Science C Unit Flashcards
(108 cards)
who were the Dutch lens-makers, Hans and Zacharias Janssen?
they invented the first compound microscope in about 1595, using a two-lens system of an eyepiece (ocular lens) and an objective lens. Because it made use of more than one lens, it was called a “compound” microscope. Magnification of this first microscope was about 20x and was significant because it extended the reach of the human eye.
Englishman Robert Hooke developed what kind of microscope?
A three-lens microscope. Is credited with using
the term “cell” to describe empty chambers observed in cork.
Anton van Leeuwenhoek, a Dutch businessman,
developed
Lenses that allowed for greater magnification; up to 250x. Under this magnification, he was the first to see the movement of single-celled organisms as small as
bacteria.
Diaphragm
Allows for control of how much light passes through the specimen. A disk found under the stage.
Base
Provides support for the parts of the microscope, foundation of the microscope, bottom portion of microscope.
Ocular lens (or eyepiece)
Type of lens found in the eyepiece, magnifies the image produced by the objective lens (10X).
Low power (Red)
Allows for the largest field of view
Arm
Can be used for carrying the microscope, holds the lenses the proper distance from the specimen
Revolving nosepiece
used to change objective lenses.
High power (Blue)
This setting allows for observation of the most detail
Magnification
Known as the power of the microscope. Total magnification = (eyepiece)(objective)
Low: (10)(4) = 40x
Medium: (10)(10) = 100x
High: (10)(40) = 400x
Magnification can also be calculated by taking a dimension of the image, such as height (hi), and dividing it by the same dimension of the object (ho). (divide diagram size by actual length)
Example: Calculate the magnification power of a microscope if a 1.4 mm long specimen (object = 0) appears to have a length of 46.3 mm (image = i).
(33X)
READ
stage clips
Used to hold the slide in place on the stage.
Course slip
Placed on top of a specimen that is mounted on a slide
Fine focus
Knob on the side of a microscope that allows for small or final adjustments in focus
Coarse Focus or Adjustment Knob
Allows for initial or large changes in focus. Moves the stage up/down.
Stage
Holds the slide/specimen
Objective lenses
Provide various levels of magnification of the specimen
Light Source
Provides light necessary to illuminate the specimen
Field of view = the entire area that you see when
you look through a microscope
You can use view a rule under the microscope to
measure the diameter of the area that you are
viewing; the field of view, however, the accuracy of
this decreases with increased magnification.
The formula below shows the relationship between
field diameter and magnification:
MHFH = MLFL Where: M = magnification H = high power
F = field of view L = low power
Example: If the low power magnification is 4x, and the
field of view diameter is 4.5 mm, what will be the field of
view diameter for a high power magnification of 40x?
Due to the small size of the field of view, sometimes the
unit micrometer is used. 1 mm = 1000 um.
Describe the process of making a wet mount
First, use tweezers to place your specimen on the slide. then, use a dropper to put a small drop of water onto the specimen. lastly, use tweezers to put the coverslip on top of the specimen. if there are bubbles, press down gently on the coverslip a couple of times until the bubbles are gone
Cell Theory
- All living things are made up of one or more cells and the materials produced by these cells.
- All life functions take place in cells, making them the smallest unit of life.
- All cells are produced from pre-existing cells through the process of cell division.
(that living organisms are made up of cells, that they are the basic structural/organizational unit of all organisms, and that all cells come from pre-existing cells.)
describe the process of bringing a sample into focus on a compound microscope
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Function of the cell wall
Found in plants; the cell wall is a rigid frame around the cell that provides strength and support.