collection methods

Question 1

investigating how size of jelly cubes(cm) affects rate of exchange

Answer 1

1.There will be two groups an experimental group and a control group

2. In the experimental group the size of the cube will be changed by using phenolphthalein agar jelly cubes with different side lengths (0.1 cm, 0.25 cm, 0.50 cm, and 1.00 cm) ana 2.00cm

3.Add the phenolphthalein agar jelly cube with a side length of 0.1 cm to a beaker.

4. Add 50cm³ of hydrochloric acid to the beaker
5. The rate of diffusion will be measured by counting the time taken (seconds) for the cube to turn from pink to colourless
6. All other variables will be kept the same e.g. concentration of phenolphthalein, concentration of hydrochloric acid

7.Repeat the above for the other cube sizes

8. For the control group repeat the above but with no hydrochloric acid
9. Repeat the experiment many times
10. If the cube with the smallest side length (0.1cm) has the most efficient exchange, then it will take the quickest time to turn from pink to colourless.

Question 2

how to view mitosis in garlic/onion root tips

Answer 2

1. The root tips have been grown and placed into fixative solution prior to class (min. 2h fixation).
2. Remove 2-3 roots from the fixative with forceps. If necessary, use a razor blade cut off the 1-1.5 cm end portion (the pointy growing root tip) and discard the rest [make sure you choose the growing end of the root, not the portion that was closer to the garlic clove].
3. Place the root tips on a glass slide with 4-5 drops of 1M HCI (enough to cover them).
4. Place the slide with root tips in acid at 60°C for 2 min [it is important that the solution does not boil or dry out; add more HCI if it is drying].
5. Add 2 drops of aceto-orcein stain (or Toluidine blue stain) to the root tips. Sit for 1min to allow the stain to penetrate the tissue. (you may need to remove excess HCI or transfer the root tips to a new slide)
6. Place a coverslip over the roots. Fold a small piece of tissue paper to about the size of the coverslip, then, with the tissue paper over the coverslip, gently and evenly press down with a finger or thumb to squash the roots.
7. View under low power to see if you have cells from the actively growing area of the root tip. The dividing garlic root cells are usually cuboidal (squarish in shape) with many large obvious nuclei. If the cells are elongated (long rectangles) you have cells from too far back in the root that are no longer dividing.

Question 3

why use the garlic root tip?

Answer 3

site where the most growth –> most mitosis

Question 4

why squash the sample?

Answer 4

allow thin sample so light can easily pass through

Question 5

why stain the sample?

Answer 5

makes chromosomes more visible

Question 6

investigating effect of light intensity on photosynthesis

Answer 6

1. There will be two groups, an experimental group and a control group
2. In the experimental group light intensity will be changed by using a globe set at different distances from the beaker (0, 10, 20, 30, 50 cm)
3. Add 100mL of water to a beaker
4. Add 50mL of water into a boiling tube
5. Add 1/2 teaspoon of hydrogen carbonate powder to the boiling tube
6. Add 1 piece of pondweed (stem facing up) to the boiling tube with a paperclip attached to weigh it down
7. Cut the stem of the pondweed on an angle whilst it is underwater
8. Add globe 0cm away from beaker
9. The rate of photosynthesis will be measured by recording the number of oxygen bubbles produced every minute for 3 minutes
10. All other variables will be kept the same e.g. species of plant, wattage of globe
11. Repeat the above for the other distances
12. For the control group repeat the above but with no light
13. Repeat the experiment many times (we will only be doing the experiment once due to time constraints)
14. If………………then

Question 7

Investigating effect of temperature on anaerobic cellular respiration

Answer 7

1. There will be two groups, an experimental group and a control group
2. In the experimental group temperature will be changed by using water baths set to 20°C, 30°C, 40°C, 50°C and 60°C
3. Add 30mL of warm water to a conical flask
4. Add 1 tbsp of yeast to the conical flask
5. Add 2 tbsp of flour to the conical flask
6. Add 1 tbsp of glucose to the conical flask
7. Add a delivery tube and connect the other end to an inverted measuring cylinder in water
8. The rate of anaerobic respiration will be measured by recording the volume of carbon dioxide gas produced after 3 minutes.
9. All other variables will be kept the same e.g. volume of water, mass of yeast
10. Repeat the above for the other temperatures
11. For the control group repeat the above but with no yeast
12. Repeat the experiment many times (we will be using class data)
13. If ____ then ___

Question 8

Investigating effect of ribena concentration on rate of osmosis * can change for temperature on rate of diffusion using colourimeter

Answer 8

1. There will be two groups, a control group and an experimental group
2. The concentration will be changed by using different concentrations of ribena-water solution(20%, 40%, 60%, 80%, 100%)
3. Label 6 boiling tubes with the concentrations of Ribena you will use.
4. Measure out Ribena for the dilutions using the volumes shown into a test tube.
5. Measure out water using the volumes shown in and add these to the test tube.
6. Gently shake the boiling tubes to make sure the solution is mixed
7. Collect a potato and cut of 6 bores using the cork borer.
8. Trim any external skin, and using a ruler and a scalpel cut into a 3cm cylinder.
9. Dry the potato cylinders on a paper towel.
10. The rate of osmosis will be measured by weighing the new volume of the potato cylinders and calculating the difference in mass(g) after 24 hours.
11. repeat above for other ribena-water solution concentrations( 40%, 60%, 80%, 100%)
12. for the control group, repeat but with no ribena
13. repeat experiment many times
14. If ___ then ___

Question 9

colourimeter

Answer 9

more pigment(leaked out of cell = more pigment diffuses out bc higher permeability) –> more light absorbed –> less light gets through
less pigment –? less light absorbed –> more light gets through

Question 10

hypothesis scaffold

Answer 10

IF iv THEN dv

Question 11

investigating how temperature affects lipase activity

Answer 11

1. There will be two groups an experimental and control group
2. In the experimental group temperature will be changed by using water baths set to 20, 30 and 40 and 50°C
3. Add 5 drops of phenolphthalein to a labelled test tube.
4. Add 5cm3 of milk to the test tube
5. Add 7cm3 of sodium carbonate to the test tube
6. Add to 20°C water bath for 5 minutes
7. Add 2cm3 of lipase, keeping the test tube in the water bath
8. The rate of lipase activity will be measured by recording the time taken for the solution to turn white (s)
9. All other variables will be kept the same e.g. concentration of phenolphthalein
10. Repeat the above for the other temperatures
11. For the control group repeat the above but with no lipase
12. Repeat the experiment many times (we will use class data)
13. If ______ then _________–