CORE PRACTICAL 3

Question 1

what is core practical 3? (1)

Answer 1

making a temporary squash preparation of a root tip to investigate the stages of mitosis under a microscope.

Question 2

what is the first step to this practical? (1)

Answer 2

the roots, when harvested, must be no longer than 1cm and must still be growing. the roots will therefore still have lots of dividing cells in a meristem region.

Question 3

what is the second step of this practical? (2)

Answer 3

fill a small bottle with 1M hydrochloric acid and place it in a thermostatically controlled water bath at 55 degrees. leave the bottle for 15 minutes, so that the acid warms to the temperature of the water bath.

Question 4

what is the third step of this practical? (2)

Answer 4

place a garlic clove in the bottle, so that the roots are submerged in the 55 degree hydrochloric acid. leave the roots in the acid for 5 minutes.

Question 5

what is the fourth step of this practical? (1)

Answer 5

when the garlic clove has been in the acid for 5 minutes, take it out and rinse the roots thoroughly in tap water.

Question 6

what is the fifth stage of this practical? (2)

Answer 6

label a small bottle or vial include a hazard warning. place a pin prick hole in the bottles cap to prevent thee lid from popping off when the vial is heated. place a small volume of the stain in the vial.

Question 7

what is the sixth stage of this practical? (2)

Answer 7

use a pair of sharp scissors on the garlic clove to cut off the root tips so they fall or can be placed in the acetic ocean use the scissors to make sure the root tips are immersed in stain. place the lid on the vial and place in the water bath for 5 minutes.

Question 8

what is the seventh step of this practical? (2)

Answer 8

use forceps to take them out of the stain and place them on a microscope slide. add a drop of water to the slide, tease the root tip apart with a needle to spread out cells and place a cover slip on top.

Question 9

what is the eighth step of this practical? (1)

Answer 9

place the slide on the stage after removing any excess stain with a paper towel, view the slide under the microscope under the high objective lens.

Question 10

why is the meristem pulled apart by a needle? (1)

Answer 10

squashing the root spreads out the cells so that there is a simple thin layer to be seen under the microscope.

Question 11

why must the cells be placed in hydrochloric acid? (1)

Answer 11

heating the root tips in hydrochloric acid increases the permeability of the cell, allowing the stain to penetrate it more easily.