3.1.2 Cells and Cell Structure Flashcards Preview

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Flashcards in 3.1.2 Cells and Cell Structure Deck (90)
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1

÷ Divide to make ____ 

bigger 

2

× Multiply to make _____

smaller

3

Describe how you convert cm → mm → μm → nm & vice versa

4

Define Magnification

How many times bigger the image is than the specimen (object)

5

Define Resolution

Minimum distance apart that two objects can be in order for them to appear as separate items

6

State the formula used to work out magnification 

7

Describe how optical (light) microscopes work

Light from bulb travels through condenser lens, then specimen, up through objective lens and through eyepiece lens into your eye

8

State the maximum magnification for an optical microscope

x 1500

9

State the maximum resolution for an optical microscope

0.2 µm

10

Name 2 pros of optical (light) microscopes

  • Easy and cheap to operate
  • Can have living specimens

11

Name 2 cons of optical (light) microscopes

  • Low resolution & magnification
    • Can't see organelles smaller than 0.2 µm (e.g. ribosomes, endoplasmic reticulum and lysosomes)
  • Specimens often need staining to show specific organelles

12

Why does optical microscopes have a maximum resolution of 0.2 µm?

∵ of the long wavelength of light rays

13

Name 2 Electron Microscopes 

  • Transmission Electron Microscopes
  • Scanning Electron Microscopes

14

Describe how transmission electron microscopes work

  1. Use electromagnets to focus a beam of electrons which is then transmitted through the specimen
  2. Denser parts of specimen absorb more electrons = makes them look darker on image you end up with

15

State the maximum resolution for a transmission electron microscope

0.1 nm

16

State the maximum magnification for a transmission electron microscope

x 10 000 000

17

Name a pro of transmission electron microscopes

  • Has highest resolutions & magnification
    • See internal structure of organelles e.g. chloroplasts

18

Name 4 cons of transmission electron microscopes

  • Non-living matter only 
  • Image in black and white and 2D
  • Preparation may distort structure/give artefacts
  • Vacuum required 
  • Elaborate preparation - staining is complex

19

Describe how scanning electron microscopes work

  • They scan a beam of electrons across specimen = knocks off electrons from specimens
  • Electrons gathered in cathode ray tube to form image

20

State the maximum magnification of SEMs

x 30,000 

21

State the maximum resolution of SEMs

20 nm

22

Name 3 pros of SEMs

  • Can form complex 3D images of sample
  • Can be used on thick specimens
  • Magnifications & resolutions are higher than light microscopes

23

Name 3 cons of SEMs

  • Large and expensive & difficult to operate
  • Specimens has to be mounted in vacuum
  • Specimen has to be dead

24

What type of cells are like algal cells?

Plant cells = have same organelles

(Can be single-celled or multicellular)

25

What type of cells are like fungal cells?

Plant cells

26

What are 2 differences between fungal and plant cells?

In fungal cells:

Cell walls are made from of chitin & they don't have chloroplasts 

27

What is the function of the cell-surface (plasma) membrane?

Regulates movement of substances into and out of cells

(has receptor molecules on it = respond to chemicals)

28

What is the function of the nucleus?

Holds genetic information of cell

29

What is the function of the nucleolus?

Makes RNA and ribosomes

30

What are chromosomes made of?

DNA and proteins

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