C1.0

Question 1

what did Robert Hooke do?

Answer 1

improved on the Janssen’s design by:

1) adding a third lens
2) adding a light to illuminate the objects

Question 2

what did Antoni van Leeuwenhoek do?

Answer 2

first person to discover the movement of living single-called organisms
microscope only had a single lens (simple microscope)
high quality lenses which allowed him to magnify objects up to 250X

Question 3

what is magnification?

Answer 3

how many times larger the image is compared to the original

Question 4

what is field of view?

Answer 4

the area that can be seen through the microscope with a particular objective lens

Question 5

what is scale?

Answer 5

a comparison between the size of a drawing and the actual size of the object

Question 6

what did galileo do?

Answer 6

imprisoned in 1630’s by the Catholic Church for claiming that the earth revolved around the sun

Question 7

what is spontaneous generation?

Answer 7

the belief that living things can emerge from non living matter

Question 8

Francisco Redi

Answer 8

Set up an experiment to illustrate that maggots did not grow spontaneously out of raw meat.
he set out two flasks:
1) one with access to air
2) one without access to air
only the flask open to air ( & flies ) had evidence of maggots
• proved that air was a necessary ingredient in life force

Question 9

John Needham

Answer 9

boiled chicken broth ( to kill bacteria ) & put it in a sealed flask. found that microorganisms still appeared
* likely because broth wasn’t heated for long enough or at a high enough temperature

Question 10

Lazzaro Spallanzani

Answer 10

repeated Needham’s experiment, but in a vacuum. which removed all of the air from the flask. no microorganisms appeared
• only proved that air was an ingredient in life force

Question 11

Louis Pasteur

Answer 11

his experiment was finally the decisive proof the scientific community needed to reject spontaneous generation once & for all.
he heated them both to sterilize them
the flasks had bent necks so they were open to air but protected from dust
I’m experiment 1 : Pasteur broke off the neck of the flask giving it access to air
In experiment 2 : he left the neck intact
overtime, microorganisms appeared in flask 1 but not flask 2
• this proved that microorganisms are not generated but the broth, but rather carried in the air & simply too small to see

Question 12

what did the Janssen brothers do?

Answer 12

Hans & Zacharias
invented the first miscroscope (1595)
considered to be a compound microscope because it used more than one lens

Question 13

what is a manipulated variable?

Answer 13

the variable that is altered between trials

Question 14

what is the responding variable?

Answer 14

the results of the changes made

Question 15

what is the controlled variables?

Answer 15

all the things that could have been changed, but were deliberately kept constant

Question 16

Robert brown

Answer 16

identified the nucleus of the cell as being responsible for controlling cell function

Question 17

Schleiden & Schwann

Answer 17

proposed that all plants and animals are composed of cells.

described cells as the basic unit of life for all organisms

Question 18

Rudolf Virchow

Answer 18

theorized that all cells arise only from pre-existing cells

Question 19

Summary of cell theory

Answer 19

• 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 also called mitosis

Question 20

what are the factors affecting the quality of an image in microscopy?

Answer 20

• magnification
• contrast ( variation of shadow & colour )
• resolution ( ability to distinguish between two structures that are very close together )

Question 21

fluorescent microscopy

Answer 21

• fluorescent stains called GFP ( green fluorescent protein ) are introduced to the specimen
• specimen is subjected to UV light
• depending on the type of dye, the cell glows either yellow, orange or green
• allows for observation of living specimens

Question 22

types of microscopy

Answer 22

• brightfield microscopes
• confocal technology
• electron microscopy
• transmission electron microscope
• scanning electron microscope

Question 23

Brightfield microscopes

Answer 23

• light passes through the specimen
• fixing and staining process kills the specimen
• you can’t view living tissues
• limited resolution
• you can’t get any higher resolution than 0.2 µm

Question 24

Confocal technology

Answer 24

• uses lasers and computers to focus the light
• you see a thin section with a high resolution
• Computer software can be used to build up a 3-D image
• fluorescent stains work better with confocal microscopes because they eliminate the blurriness of the reflected light

Question 25

Electron microscopy

Answer 25

• uses a fine beam of electrons instead of light
• The electrons pass through different materials at different rates due to differences in density
• instead of lenses, EM’s use magnetic fields to focus the image

Question 26

transmission electron microscope

Answer 26

• electrons pass through the specimen
• difficult to produce 3D images
• specimens are fixed and stained so living specimens cannot be observed

Question 27

scanning electron microscope

Answer 27

• good for observing surface features of specimens
• the specimens is fixed and coated in gold
• produce a 3D image
• uses computer to move the specimen and view it from different angles
• permit the use of live material

Question 28

gene mapping

Answer 28

decoding of a species’ genome ( which refers to all the info contained within its DNA )
also allows us to create new varieties of plants

Question 29

what are hormones?

Answer 29

they are chemicals produced in one part of your body that act on a different part

Question 30

what are receptors?

Answer 30

on the surface of cells allow transmitters to attach to the cell and carry out their function