STUDYING CELLS

Question 1

Describe light miscroscope

Answer 1

Uses light as illumination
Has a limit magnification
Lower resolution as longer light wavelength
Specimens can eb living or dead

Question 2

Describe electron miscroscope

Answer 2

Uses beam of electrons for illumination
High magnification
And higher resolution as shorter wavelength
Speciemens are dead
Specimens are thin sliced
In a vacuum

Question 3

Principle of electron microscope

Answer 3

Electrons pass tgrough speciment
Denser parts absorb more electrons
So denser parts appear darker
Electrins gave short wavelength so give high resolution

Question 4

Limitation of electron miscroscope

Answer 4

Must be in a vacuum
Specimen must be thin
Artefacts present
Long preparation time
Specimen must be dead

Question 5

Advantages of electron microscope

Answer 5

Small objects can be seen
Higher resolution as wavelenth of electrons is shorter

Question 6

Describe one feature of SEM

Answer 6

3D image

Question 7

Cell centrifugation & differential - centrifugation

Answer 7

1. Break open the cell in a blender
2. Add to a ice cold , isotonic , buffered solution
3. Mixture is filtered to remove debris
   4.differential centrifugation carried out on solution
4. Centrifugate at higher speed

Question 8

Why is cell added to ice cold , iostonic & buffered solution

Answer 8

Ice cold = reduce enzyme activity that would digest organelles
Isotonic = prevents osmosis of water in or out of orgnelles so they dont brust
Buffered = stop ph changes which could denature proteins

Question 9

What is Cell wall of fungi made up of

Answer 9

Chitim

Question 10

What is cell wall of bacteria made up of

Answer 10

Murein

Question 11

Compare eukaryotic cell and prokaryotic cells

Answer 11

P then E
Dna is circular and not associated with histones whereas Dna is linear and associated with histones
Contains no membrane bound organelles whereas does contain nucleus
No nucleas whereas does contain nucleus
Contains 70s ribosomes whereas 80s ribosomes

Question 12

Cell wall of plant

Answer 12

Cellulose

Question 13

Compare plant cell and animal cells

Answer 13

P then E
Cellulose cell wall vs no wall
Chloroplast present vs no chloroplast
Vacule vs no vacule
Carbohydrates stored as starch vs carbohydrates stored as glycogen
No centrioles vs centrioles

Question 14

Function of microvili

Answer 14

Increases surface area for absorption of digested food

Question 15

Centrioles function

Answer 15

Forms network of spindle fibres

Question 16

Lysosomes function

Answer 16

Used to hydrolyse damaged organelles

Question 17

Golgi apparatus function

Answer 17

Modifies and pacakges proteins in a vesicle & triglycerides into vesicles

Question 18

Smooth endoplasmic reticulum

Answer 18

Recombines glycerol and fatty acids to make triglycerides
Packages triglycerides into vesicle and transports thrm to golgi apparatus

Question 19

Rough endoplasmic reticulum function

Answer 19

Synthesises and transports proteinss throughout the cell

Question 20

Moctochondrion function

Answer 20

Synthesis of ATP by aerobic respiration

Question 21

Nucelus

Answer 21

Contains DNA