cells

Question 1

nucleus

Answer 1

Contains DNA which contains genes which code for protein controls cells activities
Nucleolus makes ribosomes
Nuclear pores allow substances eg. mRNA to move between nucleus and cytoplasm
nuclear envelope double membrane
nuclear pores

Question 2

ribosomes

Answer 2

no membrane - site of protein synthesis (translocation)

Question 3

rough endoplasmic reticulum

Answer 3

Ribosomes on surface synthesise proteins
Proteins processed / folded / transported inside rER
Proteins packaged into vesicles for transport eg. to Golgi apparatus

Question 4

smooth endoplasmic reticulum

Answer 4

synthesis and process lipids

Question 5

Golgi apparatus

Answer 5

modify proteins from rer package them to Golgi vesicle produce lysosomes

Question 6

Golgi vesicle

Answer 6

Transports proteins / lipids to their required
destination

Question 7

lysosomes

Answer 7

relates lysozymes to hydrolyse pathogens or worn out cell components
membrane and phoslipid bilayer

Question 8

mitochondria

Answer 8

Site of aerobic respiration
To produce ATP for energy release
cristae highly folded
matrix contains circular dna
70s ribosomes

Question 9

cell wall

Answer 9

Provides mechanical strength to the cell
So prevents cell changing shape or bursting under pressure due to osmosis
cellulose in plant and algae
chitin in fungi

Question 10

chloroplasts

Answer 10

Absorbs light energy For photosynthesis To produce organic substances
double membrane
thylakoid - linking grana
grana stacks of thylakoids
stroma containing 70s ribosomes/ circular dna/ starch granules/ thylakoid membrane

Question 11

cell vacuole

Answer 11

● Maintains turgor pressure in the cell, supporting the plant
● Contains cell sap - a store of sugars, amino acids,
pigments and any waste chemicals

Question 12

Eukaryotic cells

Answer 12

membrane bound organelles
nucleus containing DNA
80s ribosomes
large overall size
long linear dna associated with histone proteins
cell wall in plant algae and fungi

Question 13

prokaryotic cells

Answer 13

No membrane-bound organelle

No nucleus
DNA is is free in cytoplasm

DNA is short & circular
not associated with proteins

Smaller (70S) ribosomes

Cell wall in all prokaryotic cells
Containing murein, a glycoprotein

Plasmids, flagella and a capsule sometimes present

Question 14

virus general structure

Answer 14

● Nucleic acids surrounded by a capsid (protein coat)
● Attachment proteins allow attachment to specific host cells
● No cytoplasm, ribosomes, cell wall, cell-surface membrane etc.
● Some also surrounded by a lipid envelope

Question 15

optical micoscope

Answer 15

Light focused using glass
lenses
● Light passes through thin
specimen
● Light that passes through or
reflects the surface can be
seen
● Generates a 2D image of a
cross-section

Question 16

pros optical

Answer 16

✓ Can view living organisms
✓ Simple preparation
✓ Can show colour

Question 17

cons optical

Answer 17

xOnly thin specimens
× Low resolution - 200 nm
× Due to long
wavelength of light
× Can’t see internal structure
of organelles or organelles
smaller than 200nm eg.
ribosomes
× Low magnification -
x 1500

Question 18

tem

Answer 18

● Electrons focused using
electromagnets
● Electrons pass through very
thin specimen
● Denser = absorb more
electrons = darker
● Generates a 2D image of a
cross-section

Question 19

tem pros

Answer 19

✓ V. high resolution - 0.2 nm
✓ Due to short
wavelength of electrons
✓ Can see internal structures
of organelles and small
organelles eg. ribosomes
✓ High magnification -
x 1,000,000

Question 20

tem cons

Answer 20

× Dead / dehydrated
specimens, uses vacuum
× Only v. thin specimens
× Complex preparation so
artefacts often present
× Does not show colour

Question 21

sem

Answer 21

● Electrons focused using
electromagnets
● Electrons scan specimen
surface
● Reflected electrons are
detected
● Generates a 3D image of the
surface

Question 22

sem pros

Answer 22

✓ High resolution - 2 nm
✓ Due to short
wavelength of electrons
✓ Can see external / 3D /
surface structures
✓ High magnification
- x 1,000,000
✓ Thick / 3D specimens

Question 23

sem cons

Answer 23

× Dead / dehydrated
specimens, uses vacuum

× Complex preparation so
artefacts often present
× Does not show colour
× lower resolution than tem

Question 24

magnification

Answer 24

● Number of times greater the image is than the size of the real (actual) object
● Magnification = size of image / size of real object

Question 25

resolution

Answer 25

Minimum distance apart 2 objects can be for them to be distinguished as separate objects

Question 26

eye piece graticule

Answer 26

in eyepiece spans across entire field of view must be calibrated to work out side of divisions

Question 27

stage micrometer

Answer 27

on microscope slide placed on stage fixed units used to calibrate eyepiece graticule