cells

Question 1

stages of cell cycle

Answer 1

interphase dna replicates semi conservatively
so 2 sis chromatids attached by centromere and the no of organelles and vol of cytoplasm
increase
cytokinesis the cytoplasm and cell membrane divide so 2 new genetically identical daughter cells

Question 2

how do tumours and cancers form

Answer 2

mutation in genes controlling mitosis can lead to uncontrolled cell division and a tumour from if this leads to mass of abnormal cells

Question 3

why does antibody only attach to specific protein

Answer 3

antibodies have specific tertiary structure
complementary to binding site on protien

Question 4

why does virus only effect certain types of cells

Answer 4

the outside of virus has antigens with comp shape to receptor
and that receptor only found on membranes of specific cell

Question 5

what’s meant by inactive virus

Answer 5

not infecting any more cells as virus isn’t replicating
and programmed cell death prevents virus from replicating

Question 6

how can microRNA let him remain in body for years

Answer 6

bind to mrna via specific base pairing
preventing mrna being read by ribosomes
so preventing translation of protiens that cause cell death

Question 7

why would ppl stop vaccinating their children

Answer 7

fewer cases
fear of side effects
not enough vaccines available

Question 8

why’s 100% vaccination not necessary

Answer 8

more ppl immune fewer carry pathogen
unvaccinated ppl unlikely to contact infected people

Question 9

how do pathogens cause disease

Answer 9

release toxins
kill cells and tissues

Question 10

temporary mount

Answer 10

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

Question 11

how do interphase and mitosis produce genetically identical daughter cells

Answer 11

dna replicates via semi conservative replication
2 identical sister chromatids each chromatid moves to opposite poles

Question 12

principle and limitations of TEM

Answer 12

electrons pass through specimen and denser part absorbs more electrons and appear darker
electrons have short wavelength of light so high resolution
but cant look at living materials
thin specimen only and complex prep and 2d image

Question 13

prophase

Answer 13

chromosomes condense - short and thick
appear as 2 sis chromatids attached by centromere
nuclear envelope breaks down
centrioles move to opp poles of cell = spindle network
chromosomes visible as condensing but randomly arranged as not attached to SF

Question 14

metaphase

Answer 14

SF attach to chromosomes by centromere
line up along equator

Question 15

anaphase

Answer 15

SF contract
centromere divides
pulling sis chromatids to opp poles off cell
Chromatids V shaped being pulled apart at their centromeres by spindle fibres

Question 16

telophase

Answer 16

chrom uncoil long and Thin
nuclear envelope reform = to nuclei
sf centrioles breakdown
chrom in 2 sets one at each pole

Question 17

function of atp hydrolase in carrier protiens

Answer 17

atp to adp and pi releases energy
allows ions to be moved against conc gradient

Question 18

na out of cell allowing absorption of glucose

Answer 18

maintains a conc gradient for na
na moves in by FD bringing glucose with it

Question 19

how is the movement of substances affected by membrane structure

Answer 19

Phospholipid bilayer allows diffusion of small and lipid soluble susbtances and prevents diffusion of water soluble and larger substances
carrier protiens allow active transport and shape and charge of determines which substances move
number of carriers and channels determine how much movement
cholesterol affects fluidity and rigidity

Question 20

Suggest how the increase in temperature of the water caused the release
of the red pigment.

Answer 20

damages cell surface membrane
soo membrane protiens denature
increasing fluidity and damage to phospholipid bilayer

Question 21

how are membranes adapted for rapid transport

Answer 21

folded membrane increases surface area
lots of protein channels and carriers for FD

Question 22

how does high salt in blood plasma lead to build up of tissue fluid

Answer 22

high salt - low wp of tissue fluid
less water returns to capillary via osmosis

Question 23

Outline the role of organelles in the production, transport and release of
proteins from eukaryotic cells.

Answer 23

dna in nuclues codes for protiens
RER produce synthesise protiens
mitchondria produce atp for protein synthesis
Golgi apparatus modifies protiens

Question 24

why is second centrifuge tube span at higher speed

Answer 24

mitochondria is less dense than nuclei or first pellet

Question 25

No organelles are visible in the cytoplasm of this red blood cell. why

Answer 25

cytoplasm of RBC filled with HB

Question 26

Suggest an explanation for the appearance of the cell-surface membrane
as two dark lines.

Answer 26

membrane has phospholipid bilayer
stain binds to phosphate
on inside and outside of membrane

Question 27

general structure of virus particle

Answer 27

nucleic acid surrounded by capsid
AP to attach to specific host cells
no cyto ribosome cell wall csm
some have lipid envelope

Question 28

cancer treatment to control cell division

Answer 28

some disrupt spindle formation
chrome cant attach. to SF by centromere chromatids cant be separated to opp poles slowing mitosis
prevent dna replication during interphase
cant make 2 copies of each chromosome slows mitosis

Question 29

prok cell replication

Answer 29

circular dna replicates
plasmids replicate
division of cytoplasm to 2 daughter cells
one copy circular dna variable no plasmids

Question 30

viral replication

Answer 30

AP attach to comp receptors on host cell
inject nucleic acid into host cell
infected host cell replicates
so nucleic acid replicates
cell produces viral protiens
virus assembled and released

Question 31

how to prep squashes of cells from root tips

Answer 31

cut thin slice root tip using scalpel and mount. onto slide
soak root tip in hcl - rinse sep cells, stop mitosis, and cells more easily squashed
stain for dna and lower coverslip using mounted needle at 45 w out trapping air bubbles
squash by firmly press down on glass slip not push sideways to avoid rolling cells together and breaking chromosomes

Question 32

cell membranes adapted for other functions

Answer 32

phospholipid bilayer is fluid can bend for vesicle formation
glycoproteins and lipids act as receptors and antigens for cell signalling

Question 33

role of carrier protiens and importance of hydrolysis of atp in AT

Answer 33

comp substance binds to specific carrier protein
atp binds hydrolysed to adp and pi
carrier protein bind shape releasing substance on side of higher conc
pi released and protein returned original shape

Question 34

co transport

Answer 34

2 Dif substances bind and move simultaneously via a cotansporter protein one against and oe with conc gradient
NA AT epithelial cells to blood estab conc gradient of na higher in lumen than epethlial
na enters epithelial cells down its conc gradient with glucose against conc gradient via cotransporter protien
glucose move down conc gradient into blood via FD

Question 35

what does high absorbance suggest about cell membrane

Answer 35

more permeable and damaged
as more pigment leaks out making surrounding solution more concentrated

Question 36

temp affect on permeability

Answer 36

permeability increases
phospholipids gain KE increasing fluidity
transport protiens denature at high temp h bonds break - change tertiary strcutre

Question 37

lipid soluble substance affect on permablity of CSM

Answer 37

conc increase and permeability increases
ethanol may dissolve phospholipid bilayer