things i fucked on the past papers x

Question 1

suggest one disadvantage of cell counts performed using the haemocytometer

Answer 1

time consuming. you cant distinguish dead cells from living cells

Question 2

how can you minimise harm to animals during experiments

Answer 2

replacement
reduction
refinement

Question 3

what is an advantage of an in vivo trial

Answer 3

allows possible side effects to be seen

Question 4

describe an ethical issue that the researchers would need to consider before this trial

Answer 4

right to withdraw
informed consent

Question 5

what does replacement mean

Answer 5

replace with another biological system

Question 6

what does refinement mean

Answer 6

refine techniques

Question 7

what does reduction mean

Answer 7

use less subjects

Question 8

diabetes insipidus results from failure to recruit water channel proteins to the cell membrane. identify the cause of recruitment failure in this individual

Answer 8

failure to produce ADH

Question 9

trypan blue is used as a vital stain to identify viable cells when viewed in a haemocytometer. a vital stain does what?

Answer 9

only stains dead cells

Question 10

the binding of oxygen to haemoglobin is affected by small changes in temperature or pH. which of the following changes would decrease haemoglobins affinity for oxygen

Answer 10

increased temperature
decreased ph

Question 11

what does positive control mean

Answer 11

a group in an experiment that receives a treatment with a known result.
treatment that is included to check that the
system can detect a positive result when it
occurs

Question 12

what does negative control mean

Answer 12

provides results in the absence of a treatment.
used to identify exterior variables that can have an effect that were not previously accounted for

Question 13

most birds have four types of cone cells. name the additional wavelength range to which these organisms are sensitive

Answer 13

ultraviolet

Question 14

describe how protein electrophoresis is used to separate proteins

Answer 14

the charge separates proteins in the gel on the basis of their size shape and charge

Question 15

suggest one reason why counting organisms is an appropriate indirect sampling technique

Answer 15

the disturbance is minimised

Question 16

discuss the role of amino acid r groups in the determination of tertiary structure of proteins

Answer 16

tertiary structure is a folded polypeptide
the conformation is determined by the order of amino acids
there are different r groups such as basic, acidic, polar and non polar.
there are different interactions holding the shape in place such as disulphide bridges and london dispersion forces

Question 17

discuss the role of amino acid r groups in influencing the location of proteins within cells

Answer 17

hydrophilic groups are mostly at the surface of a soluble protein, which are found in the cytoplasm
in soluble proteins, the hydrophobic groups may cluster at the centre of a protein.
membrane proteins are integral or peripheral
some integral proteins are transmembrane or channels
peripheral proteins have fewer hydrophobic r groups interacting with the phospholipids

Question 18

discuss the cell membranes under the heaidng of the phospholipid bilayer as a selective barrier

Answer 18

the membrane has hydrophilic and hydrophobic regions
hydrophilic substances cant pass across the membrane
hydrophobic can
ozygen carbon dioxide and water can all pass through the membrane
protein channels and pumps are required to transport hydrophilic molecules across the membrane

Question 19

discuss the cell membrane under the heading of types of transport proteins and their functions

Answer 19

channels and pumps are transmembrane proteins that can create concentration gradients
movement through channels is passive, as molecules move down a concentration gradient
transporter proteins change their conformation to transport molecules across the membrane
conformational change in active transport requires energy from the hydrolysis of ATP
describe sodium potassium pump

Question 20

which pair of cell types are fused in order to produce monoclonal antibodies

Answer 20

b lymphocyte and myeloma

Question 21

what needs to happen to p53 and retinoblastoma to increase the rate of cell division

Answer 21

p53 inhibited
retinoblastoma phosphorylated

Question 22

name the level of protein structure describing several connected polypeptide subunits

Answer 22

quaternary

Question 23

what are primary cell lines

Answer 23

they are sourced directly from normal animal tissue and are have a limited number of cell division s

Question 24

which events contribute to the depolarisation of the resting potential of a neuron

Answer 24

• binding of a neurotransmitter to a neuron
• opening of ligand gated ion channels
• opening of voltage ligand gated ion channels

Question 25

monoclonal antibodies can be produced in a laboratory using hybridomas that are prepared by fusing together b lymphocytes and myeloma cells. name the chemical used to fuse these two cell types together

Answer 25

PEG

Question 26

explain why it is important to control pH in immunoassays

Answer 26

ph affects the structure of proteins because it impacts the interactions between the R groups
because of this the proteins would have a reduced affinity for binding to the substrate

Question 27

state the meaning of the term monoclonal

Answer 27

this means the antibodies are derived from a single clone of cells

Question 28

how does the binding of ATP result in the opening of the chloride ion channel

Answer 28

binding to the protein causes a conformational change

Question 29

what is meant by epidemiology

Answer 29

study of outbreak

Question 30

explain why an observational study can only suggest a possible link

Answer 30

because it does not show causation, just correlation

Question 31

discuss signalling molecules and signal transduction under the heading of hydrophilic signalling molecules and signal transduction

Answer 31

hydrophilic signaling molecules include neurotransmitters,
and peptide hormones
the receptors are specific and are transmembrane proteins
the molecule binds to a receptor on the cell surface, causing a conformational change, bringing about a response.
this activates g proteins and proteins that regulate gene transcription

Question 32

discuss signalling between cells under the heading of insulin signalling and diabetes

Answer 32

binding of insulin to its receptor triggers glut4 recruitment to the cell membrane of fat and muscle cells
type 1 diabetes is a reduced production of insulin
this leads to failure to recruit of glut4 so there is impaired glucose uptake
exercise increase glut4 recruitment

Question 33

discuss control of the cell cycle under the heading of phases of the cell cycle and the importance of cell cycle checkpoints

Answer 33

lack of control of the cell cycle can result in degenerative diseases and cancer
the phases are g1, s, g2, and m
there are checkpoints at g1 g2 and m
g1 and g2 are growth phases
s phase is dna replication
size and mass of cell is assessed at the g1 checkpoint