CramX Logo
RegisterLog in
Back to FlashcardsBiology / 3.3: Microscope Measurements and Required Practical

3.3: Microscope Measurements and Required Practical

Biology10 CardsCreated 9 months ago

This deck covers key concepts related to microscope measurements and practical laboratory techniques, including the use of eyepiece graticules, calibration, and methods for calculating the mitotic index.

Report

What is an eyepiece graticule?

An glass disc that is placed in the eyepiece of a microscope. A scale is etched on the glass disc.

Rate to track your progress ✦

Tap or swipe ↕ to flip
Swipe ←→Navigate
1/10

Key Terms

Term
Definition
What is an eyepiece graticule?
An glass disc that is placed in the eyepiece of a microscope. A scale is etched on the glass disc.
Why can’t the scale be directly used to measure the size of objects under an objective lens?
Because each objective lens will magnify to a different degree
How do you calibrate the eyepiece graticule?
Use a stage micrometer

Describe a method to calculate the mitotic index of cells

1. Heat 1 mol dm​-3 H​ Cl at ​60​​°C​​ in a water bath.
2. C​ut a small sample of the ​root tip​​ using a ​scalpel​​.
3. Transfer root tip to...

What is the equation for mitotic index?
Mitotic index=number of cells with visible chromosomes÷total number of cells in sample
Why do cells need to be taken from the root tip?
Because this is the region of cells undergoing mitosis

Related Flashcard Decks

Biology

Purpose of Mitosis

This deck covers the fundamental concepts of mitosis, including its purpose, reasons for cell division, and related biological processes.

5 cards
View Deck
Biology

BIOL1020 - Lecture 7 - Cellular Energy Generation and Photosynthesis

This deck covers key concepts from cellular respiration and photosynthesis, including equations, processes, and differences between the two systems.

19 cards
View Deck
Biology

Biology NEET - XI: Chapter 11- Transport in Plants Part 2

This deck covers key concepts from Chapter 11 of the NEET Biology syllabus, focusing on transport mechanisms in plants, including diffusion, osmosis, and transpiration.

20 cards
View Deck
Biology

Biology - Chapter 8.1 - Outline of the Nervous System Part 2

A flashcard deck covering key concepts from Chapter 8.1, including cranial nerves, meninges, glial cells, neurons, and related diseases.

14 cards
View Deck
Biology

Chapter 14 Lipids Part 2

A set of flashcards covering important concepts related to lipids, including types of lipids, their structures, and their functions in cell membranes.

14 cards
View Deck
Biology

OCR Biology A - 2.1.4 - Enzymes Part 1

This deck covers key concepts about enzymes, including their properties, mechanisms, and roles in biological processes. It includes definitions, hypotheses, and examples of enzyme regulation and inhibition.

20 cards
View Deck
Biology

Photosynthesis and Cellular Respiration

This deck covers key concepts of photosynthesis and cellular respiration, including their purposes, reactants, products, and how they interrelate to support life.

18 cards
View Deck
Biology

Calvin Cycle

A deck of flashcards covering the key concepts of the Calvin Cycle, including its location, phases, and associated enzymes.

5 cards
View Deck
Biology

Mastering Biology: Nucleic Acids Part 1

This deck covers fundamental concepts about nucleic acids, including nucleotide structure, DNA and RNA differences, and nucleic acid polymerization.

15 cards
View Deck
3.3: Microscope Measurements and Required Practical
TermDefinition
What is an eyepiece graticule?
An glass disc that is placed in the eyepiece of a microscope. A scale is etched on the glass disc.
Why can’t the scale be directly used to measure the size of objects under an objective lens?
Because each objective lens will magnify to a different degree
How do you calibrate the eyepiece graticule?
Use a stage micrometer

Describe a method to calculate the mitotic index of cells

1. Heat 1 mol dm​-3 H​ Cl at ​60​​°C​​ in a water bath.
2. C​ut a small sample of the ​root tip​​ using a ​scalpel​​.
3. Transfer root tip to ​HCl​​ and ​incubate​​ for 5 minutes.
4. Remove from HCl and wash sample in cold distilled water and ​remove the very
tip ​​using a scalpel.
5. Place tip on a microscope slide and add a few drops of ​stain​​
This makes the ​chromosomes visible​​ and will therefore show which cells
are undergoing mitosis.
6. Lower the cover slip down carefully onto the slide. Make sure there are ​no air
bubbles ​​in the slide which may distort the image, and that the​ coverslip doesn’t
slide sideways which could damage the chromosomes.
7. Place under a microscope and set the ​objective lens​​ ​​on the lowest
magnification.
8. Use the ​coarse adjustment knob​​ ​​to move the lens down to just above the slide.
9. Use the ​fine adjustment knob​​ ​​to carefully re-adjust the focus until the image is clear​​
10. To calculate ​mitotic index​​, ​​cells ​undergoing mitosis​​ must be counted (cells with ​chromosomes visible​​), as well as the​ total number of cells​​.

What is the equation for mitotic index?
Mitotic index=number of cells with visible chromosomes÷total number of cells in sample
Why do cells need to be taken from the root tip?
Because this is the region of cells undergoing mitosis
Why does the root tip need to be firmly squashed?
In order to get a thin layer of cells which light can pass through
Why was a stain used?
To make chromosomes visible
Why were the root tips placed in hydrochloric acid?
In order to soften the tissues and separate the cells
Why were the root tips heated at 60 degrees for 5 mins
To increase the kinetic energy of the molecules, increasing the rate of reaction with the acid, denaturing proteins, softening cells and stopping mitosis