Key Concepts In Biology Flashcards
What did Robert Hooke use to discover cells in 1665.
A microscope that contain two lenses still I see today
What did Hookes microscope have?
A magnification of about x30 (it made things appear about 30 times bigger)
What would a person magnified about 30 times be roughly the same size as?
The Statue of Liberty in New York
What do you do to work out a microscopes magnification?
You multiply the magnifications of its two lenses together ? So it would be the eyepiece lens X the objective lens
Why was Hookes microscope not very powerful and who made a better quality one?
Because the glass was poor quality and Antonine van Leeuwenhoek (1632-1823) found a way of making much better lenses although they were very small
What did Antonio use these lenses for?
To construct microscopes with single lenses which had magnifications up to x270.
In 1675 what did Antonio van Leeuwenhoek examine under his microscope?
He examined a drop of rainwater and was surprised to find tiny organisms which he called animalcules. Fascinated by his discovery he searched for animalcules in different places
What does detail obtained by a microscope also depend on?
It’s resolution
What is resolution?
The smaller distance between two points that can still be seen as two points
What did van Leeuwenhoek best microscopes have a resolution of?
0.0014 mm two points that were 0.0014 mm or further apart could be seen as row points, but two points closer together than this appeared as a single point
With the development of stains for specimens and better lenses and light sources today’s best light microscopes magnify up to x1500 what do the resolutions go down to?
0.0001 mm
When was the electron microscope invented and what did it use instead of light?
In the 1930s and it used beams of electrons to pass through a specimens to build up an image. These microscopes can magnify up to x2 000 000 with resolutions down to 0.0000002 mm
What do electron microscopes allow is to see?
Cells with great detail and clarity
Go to page 3
And look at table e
What does the most common microscope used today contain?
Two lenses and was invented at the end of the 16th century
What does the nucleus do?
Controls the cell and its activities, inside it are chromosomes which contain DNA, it is especially large in white blood cells
What does the cytoplasm contain?
Ribosomes
What are scale bars?
Often shown on micrograph a and are also used to estimate sizes
What are specialised cells?
They are cells that have a specific function and are adapted to their function
What are two specialised cells that are used for reproduction?
Gametes (egg cell and sperm cell)
Why are bacteria difficult to see with a light microscope?
They are very small and mostly colourless, but stain makes them show up
What are the characteristics of a bacteria cell?
Flagellum Plasmids Chromosomal DNA slime coat (for protection) Flexible cell wall Cell membrane Cytoplasm
What is synthesis?
Once small molecules are absorbed by the body, they can be used to build the larger molecules that are needed in cells and tissues. Building larger molecules from smaller subunits is called synthesis
Why are complex carbohydrates and proteins both polymers?
They are made up of many small similar molecules
Where is amylase found and what is it used for?
Found in the saliva and small intestine, and used for breaking down starch to small sugars such as maltose
Where is catalase found and what is it used for?
Found in most cells but especially liver cells, and used for breaking down hydrogen peroxide made in many cell reaction to water and oxygen
When is stack synthase found and what is it used for?
Is found in plants and used for synthesis of starch from glucose
Where is DNA polymerase found and what is it used for?
It’s found in the nucleus and used for synthesis of DNA from its monomers
