WJEC mark sheme summer 2005 - thiacin...F212 Mark Scheme June 2010 Question Expected Answer Mark Additional Guidance 2 (a) placing, living things / organisms / named organisms, into,

WJEC

Classification, Evolution &

Biodiversity

Class Questions

Mark Scheme

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21

UNIT B1 5

Question Answers/Explanatory Notes MarksAvailable

1. (a) (i) red squirrel

panda

any whale/dolphin

tiger

Any suitable 3 species [1]

(ii) (ii) poaching/overfishing/overhunting

habitat destruction/deforestation

competition from introduced species (not: increased competition)

pollution (not: climate change unequal)

Any suitable 2 reasons leading to endangerment Not just population effect

[1]

(b) (i) Cochlea [1]

(ii) Perilymph [1]

(iii) Basilar [1]

[5]

2. (a) Chordata

Pisces/Fish [2]

(b) Unable to reproduce/interbreed with each other to produce fertile/viable offspring; (not; they cannot reproduce)

Any sensible reason for not interbreeding, e.g. behaviour. (not: geographical isolation)

Have different characteristics/features/appearance.

Any 2 [2]

(c) Reference to DNA/genetic fingerprinting/base sequencing/ immunological comparison;

Close similarities should be present between the species. (i.e. technique and related result)

[2]

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F212 Mark Scheme June 2010

Question Expected Answer Mark Additional Guidance 2 (a) placing, living things / organisms / named organisms, into,

groups / categories / taxa / named taxonomic groups ;based on / AW, similarity / difference ;

2

ACCEPT ‘grouping living things’ Look for the idea of similar organisms being placed in the same group or different organisms being placed in different groups

2 (b) (i)

1

2

3

4

5

morphology / anatomy / (observable / physical) features / appearance / AW ; biochemistry / cytochrome C ; genes / DNA / genetics / RNA ; behaviour / physiology / embryology ; idea of shared, evolutionary past / phylogeny ;

3 max

ACCEPT suitable examples for mps 1 to 4

1 CREDIT cell features e.g. nucleus / membrane- bound organelles / cell wall / prokaryotic-eukaryotic features / unicellular

2 CREDIT component of cell wall

3 IGNORE chromosomes

4 ACCEPT ‘how they feed’ / nutrition / ‘how they reproduce’

5 ACCEPT ‘how closely related’ IGNORE refs to interbreeding / fertile offspring

2 (b) (ii) T S R W U Q ; ; ;

3

Mark the order of letters (ignoring the dotted lines) All 6 in correct order = 3 marks If any incorrect, then credit T S in order at beginning = 1 mark U Q in order at end = 1 mark R before W anywhere in the sequence = 1 mark

5

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Question Expected Answer Mark Additional Guidance 2 (c)

1

2

3

4

5

6

3 domains AND 5 kingdoms ; domains are, bacteria / eubacteria, AND, archaea / archaebacteria, AND, eukarya / eukaryotes ; kingdoms are prokaryotes AND protoctists AND fungi AND plants AND animals ; eukaryotes split into different kingdoms / all eukaryotes are in the same domain ; all prokaryotes are in the same kingdom / prokaryotes split into different domains ; domain classification based on, rRNA / ribosomes / RNA polymerase / protein synthesis / enzymes / flagella / membrane structure ; 4 max

ACCEPT phonetic spellings throughout ACCEPT alternative terms for names of kingdoms and domains throughout (e.g. plants / plantae)

2 ACCEPT ‘eukaryota’

3 DO NOT CREDIT protists / protozoa

6 IGNORE RNA unqualified DO NOT CREDIT other forms of RNA

ACCEPT any detail of protein synthesis

Total 12

6

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Mark Scheme � General Certificate of Education (A-level) Biology � Unit 2: The Variety of Living Organisms � January 2011

Question Marking Guidance Mark Comments

3(a) Kingdom, phylum and class;; 2 Lose 1 mark for each error (i.e. omission or incorrect response). Sequence not essential.

3(b)(i) Shows evolutionary relationship; 1

3(b)(ii) 26; 1

3(c)(i) 1. Base sequence will be similar/some bases in common;

2. These bases will bind together/hydrogen bonds/complementary pairs;

2 Do not accept same here.

Accept converse providing that it is clear that the converse argument is being made.

3(c)(ii) 1. Relationship is closer/more complementary bases/more base pairs;

2. More hydrogen bonds; 3. More heat energy needed (to separate bonds);

2 max

Do not allow stronger hydrogen bonds.

Not higher temperature as this is in question.

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Mark Scheme � General Certificate of Education (A-level) Biology � BIOL2 � January 2012

5

Question Marking Guidelines Mark Comments

3(a)(i) Synodontis batensoda / S. batensoda;

1 Ignore spellings

3(a)(ii) Mochokus niloticus; 1 Ignore spellings

3(b) 5; 1

3(c)(i) Fertile offspring produced; 1 Allow suitable description of offspring being fertile.

3(c)(ii) 1. Attracts/recognises same species;

2. Attracts/recognises mate/opposite sex;

3. Indication of sexual maturity/ fertility / synchronises mating;

4. Stimulates release of gametes;

5. Form pair bond;

2 max Attracts mate of the same species = two marks.

3. ��

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Mark Scheme – General Certificate of Education (A-level) Biology – BIOL2 – January 2013

5


3(a) Kingdom Animalia

Phylum Chordata

Class Mammalia

Order Carnivora

Family Felidae

Genus Panthera

Species pardus

2 One mark for each correct column

Do not award mark for last column if ‘Pardus’ is clearly stated

Accept: Panthera pardus in final box

3(b) (For the leopard and cheetah)

1. More hydrogen bonds (form);

2. Similar DNA sequence(s) / similar base sequence(s) / more complementary bases / more base pairs;

2 Accept converse argument for leopard and puma

Neutral: similar DNA

2. Idea of ‘more’ must be clear

3(c)(i) 1. Drop in population / many killed / only single female left;

2. Idea of reduced/low genetic variation/diversity / reduction in (variety of) alleles / smaller gene pool;

2

3(c)(ii) 1. Mutation affecting sperm cell or production (in small population);

2. Errors during meiosis;

3. Inbreeding / closely related cheetahs breed;

4. High chance of inheriting allele / high frequency of allele (in the population);

2 max

4. Accept: high frequency of homozygous/two recessive alleles

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Mark Scheme – General Certificate of Education (A-level) Biology – BIOL2 – June 2013

6


3(a)(i) 1. Groups within groups;

2. No overlap (between groups);

2 1. Accept: idea of larger groups at the top / smaller groups at the bottom

3(a)(ii) (Grouped according to) evolutionary links/history/relationships / common ancestry;

1 Neutral: closely related

Neutral: genetically similar

3(b)(i) 1. (Only) one amino acid different / least differences / similar amino acid sequence / similar primary structure;

2. (So) similar DNA sequence/ base sequence;

2

3(b)(ii) 1. Compared with humans / not compared with each other;

2. Differences may be at different positions / different amino acids affected / does not show where the differences are (in the sequence);

1 max Accept: degenerate code / more than one triplet (codes) for an amino acid

3(b)(iii) 1. All organisms respire/have cytochrome c;

2. (Cytochrome c structure) is more conserved / less varied (between organisms);

1 max Accept: converse arguments for haemoglobin

1. Accept ‘more’ instead of ‘all’

1. Accept ‘animals’ instead of organisms’

2. Neutral: cytochrome c is conserved

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BY2

1. One mark for each line:-

Animalia: Fungi: Protoctista: Plantae: Prokaryotae. [5] (no mark if extra ticks present)

[Total 5 marks]

2. (a) Wings of birds and bats. [1]

(b) (i) Adaptive radiation (Allow Speciation / Natural Selection) [1]

(ii) No competition from other birds / vacant niches / subsequent intraspecific competition (Any two) [2]

(c) Unable to interbreed and produce fertile offspring [1] (allow: breed together. Not: unable to breed)

(d) DNA profiling/hybridisation (comparing DNA or equivalent e.g. fingerprinting) (not: looking at DNA/electrophoresis unqualified) [1]

[Total 6 marks]

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Question MarkScheme

4 (a) Chordata/chordates (accept vertebrata/vertebrates). 1

(b) (i) Pentadactyl (limb). 1

(ii) B. 1

(ii) Phoca. 1

(c) (i) Homologues/homologous. (not: analogous/adaptive radiation) 1

(ii) They suggest the existence of shared/common ancestors

(not: similar ancestors)

1

(d) (i) 6. 1

(ii) Macroderma gigas. 1

(e)

1

9 MARKS

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12

Question Answer Mark

2. (a) (i) Arthropoda 1

(ii) jointed legs max

exoskeleton

fluid-filled body cavity / haemocoel/ open circulatory system

2

Segmentation/ segmented body NOT large brain

(b) (i) a group of organisms that can interbreed / breed with each other to

produce fertile offspring

1

(ii) Genus 1

(iii) DNA base sequencing / hybridisation/ sequencing analysis/ DNA

electrophoresis Not DNA analysis/ analysis alone

genetic fingerprinting or profiling/

amino acid sequencing of proteins / differences in protein structure

(not: biochemical methods unqualified) NOT compare DNA/ genes

1

(iv) high level of similarity shows that they are closely related / converse

argument. Needs to relate to 2 a (iii)

1

Question Total 7

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11 © WJEC CBAC Ltd.

GCE BIOLOGY - BY2

Mark Scheme - January 2013

Question Marking details Marks Available

1 (a) A species is a group of organisms that {can interbreed/

reproduce};

(under natural conditions) produce fertile offspring;

2

(b) (i) birds; 1

(ii) Borneo {1.61/ 1.62/1.6}; 1

(iii) (Least at poles to) {greatest/ increasing} at equator; 1

(c) (i) X at second split from left or anywhere along that line; 1

(ii) Same genus( but different species)/ tells us the genus; 1

(d) (i) homologous; 1

(ii) analogous;

1

Question 1 total [9]

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Biology - AQA GCE Mark Scheme 2010 June series

9

Question Part Sub Part Marking Guidance Mark Comments 6 (a) Most closely (related) to chimpanzee / most recent common

ancestor; Least (related) to dogfish / least recent common ancestor;

1 1

�� chimpanzee as equivalent to second mark point. Allow answers which compare similarity in DNA/genetic material. Marks should not be awarded for answers which only compare amino acid sequences without any indication of relationships. Al�� and ��for dogfish

6 (b) Is present in all eukaryotes; 1

6 (c) Reference to base triplet/triplet code / more bases than amino acids / longer base sequence than amino acid sequence; Introns/non-coding DNA; Same amino acid may be coded for / DNA code is degenerate;

1 1 1

2 max Different (base) triplets code for same amino acid = 2 marks Reject different amino acids are formed/produced. Ignore reference to codon.

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Question Expected Answers Mark Additional Guidance 6 (a) (i)

3 parts to body ; head + thorax + tail ; segmented ; lateral spines / spines from both sides of head ; thorax / tail , similar shape ;

3 max

Mark the first answer on each numbered line. ACCEPT wherever seen ACCEPT ‘a lateral spine’ ACCEPT description of thorax / tail shape

6 (a) (ii) anterior spine (from head) on A ;longer lateral spines on B ;less rounded / AW , head on B ;any other reasonable difference ; ;

2 max

Mark the first answer on each numbered line. Answers must state either species A or species B ACCEPT ora throughout e.g. (greater) fusion of tail segments in B

grooves around edge of head in B outline of tail section (more) curved in A

A has more segments CREDIT any clear description of a difference

6 (b) 1

23

4

56

idea of fossils show changes over time ;idea that there are methods to date fossils ;idea of simplest / most different from modern , species /

AW , in oldest rocks ; idea of showing , links / relationships , between , groups /

species / organisms / taxa ; many fossils organisms no longer exist ;idea of compare DNA extracted from some fossils ; 2 max

2

4

ACCEPT it is possible to date fossils

ACCEPT ref to common ancestor of two species Answers could refer to links between species A and species B

Total [7]

14

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F212 Mark Scheme January 2012

Question Answer Marks Guidance 4 (a)

taxonomy / taxonomic ; hierarchy ; phylogeny / phylogenetic ;

3 Mark the first answer. If the answer is correct and an additional answer is given that is incorrect or contradicts the correct answer then = 0 marks ACCEPT phonetic spelling throughout

ACCEPT hierarchical system

(b) (i)

1 (cells have) no cell wall ;

2 heterotrophic ; 3 eukaryotic ; 4 multicellular ; 5 (fertilized eggs develop into), blastula / ball of cells ; 6 high degree of mobility / AW ;

2 max Mark the first answer on each prompt line.

1 DO NOT CREDIT absence of a qualified cell wall, e.g. ‘no cellulose cell wall’

2 ACCEPT phonetic spelling 3 ACCEPT named eukaryotic cell feature 4 IGNORE references to tissues

6 DO NOT CREDIT unqualified references to movement

ACCEPT refs to mobility during part of life cycle

IGNORE cilia / flagella

(ii)

Eukaryota(e) / Eukarya / eukaryote(s) ;

1 Mark the first answer. If the answer is correct and an additional answer is given that is incorrect or contradicts the correct answer then = 0 marksIGNORE case of initial letter

14

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Question Answer Marks Guidance (iii)

1 all are in same family as all, are closely related ;

2 kea and kaka are both, same genus / Nestor ; ora for kakapo

3 kea and kaka, are more closely related / share more recent common ancestor, (than with kakapo) ;

4 kea and kaka have more genes in common / AW (than with kakapo) ;

5 example of genetic similarity (between kaka and kea) evident from Fig 4.1 ;

6 differences between, kea and kaka / all three, are great enough for each to be described as a different species ;

4 max Candidates may refer to individual species using common or scientific names. ACCEPT use of either or both. IGNORE case of initial letter

1 idea of link between family and close relationship must be made

3 ACCEPT ora for less close relationship between kakapo and others

4 ACCEPT ora 4 Answers must refer to genes / genetics / DNA

4 IGNORE cytochrome c

5 E.g. kaka and kea both brown / kaka and kea both have similar shaped beaks

5 IGNORE unqualified references to appearance

(c) (i) differences ; in / within / between, species ;

2

ACCEPT within a population

15


Question Answer Marks Guidance (c) (ii)

genetic differences / different alleles / inherited differences ;

environment / diet / disease ;

2 Mark the first suggestion on each prompt line. ACCEPT different genes

ACCEPT mutation

ACCEPT sex

IGNORE ‘different habitat’

(c) (iii)

only small number have been sampled / AW ;

idea that individuals sampled may not be representative of population ; data collected when population was larger / smaller population may mean range has changed ;

2 Mark the first two reasons – ignore prompt lines. ACCEPT ‘whole population has not been sampled’

IGNORE rare unqualified ACCEPT larger ones more likely to be caught / measured

ACCEPT individuals sampled from one area might be different from average of whole population

16


Question Answer Marks Guidance 4 (d)

Name

1 speciation ;

Mechanism – max 2 marks

2 isolation / separation, (of populations) ;

3 further detail of isolating mechanism ;

4 mutation / genetic variation ;

5 natural selection / description of natural selection ;

6 different selection pressure(s) (in different environment) ;

7 (enough) time to allow changes in population to

prevent interbreeding / AW ;

3 max

1 IGNORE ‘natural selection’ on name line

2 IGNORE barrier

3 e.g. river, mountain, reproductive, geographical, temporal, polyploidy, qualified barrier

3 IGNORE allopatric / sympatric unqualified

5 description must mention differential survival and genes being passed on

6 IGNORE selection pressure unqualified 6 ‘different’ can be described using an example

Total 19

17


8

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Mark Scheme � General Certificate of Education (A-level) Biology � BIOL2 � January 2012

9

Question Marking Guidelines Mark Comments

7(a)(i) Produces a more reliable mean/average / makes sure sample was representative / reduce effect of extreme values / identify anomalies;

1 Ignore references to chance

7(a)(ii) Removes bias; 1

7(b) Two marks for correct answer of 5.8;;

One mark for incorrect answer that clearly shows denominator as 216;

2

7(c) 1. Increase in variety of plants/shrubs/grass;

2. More habitats/niches;

3. Greater variety of food sources / more food sources;

3

3. Answers only referri��

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Mark Scheme – General Certificate of Education (A-level) Biology – Unit 2: The Variety of Living Organisms – June 2012

9

Question Marking Guidelines Marks Comments

7(a) Removes bias; 1

7(b)(i) 1. 1.28 / 1.29 / 1.285 / 1.3;;

2. Answer incorrect but shows clear understanding of �;

2 1. Ignore more than 3dp

2. �� denominator written out. Incorrect denominator but evidence of understanding gains mark

7(b)(ii) Diversity index would be lower (NO MARK)

1. Fewer species / Beech aphid/Large white butterfly/7-spot ladybird absent /only three species / species diversity lower;

2. Mostly one species / mostly bird-cherry aphid;

3. Fewer plant species;

2 max Assume wheat field if site unspecified

1. Allow species richness in context of few species

3. Allow one type of food source if clearly plant

7(c) For:

1. Data support the claim / evidence supports claim;

Against:

2. Only wheat field / only comparing with wood / one type of habitat /only insects considered;

2 max

1. Ignore reference to correlation/causation

7(d) 1. Greater variety of plants;

2. Another habitat / more habitats / places to live / niches;

3. Another food source / more food types;

2 max

3. Answers referring to 'more food' should not be credited. Allow reference to either animal or plant as foods

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WJEC mark sheme summer 2005 - thiacin...F212 Mark Scheme June 2010 Question Expected Answer Mark Additional Guidance 2 (a) placing, living things / organisms / named organisms, into,