June 2016 wjec unit 1?

Question 1

Structures labelled X that can be seen in the photomicrograph?

Answer 1

chromosomes/chromatids

Question 2

Explain why some stain would be seen in other parts of the cell?

Answer 2

DNA is found in other parts of the cell
in mitochondria

Question 3

Describe the differences between the genetic material of the influenza virus and the genetic maerial found within the nucleus of the epithelial cell it infects?

Answer 3

DNA is double stranded
deoxyribose
contains thymine
larger moelcule
genetic material contained in nucleus

RNA
single stranded
ribose
contains uracil
shorter molecule
genetic material not contained in nucleus

Question 4

Describe how the viral RNA is replicated?

Answer 4

viral RNA acts as a template
free nucleotides attach to their complementary base pairs
adenine with uracil - cytosine with uanine
RNA polymerase catalyses the formation of the new RNA molecule
forming the sugar phosphate backbone

Question 5

Describe how proteins in the capsid are produced?

Answer 5

via the process of translation
mRNA attaches to a ribosome
tRNA brings a specific amino acid
complementary base pairing between mRNA codon and tRNA codon
Ribosome has room for 2 tRNA molecules
condensation reaction occurs
ribosome moves to the next codon
post translation processing

Question 6

Explain why the virus is unable to synthesis its own capsid?

Answer 6

does not posess any ribosomes/organelles
for protein synthesis
does not possess mitochondria/cannot produce its own ATP for process

Question 7

Calculate the magnification that was used to take the photomicrograph?

Answer 7

13mm
13x10000 = nanometres
23000032.3 = 402.48

Question 8

Structure of the cell wall?

Answer 8

straigh chains of beta glucose
which provides strength to the cell wall
when the solute potential changes, water potential will also change, cauisng water to move into the cell wall prevents osmotic lysis/ cell bursting

Question 9

Identify 2 differences and one similarity between these 2 species?

Answer 9

Both contain ribosomes /cell membranes/dna
spogyra
membrane bound organelles
both enclosed within nuclear membrane
linear DNA
80 s ribosome

nostoc
membrane bound organelles
dna free in cytoplasm
loop of dna
70s ribosomes

Question 10

1 biochemical test that the student could have carried to distinguish between 2 solutions?

Answer 10

biuret - copper sulphate + sodium hydroxide
blue to purple - no heat
heat both solutions with acid ( neutralise with naoh)
add benedicts reagent - copper sulphate + potasium hydroxide
blue to brick red

Question 11

2 additional variables that the student should control to ensure that results recorded would be repeatable?

Answer 11

temperature
enzyme concentration
wavelength of light
method of mixing it

Question 11

What conclusions can be drawn from the data regarding the hypothesis being tested?

Answer 11

hypothesis is incorrect
fastest rate of reaction where the largest volume produced is at volume 4
rate of reaction= 3 times faster at pH 4 than at pH7

Question 12

With reference to the data explain how and why you would modify the method to determine the optimum pH more accurately?

Answer 12

there is overlap in the repeat reading at low pH
repeat the experiment with a range of intermediate values between pH 3-5

Question 13

Use the information provided to describe how oxygen and sodium ions cross the membrane?

Answer 13

Oxygen is lipid soluble so diffuses across the phospholipid bilayer
sodium ions are cotransported with glucose throughout the channel and carrier proteins
movement through the channel can be by active transport as channel is lined with polar charges

Question 14

Explain why it is important for the survival of the carp to produce large volumes of dilute urine?

Answer 14

% ion composition of fresh water is lower than in the carps blood plasma
the water potential of fresh water is higher than the water potential of the blood
carp takes in water through the gills by osmosis
the carp produces large volumes of dilute urine
preventing osmotic ions of the cell
maintains ion composition

Question 15

They are important in maintaining the ion composition of the blood plasma?

Answer 15

% ion composition of sea water is greater than the blood plasma / sea water is hypertonic
ions will move into blood plasma by facilitated diffusion
therefore ions must be actively transported out of blood plasma in the surrounding sea water

Question 16

Suggest which cell was taken from the salmon in fresh water and which was aken from the salmon whilst in sea water?

Answer 16

Cell 1 is from the salmon in the sea water
contains more mitochondria to provide ATP for respiration/active transport

Question 17

Scientists concluded that one of the causes of death in these animals is their inability to maintain blood plasma ion concentrations?

Answer 17

as the percentage of ion composition of the blood plasma is higher than surrounding water
ions will move out of the fish by facilitated diffusion
acidificaion will denature the channel proteins in the specalised cells
therefore fewer ions is actively transported into fish