Topic 3 Practicals Flashcards
Plant tissue culture practical: Which chemicals would you need to add to stimulate the stem cells to specialise?
a growth regulator
Plant tissue culture practical: What other nutrients would you need to provide in the agar? Why?
- Glucose- for respiration to provide ATP
- Magnesium ions- for making chlorophyll for photosynthesis
- Nitrogen ions- for making proteins/DNA for growth
- other mineral ions
Plant tissue culture practical: How would you know if the plant leaf tip was totipotent?
a whole new plant would grow
Plant tissue culture practical: Why would the nutrient agar and leaf tip need to be placed under a light bank?
Plants need light energy absorbed by chlorophyll to photosynthesise to produce glucose, and therefore is needed for cell division and growth via respiration
Plant tissue culture practical: Why would you place a heat shield between the light bank and the agar/leaf tip?
Heat may damage the plant via drying it out or denaturing enzymes, temperature is a control
Plant tissue culture practical: Why would you place he agar/leaf tip in a bottle and cover with cling film rather than a lid?
- plant will release oxygen as it grows
- light must be able to reach the plant, reduces water loss
- for safety
- prevent pathogenic microbes from contaminating bottle
Plant tissue culture practical: Why would you keep everything sterile in this experiment?
- use aseptic technique
- prevent contamination and growth of pathogenic microbes/organisms in the agar that would compete with the plant for nutrients
-may harm the researchers
Plant tissue culture practical: which variables would need to be controlled if you were comparing plant totipotency in a leaf tip in two different plant species?
- agar nutrient make up
- growth regulators used
- growth time
- light intensity
- volume of explant
- temperature
- volume of agar
Plant tissue culture practical: What else would you do to improve the reliability and therefore validity of the experiment?
- grow at least five cultures per plant species
- repeat investigation at least 5 times
Root squash practical: Name the stain used to make the chromosome visible during garlic root squash
- toluidine blue
Root squash practical: Why is acid used during a garlic root squash?
- softens plant tissue to allow for maceration
Root squash practical: Why is the root ‘tip’ used when preparing a garlic root squash?
this is where the meristem is
Root squash practical: Why is the slide heated during a garlic root squash?
to intensify the stain
Root squash practical: how many millimetres of root tip is used to produce a root tip squash to observe mitosis?
3-5mm
Root squash practical: Describe how to carry out a root tip squash
- cut 5mm of root tip
- place in acid to break middle lamella
- place in water for 5 minutes to wash off acid
- Transfer to microscope slide and macerate with a mounted needle, to separate cells in order to obtain a ingle layer of cells
- Stain with toluidine blue
- place coverslip and gently squash
- observe cells under a microscope at 400x
Root squash practical: What are the controls?
- concentration of HCl used
- time in HCL
- plant source
Root squash practical: What are the safety risks and the precautions that should be taken?
- risk of cutting with scalpel, cut away from you
- skin/eye damage from HCL and stain, wear lab coat/safety goggles/gloves
- coverslip may break and cut skin, press down on coverslip with towels
Root squash practical: What is the equation for mitotic index?
mitotic index= number of cells with visible chromosomes/ total number of cells in the field of view
Root squash practical: What is the field of view?
the number of cells you can see/count
