Corrections

Question 1

What features do bacterium’s have? Which ones do HIV share?

Answer 1

They have RNA to major proteins, enzymes to catalyse reactions and a cell wall. They have flagellum, mesosomes ( used in respiration ) and are surrounded by a CAPSULE unlike eukaryotes.

HIV does not have a cell wall, but has RNA due to its generic code. It also have enzymes ( eg RNA reverse transcriptase from DNA to RNA ) and is surrounded by genetic matieral called a capsid.

Question 2

Why can an enzyme sometimes not digest?

Answer 2

It may not have a complementary shape so it cannot bind.

Question 3

How is ATP reysnthesised, and it’s used?

Answer 3

By ADP and phosphate ion using ATP synthase

Provides energy for other reactions
Adds phosphate to other substances and makes them more reactive

Question 4

How do we know if a SEM is being used?

Answer 4

3D image and black and white

Question 5

What is the benefit of the hydrolysis of sucrose for plants?

Answer 5

Produces fructose and glucose

Glucose can be used in respiration to produce ATP for growth

Question 6

Describe induced fit enzyme model

Answer 6

Before the enzyme binds, active site is not complementary to the shape of the substrate. The shape of the active site changes as the substrate binds to accommodate to the substrate, bending bonds in the substrate.

Question 7

Conc time graph description for enzyme

Answer 7

Initially, there is a high rate of reaction due to plenty of starch substrates and lots of ESC complexes. Then, the increase in concentration of maltose ( product ) slows down/decreases as starch ( substrate ) is used up.

LEVELS off when no substrate left.

Question 8

How do you gather data for an absorbance conc graph?

Answer 8

1) use different concentrations of maltose ( eg ) and produce the known concentrations
2) measure the colourimeter value and absorbance of each solution
3) plot this on a calibration curve

Y axis = absorbance

X axis = concentration

DRAW A CURVE

Use the absorbance to find the conc of sample from calibration curve

Question 9

How do vaccines lead to antibody production?

Answer 9

The vaccine has an antigen. This antigen is displayed on the surface and forms an APC. Specific T helper cells bind to this and are activated. These undergo mitosis to produce B plasma cells. B blasma cells produce antibodies.

Question 10

How do u use a eyepiece graticule

Answer 10

Measure each stoma using an eyepiece graticule

Calibrate the eyepiece graticule against a stage micrometer

Take a number of measurements

Question 11

Use the word FEWER and I’m being so fr

Question 12

Exam q ; why does this antibody only damage nerve cells

Answer 12

The antibody is a protein wirh a specific tertiary structure. It has a binding site which is complementary to only one antigen. The antigen for this antibody is only found on nerve cells, so the antibody only binds to this antigen forming an antigen antibody complex

Question 13

What makes results not valid?

Answer 13

• no use of statistical test
• weak correlation
• only one study
• missing data ( i,e no information ) so you cannot compare everything

Question 14

Why do all cells have a mutation?

Answer 14

This is because the cells are all derived from a zygote ( singe cell ). Mitosis occurs produces genetically identical cells so they all have the mutation

Question 15

Exam Q : gap in pulmonary artery

Answer 15

Oxygenated blood from aorta leaks into the pulmonary artery

Less oxygen delivered to cells, and not enough oxygen for aerobic respiration

Question 16

Describe the cohesion tension theory of the xylem

Answer 16

Water is lost in the leaf through transpiration

This lowers the water potential of the plant cells

Therefore, water is pulled up the xylem creating tension

Water molecules are cohesive and therefore stick together to form a continuous column/stream

Adhesion forces between water and walls of xylem

Question 17

How do we form mRNA?

Answer 17

This is by breaking hydrogen bonds to separate DNA strands.

The template strand is used to make mRNA.

Complementary base pairing therefore A U C G

RNA nucleotides join by RNA polymerase

We form mRNA by removing introns

Question 18

Explain the release of red pigment from beetroot when increased temp

Answer 18

Proteins denature

Damage to the plasma me,brand

There is an increased fluidity

Question 19

How a sigmoid curve formed?

Answer 19

When the first oxygen molecule binds, causes a change in shape

Therefore allows more oxygen to bind

COOPERATIVE BINDING

Question 20

Describe trends as significant/large increase

Question 21

How do structures hve different tertiary stuctures?

Answer 21

Due to different sequences of amino acids and forms hydrogen and ionic bonds in different places

Question 22

Why do we press on a cover slip?

Answer 22

To spread out cells so light passes through

Question 23

How could it be ensured the mitotic index was ACCURATE?

Answer 23

Repeat counts to ensure the figures are correct

Examine larger field of views to ensure it is a representative sample

Question 24

Why do we use controls?

Answer 24

This is to compare the effects of other treatment, and see the effect of the given substance,

Question 25

How can differences in the primary structure of haemoglobin be used to provide evidence for phylogenetic relationships?

Answer 25

Mutations cause a change in the DNA base sequence. A change in the DNA base sequence causes a change in the sequence of amino acids. If there are more differences in the sequence of amino acids, there is more distantly related.

Closely related mutations have fewer mutations and therefore less differences in sequences of amino acids.

Distant related species have an earlier common ancestor, but closely related species have a recent common ancestor.

Question 26

Compare and contrast eukaryotic and prokaryotic DNA

Answer 26

Eukaryotic

Bound/ associated with histones
Longer
Linear ( whereas prokaryotic is circular )
Contains introns ( non coding regions )

Similarities

Both have the same nucleotide structure and joined by phosphodiester bonds

Similar DNA in mitochondria and chloroplasts

Question 27

Reasons why the antibiotic resistance bacteria is more common, and why does percentage of resistant remain constant?

Answer 27

If used in a higher dosage, resistant bacteria is more likely to survive and pass on alleles to offspring for resistance

Bacteria is always reproducing THERREFORE pass on the resistant allele. No selection pressure against resistant bacteria

Question 28

How can this method be improved for data collection ( biodiversity )?

Answer 28

Collect at more times of year so more points for LOBF

Collect number of individuals so you can calculate index of diversity

Collect from more sites to increase accuracy of mean data

Question 29

How does an ES complex increase the ROR?

Answer 29

It reduces the activation energy by bending bonds

Question 30

What do we calculate the index of diversity with?

Answer 30

The number of individuals of each species

Question 31

How to ensure the diversity of index is representative?

Answer 31

Use a larger sample or random sample

Question 32

Why does biodiversity decrease when we use larger fields?

Answer 32

Less species

Question 33

How do arterioles reduce blood flow?

Answer 33

The walls of the smooth muscle contract and this constricts lumen of arteriole

Question 34

How do you reduce uncertainties?

Answer 34

Use instruments with finer graduations

Question 35

How does the structure of a protein depends on the amino acids it contains?

Answer 35

The structure is determined by the relative position of the R group.

Tertiary structure determined by interactions between R groups.

Question 36

What is passive immunity and active immunity? Compare

Answer 36

Passive immunity is introducing antibodies into the body from the outside. They have no memory cells and plasma cells. It has short term immunity as the antibody breaks down. Active immunity is the production of antibodies by plasma cells following exposure to a pathogen. It does involve production of memory and plasma cells. It provides long term immunity as antibody is produced in response to an antigen. Active can take time, passive is fast acting