Key Concepts In Biology

Question 1

What did Robert Hooke use to discover cells in 1665.

Answer 1

A microscope that contain two lenses still I see today

Question 2

What did Hookes microscope have?

Answer 2

A magnification of about x30 (it made things appear about 30 times bigger)

Question 3

What would a person magnified about 30 times be roughly the same size as?

Answer 3

The Statue of Liberty in New York

Question 4

What do you do to work out a microscopes magnification?

Answer 4

You multiply the magnifications of its two lenses together ? So it would be the eyepiece lens X the objective lens

Question 5

Why was Hookes microscope not very powerful and who made a better quality one?

Answer 5

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

Question 6

What did Antonio use these lenses for?

Answer 6

To construct microscopes with single lenses which had magnifications up to x270.

Question 7

In 1675 what did Antonio van Leeuwenhoek examine under his microscope?

Answer 7

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

Question 8

What does detail obtained by a microscope also depend on?

Answer 8

It’s resolution

Question 9

What is resolution?

Answer 9

The smaller distance between two points that can still be seen as two points

Question 10

What did van Leeuwenhoek best microscopes have a resolution of?

Answer 10

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

Question 11

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?

Answer 11

0.0001 mm

Question 12

When was the electron microscope invented and what did it use instead of light?

Answer 12

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

Question 13

What do electron microscopes allow is to see?

Answer 13

Cells with great detail and clarity

Question 14

Go to page 3

Answer 14

And look at table e

Question 15

What does the most common microscope used today contain?

Answer 15

Two lenses and was invented at the end of the 16th century

Question 16

What does the nucleus do?

Answer 16

Controls the cell and its activities, inside it are chromosomes which contain DNA, it is especially large in white blood cells

Question 17

What does the cytoplasm contain?

Answer 17

Ribosomes

Question 18

What are scale bars?

Answer 18

Often shown on micrograph a and are also used to estimate sizes

Question 19

What are specialised cells?

Answer 19

They are cells that have a specific function and are adapted to their function

Question 20

What are two specialised cells that are used for reproduction?

Answer 20

Gametes (egg cell and sperm cell)

Question 21

Why are bacteria difficult to see with a light microscope?

Answer 21

They are very small and mostly colourless, but stain makes them show up

Question 22

What are the characteristics of a bacteria cell?

Answer 22

Flagellum 
Plasmids
Chromosomal DNA 
slime coat (for protection) 
Flexible cell wall
Cell membrane 
Cytoplasm

Question 23

What is synthesis?

Answer 23

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

Question 24

Why are complex carbohydrates and proteins both polymers?

Answer 24

They are made up of many small similar molecules

Question 25

Where is amylase found and what is it used for?

Answer 25

Found in the saliva and small intestine, and used for breaking down starch to small sugars such as maltose

Question 26

Where is catalase found and what is it used for?

Answer 26

Found in most cells but especially liver cells, and used for breaking down hydrogen peroxide made in many cell reaction to water and oxygen

Question 27

When is stack synthase found and what is it used for?

Answer 27

Is found in plants and used for synthesis of starch from glucose

Question 28

Where is DNA polymerase found and what is it used for?

Answer 28

It’s found in the nucleus and used for synthesis of DNA from its monomers