Biology A-Level Practicals

1. make two ____ samples

take 2 flat bottomed tubes and add 5cm^3 ____ ____ to each

add 5cm^3 distilled water to one tube to indicate the ____ of enzyme activity

add 5cm^3 distilled water to the other to indicate the colour of a completely ____ sample

2. take 3 test tubes and measure 5cm^3 milk into each and stand in a water bath at 10 degrees C for 5 minutes to ____

3. add 5cm^3 ____ to each tube simultaneously and start the timer

this enzyme hydrolyses the ____ protein in milk, which, when hydrolysed, decolorises the milk

4. record ____ taken for the milk samples to become colourless

5. repeat steps 2 to 4 at ____ of 20, 30, 40 and 50 degrees C

6. find the mean time for the milk to be hydrolysed. rate of reaction = 1/____

1. heat standard hydrochloric acid solution in a ____ ____ at 60 degrees C

2. cut a small sample of the root tip using a ____

3. transfer root tip to the HCl and ____ for 5 minutes

4. remove from acid, wash sample in cold ____ ____, and remove the tip using a scalpel

5. place the tip on a microscope ____

6. add a few drops of a stain such as ____ ____

the stain makes the chromosomes visible and therefore shows which cells are undergoing ____

7. lower the ____ ____ down onto the slide

make sure there are no ____ ____ to interfere with the clarity of the image

ensure the cover slip does not slip sideways as this could damage the ____

8. place under a microscope and set the ____ lens to the lowest magnification

9. focus using the coarse and fine ____ ____

1. make a series of ____ of 1M sucrose solution at 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0M

2. measure 5cm^3 of each dilution into separate ____ ____

3. use a ____ ____ to cut out six potato chips

4. use a ____ to cut them to identical lengths using a scalpel

5. take the ____ of each chip using a balance

6. place each chip in a ____ test tube and leave for 20 minutes

7. remove each potato, pat ____ using a paper towel, and take the final masses

8. calculate ____ change in mass for each chip

9. plot a graph of percentage change in mass against ____ concentration

the point at which the line of best fit intercepts the x axis is the point where the solution is ____ to the potato

1. cut beetroot into 6 identical cubes using a ____

2. rinse to clean off any ____ released by cutting

3. place the cubes in test tubes containing an equal volume each of ____ ____

4. place each test tube in a ____ ____ at 20, 30, 40, 50, 60, 70 and 80 degrees and leave for 20 minutes

5. set the colorimeter to the filter with the highest ____ (yellow/orange range)

6. zero with a ____ of distilled water

7. filter each sample into a cuvette using ____ paper

8. measure the absorbance for each solution. a higher absorbance indicates higher pigment ____

higher pigment concentration indicates a more ____ membrane

as temperature increases, permeability increases because membrane proteins ____

this creates gaps for the ____ molecules to pass through

at low temperatures, the ____ have little energy and are closely packed causing low permeability

1. wipe down surfaces with ____ cleaner

2. set up a Bunsen burner in the work space to create a ____ current to draw microbes away from the culture

3. unscrew the bottle and flame the ____

4. use a sterile pipette or ____ ____ to transfer bacteria from the broth to the agar plate

5. use sterile forceps to place a multi-disc ____ ring on the plate

6. lightly tape a lid on, invert, and ____ at 25 degrees C for 48 hours

ensure the lid is not taped around the entire dish as this prevents ____ entering and promotes growth of harmful anaerobic bacteria

7. ____ equipment and disinfect work surfaces

the ____ ____ ____ is where bacteria did not grow

1. draw a ____ line about 1cm from the bottom of the chromatography paper

2. cut a section of leaf and place it in a ____

3. add 20 drops of ____

4. use the ____ to grind up the leaf sample to release the pigments

5. use a ____ ____ to extract some of pigment and plot it onto the centre of the baseline

6. suspend the paper in the ____ so that the level of liquid lies below the pencil line

7. leave until the solvent has run up the paper near to the top, at which point remove and mark the ____ ____

8. calculate the ____ value for each separated spot

9. compare the ____ values to a database

1. remove ____ from leaf samples

2. ____ using a pestle and mortar

3. place into a chilled ____ ____

4. use a ____ ____ and funnel to filter the sample into a beaker

5. suspend the beaker in an ____ ____ to keep the sample chilled

6. transfer to ____ tubes and ____ at a high speed for 10 minutes to separate chloroplasts into the pellet

7. remove supernatant and add pellet to the fresh ____ ____ which should be stored on ice

8. set colorimeter to red filter and zero using a cuvette containing chloroplast extract and ____ ____

9. place test tube in the rack 30cm from light source and add ____

10. immediately take a sample and measure ____. repeat every 2 minutes for 10 minutes

11. repeat for different distances from the lamp to vary the ____ ____

this experiment should be done in a ____ room

ensure the ____ is constant because samples very close to the lamp may have an increase

plot a graph of absorbance against time for each ____ from the light

as light intensity decreases, rate of photosynthesis decreases because of slower ____

hence the DCPIP accepts less electrons so takes long to turn from blue to ____

therefore, a higher absorbance indicates a ____ rate

1. set up ____ ____ at a range of temperatures

2. add 5cm^3 yeast and 5cm^3 glucose in ____ solution to three test tubes per temperature

3. place them in the water bath and leave them for 10 minutes to ____

4. add 2cm^3 ____ ____ to the test tubes and start the timer

5. ____ for 10 seconds and return to water baths

6. record time taken to turn _____

7. find the mean of the results for each temperature and calculate average rate of respiration as 1/____

1. set up a ____ ____ to have 4 quadrants: high/low light intensity and high/low humidity

2. use dark ____ to block out the light on one half

3. use wet paper towel to make ____ areas and a drying agent to make dry ones

4. place 10 ____ in the centre of the choice chamber using a spoon

5. leave for 10 minutes and record how many are in each ____

6. repeat several times and use the ____ ____ test to determine significance

1. create a ____ ____ of glucose from concentrations 0 to 10 mmol dm^-3

2. add 2cm^3 of each of the known samples to separate boiling tubes and add 2cm^3 ____ solution

3. place boiling tubes in a ____ ____ at 90C for 4 minutes

4. use ____ to remove the boiling tubes and leave to cool

5. use colorimetry to determine ____. use the red filter. glucose concentration will be directly proportional to ____

6. plot a ____ ____ of concentration against absorbance

7. repeat with the urine sample and use the calibration curve to determine its ____ concentration

1. choose a 5x5m area to take ____ from

2. use a ____ ____ ____ to generate 10 sets of random coordinates

3. use two tape measures to create a set of ____ off which coordinates can be read

4. place the ____ at each of the coordinates, placing the bottom left corner on the coordinate each time

5. record ____ ____ of the chosen species

6. measure the ____ ____

e.g. for light intensity, use a ____ to take a reading