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Cell Division Mark Scheme

Level Edexcel

Subject Biology

Exam Board GCSE(9-1)

Topic Cells and Control

Sub Topic Cell Division

Booklet Mark Scheme

Time Allowed: 41 minutes

Score: /34

Percentage: /100

Question Number

Answer Acceptable answers Mark

1(a) A differentiate into any type of cell (1)

Question Number


1(b) Any two structures from the list with at least one matched adaptation:

Structures (maximum of 2)

• biconcave shape (1)• no nucleus (1)• thin membrane (1)• flexible / small (1)• contains haemoglobin (1)

(matched) adaptation (maximum of 2)

• large surface area / increaseoxygen uptake (1)

• to increase amount ofhaemoglobin / oxygen-carryingcapacity (1)

• so short distance for diffusion(1)

• to get through capillaries (1)• to bind oxygen (1)

(3)

Question Number


1(c) A description including two of the following points

• clotting / to seal a wound /scab formed (1)

• stop bleeding (1)

• prevent infection / entry ofmicrobes (1)

• fibrin (1)(2)


Question Number

Indicative Content Mark

1(d) QWCQ A comparison between mitosis and meiosis including

Mitosis • (genetically) identical cells produced• two daughter cells• one division• diploid daughter cells• identical set of chromosomes• occurs in the formation of body cells• for growth and repair (of body tissues)

Meiosis • (genetically) non-identical cells• four daughter cells• 2 divisions• haploid daughter cells• half the number of chromosomes• occurs in the formation of gametes• for sexual reproduction• results in genetic variation (6)

Level 0 No rewardable content 1 1 - 2 • a limited description including two points on either meiosis or

mitosis there maybe confusion between the two but this does notnegate the level

• the answer communicates ideas using simple language and useslimited scientific terminology

• spelling, punctuation and grammar are used with limited accuracy2 3 - 4 • a simple description including one comparison of meiosis and

mitosis or a detailed description of either mitosis or meiosis• the answer communicates ideas showing some evidence of clarity

and organisation and uses scientific terminology appropriately• spelling, punctuation and grammar are used with some accuracy

3 5 - 6 • a detailed comparison of both meiosis and mitosis – at least twocorrect comparisons made

• the answer communicates ideas clearly and coherently uses a rangeof scientific terminology accurately

• spelling, punctuation and grammar are used with few errors



Question Number


2(a)(i) 0.5 / 0.5 picogram Accept: 0.5 picograms

accept: the same (mass) as the sperm cell (1)

Question Number


2(a)(ii) C haploid (1)

Question Number


( thymine with adenine, cytosine with guanine

(1)

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2(a)(iv) weak hydrogen bonds / hydrogen bonds / hydrogen (1)

H (bond) (1)

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2(b)(i) A description including three of the following points:

• cell divides / cell division /cell splits(1)

• two cells produced (1)

• (both) diploid (1)

• (both) cells are geneticallyidentical (1)

credit correct reference to stages of mitosis: DNA replication / chromosomes duplicate (1) Chromosomes line up along the equator / middle of the cell (1) chromosomes pulled to either end of cell (1) cytokinesis / cytoplasm splits (1) (3)

2(a)(iii)


Question Number


2(b)(ii) A description including three of the following points:

• ref (to many) cell divisions/ eq (1)

• growth (1)

• ref to differentiation /specialisation (1)

• ref to stem cells (1)

accept: gets bigger / larger

accept: become specific cells

(3)


Question Number


3(a)(i) Correct substitution i.e. (-0.5 ÷ 10.3) x 100 (1)

- 4.85 / - 4.9

Accept data correctly put into other acceptable methods.

Accept answer with more decimal places eg: - 4.8543 / - 4.854368932

Full marks for correct bald answer award max of one mark if negative is not written eg 4.85 / 4.9

(2)

Question Number


3(a)(ii) better / easier / more valid comparison can be made between values /can make more valid conclusion / because the original / starting masses of potato were not the same / Idea of easier to visualise the size of the change

Ignore makes the results / test reliable / accurate

(1)


Question Number


3(b) A description including the following:

Produce two (daughter)cells

which are geneticallyidentical

and diploid

Accept DNA for chromosomes throughout

Also credit details of the process of mitosis

chromosomes replicates (1)

spindle fibres form / chromosomes attached to spindle (1)

Chromosomes arranged on equator / middle of cell / chromosomes pulled apart /pulled to poles /separation of sets of chromosomes (1)

Idea of nucleus reforming / New cell wall formed (to divide cell) / cytokinesis / description of cytokinesis (1)

(3)


(Total for question 3 = 12 marks)

Question Number


QWC *3(c) A explanation to include some of the following points

active transport requires energy (active transport moves mineral ions) from the soil into root (hair cells) reference to pumps (in the cell membranes) from a low concentration to a high concentration/against

their concentration gradient

reference to mineral ions / mineral salts accept namedminerals eg nitrates

diffusion is a passive process gases diffuse from high to low concentration/down their

concentration gradient

gas exchange in the leaf occurs by diffusion carbon dioxide diffuses in to air spaces in leaves / into cells for photosynthesis / produces glucose oxygen diffuses in for respiration (6)

Level

0 No rewardable content

1 1 - 2 a limited explanation that gives information about active transportOR diffusion in the correct context e.g. minerals ions aretransported into root (hair cells)

the answer communicates ideas using simple language and useslimited scientific terminology

spelling, punctuation and grammar are used with limited accuracy2 3 - 4 a simple explanation that gives details of active transport or

diffusion transporting materials e.g. carbon dioxide diffuses intoleaves down their concentration gradient OR a limited explanationof both active transport and diffusion

the answer communicates ideas showing some evidence of clarityand organisation and uses scientific terminology appropriately

spelling, punctuation and grammar are used with some accuracy3 5 - 6 a detailed explanation that describes both processes e.g. active

transport requires energy to transport mineral ions into the roothair cell AND carbon dioxide diffuses into the leaf forphotosynthesis

the answer communicates ideas clearly and coherently uses arange of scientific terminology accurately

spelling, punctuation and grammar are used with few errors


Specialised Cells and

The Nervous System Mark Scheme

Level Edexcel

Subject Biology



Sub Topic Specialised Cells and The Nervous System

Booklet Mark Scheme


Score: /41

Percentage: /100

Question Number


1(a)(i) nucleus (1) (1)

Question Number


1(a)(ii) C In DNA, the bases A - T are complementary (1)

Question Number


1(b) A definition including two of the following:

a sperm fuses with egg /penetrates the egg (1)

nuclei/genetic informationfuses /combines (1)

reference to haploidgametes /gametes have23 chromosomes (1)

reference to cell madebeing diploid / has 23 pairsof chromosomes / zygoteformed (1)

Ignore sperm meets egg

(2)

Question Number


1(c)(i) A description that includes the following:

(aerobic) respiration /using glucose / usingoxygen (1)

energy released (formovement / swimming /metabolism)(1)

(2)


Question Number


1(c)(ii) An explanation including two of the following:

a change in a base/basesequence/order of bases /a change in mRNA (1)

named change e.g.addition/deletion (1)

reference to change in anamino acid / order ofamino acids (1)

Accept codon, triplet, genetic code for base.

substitution/deletion/other named gene mutation.

(2)

(Total for question 1 = 8 marks)


Question Number


2a (i) B – the glucose content of their blood

(1)

Question Number


2a (ii) An explanation linking three of the following points:

• (the hormone) insulin (1)

• (insulin )is injected (intosubcutaneous fat) (1)

• use a low carbohydrate/healthy diet (1)

• (increase) exercise (1)

• to lower blood glucoselevels / when bloodglucose levels get too high/ regulate glucoselevels(1)

use of epipen

(3)

Question Number


2b Body Mass Index calculation:

120/1.82 (1)

37 (1)

ecf for correct manipulation with incorrect figures

(2)


Question Number


QWC *2(c) An explanation including the following points in a logical order:

• a reflex response is an involuntary response• reflex responses do not involve the brain• reflex responses involve sensory neurones• reflex responses involve relay neurones• reflex responses involve motor neurones• relay neurones are in the spinal cord• impulses travel along neurones as electrical signals• the axon is insulated by the myelin sheath• which ensures the electrical signal does not lose energy••

at the junction between two neurones there is a synapsethe message is carried across the synapse byneurotransmitters

• the message travels from the stimulus along the axon anddendron of the sensory neurone to the spinal cord

• the reflex arc is important to keep the body safe

(6)

LevelLev No rewardable content 1 1-2 • A limited written explanation of some of the neurones involved in the

reflex arc or a limited explanation of how messages /impulses aretransmitted as electrical signals


• spelling, punctuation and grammar are used with limited accuracy2 3-4 • A simple explanation of the neurones involved in the reflex arc in the

correct order, with the method of transmission along neurones, oneneurone may be missing or a detailed description of all of theneurones in the reflex arc and the role of the CNS

• the answer communicates ideas showing some evidence of clarityand organisation and mostly uses scientific terminologyappropriately

• spelling, punctuation and grammar are used with some accuracy3 5-6 • A detailed explanation of the neurones involved in the reflex arc in

the correct order, with the method of transmission along neuronesincluding the role of the synapse and/or myelin sheath.




Question Number


3(c) a description including two of the following

• insulates (electrical signal)(1)

• the axon (1)

• speeds up the impulse (1)

ignore protects / protection

accept message / signal for impulse

(2)

Question Number


3(a)(i) A(1)

Question Number


3(a)(ii) A(1)

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3(b) an explanation linking the following

• from receptor (cells) /sense organ (1)

• to the {brain / spinal cord/ CNS / synapse / otherneurone}(1)

• as an electrical impulse (1)

Accept named sense organ

electrical message/signal Ignore references to current

(2)


Question Number


3(d) a description including three of the following

• receptor cells (pick up astimulus) (1)

• sensory neurone sends amessage to the spinal cord/ relay neurone / CNS (1)

• the message travels fromthe relay neurone / CNS /spinal cord to the motorneurone (1)

• (this initiates a response)in the effector / muscle /gland (1)

• message travels acrosssynapse (byneurotransmitters) (1)

accept the correct nerve pathway diagram for 3 marks

accept nerve for neurone

(3)



Question Number


4(a) A differentiate into any type of cell (1)

Question Number


4(b) Any two structures from the list with at least one matched adaptation:

Structures (maximum of 2)

• biconcave shape (1)• no nucleus (1)• thin membrane (1)• flexible / small (1)• contains haemoglobin (1)

(matched) adaptation (maximum of 2)

• large surface area / increaseoxygen uptake (1)

• to increase amount ofhaemoglobin / oxygen-carryingcapacity (1)

• so short distance for diffusion(1)

• to get through capillaries (1)• to bind oxygen (1)

(3)

Question Number


4(c) A description including two of the following points

• clotting / to seal a wound /scab formed (1)

• stop bleeding (1)

• prevent infection / entry ofmicrobes (1)

• fibrin (1)(2)


Question Number


*4dQWC A comparison between mitosis and meiosis including

Mitosis • (genetically) identical cells produced• two daughter cells• one division• diploid daughter cells• identical set of chromosomes• occurs in the formation of body cells• for growth and repair (of body tissues)

Meiosis • (genetically) non-identical cells• four daughter cells• 2 divisions• haploid daughter cells• half the number of chromosomes• occurs in the formation of gametes• for sexual reproduction• results in genetic variation (6)

Level 0 No rewardable content 1 1 - 2 • a limited description including two points on either meiosis or

mitosis there maybe confusion between the two but this does notnegate the level


• spelling, punctuation and grammar are used with limited accuracy2 3 - 4 • a simple description including one comparison of meiosis and

mitosis or a detailed description of either mitosis or meiosis• the answer communicates ideas showing some evidence of clarity

and organisation and uses scientific terminology appropriately• spelling, punctuation and grammar are used with some accuracy

3 5 - 6 • a detailed comparison of both meiosis and mitosis – at least twocorrect comparisons made




The Brain and The Eye Mark Scheme

Level Edexcel

Subject Biology



Sub Topic The Brain and The Eye

Booklet Mark Scheme


Score: /21

Percentage: /100

Question number

Answer Mark

1(a)(i) D (1)

Question number

Answer Mark

1(a)(ii) C (1)

Question number

Answer Mark

1(a)(iii) cerebrum (1)

Question number

Answer Mark

1(b) An explanation that makes reference to: identification – knowledge (1 mark) and reasoning /justification – knowledge (1 mark): • embryonic stem cells can be stimulated to produce cells

of the retina (1)• which can be transplanted into a patient’s eye to

replace the damaged cells (1) (2)

Question number

Answer Mark

1(c) Any three improvements from the following: • vary the time for computer usage (1)• the activity used on the computer must be the same for

each person (1)• control the intake of food/drink/drugs before and during

the test (1)• repeat the test at different times of the day (1)• repeat the test using more people (1) (3)

Question number

Answer Additional guidance Mark

1(d)(i) • 0.258+0.685+0.236+0.246+0.268

= 0.339 (1) 5• 339 (ms) (1)

award full marks for correct numerical answer without working

(2)

Question number

Answer Mark

1(d)(ii) • it is the median value

(1)


Question Number

Answer Mark

Q02(a)i structure A – dendron / dendrite

structure B – nucleus

answers must be in the correct order

(2)

Question

Number


2(a)(ii) B electrical impulses (1)

Question

Number


2(a)(iii) A description to include:

insulates the (electrical)

impulse / insulates the {axon

/ neurone} (from surrounding tissue) (1)

allows quicker (electrical)

conductance (1)

accept: speeds up transmission / sends

{impulses / signals} faster

ignore references to protection of the axon

ignore reference to

messages

(2)

Question Number

Answer Mark

Q02aiv synapse(s) / synaptic cleft / synaptic gap (1)


Question Number


2(b) A description linking four of the following

{receptor} detects a stimulus

(1)

sensory neurone passes

(impulse)to {relay neurone / spinal cord / CNS} (1)

relay neurone in spinal cord

/CNS (1)

relay neurone passes (impulse) onto motor neurone

(1)

motor neurone passes (impulse) to {effector /

muscle /gland} (1)

{effector / muscle /gland}

initiates response (1)

accept sensory neurone to motor neurone for 1 mark

(4)

Total for question 2 = 10 marks


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