Required Practical 2 - Preparation of Stained Root Tip Squash Flashcards

1
Q

Suggest why an optical microscope is used

A

Has a high enough magnification to view chromosomes

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2
Q

Suggest why root tip is gently squashed onto microscope slide

A
  • gently to avoid damage to cells

- thin layer of cells to take up better stain and for light to penetrate easily to clear observation

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3
Q

Suggest why root tip is soaked in hydrochloric acid

A
  • necessary to dissolve middle lamella

- cells spread easily for clear observations

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4
Q

Suggest why root tip is heat treated

A

Allows chromosomes to take a deeper stain

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5
Q

Suggest the purpose of a stain and give an example

A
  • Toluidene/Orcein

- easily identify chromosomes with DNA due to contrast

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6
Q

Suggest why a root tip is used to observe mitosis

A
  • contain meristem tissue

- cells undergo regular mitosis

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7
Q

Suggest why the root tip of onion, garlic or shallot is usually used

A
  • easy to grow in large numbers

- can take up stain and be flattened onto slide

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8
Q

Suggest why it is important the coverslip is not moved side to side

A
  • avoid breaking chromosomes

- avoid overlapping/rolling cells

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9
Q

Suggest why it is sensible to mount both sides of root tip

A
  • easy to confuse ends

- cells behind the meristem elongate and are easier to differentiate under the microscope

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10
Q

Describe how you could make a temporary mount of a piece of plant tissue to observe starch grains using an optical microscope

A
  • cut a thin slice of plant tissue
  • place on a glass side using forceps and add a drop of water
  • add a few drops of iodine (or other appropriate stain)
  • lower coverslip using a mounting needle
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