CELL DIVISION  

 

 

 

 

 

 

 

 

 

 

 

 

MEIOSIS 

ANSWERS TO PAST PAPER 

QUESTIONS  

© WJEC CBAC Ltd. 2

Question Marking details Marks Available

2 (a) (i) Meiosis; correct spelling only 1

(ii) Anther / ovary / ovule / pollen mother cell/ pollen / pollen sac /

embryo sac / megaspore / microspore;

1

(iii) 1-E , 2- C, 3-D, 4-F, 5-A, 6-B 2

(iv)

0/1/2 correct = 0 marks

3/4 correct = 1 mark

5 correct = 2 marks

6

1

(b) (i)

(ii)

Both required for 1 mark A metaphase II

C metaphase I

Any two from:

C/metaphase I A/metaphase II pairing of chromosomes/

bivalent

chromosomes not paired/ no

bivalent

centromeres not on equator centromeres on equator

chromosomes either side of

equator

chromosomes on equator

chiasma present no chiasma

Comparison needed for each mark

Ignore references to numbers of chromosomes/ haploid/

diploid

1

2

(c) Crossing over;

{Independent/random} {assortment/ segregation};

2

Question 2 total [10]

© WJEC CBAC Ltd.

47

Question Marking details Marks Available

3 (a) (i) Produce {gametes / sex cells} / halves chromosome number / produces haploid cells / introduce genetic variation;

1

(ii) Testes / ovaries; 1 (b) (i) X–centriole AND Y–spindle (fibre) / microtubules; 1 (ii) div I

2 chromosomes in each cell 1 big 1 little; straddling equator; Ignore lack of crossing over div II 2 chromosomes in each cell 1 big 1 little; showing correct recombinants;

4

(c) 1 pair reversed across equator; 1 (d) (i) Prophase I; NOT prophase alone 1 (ii) Drawing showing non sister chromatids crossing over;

and parts being exchanged; Accept correct annotations or second diagram

2

(iii) Crossing over / chiasmata; 1 Question 3 Total [12]

© WJEC CBAC Ltd.

48

Question Marking details Marks Available

3 (a) 40; 1

(b) (i) Correct diagram;

two chromosome pairs vertically orientated

one of each pair on each side of the equator

one pair of chromosomes bigger than the other

1

(ii) Correct labelling of

chromatid, centromere, centriole, spindle fibres

2 marks for 4 correct labels

1 mark for 2 or 3 correct labels

2

(iii) Correct diagrams;

Two chromosomes in each cell (one large and one small)

Centromeres on dotted line

1

(iv) {Random/ independent} assortment of {chromosomes/

chromatids}/ description of {random/ independent assortment};

crossing over/ chiasmata;

produces haploid cells;

3

Question 3 Total [8]

© WJEC CBAC Ltd. 5

Question Marking details Marks Available

AO1 AO2 AO3 Total Maths Prac 3 (a) J, K & M = 2 marks

2 correct = 1 marks 0/1 correct = 0 marks If use more than three letters then deduct one mark for each additional letter

2 2

(b) (i)

4 correct for 2 marks 2/3 correct for 1 mark 0/1 correct = 0

2 2

(ii) Eggs/ female gametes/ ova are produced by meiosis (1) Sperm/male gametes are produced by mitosis (1)

2 2

(c) (i) 1. 3.4 units DNA {before replication / in early interphase}/ {quantity of DNA halves/ returns to original value} {following

cytokinesis / (at the end of )telophase} (1) 2. {6.8 units of DNA/ DNA doubles} due to DNA replication (1) 3. (6.8 units of DNA will be present during) (Late) interphase/

prophase/ metaphase/ anaphase(1)

3 3

© WJEC CBAC Ltd. 6

Question Marking details Marks available

AO1 AO2 AO3 Total Maths Prac (ii) {mitosis is faster/ more mitosis} in young spider mites than older

spider mites/ ORA (1) Young spider mite - mitosis required for growth (and repair of muscle tissue) / Older spider mite – mitosis required for repair (of muscle tissue only) (1)

2 2

Question 3 total 0 7 4 11 0 0

© WJEC CBAC Ltd. 12

Question Marking details Marks available

AO1 AO2 AO3 Total Maths Prac

7 ESSAY

A is meiosis, B is mitosis; The significance of mitosis � daughter cells are genetically identical; � growth; � repair/healing following damage and disease; � repeated cell renewal/continuous cell division – with e.g.

such as skin/gut lining/bone marrow and R & WBC production;

� maintains chromosome number;

The significance of meiosis � produces non identical/genetically different daughter cells; � Gamete production ; � Raw material for evolution/survival of the fittest; � Some comment on advantage of sexual reproduction in the

event of environmental change/disease; � Some mention of sources of variation – crossing over in

prophase 1 and random assortment; � Haploid cells produced so that at fertilisation the diploid

number is regained;

Tumour formation � Reference to a genetic change in B which allows mitosis to

continue in an unrestricted way. Solid mass of cells which prevent normal cells from functioning. Reference to benign/malignant. Cell division stops after meiosis;

5

4

© WJEC CBAC Ltd. 13

Question Marking details Marks available

AO1 AO2 AO3 Total Maths Prac

7-9 marks Indicative content of this level is…

� Detailed coverage of significance of mitosis, meiosis and tumour formation.

The candidate constructs an articulate, integrated account, correctly linking relevant points, such as those in the indicative content, which shows sequential reasoning. The answer fully addresses the question with no irrelevant inclusions or significant omissions. The candidate uses scientific conventions and vocabulary appropriately and accurately.

4-6 marks Indicative content of this level is

� Some coverage of significance of mitosis and meiosis. Reference to tumours may be missing/ incorrect

The candidate constructs an account correctly linking some relevant points, such as those in the indicative content, showing some reasoning. The answer addresses the question with some omissions. The candidate usually uses scientific conventions and vocabulary appropriately and accurately.

© WJEC CBAC Ltd. 14

Question Marking details Marks available

AO1 AO2 AO3 Total Maths Prac

1-3 marks Indicative content of this level is…

� Some coverage of significance of mitosis or meiosis. The candidate makes some relevant points, such as those in the indicative content, showing limited reasoning. The answer addresses the question with significant omissions. The candidate has limited use of scientific conventions and vocabulary.

0 marks The candidate does not make any attempt or give a relevant answer worthy of credit.

Question 7 total 5 4 0 9 0 0

5 © WJEC CBAC Ltd.

Question Marking details Marks Available AO1 AO2 AO3 Total Maths Prac

3 (a) A = chromatid (1) ignore sister / daughter reject chromosome B = centromere (1)

2 2

(b) (i) crossing over / synapsis / chiasmata formation (1) reject chiasmata are exchanged/ crossed over in Prophase I (of meiosis) (1)

2

2

(ii) Any two (x1) from: � {two (cell) divisions/ two named phases I and II} (producing

four cells) (1) � crossing over/ independent assortment/ or description of(1) � Only one chromatid from each pair of chromosomes in each

daughter cell

2 2

(iii) {more difficult for/ less likely that/ more rare that/ lower probability that} crossing over to take place (1) because Y chromosome shorter than X chromosome/OWTTE (1)

1 1 2

Question 3 total 7 0 1 8 0 0

3 © WJEC CBAC Ltd.

Question Marking details Marks Available AO1 AO2 AO3 Total Maths Prac

1 (a) (i) {A has/meiosis I results in} two {cells/nuclei} and {B has/ meiosis II results in} 4 / A results from one division and B results from two divisions (1)

1 1 1

(ii) plane/angle of section of through cell may not include a nucleus (1) (where nucleus visible) may have been cut at different {levels/planes} (1)

1 1 2 2

(b) anaphase II meiosis (1) Any two (x1) from: Cell is haploid as only 4 chromosomes / resulting cells will {only have one copy of each chromosome/be haploid} (1) if mitosis two copies of each chromosome / lack of homologous pairs (1) if anaphase I each chromosome would have 2 chromatids / (anaphase II) involves the separation of (sister) chromatids (1)

2 1 3

Question 1 total 1 4 1 6 0 3

4

Questions Marking details Marks

Available

4. (a) 2 chromosomes in female cell;

1 chromosome in male cell;

Diagrams must match each other.

Accept ‘chromatids’ in each cell. Do not accept chromatid in male

cell if chromosomes drawn in female cell or opposite.

2

(b) (i) 2 Chromosomes arranged on equator of spindle; (ignore orientation) 2

2 V shaped {chromosomes / chromatids} with centrosomes towards

each centriole/pole;

Ecf from one diagram to other.

(ii) Labelling: chromatids, centromere, spindle, centrioles, equator, cell

membrane.

2 marks for 4 correct labels on either diagram;

1 mark for 3.

2

(iii) To provide {genetically identical cells / clones};

Repair / replacement {of cells / tissue} / regeneration qualified;

NOT growth.

2

(iv) Making gametes / sperm cells / sex cells / produce haploid cells for

reproduction;

1

(v) Meiosis / reduction division;

Spelling must be correct.

1

(vi) Genetic variation (in the offspring) / restore diploid number (in

zygote) OWTTE;

1

(c) Fertilised eggs will develop into females, unfertilised eggs into

males; (both for 1 mark);

Accept: fertilised will give genetically varied ants, unfertilised would

give clones;

IGNORE haploid / diploid.

1

Question total 12

29

Question Answers/Explanatory Notes Marks Available 6. (a) (i) Fucus (correct spelling) [1] (ii) Nuclear membrane / nucleus; linear DNA; histones / protein associated with DNA in chromosomes; large/70s ribosomes; mitochondria /ER/Golgi/chloroplasts/ membrane bound organelles; cellulose/chitin cell wall; cilia / flagella 9 + 2 structure/centrioles; [2 max] (not: membrane bound DNA) (b) (i) 4 cells from meiosis, each undergo 4 mitotic divisions = 16; Answer 64; [2] (ii) Meiosis variation; Meiosis halves the number of chromosomes/makes haploid cells (allowing sexual reproduction)/number restored when gametes join; [2] Mitosis increase numbers/chance of fertilisation; [1] (not: ref clones/amount) (c) (i) shown on diagram clockwise: diploid, haploid, diploid [3] (2n/n/2n= 2 marks max) (ii) mitosis (exact spelling); [1] (d) (i) Buoyancy, store gases [1] (ii) Daytime rate of photosynthesis exceeds respiration Carbon dioxide levels fall, oxygen levels rise; Could be a certain light intensity when no change / rate of P = rate of R/compensation point; Night time (no light) no photosynthesis but respiration takes place; Carbon dioxide levels rise, oxygen levels fall; [4 max] [4]

12

QuestionMark

Scheme

5 (a) (i) Meiosis (correct spelling).

(ii) Fertilisation.

(iii) Zygote. (allow: mitosis)

(iv) Mitosis. (correct spelling)

[4 correct = 2, 3 correct = 1] 2

(b) X - haploid, Y - diploid.

Colonise area quickly/reduce parasite transmission

1

(c) (i) Rapid increase in numbers/energy for mating is saved/where

environment is stable/ useful features maintained.

(not: its quicker/one parent needed/clones)

1

(ii) Variation/variety in offspring needed to adapt to new conditions or

example/survival advantage;

(sexual reproduction) leads to variation.

1

1

(d) (i) Joining together gametes/fusing of sperm and eggs (sperms

introduced) inside (female's) body/reference to intromittent organ.

(not: zygote formation)

1

(ii) Reduced number of gametes produced/more chance of gametes

meeting/fertilisation/less chance of gametes being wasted;

allows (male) gamete to become independent of water ref. prevent

dehydration;

embryo/zygote can be better protected; (not: it/offspring/baby)

resistant stage in life cycle/ref. shelled egg. (any 3)

3

(iii) Embryo can receive nutrition during development. 1

10 MARKS