
  • Flaming culture bottlenecks to prevent contamination
  • Use a sterile pipette
36
Q

Give one reason why the student used aseptic techniques - RP6

A

The technique minimises the risk of bacteria from air contaminating the agar plate

37
Q

The student incubated the agar plates at 25degrees. Suggest one reason why she didn’t incubate them at a higher temperature? - RP6

A

A higher temperature could be closer to the optimum temperature for bacteria that causes human disease. This would be dangerous for the student

38
Q

Why do you transfer same volume of liquid of culture onto agar plate

A

Same number of bacteria to allow for comparison

39
Q

Explain the purpose of boiling the agar

A

Avoid contimination of other bacteria