EDEXCEL Biology Unit 2 6BIO2 21st May 2012

What does everyone reckon full ums will be on this one. I think I got around 75/80 looking at the unofficial mark scheme

I think I got somewhere in that region too, and I'm hoping for 100%.

In January my friend got 100% for his Unit 1 on only 72/80, so we may be pleasantly surprised. :-)

is it just me who has noticed the unofficial mark scheme is out of 73? what's happened to the other 7 marks?

Yes we are missing a question/s, or the marks have been awarded lower for the questions.

Yeah for that question I said one of the male nuclei's fusing with the two polar nuclei's to form the endosperm (3n), (food storage for the developing plant). I also said the other nuclei fuses with the gamete to form the developing plant cell..

I dunno if I would get any marks though :/

Why wouldn't you get any marks for that? :confused

Unofficial Mark Scheme (*Improvements)


1) Identify the organelles labelled: (3)
A - Rough endoplasmic reticulum
B - Mitochondria
C - Nucleolus

What moves to opposites sides on the cell during prophase: G/ Centrioles
What disappears during prophase: C / Nucleolus

*Some people wrote it instead of refering to letters, I think they will have an allow*

2) Fill in the blanks:
(beta) Glucose
Cellulose
Hydrogen (bonds)
Pits
Plasmodesmata

3) Why are all the fibres taken from the same plant: (1)
- So that they are all genetically identical/So genotype doesn't effect results
- Prevent Genetic varation

Why are the fibres dried and soaked at the same temperature? (1)
- So that temperature doesn't affect the results
- So they are stored in same conditions
- Only contrasting/independent variable is whether wet or dry

Which fibre is stronger: (or something along those lines) (2)
- The wet fibres, since they can support a greater mean mass than the dry fibres

Which results are less reliable? (2)
- The wet fibre result - wet fibres have a range of 1100, dry fibres have a range of 300, so smaller range = more reliable, wet fibre also had an anomolous result.

Dry fibres 3,4,5 had knot in them, so the results may have been underestimates
Give evidence that supports this: (1)
- The fact that 3 and 4 both had break forces lower than the mean.

Give evidence that doesn't support this (1)
- The fact that 5 was over the mean value of break force.
- 5 with a knot required same tensile strength as 1 which did not have a knot

Two things that had to be considered when selecting 10 fibres: (2)
- Length of fibre
- Diameter of fibre
- Mass of fibre?? (this is what I wrote but I'm not so sure whether it is right, can someone confirm this for me please!)

Why were safety goggles worn?
It can snap suddenly and hit your eye
- Protected eyes, if fibre unattached from digital meter
- Prevents Injury occurring

4) Why was the experiment carried out at 37 degrees: (1)
- That's (core) human body temperature
- Acts as a control as it's the same temperature as it was before incubation
- Act as comparison data to see the change in altering temperature again body temperature
Give a reason, for safety, for covering the beaker with clear plastic film: (2)
- Prevent contamination
- Prevent anerobis respiration
- Reduces chance of pathogenic bacteria growing

Give one reason, other than safety, for covering the beaker with clear plastic film: (1)
- To be able to see inside the beaker clearly? (This was my guess, can someone else suggest a better answer, please?)
- So light can enter for photosynthesis to occur.

Explain 3 ways in which the human sperm cell is adapted to it's function: (6)
- Has flagellum
= To be able to swim towards the egg cell for fertilisation to take place
- Has haploid nucelus
= So that full complement/diploid number can be restored at fertilisation
- Has acrosome in the head
= So that the zona pellucida can be digested when the sperm penetrates the egg cell.
- A lot of mitochondria
= Provide energy in the form of ATP so that the sperm can reach the egg cell. *Also assist flagellum in movement

5) Explain the term haploid nucleus: (2)
Contains half the number of chromosomes than a normal cell.

Describe the change in pH: (2)
- Begins at neutral
- pH increases then decreases
- Non Linear Pattern

Explain how happens to the amino acids from when they are made to when they are secreted as enzymes in the style: (6)
- Proteins enter rER
- They become packages into vesicles
- They assume their 3 dimensional shape
- They move to golgi apparatus/vesicles fuse with golgi
- Proteins are modified
- Become packed into vesicles, again
- Vesicles leave golgi/ fuse with cell surface membrane
- Proteins are secreted from vesicles via exocytosis

6) Why was Drug P chosen instead of Drug Q:
49% - P Range (45-51)
46% - Q Range (41-51)
- Drug P has a lower range than Q (at 6% compared to 10%) which means that it is more likely that people will benefit from the drug, it is more reliable as a treatment option.
- Drug P is 3% (or 4%) more successful than Q.
- Both drugs are trying to cure the same illness so it is better to choose the more effective drug as the only one to be prescribed.
-Both drugs have been through a three phase trial and so are considered safe for general distribution

Tick boxes: (2)
Doesn't treat humans effectively:
Phase 2
At which phase did they stop due to effects being different from what was observed on animals:
Phase 1

Pie chart question, identify and explain which section represents phase 3:
C (the largest segment)
Reason: Phase 3 testing is carried out on a big scale

Tick if present in both William Withering and current testing, cross if not: (3)
Tested for correct dosages - Yes
Tested on animals - No
Carries out doubleblind trials - No

7) What organ is shown: (1)
C - Stem
*This is WRONG, the answer is Leaf

What two structures shown in the diagram contain lignin: (1)
B - Q and R

Define the term tissue:
A group of similar cells working together to carry out a function.

Tissue present at U show totipotency. Explain why tissue from R would not be used instead of U. (3)
- R represents xylem vessels
- Xylem tissue is differentiated for their function
- Lignin is impregnanted in Xylem
- They are dead tissue that cannot divide by mitosis to become new cells
- Xylem tissue are not unspecialised and will not show totipotency


8) Size of seed: 7mm
Reason: Because it has the highest germination success

What was the increase, in percentage, from 3mm to 6mm:
What I did was:
20 - 4 = 16
16/20 * 100 = 80%
But I know there's been a lot of confusion about this question so I'm not sure what the actual answer is but from what has been said by the majority of people on this thread, it's either 80% or 400%.
(20-4/4) * 100 = 400%

Why is it useful to store different species of seeds? (3)
- Increase genetic diversity
- Prevent inbreeding
- Genetic variation

What do seedbanks do in order to ensure long-term survival? (4)
- Reference to drying the seeds
- Reference to storing them in cold conditions
- Check seeds regularly for viability
- Keep in sterile conditions to prevent airbourne contaminents competiting with seeds, or encouraging process of decay




Hope I cleared this up for people who felt there answers were not there.

Unofficial Mark Scheme (*Improvements)


1) Identify the organelles labelled: (3)
A - Rough endoplasmic reticulum
B - Mitochondria
C - Nucleolus

What moves to opposites sides on the cell during prophase: G/ Centrioles
What disappears during prophase: C / Nucleolus

*Some people wrote it instead of refering to letters, I think they will have an allow*

2) Fill in the blanks:
(beta) Glucose
Cellulose
Hydrogen (bonds)
Pits
Plasmodesmata

3) Why are all the fibres taken from the same plant: (1)
- So that they are all genetically identical/So genotype doesn't effect results
- Prevent Genetic varation

Why are the fibres dried and soaked at the same temperature? (1)
- So that temperature doesn't affect the results
- So they are stored in same conditions
- Only contrasting/independent variable is whether wet or dry

Which fibre is stronger: (or something along those lines) (2)
- The wet fibres, since they can support a greater mean mass than the dry fibres

Which results are less reliable? (2)
- The wet fibre result - wet fibres have a range of 1100, dry fibres have a range of 300, so smaller range = more reliable, wet fibre also had an anomolous result.

Dry fibres 3,4,5 had knot in them, so the results may have been underestimates
Give evidence that supports this: (1)
- The fact that 3 and 4 both had break forces lower than the mean.

Give evidence that doesn't support this (1)
- The fact that 5 was over the mean value of break force.
- 5 with a knot required same tensile strength as 1 which did not have a knot

Two things that had to be considered when selecting 10 fibres: (2)
- Length of fibre
- Diameter of fibre
- Mass of fibre?? (this is what I wrote but I'm not so sure whether it is right, can someone confirm this for me please!)

Why were safety goggles worn?
It can snap suddenly and hit your eye
- Protected eyes, if fibre unattached from digital meter
- Prevents Injury occurring

4) Why was the experiment carried out at 37 degrees: (1)
- That's (core) human body temperature
- Acts as a control as it's the same temperature as it was before incubation
- Act as comparison data to see the change in altering temperature again body temperature
Give a reason, for safety, for covering the beaker with clear plastic film: (2)
- Prevent contamination
- Prevent anerobis respiration
- Reduces chance of pathogenic bacteria growing

Give one reason, other than safety, for covering the beaker with clear plastic film: (1)
- To be able to see inside the beaker clearly? (This was my guess, can someone else suggest a better answer, please?)
- So light can enter for photosynthesis to occur.

Explain 3 ways in which the human sperm cell is adapted to it's function: (6)
- Has flagellum
= To be able to swim towards the egg cell for fertilisation to take place
- Has haploid nucelus
= So that full complement/diploid number can be restored at fertilisation
- Has acrosome in the head
= So that the zona pellucida can be digested when the sperm penetrates the egg cell.
- A lot of mitochondria
= Provide energy in the form of ATP so that the sperm can reach the egg cell. *Also assist flagellum in movement

5) Explain the term haploid nucleus: (2)
Contains half the number of chromosomes than a normal cell.

Describe the change in pH: (2)
- Begins at neutral
- pH increases then decreases
- Non Linear Pattern

Explain how happens to the amino acids from when they are made to when they are secreted as enzymes in the style: (6)
- Proteins enter rER
- They become packages into vesicles
- They assume their 3 dimensional shape
- They move to golgi apparatus/vesicles fuse with golgi
- Proteins are modified
- Become packed into vesicles, again
- Vesicles leave golgi/ fuse with cell surface membrane
- Proteins are secreted from vesicles via exocytosis

6) Why was Drug P chosen instead of Drug Q:
49% - P Range (45-51)
46% - Q Range (41-51)
- Drug P has a lower range than Q (at 6% compared to 10%) which means that it is more likely that people will benefit from the drug, it is more reliable as a treatment option.
- Drug P is 3% (or 4%) more successful than Q.
- Both drugs are trying to cure the same illness so it is better to choose the more effective drug as the only one to be prescribed.
-Both drugs have been through a three phase trial and so are considered safe for general distribution

Tick boxes: (2)
Doesn't treat humans effectively:
Phase 2
At which phase did they stop due to effects being different from what was observed on animals:
Phase 1

Pie chart question, identify and explain which section represents phase 3:
C (the largest segment)
Reason: Phase 3 testing is carried out on a big scale

Tick if present in both William Withering and current testing, cross if not: (3)
Tested for correct dosages - Yes
Tested on animals - No
Carries out doubleblind trials - No

7) What organ is shown: (1)
C - Stem
*This is WRONG, the answer is Leaf

What two structures shown in the diagram contain lignin: (1)
B - Q and R

Define the term tissue:
A group of similar cells working together to carry out a function.

Tissue present at U show totipotency. Explain why tissue from R would not be used instead of U. (3)
- R represents xylem vessels
- Xylem tissue is differentiated for their function
- Lignin is impregnanted in Xylem
- They are dead tissue that cannot divide by mitosis to become new cells
- Xylem tissue are not unspecialised and will not show totipotency


8) Size of seed: 7mm
Reason: Because it has the highest germination success

What was the increase, in percentage, from 3mm to 6mm:
What I did was:
20 - 4 = 16
16/20 * 100 = 80%
But I know there's been a lot of confusion about this question so I'm not sure what the actual answer is but from what has been said by the majority of people on this thread, it's either 80% or 400%.
(20-4/4) * 100 = 400%

Why is it useful to store different species of seeds? (3)
- Increase genetic diversity
- Prevent inbreeding
- Genetic variation

What do seedbanks do in order to ensure long-term survival? (4)
- Reference to drying the seeds
- Reference to storing them in cold conditions
- Check seeds regularly for viability
- Keep in sterile conditions to prevent airbourne contaminents competiting with seeds, or encouraging process of decay


Hope I cleared this up for people who felt there answers were not there.

The correct answer is stem ...
Just because you wrote 'leaf' in the exam does not make it correct ...

Leaf is an organ comprised of tissues ...

Yeah pretty much so. I had the same answers as you had throughout, but I want to keep my hopes low though.

By the way, have you covered all the questions?, because i calculated all the marks up on your unofficial MS and it comes to 70. something, but I may have missed something out somewhere.

@simplegirl
I think it was the spindle fibre thing that you missed out
the meiosis question? in human body temp thingy

Erm, I vaguely recall something to do with spindle fibres but I'm not sure. Do you remember the exact question?

The correct answer is stem ...
Just because you wrote 'leaf' in the exam does not make it correct ...

Leaf is an organ comprised of tissues ...