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AS Biology (F211) - Jan 2013 Unofficial Mark Scheme

I tried to come up with the questions and answers from memory, so feel free to correct me where I'm wrong

1.
a. List three reasons why large animals, such as mammals, need a transport system. [3]

•

Small Surface Area:Volume ratio/Idea diffusion too slow;

•

High metabolic activity requires a lot of nutrients;

•

Cells near the surface can get the nutrients/nutrients used up by the time they reach cells deeper in the organism;

•

Transport system needed to supply cells deeper in the organism

b. Give the full name of the diagram used to measure electrical impulses. [1]

•

Electrocardiogram (trace);

c. Give the name of the labels A and B in the Insert. [2]

•

A - Sinoatrial Node/Pacemaker;

•

B - Atrioventricular Node;

d. Why is it important that the electrical impulse is delayed? [2]

•

Allows the blood to flow into the ventricles from the atria;

•

Increasing the blood pressure in the ventricles;

•

Causing the aortic/pulmonary valves to open;

e. Explain why the electrical impulse travels to the apex of the heart. [2]

•

To create the contraction of the ventricles from the bottom;

•

To push the blood up and out of the aorta/pulmonary artery;

2.
a. What is the name of the process of asexual reproduction in yeast cells? [1]

•

Budding/Binary Fission;

b. Outline the process of asexual reproduction in yeast cells. [2]

•

Mitosis occurs in the nucleus of the yeast cell;

•

A bulge develops on the side of the cell;

•

Cell membrane remains intact/cell organelles move the the bud;

•

bud splits from the yeast cell to produce a genetically identical daughter cell;

c. Ignoring the number of scars on the diagram, calculate the number of times the yeast cell could reproduce. [2]

•

Mark for working - Surface Area of Yeast Cell / Area of Scar - (4*3.14*1.5²)/(3.14*0.5²);

•

Mark for answer - 36;

d. Explain why the yeast cell might not be able to reproduce to its potential. [2]

•

Scars are circular;

•

So can not occupy total surface area/spaces between circular scars;
or

•

Cell Cycle mainly in Interphase;

•

So yeast Cells may die before reproducing 36 times;

e. (QWC) Explain how cells are organised in a multicellular organism [5]

•

A tissue is a group of cells working together to perform a function;

•

Example of tissue/function;

•

An organ is a group of tissues working together to perform a function;

•

Example of organ/function;

•

An organ system is a group of organs working together to perform a life function;

•

Example of organ system/function;

•

AVP;

•

Use of 3 of the following words in correct context: tissue, organ, organ system, specialised...

3.
a. What is missing from the students table? [2]

•

Units of Measurement;

•

Used to calculate rate of bubble movement;
or

•

Table of results;

•

Used to calculate mean rate.

b. Describe and explain the results on the table. [3]

•

As the number of leaves increase, the mean rate of bubble movement increases;

•

Use of figures from the table;

•

Increased number of stomata/surface area;

•

Increase in transpiration;

c. Explain why the students statement would effect the result and how he could improve the experiment. [6]

•

Different Size leaves result in difference number of stomata/larger surface area;

•

Use shoots with similar size leaves;

•

Wet leaves creates a humid microclimate/Reduces water potential gradient;

•

Wait for the leaves to dry;

•

Heat increases rate of evaporation/Light causes stomata to open;

•

Control the temperature/light intensity e.g. windowless room;

4.
a. Complete the gaps in the paragraph. [3]

•

Fluid Mosaic Model;

•

Active;

•

Lipids/Oxygen/Carbon Dioxide;

•

Carrier

b. Explain what the term cell signalling means. [1]

•

Cell Signalling is a process that leads to communication and coordination between cells;

•

Example of cell signalling;

c. (QWC) Explain the process of cell signalling. [4]

•

Glycoproteins/Glycolipids in plasma membrane;

•

Receptor;

•

Cell Signalling Molecule/Example e.g. hormones/enzymes;

•

Bind to receptor;

•

Which has a complimentary shape;

•

Use 3 of the following terms in correct context: Receptor, Glycolipid, Glycoprotein, Complimentary shape...

5.
a. Which organelles are present in a plant cell, animal cell and bacterial cell? [4]

Table

1 mark for each correct row.

b. Which test tubes contained the following organelles? [4]

•

Nuclei - 1;

•

Ribosomes - 4

•

Mitochondria - 2

•

Lysosomes - 2

c. Which organelle from above is the smallest? [1]

•

Ribosome;

6.
a. Explain the importance of lignin. [3]

•

Waterproofs xylem vessel wall/Stops water loss from Xylem wall;

•

Creates pits to allow water transport from Xylem vessel to other tissues;

•

Pattern in Lignin allows it to be flexible;

•

Supports the Xylem vessel/stops it from collapsing;

b. Explain the importance of cartilage. [3]

•

C - rings to allow movement of food in trachea

•

Gives support to the trachea;

•

Stops it from collapsing during inhalation;

•

Allows the neck to bend without damaging trachea;

c. Comment on the data about surface area and volume of the body/lungs. [3]

•

Small Surface Area:Volume ratio

•

Insufficient for bodys need;

•

Need a specialised exchange surface;

•

Such as alveoli;

•

Which has a large surface area for more gaseous exchange;

Please note, these are only some of a wide range of answer. If you're answer isn't on here, it could still be correct.

(edited 11 years ago)

Scroll to see replies

Reply 1

QuantumSuicide

There are quite a few controversial answers on here. Some marks are also incorrect...

Reply 2

QuantumSuicide

Since when did plants not have cellulose cell walls? Sorry but this is a fail thread.

(edited 11 years ago)

Reply 3

Conclusive

Yes and also the 2 marks your missing aren't they for the second potometer question which is a 3 mark question..-
"Describe and explain the data in the students table [3]"

Reply 4

malparslan

Original post by SomePotential

I tried to come up with the questions and answers from memory, so feel free to correct me where I'm wrong

1.
a. List three reasons why large animals, such as mammals, need a transport system. [3]

•

Small Surface Area:Volume ratio/Idea diffusion too slow;

•

High metabolic activity requires a lot of nutrients;

•

Cells near the surface can get the nutrients/nutrients used up by the time they reach cells deeper in the organism;

•

Transport system needed to supply cells deeper in the organism

b. Give the full name of the diagram used to measure electrical impulses. [1]

•

Electrocardiogram (trace);

c. Give the name of the labels A and B in the Insert. [2]

•

A - Sinoatrial Node/Pacemaker;

•

B - Atrioventricular Node;

d. Why is it important that the electrical impulse is delayed? [2]

•

Allows the blood to flow into the ventricles from the atria;

•

Increasing the blood pressure in the ventricles;

•

Causing the aortic/pulmonary valves to open;

e. Explain why the electrical impulse travels to the apex of the heart. [2]

•

To create the contraction of the ventricles from the bottom;

•

To push the blood up and out of the aorta/pulmonary artery;

2.
a. What is the name of the process of asexual reproduction in yeast cells? [1]

•

Budding/Binary Fission;

b. Outline the process of asexual reproduction in yeast cells. [2]

•

Mitosis occurs in the nucleus of the yeast cell;

•

A bulge develops on the side of the cell;

•

Cell membrane remains intact/cell organelles move the the bud;

•

bud splits from the yeast cell to produce a genetically identical daughter cell;

c. Ignoring the number of scars on the diagram, calculate the number of times the yeast cell could reproduce. [2]

•

Mark for working - Surface Area of Yeast Cell / Area of Scar - (4*3.14*1.5²)/(3.14*0.5²);

•

Mark for answer - 36;

d. Explain why the yeast cell might not be able to reproduce to its potential. [2]

•

Scars are circular;

•

So can not occupy total surface area/spaces between circular scars;
or

•

Cell Cycle mainly in Interphase;

•

So yeast Cells may die before reproducing 36 times;

e. (QWC) Explain how cells are organised in a multicellular organism [5]

•

A tissue is a group of cells working together to perform a function;

•

Example of tissue/function;

•

An organ is a group of tissues working together to perform a function;

•

Example of organ/function;

•

An organ system is a group of organs working together to perform a life function;

•

Example of organ system/function;

•

AVP;

•

Use of 3 of the following words in correct context: tissue, organ, organ system, specialised...

3.
a. What is missing from the students table? [1]

•

Units of Measurement;

b. Explain why the students statement would effect the result and how he could improve the experiment. [6]

•

Different Size leaves result in difference number of stomata/larger surface area;

•

Use shoots with similar size leaves;

•

Wet leaves creates a humid microclimate/Reduces water potential gradient;

•

Wait for the leaves to dry;

•

Heat increases rate of evaporation/Light causes stomata to open;

•

Control the temperature/light intensity e.g. windowless room;

4.
a. Complete the gaps in the paragraph. [3]

•

Fluid Mosaic Model;

•

Active;

•

Lipids/Oxygen/Carbon Dioxide;

•

Carrier

b. Explain what the term cell signalling means. [2]

•

Cell Signalling is a process that leads to communication and coordination between cells;

•

Example of cell signalling;

c. (QWC) Explain the process of cell signalling. [4]

•

Glycoproteins/Glycolipids in plasma membrane;

•

Receptor;

•

Cell Signalling Molecule/Example e.g. hormones/enzymes;

•

Bind to receptor;

•

Which has a complimentary shape;

•

Use 3 of the following terms in correct context: Receptor, Glycolipid, Glycoprotein, Complimentary shape...

5.
a. Which organelles are present in a plant cell, animal cell and bacterial cell? [4]

Table

1 mark for each correct row.

b. Which test tubes contained the following organelles? [4]

•

Nuclei - 1;

•

Ribosomes - 4

•

Mitochondria - 2

•

Lysosomes - 2

c. Which organelle from above is the smallest? [1]

•

Ribosome;

6.
a. Explain the importance of lignin. [3]

•

Waterproofs xylem vessel wall/Stops water loss from Xylem wall;

•

Creates pits to allow water transport from Xylem vessel to other tissues;

•

Pattern in Lignin allows it to be flexible;

•

Supports the Xylem vessel/stops it from collapsing;

b. Explain the importance of cartilage. [3]

•

C - rings to allow movement of food in trachea

•

Gives support to the trachea;

•

Stops it from collapsing during inhalation;

•

Allows the neck to bend without damaging trachea;

c. Comment on the data about surface area and volume of the body/lungs. [3]

•

Small Surface Area:Volume ratio

•

Insufficient for bodys need;

•

Need a specialised exchange surface;

•

Such as alveoli;

•

Which has a large surface area for more gaseous exchange;

3 a was two marks

Reply 5

SomePotential

Original post by QuantumSuicide

Since when did plants not have cellulose cell walls?

Sorry, was a typo. Can't see the columns when using the table codes.

Original post by Conclusive

Yes and also the 2 marks your missing aren't they for the second potometer question which is a 3 mark question..-
"Describe and explain the data in the students table [3]"

Thanks

Original post by malparslan

3 a was two marks

Are you sure? I recalled it being 1 mark.

Reply 6

joe1545

If i was to go by this i would get 50/60 which should be an A, but im not sure i didnt check over everything, i could get more if the mark scheme is different or less :/

Reply 7

QuantumSuicide

Cell signalling was 1 mark. Defo!

Reply 8

phaseshift

The table question about what the student had left out was 2 marks as well. I do not think it was the units of measurement though.

The table of results was missing the individual test results that were used to calculate the mean.

Reply 9

mariam.therese

guys everyone thats throwing a hissy fit leave the poor chap alone. theyve done a good job at doing this, of course its not perfect because its not by the exam board...at least it gives us a 'rough' wait until march if you want to be picky.

Reply 10

rainingdewdrops

thanks a lot for this! but on the cartilage question isn't it the esophagus that does the swallowing of the food? also for 6a could you also include that it allows for adhesion because water is attracted to it?
finally im not sure if this is right but for 2d could you say because mutations were found in the checking process causing the cycle to start again?
thanks again!! this is very much appreciated :smile:

Reply 11

Euannn

Thank you, much appreciated :smile:

Reply 12

niveous

thank you so much, according to this, I got 49 despite getting the entire of that 5 mark question wrong cause I thought it wanted me to talk about the cytoskeleton... fml... anyway, thanks!

Reply 13

SomePotential

Original post by rainingdewdrops

The cartilage lets the oesophagus contract, sorry, that point could have been clearer in my post. For 6a, yes, you'd probably get the mark for that. For question 2d, I've heard of a range of different answers and I have no idea what the mark scheme will actually allow. Your point makes sense, it depends on how OCR makes the mark scheme.

Reply 14

mrdw

So binary fission is ok for 2a? I put that :/

Posted from TSR Mobile

Reply 15

own

Hi, do you think that one of the errors in the students table could be lack of time scale? :smile:

Also for the question about the structure of the body etc, the [5] does that include QWC?

Reply 16

own

Original post by niveous

thank you so much, according to this, I got 49 despite getting the entire of that 5 mark question wrong cause I thought it wanted me to talk about the cytoskeleton... fml... anyway, thanks!

Yeah i didn't put that, however at points in the paper I found it vague/not very obvious what they wanted. It was annoying as there was no question that I thought I could really stick my teeth into, such as a question about the phloem etc which was a shame :s-smilie:

Reply 17

sniperandak47

does anyone have any idea ,what the grade boundaries would be doesn't have to be exact ?

Reply 18

username967796

Original post by mrdw

So binary fission is ok for 2a? I put that :/

Posted from TSR Mobile

Binary fission is cell replication of bacterial cells

Posted from TSR Mobile

Reply 19

SomePotential

Original post by mrdw

So binary fission is ok for 2a? I put that :/

Posted from TSR Mobile

Yeast cells can divide by Binary Fission, but I don't think it's on our specification. I do recall seeing it on a previous mark scheme, so I decided to include it.

Original post by own

Hi, do you think that one of the errors in the students table could be lack of time scale? :smile:

Also for the question about the structure of the body etc, the [5] does that include QWC?

You might have to clarify that due to a lack of time scale you do not know the actual rate of bubble movement. But I don't know how harsh the actual markscheme will be. And yes, the [5] includes the QWC mark. So you'd need to make 4 points + 1 mark for QWC.

Original post by sniperandak47

does anyone have any idea ,what the grade boundaries would be doesn't have to be exact ?

I'd presume they'd be similar to last years Jan exam, so something like;
A - 43
B - 38
C - 33
D - 29
E - 25

Full UMS would be around 55, based on the only grade boundary I could find for full UMS which was from the June 2010 series.