CORE PRACTICALS

Question 1

What is the first stage of the membrane permeability practical? (1)

Answer 1

Cut equal sized pieces.

Question 2

What is the second stage of the membrane permeability practical? (1)

Answer 2

Rinse under running water.

Question 3

What is the third stage of the membrane permeability practical? (3)

Answer 3

Place pieces in equal volumes of distilled water:
-use a range of temperatures
-leave for equal time

Question 4

What is the fourth stage of the membrane permeability practical? (1)

Answer 4

Remove pieces carefully and shake each solution gently.

Question 5

What is the fifth stage of the membrane permeability practical? (1)

Answer 5

Asses amount of pigment lose using a calorimeter to measure the absorbance or transmission value of the solution.

Question 6

What is the sixth stage of the membrane permeability practical? (3)

Answer 6

Plot values on graph:
-temperature on the x-axis
-absorbance or transmission on the y-axis

Question 7

Why does stage 1 occur in the membrane permeability practical? (1)

Answer 7

To control the variable of sample sizes.

Question 8

Why does stage 2 occur in the membrane permeability practical? (1)

Answer 8

To remove all betalain (pigment) released by cutting.

Question 9

Why does stage 3 occur in the membrane permeability practical? (1)

Answer 9

Temperature if the independent variable so must be varied but the volume of the distilled water and the time in it need to be kept constant.

Question 10

Why does stage 4 occur in the membrane permeability practical? (1)

Answer 10

To disperse any pigment.

Question 11

Why does stage 5 occur in the membrane permeability practical? (1)

Answer 11

Use of calorimeter ensures the results are quantitative.

Question 12

Why does stage 6 occur in the membrane permeability practical? (1)

Answer 12

To allow the relationship between the two variables to be easily seen.

Question 13

What does little change in a membrane permeability graph indicate? (1)

Answer 13

There is little to no pigment leakage between these temperatures because the lipid layer in the membrane is still intact.

Question 14

What does a sudden change in a membrane permeability graph indicate? (3)

Answer 14

There is a sudden increase in leakage of pigment out of the beetroot pieces. This is probably due to disruption of the membrane as it becomes more fluid at (specified temperature) .denaturation of the membrane protein channels also may play a part.

Question 15

What happens to the phospholipid bilayer when the temperature increases? (2)

Answer 15

As the temperature increases, phospholipids will become more fluid, allowing molecules to leak from the cell, membrane proteins may also change shape.

Question 16

What is the first stage of the observation of mitosis growth practical? (1)

Answer 16

Cut final 5mm of a root tip from a plant such as an onion.

Question 17

What is the second stage of the observation of mitosis growth practical? (1)

Answer 17

Add stain (orcein) and usually an acid.

Question 18

What is the third stage of the observation of mitosis growth practical? (1)

Answer 18

Gently break open on a microscope slide and squash carefully.

Question 19

What is the fourth stage of the observation of mitosis growth practical? (1)

Answer 19

Add more stain and warm, then look at slide on microscope.

Question 20

Why does stage 1 of the observation of mitotic growth occur? (1)

Answer 20

This is where mitosis occurs in the root.

Question 21

Why does stage 2 of the observation of mitotic growth occur? (1)

Answer 21

Stain to ‘highlight’ chromosomes acid is used to separate the individual cells.

Question 22

Why does stage 3 of the observation of mitotic growth occur? (1)

Answer 22

To spread out the cells so the layer is only one cell thick for ease of viewing.

Question 23

Why does stage 4 of the observation of mitotic growth occur? (1)

Answer 23

Warm to intensify the stain, use a microscope because the cells and chromosomes are small.

Question 24

What are the safety precautions of stage 1 of the observation of mitotic growth? (1)

Answer 24

Care when cutting.

Question 25

What are the safety precautions of stage 2 of the observation of mitotic growth? (1)

Answer 25

Eye and skin care with acid and stain.

Question 26

What are the safety precautions of stage 3 of the observation of mitotic growth? (1)

Answer 26

Careful not to break glass slide.

Question 27

What are the safety precautions of stage 4 of the observation of mitotic growth? (1)

Answer 27

Eye and skin care with stain and potential burning due to heat.

Question 28

What are the common stains uses in practicals? (4)

Answer 28

-iodine solution
-ethanoic orcein
-methylene blue
-phloroglucinol

Question 29

STAIN
What is iodine solution used for? (1)

Answer 29

Stains starch blue-black

Question 30

STAIN
what is ethanoic orcein used for? (1)

Answer 30

Stains DNA reddish-purple

Question 31

STAIN
what does methylene blue do? (1)

Answer 31

Stains nuclei and chromosomes blue.

Question 32

STAIN
what does phloroglucinol? (1)

Answer 32

Stains lignin, found in plant cells, red.

Question 33

What is the first stage of the light microscope practical? (2)

Answer 33

Carry a microscope from the storage area to your bench, use both hands, one supporting the base and the other holding the arm of the microscope.

Question 34

What is the second stage of the light microscope practical? (2)

Answer 34

Place the microscope on the bench so that it is flat and so that it is far away from the edge to reduce risk of it falling off. Adjust seating so that you can see it comfortably.

Question 35

What is the third stage of the light microscope practical? (2)

Answer 35

Ensure the built in lamp is set at its minimum setting before plugging in the power cable. Then adjust the lamp to about two-thirds of maximum setting.

Question 36

What is the fourth stage of the light microscope practical? (1)

Answer 36

Select a low-power objective lens by rotating the nosepiece.

Question 37

What is the fifth stage of the light microscope practical? (2)

Answer 37

Put the slide onto the stage so that the coverslip if facing upwards and the specimen is located centrally below the objective lens.

Question 38

What is the sixth stage of the light microscope practical? (2)

Answer 38

View the specimen by looking down the eyepiece lens, focus the image of the specimen, first using the course focus control and then the fine focus control.

Question 39

What is the seventh stage of the light microscope practical? (2)

Answer 39

Focus the condenser by placing a sharp object such as a mounted needle on the centre of the light source. Adjust the condenser until the sharp object are in focus together.

Question 40

What is the equation for magnification? (1)

Answer 40

Size of image / size of specimen