OCR A-level Biology A Biological diversity - 13th June 2019 Unofficial Markscheme Watch

1865Cloudie
Badges: 6
Rep:
?
#1
Report Thread starter 3 days ago
#1
Define osmosis : the process by which water moves across partially permeable membranes down a water potential gradient

Why is osmosis important for the shape of plants

Water moves into cells down a water potential gradient this Increases hydrostatic pressure on cell wall in cell maintaining turgidity. This allows stomata to open only when turgid. Without osmosis plant cells would be flaccid and would not keep the plants shape.

Solution level increased inside capillary tube X . What can be said about the composition of tube X and Tube Y and explain why?

Tube Y is hypotonic (more dilute and higher water potential than X. Therefore water moves in by osmosis down a diffusion gradient into X as X is hypertonic (lower water potential less dilute than Y ) until equilibrium is met.

Explain different levels in biodiversity or something
Species diversity
Habitat biodiversity
Genetic diversity
Go on to talk about species evenness and the effects of low species evenness , few dominant species , specific adaptations , lower genetic diversity resulting in a lesser ability to adapt to environment. Visa Versa

Explain the process of coppicing and how it increases biodiversity

Cut trees low down but do not remove them from the ground provides a sustainable way on obtaining timber etc etc Rotational coppicing
More light to the ground of woodland more access to light more photosynthesis . Plants grow this provides more habitats this increases habitat diversity and species biodiversity of plants . Habitats becomes more available so more species move in increasing species diversity as there are more places to live. This in turn increases genetic diversity leading to more resistance to disease etc etc

Importance of water density for living organisms
- insulating layer as when water freezes it’s less dense than liquid
- temperature buffer - high specific heat capacity
- coolant high latent heat of evaporation.

DNA purification forgot to revise lol


Last Q about try tryglycerides
2 marks explain hydrolysis
Tryglycerides has 1 glycerol
3 fatty acids with ester linkages
Hydrolysis reactions breaks the ester linkages using water to produce 3 fatty acids and 1 glycerol

Why did they use percentage change
Because they kept surface area the same that does not necessarily mean the same mass
. Makes results more comparable.

How did tourists increase biodiversity
Increase funding for conservation groups and local people to contribute to the ecosystem.
Funding allows them to restore ecosystems and therefore increase habitat and species biodiversity

Why is dolly the sheep not the same as the tadpole

- embryo is implanted into surrogate mother
- here it just becomes a tadpole then a frog

0.69 for simpsonis, and 45.3% for hardy weinberg

Why does gene therapy not work to cure Huntington’s disease
Gene therapy does not work for Huntington’s Huntington’s disease in genetically inherited, in order to cure it germ line therapy must take place which is illegal

Addition of a gene would alter other genes

A gene could be inserted into another gene making the original gene non functioning

Control variable of pregnancies

- type of mouse , monkey , sheep should be the same As the have different reproductive potential
Same conditions for each individual within each type of animal ie same heat food water
- same number of original pregnancies

6 marker on plant fertilisation validity

- Control temperature , ph of soil , light exposure , humidity,
- Keep the concentration of fertiliser the same and add equal volumes at regular intervals over a period of time
- Repeat the process at least 3 times this allows us to identify anomalies and disregard them and calculate a mean and therefore a statistical test such as the T test
- Make sure both plants have the same surface area of leaves at first to reduce affect of transpiration


Which one has the highest sucrose concentration
Courgette as the concentration of sucrose increases from 0 to 0.7. The percentage change in mass decreases the least. This means that water is moving via osmosis down a water potential gradient into courgette at the slowest rate or something like that I’m weird lol
3
reply
Sara saeed
Badges: 9
Rep:
?
#2
Report 3 days ago
#2
Please write the answers to the question you remember! OCR PAPER 2
Last edited by Sara saeed; 3 days ago
0
reply
Evil Homer
Badges: 16
Rep:
?
#3
Report 3 days ago
#3
(Original post by Sara saeed)
Please write the answers to the question you remember!
What exam board is this for?
0
reply
Sara saeed
Badges: 9
Rep:
?
#4
Report 3 days ago
#4
(Original post by Evil Homer)
What exam board is this for?
OCR
Posted on the TSR App. Download from Apple or Google Play
0
reply
12kirn
Badges: 2
Rep:
?
#5
Report 3 days ago
#5
What did people put for cloning/vegetative propagation?
0
reply
Rosiepointon5
Badges: 5
Rep:
?
#6
Report 3 days ago
#6
Cut from shoot tip - explant
Sterelise to kill micro organisms
Grows into a callus
Seperate and Re plant into greenhouse
(Original post by 12kirn)
What did people put for cloning/vegetative propagation?
4
reply
KaasimAnwarr
Badges: 8
Rep:
?
#7
Report 3 days ago
#7
It never asked about the process for that it asked about the advantages. It asked about the process for plant cuttings.
(Original post by Rosiepointon5)
Cut from shoot tip - explant
Sterelise to kill micro organisms
Grows into a callus
Seperate and Re plant into greenhouse
15
reply
y.u.mad.bro?
Badges: 21
Rep:
?
#8
Report 3 days ago
#8
(Original post by KaasimAnwarr)
It never asked about the process for that it asked about the advantages. It asked about the process for plant cuttings.
Nope. The first question was how to carry out the process and the advantages question was after that.
7
reply
KaasimAnwarr
Badges: 8
Rep:
?
#9
Report 3 days ago
#9
The advantages for vegetative propagation I put were that you get many clones per plant and that you can choose desirable characteristics.

The process for plant cuttings is cutting a section off the plant (I.e. stem- I also mentioned that you cut between leaf joints). Then dip the base in rooting hormone/powder. Root grows and plant develops, etc
(Original post by KaasimAnwarr)
It never asked about the process for that it asked about the advantages. It asked about the process for plant cuttings.
6
reply
KaasimAnwarr
Badges: 8
Rep:
?
#10
Report 3 days ago
#10
I don’t remember that, does anyone else?
(Original post by y.u.mad.bro?)
Nope. The first question was how to carry out the process and the advantages question was after that.
1
reply
nicholasflee
Badges: 13
Rep:
?
#11
Report 3 days ago
#11
what did you guys get for the multiple choice question on hox genes, i wasn't sure between the two options. One said that the sequence varies between taxonomic levels, produced transcription factors and mutations were random, the other said that the sequence was similar between animals, produced polypeptides and caused lethal mutations. Am not sure which one
0
reply
KaasimAnwarr
Badges: 8
Rep:
?
#12
Report 3 days ago
#12
I think I wrote about it being lethal
(Original post by nicholasflee)
what did you guys get for the multiple choice question on hox genes, i wasn't sure between the two options. One said that the sequence varies between taxonomic levels, produced transcription factors and mutations were random, the other said that the sequence was similar between animals, produced polypeptides and caused lethal mutations. Am not sure which one
11
reply
KaasimAnwarr
Badges: 8
Rep:
?
#13
Report 3 days ago
#13
Well ticked that one, not wrote about it😅
(Original post by KaasimAnwarr)
I think I wrote about it being lethal
0
reply
Kodyyy
Badges: 3
Rep:
?
#14
Report 3 days ago
#14
Yhh that question was there
(Original post by KaasimAnwarr)
I don’t remember that, does anyone else?
1
reply
KaasimAnwarr
Badges: 8
Rep:
?
#15
Report 3 days ago
#15
What did it ask exactly? I’m sure there was one on plant cuttings because people from my college remembered it too. I’m don’t remember the exact question?
(Original post by Kodyyy)
Yhh that question was there
0
reply
KaasimAnwarr
Badges: 8
Rep:
?
#16
Report 3 days ago
#16
I*
(Original post by KaasimAnwarr)
What did it ask exactly? I’m sure there was one on plant cuttings because people from my college remembered it too. I’m don’t remember the exact question?
0
reply
nicholasflee
Badges: 13
Rep:
?
#17
Report 3 days ago
#17
(Original post by KaasimAnwarr)
I think I wrote about it being lethal
don't hox genes make transcription factors?
3
reply
Cerysoliver
Badges: 3
Rep:
?
#18
Report 3 days ago
#18
Did anyone else get 0.6 something for Simpsons Diversity index and 45.3 (D I think) for hardy Weinberg??
22
reply
positivee
Badges: 8
Rep:
?
#19
Report 3 days ago
#19
What did everyone get for the hardy Weinberg Mcq
0
reply
KaasimAnwarr
Badges: 8
Rep:
?
#20
Report 3 days ago
#20
I wasn’t confident about that so I might’ve gotten it wrong tbh

(Original post by nicholasflee)
don't hox genes make transcription factors?
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • Manchester Metropolitan University
    Undergraduate Open Day Undergraduate
    Wed, 19 Jun '19
  • University of West London
    Undergraduate Open Day - West London Campus Undergraduate
    Wed, 19 Jun '19
  • University of Warwick
    Undergraduate Open Day Undergraduate
    Fri, 21 Jun '19

How did your AQA A-level Biology Paper 2 go?

Loved the paper - Feeling positive (449)
19.03%
The paper was reasonable (1101)
46.65%
Not feeling great about that exam... (519)
21.99%
It was TERRIBLE (291)
12.33%

Watched Threads

View All