2.1

Question 1

distinguishing feature of euk

Answer 1

cytoplasm containing membrane bound organelles
dna enclosed in nucleus

Question 2

strcutre and function of cell surface membrane

Answer 2

hydrophilic phosphate heads attracted to water
hydrophobic fatty acid tails repel water
selectively permeable so control passage of substances in and out of cell
molecules receptors and antigens on surface allowing cell recognition

Question 3

nucleus

Answer 3

nuclear envelope
double membrane
has nuclear pores
stores genetic info coding for polypeptides
site of dna replication
site of transcription producing mrna
nucleolus makes ribosomes and rRNA

Question 4

ST ribosome

Answer 4

made of ribosomal RNA and proteins
not membrane bound
site of protein synthesis

Question 6

RER

Answer 6

ribosomes on surface synthesise protiens
protiens processed and transported inside RER
protiens packaged into vesicles for transport

Question 7

ser

Answer 7

synthesise and process lipids
eg cholesterol and steroid hormones

Question 8

Golgi apparatus

Answer 8

modify protiens eg add carbs to produce glycoproteins
modify lipids eg add carbs to make glycolipids
package protiens and lipids into Golgi vesicle
produce lysosomes

Question 9

Golgi vesicle

Answer 9

transport proteins and lipids to required destination
move and fuse with CSM

Question 10

lysosomes

Answer 10

release hydrolytic enzymes
break down pathogens and worn out parts of cell

Question 11

Mitochondria

Answer 11

outer membrane
cristae is the inner membrane fold
matrix containing 70s ribosomes and circular dna
site of aerobic respiration producing app for energy release

Question 12

chloroplasts

Answer 12

double membrane
stroma containing 70s ribosome, thylakoid membrane, circular dna, starch granules
lamella is the thylakoid linking grana
grant are stacks of thylakoids
absorb light energy for photosynthesis to produce organic substances

Question 13

cell wall in plants algae and fungi

Answer 13

mainly of cellulose in plants and algae
chitin in fungi
provide mechanical strength to cell so prevent cell changing shape or bursting under pressure due to osmosis

Question 14

cell vacuole

Answer 14

tonoplast membrane and cell sap
maintain turgor pressure in cell
cell sap store sugars AA pigment and waste chemicals

Question 15

euk cell

Answer 15

membrane bound organelles
nucleus containing dna and dna is long and linear associated with histones
80s ribosomes in cytoplasm
cellulose or chitin cell walls
no plasmids

Question 16

Prokaryotes

Answer 16

no membrane bound organelles
no nucleus so dna is free in cytoplasm
dna is short and circular no histone
70s ribosomes
cell wall murein

Question 17

virus why’s it described as a cellular and non living

Answer 17

a cellular as not made of cells no cell membrane cytoplasm
non living no metabolism cant independently respire

Question 18

general structure of virus

Answer 18

nucleic acid surrounded by capsid
AP attach to specific host cells
no cyto ribosome
sometimes surrounded by lipid envelope

Question 19

optical microscopes

Answer 19

light focused using glass lenses
light passes through specimen and different structures absorb different wavelengths and amounts

Question 20

optical pros and cons

Answer 20

2d
low resolution bc long wavelength of light
cant see internal strucutres
thin specimen
low magnification 1500
can see living organism in colour and simple prep

Question 21

TEM

Answer 21

electrons focused using electromagnets
electrons pass through specimen and denser parts absorb more and appear darker

Question 22

TEM pros and cons

Answer 22

2d image
very high resolution as short wavelength of electrons
can see internal strucutres
v thin specimen
high mag 1000000
dead organisms in vacuum
complex prep no colour

Question 23

SEM

Answer 23

electrons focused using electromagnets
electrons deflected and bounce of specimen surface

Question 24

SEM pros and cons

Answer 24

3d
high resolution as short wavelength of electrons
cant see internal structures
specimen doesnt need to be thin
high mag 1000000
dead vacuumed organisms
complex prep
no colour

Question 25

magnification formula

Answer 25

size of image divided by actual size

Question 26

units order

Answer 26

M
MM
UM
NM
times a 1000 each time up to down

Question 27

size of object viewed by optical microscope

Answer 27

line up eye piece graticule with stage micrometer
calibrate eyepiece graticule - use stage mircometre to calc size of dvisions on eyepiece graticule
take eyepiece away and use graticule to measure how many divisions make up object
calc size of object - multiply no of divsions by size of divsions
recalibrate eyepeice graticule at dif magnifications
i

Question 28

cell fractionation

Answer 28

homogenise tissue using blender
distrupts cell memb and breaks cell open releasing contents
place in
cold to stop enzyme activity so organelles not broken or damaged
isotonic so water doesnt move in and out by osmosis so they dont burst
buffered to keep ph constant so enzymes dont denature
filter homogenate to remove large unwanted debris

Question 29

ultracentrifugation

Answer 29

separate organelles in order of density and mass
centrifuge homogenate at hifh spped
remove pellet of heaviest organelles respin supernantant at higher speed
repeat at higher speeds until seperated out each time pellet made of lighter organelles
nuclei chloro mito lyso ER ribo

Question 30

Describe how you could make a temporary mount of a piece of plant tissue to observe the
position of starch grains in the cells when using an optical (light) microscope.

Answer 30

add drop of water to glass slide
obtain thin section of plant tissue and place on slide
stain with iodine in potassium iodide
lower coverslip using mounted needle