Microscopes and Ecology (mixed sorry)

Question 1

Microscopes

What are optical microscopes or light microscopes?

Charactaristics of this microscope

Answer 1

• Use light focussed through a series of lenses
• Magnify to 400x
• Resolution is limited by the wavelength of light
• Specimen must be thin and mostly transperant to let light pass through
• Can view living tissue and organisms
• Can use a stain
• Not expensive and easy to use

Question 2

What are electron microscopes?

Charactaristics of the microscope

Answer 2

• Use short wavelengths of electrons to produce high-resolution imaes of extreemley small objects
• Specimin has to be dead

Question 3

Microscopes

What are the two types of electron microscopes?

Answer 3

TEM(Transmission Electron Microscope)
* Thin sections of non-living material
* Beam of electrons pass through the specimin and are scattared
* Magnetic lenses focus onto the florecent screen
* Magnification up to 5,000,000x
* Resolution up to 1nm
* 2D, black and white image only

SEM(Scanning Electron Microscope)
* Sample is coated in thin layer of gold or palladium
* Scans surface of a sample with a rpimary beam of electrons, which knocks electrons from the samples surface
* These secondary electrons are collected, amplified and transmitted oto a viewing screen to produce a 3D, black and white image
* Only of the outside surface and can be any thickness
* Magnification: 100,000x
* Resolution: up to 20nm

Question 4

Natural Selection

What are the key components to natural selection

ICEAGE

Answer 4

Inhereted variation exists within a population
Competition results from an overproduction of offspring
Environmental pressures lead to differential reproduction
Adaptations which benifit survival are selected for
Genotype frequency changes across generations
Evolution occurs within the population

Question 5

Ecology

What is Charl Darwins theory?

Answer 5

The theory of natural selection.