Botany Lab Practical 1

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Questions and Answers

How many layers of cells are there in the Elodea leaf?

Two layers thick.

How should a coverslip be applied to a drop of water on a microscope slide?

Dip one edge in the water drop and then lower the rest of the coverslip.

What parts of cells are normally visible with the aid of a compound light microscope?

Cell wall, middle lamella, chloroplasts, chromoplasts, amyloplasts, central vacuole, and nucleus.

When chloroplasts appear to be moving within a living cell, what is the cause of their movement called?

<p>Cytoplasmic streaming (cycosis).</p> Signup and view all the answers

Where is the cytoplasm located in most living cells, such as those of Elodea?

<p>Surrounds membrane-bound organelles and is contained within the cell wall and plasma membrane.</p> Signup and view all the answers

If present in a cell, where are anthocyanin pigments located?

<p>Within the central vacuole.</p> Signup and view all the answers

How does the chromoplast differ from the chloroplast?

<p>Chloroplasts contain chlorophyll and carry out photosynthesis, while chromoplasts do not.</p> Signup and view all the answers

In what region of a cell are chloroplasts located?

<p>Towards the cell wall.</p> Signup and view all the answers

If you could see it, where would you look for the nucleus in the Elodea leaf?

<p>Against the plasma membrane, next to the cell wall.</p> Signup and view all the answers

How would you distinguish a starch grain from a chloroplast?

<p>Starch grains are colorless while chloroplasts are green.</p> Signup and view all the answers

Where would you expect to find a nucleolus?

<p>Within the nucleus.</p> Signup and view all the answers

Why should only lens paper be used to clean microscope lenses?

<p>Because the lenses scratch easily.</p> Signup and view all the answers

What is the function of the condenser?

<p>To concentrate light in the plane in which you are viewing the object.</p> Signup and view all the answers

What is resolution?

<p>The capacity to separate tiny, close objects.</p> Signup and view all the answers

Where should an adjustable condenser be set for maximum resolution?

<p>Turn knob so the top lens is as close to the stage as possible, then back it off no more than a millimeter.</p> Signup and view all the answers

What is the function of the iris diaphragm?

<p>Regulates the amount of light that passes through an object.</p> Signup and view all the answers

What happens to light intensity when increasing magnification?

<p>Light intensity decreases.</p> Signup and view all the answers

What happens to the actual amount of field visible when magnification is increased?

<p>The field of vision does not change, but the size of the objects changes.</p> Signup and view all the answers

Calculate the magnification of the lens system for the dissecting microscope at the zoom setting of 0.7.

<p>7x</p> Signup and view all the answers

Calculate the magnification of the lens system for the dissecting microscope at the zoom setting of 1.5.

<p>15x</p> Signup and view all the answers

Calculate the magnification of the lens system for the dissecting microscope at the zoom setting of 3.0.

<p>30x</p> Signup and view all the answers

Calculate the magnification of the lens system for the compound microscope while using scanning power.

<p>40x</p> Signup and view all the answers

Calculate the magnification of the lens system for the compound microscope while using low power.

<p>100x</p> Signup and view all the answers

Calculate the magnification of the lens system for the compound microscope while using high power.

<p>400x</p> Signup and view all the answers

What is the function of the interpupillary adjustment on the dissecting microscope?

<p>Allows different individuals to use the same microscope with varying eye distances.</p> Signup and view all the answers

Flashcards

Elodea leaf structure

Two layers of cells that provide structural support.

Cytoplasm

Gel-like substance within the cell, containing organelles.

Central vacuole

Large organelle that Stores waste and regulates turgor pressure.

Anthocyanin pigments

Pigments found in the central vacuole of plant cells.

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Chloroplast location

Organelles near the cell wall because of central vacuole pressure.

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Chromoplasts

Organelles lacking chlorophyll and do not perform photosynthesis.

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Avoid bubbles

Lower the coverslip at an angle to prevent this.

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Compound light microscope

Use this type of microscope to view cell wall, chloroplasts, and nucleus.

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Resolution

The ability to distinguish between two close objects.

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Iris diaphragm

Controls the amount of light reaching the specimen.

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Light intensity

Microscope setting that decreases with increased magnification.

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Nucleus location

Located next to the plasma membrane and near the cell wall.

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Starch grains

Cell components that are colorless compared to chloroplasts.

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Lens paper

Use only this to clean microscope lenses.

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Interpupillary adjustment

Accommodates different user eye distances.

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Study Notes

Elodea Cell Structure

  • Elodea leaves consist of two layers of cells, providing structural density.
  • Cytoplasm is gel-like, surrounding organelles within the plasma membrane and cell wall.
  • Central vacuole is large, storing waste and regulating turgor pressure in plant cells.
  • Anthocyanin pigments, if present, are located in the central vacuole.

Chloroplasts and Chromoplasts

  • Chloroplasts are typically located near the cell wall due to pressure from the central vacuole.
  • Chromoplasts lack chlorophyll and do not perform photosynthesis, unlike chloroplasts which do contain chlorophyll.

Microscopy Techniques

  • A coverslip should be applied by first dipping one edge into the water and then lowering it to avoid bubbles.
  • For viewing cell structures, a compound light microscope reveals components such as the cell wall, chloroplasts, and possibly the nucleus.
  • Resolution refers to the ability to distinguish close objects; the condenser should be set for maximum resolution and adjusted closely to the stage but not touching.

Microscope Features

  • The iris diaphragm controls the amount of light reaching the specimen.
  • Light intensity changes inversely with magnification: it decreases with increased magnification and increases with reduced magnification.
  • As magnification increases, the size of the objects changes, but the actual field of vision remains constant.

Nucleus and Starch Grains

  • The nucleus in an Elodea leaf cell can be found adjacent to the plasma membrane and near the cell wall.
  • Starch grains appear colorless compared to the green of chloroplasts, and they can be larger than chloroplasts depending on storage.

Microscope Maintenance

  • Only lens paper should be used to clean microscope lenses to avoid scratching the delicate surfaces.

Microscopy Magnification Calculations

  • Dissecting microscope magnifications are calculated by multiplying the zoom knob setting by 10x, yielding:
    • 0.7 = 7x
    • 1.5 = 15x
    • 3.0 = 30x
  • For compound microscopes, magnifications are:
    • Scanning (Red): 40x
    • Low Power (Yellow): 100x
    • High Power (Blue): 400x

Interpupillary Adjustment

  • The interpupillary adjustment on a dissecting microscope accommodates different user eye distances for comfortable viewing.

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