Chapter 2. Basic components of living systems

Question 1

By who and when was the first cell observed

Answer 1

In 1665 by Robert Hooke using a light microscope

Question 2

By who and when were the first living cells observed

Answer 2

1674-1863 by Anton van Leeuwenhoek

Question 3

By who and when was there evidence for the origin of new plant cells

Answer 3

1832 by Barthélemy Dumortier

Question 4

By who and when was the nucleus first observed

Answer 4

1833 by Robert brown

Question 5

By who and when was the birth of a universal cell theory theory

Answer 5

1837-1838 by Matthias Schielden

Question 6

What was the first universal cell theory

Answer 6

It was proposed that all plants and animals are composed of cells and cell products

Question 7

By who and when was the first evidence for the origin of new animal cells

Answer 7

1844 (1855) by Robert Remak

Question 8

By who and when was spontaneous generation disproved

Answer 8

1860 by Louis Pasteur

Question 9

How does a light microscope work (briefly outline)

Answer 9

It has two lenses, the eyepiece lens and the objective lens. The objective lens produces a magnified image which is magnified again.

Question 10

What is the benefit of using two lenses compared to one in a simple light microscope

Answer 10

The objective/eyepiece lens configuration allows for much higher magnification and reduced chromatic aberration

Question 11

What is chromatic aberration

Answer 11

The failure of a lens to focus all colours to the same point

Question 12

What is the purpose of staining

Answer 12

To increase contrast between different parts of a cell

Question 13

What is magnification

Answer 13

How many times larger an image appears compared to its actual size

Question 14

What is resolution

Answer 14

The ability to see individual objects as separate entities

Question 15

What is the equation for magnification

Answer 15

magnification = image size / actual size

Question 16

What is the equation for actual size of an object

Answer 16

Actual size of an object = size of image / magnification

Question 17

What is the equation for size of the image

Answer 17

Size of image = magnification x actual size of object

Question 18

What is the benefit to using a electron microscope over a light microscope

Answer 18

Higher magnification

Question 19

What is the limiting factor to a light microscope

Answer 19

Resolution

Question 20

Outline how an electron microscope works

Answer 20

A beam of electrons with less than 1nm wavelength is used to illuminate the specimen. This means more detail of the cell can be seen because electrons have a much smaller wavelength than light waves.

Question 21

Up to what magnification can electron microscopes produce

Answer 21

x500 000

Question 22

What are the two types of electron microscope

Answer 22

Transmission electron microscopes (TEM) and Scanning electron microscopes (SEM)

Question 23

Explain how a transmission electron microscope works

Answer 23

A beam of electrons is transmitted through a specimen and focused to produce an image

Question 24

What is the strength of using a transmission electron microscope

Answer 24

It has the best resolution of up to 0.5nm

Question 25

Explain how a scanning electron microscope works

Answer 25

A beam of electrons is fired at the specimen and then the electrons that are reflected are collected.

Question 26

What is the resolution of a scanning electron microscope

Answer 26

Between 3-10nm

Question 27

What is the benefit to using a scanning electron microscope

Answer 27

Gives a 3D image

Question 28

Which of a light microscope or an electron microscope

is cheapest

Answer 28

Light microscope

Question 29

Which of a light microscope or an electron microscope is easier to use

Answer 29

Light microscope is small and portable

Question 30

Which of a light microscope or an electron microscope has complex sample preparation

Answer 30

Light microscope

Question 31

What can be a problem that occurs with sample preparation of an electron microscope

Answer 31

Can lead to sample distortion

Question 32

Which of a light microscope or an electron microscope requires a vacuum

Answer 32

Electron microscope

Question 33

Which of a light microscope or an electron microscope gives images in colour

Answer 33

Light Microscope

Electron microscope is usually in black and white

Question 34

Which of a light microscope or an electron microscope has magnification up to x2000

Answer 34

Light microscope

Question 35

Which of a light microscope or an electron microscope has a resolving power of 200nm

Answer 35

Light microscope

Question 36

Which of a light microscope or an electron microscope requires the specimens to be dead

Answer 36

Electron microscope

Question 37

Aside of light and electron microscopes what is the other main type of microscope

Answer 37

Laser scanning confocal microscope

Question 38

How does a laser scanning confocal microscope work

Answer 38

It moves a single spot of a focused light across a specimen. This causes florescence from the components labelled with a dye. The light emitted from a specimen is filtered through a pinhole aperture forming an image

Question 39

What is the benefit of using a laser scanning confocal microscope

Answer 39

Very high resolution

Question 40

What are the two fundamental types of cell

Answer 40

Prokaryotic and eukaryotic

Question 41

What is a prokaryote

Answer 41

A single celled organism

Question 42

What is a eukaryote

Answer 42

Multicellular organisms