MARK SCHEME for the October/November 2013 series 5090 BIOLOGY. 5090/21 Paper 2 (Theory), maximum raw mark 80

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1 CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Ordinary Level MARK SCHEME for the October/November 2013 series 5090 BIOLOGY 5090/21 Paper 2 (Theory), maximum raw mark 80 This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge will not enter into discussions about these mark schemes. Cambridge is publishing the mark schemes for the October/November 2013 series for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level components and some Ordinary Level components.

2 Page 2 Mark Scheme Syllabus Paper GCE O LEVEL October/November Mark schemes will use these abbreviations: ; separates marking points / alternatives () contents of brackets are not required but should be implied R reject A accept (for answers correctly cued by the question, or guidance for examiners) AW alternative wording (where responses vary more than usual) AVP alternative valid point (where a greater than usual variety of responses is expected) ORA or reverse argument underline actual word underlined must be used by candidate (grammatical variants excepted) max indicates the maximum number of marks that can be given + statements on both sides of the + are needed for that mark

3 Page 3 Mark Scheme Syllabus Paper GCE O LEVEL October/November Question Mark Scheme Mark Clarification 1 (a) (i) label line must touch the sweat gland; [1] A label on gland or duct A (i) = gland (ii) label line must touch some part of receptor under Malpighian layer; [1] (ii) = temp receptor (b) (i) (temperature / it) increases / rises; [1] R cooler / decreases OWTTE (ii) In either order: sweat; wider blood vessels / capillaries / more blood; [2] R veins (c) (i) (ii) arteriole; the upper horizontal blood vessel labelled; [2] less blood (flows); to capillaries ( R capillaries constrict) to sweat glands; blood carries heat / less heat carried less heat lost by skin / radiation ; less sweat produced; ref to latent heat of vaporisation; A Artery (the word ignore what is labelled) (ignore name given to it) A less heat lost by blood [max 4] [Total 11]

4 Page 4 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) (i) antagonistic; [1] (ii) one muscle contracts; while the other relaxes; muscles can only contract / only pull / never push; one muscle causes a change, the other restores the position AW; e.g. so the action can be reversed. [max 3] A for max 1 muscles can contract + relax A oppose one another (iii) ciliary muscle / sphincter muscle or any named / heart / diaphragm; [1] (b) In either order : hinge + elbow / position described; ball and socket + shoulder / position described; [2] A any correct, the two listed are on the syllabus (c) ball + on scapula / shoulder blade; socket + on humerus normally the other way round / the reverse of normal; [3]

5 Page 5 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) water + any part of the alimentary canal after the oesophagus; ions / minerals / named + ileum; vitamins / named + ileum / colon glucose + ileum [max 2] A small intestine for ileum (b) fibre / roughage / cellulose / fruits / seeds / tomato skins / maize pericarps; [1] A any suitable named plant part (c) products drawn in correct absorptive vessel All correct = 2 marks 2 correct = 1 mark ;; all molecules totally digested ; 2 products correctly named ; [max 4] I any diagrams in the intestine R any products drawn in both capillaries and lacteals All bonds must be broken a minimum of 3 products of each type required. (d) (i) amino acids; glucose/ other named monosaccharide; vitamins / named; ions / salts / minerals / named; water; (ii) in solution; in blood / plasma; by (hepatic) portal vein; [max 3] [max 2] [Total 12]

6 Page 6 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) Carbon dioxide / CO 2 ; carbon monoxide / CO; soot / particulates / carbon; [max 2] (b) water present in soil; absorbed by root; ref xylem; lost to atmosphere + from leaves / aerial parts or ref to evaporation / transpiration / diffusion ; released / produced from respiration (or described); A ground, ref to water table A forms clouds AW + water vapour released [max 3] (c) (the cow) excretion; urea; ref to faeces ; decomposition ref to nitrification; (max.3) (the factory) oxides of nitrogen or named; dissolved (in rainwater) / ref to acid rain ; A other named nitrogen excretory products. I urine A forms ammonia, nitrite, nitrate I names of bacteria R refs to denitrification and nitrogen fixation [max 4] [Total 9]

7 Page 7 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) (i) light / chlorophyll / water; [1] (ii) any temperature with units between 15 o C and 29 o C; any 2 from: ref. to enzymes; work slower at lower temps / below optimum ref to less kinetic energy / collisions AW; plant has slower (metabolic) rate AW; [1] [max 2] A reduces the rate A slower rate of photosynthesis (b) light intensity AW; stomata open / allow CO 2 to enter; supplies light energy for photosynthesis; plants do not photosynthesise in the dark; increase in light increases photosynthesis (rate); [4] [Total 8]

8 Page 8 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) support / rigidity; lignin; conduct/transport of water; ions / minerals / salts; ref to narrow/hollow/continuous / lumen; from roots(hair) + ref to any aerial part of plant; R transport of amino acids / sugars [max 3] (b) ref enzyme / named enzyme; action of enzyme ; named product of enzyme action; ref to solubility of product diffusion(from storage cells to phloem or vice versa); to phloem; sucrose/amino acids (moved up phloem) ; ref translocation/transport up stem; no photosynthesis at night ; (energy) released during respiration; sugar provides energy for growth; amino acids make proteins; to make new cytoplasm / cells; [max 7] A amino acids / glucose / sugar R produced

9 Page 9 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) *ref. to against concentration gradient; A a description (plants) any 2 from: minerals / ions / salts; from soil; via root hairs; *credit once only, under plants or humans, (humans) any 2 from: glucose; from gut; via villi ; [max 4] (b) (i) movement of molecules / particles / ions; high concentration to low; [2] (ii) ref. crossing a membrane ; thin; oxygen in (to cell) ; glucose in (to cell) ; carbon dioxide out (of cell) ; [max 4] A ref to entering named plant or animal cell Allow 1 mark for O 2 in + Co 2 out - if only refer to gases in the lungs.

10 Page 10 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) cell division; ref. to chromosomes; diploid to haploid; gamete formation/ named gametes; all gametes genetically different; fertilisation restores chromosome number / AW; leads to variation in population; [max 4] A halving of chromosome number (b) name of fruit / seed (not linked to following marks); structural feature of fruit/seed that is a wind-dispersal adaptation; ref. large surface area / buoyancy; *wind removes fruit / seed from parent plant; Accept * points for descriptions of pollen for max 3 *seed relatively light in mass; [max 6] *to delay descent of seed AW; spread over large area / prevent overcrowding / competition ; e.g. floats for long time / increases air resistance

11 Page 11 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) ref. to an ecosystem / food chain / web; total number v. total mass of organisms (at each trophic level); biomass pyramids usually pyramid-shaped; numbers pyramids variable in shape pyramid of numbers takes no account of size/mass of organism) AW; [max 3] A on a diagram with all trophic levels credibly named. A clear diagrams with correct shape A clear diagrams with nonpyramidal shape (b) (energy gained) by photosynthesis in plants / producers; from (sun)light; correct ref. light energy + chemical energy; eaten by animals; named food molecule consumed AW; (energy lost) as heat; electrical / nerve impulses; growth / reproduction; movement / muscle contraction; excretion; [max 7]

12 CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Ordinary Level MARK SCHEME for the October/November 2013 series 5090 BIOLOGY 5090/22 Paper 2 (Theory), maximum raw mark 80 This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge will not enter into discussions about these mark schemes. Cambridge is publishing the mark schemes for the October/November 2013 series for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level components and some Ordinary Level components.

13 Page 2 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) (i) vein; [1] (ii) valve; [1] (b) a valve shown with flaps touching; vessel widest at correct side of valve + walls shown both before and after valve; [2] (c) (vein) empty / no blood flowing through; blood has been pushed out of (vein); * blood cannot flow back (due to valve / from B); * finger on the right / at D + prevents blood flowing; walls of vein thin thus not visible beneath skin AW; [max 4] (d) muscle + contraction(s); increase blood pressure; increases circulation / blood flow / helps fill (vein) with blood; [2]

14 Page 3 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) damage / breaks AW (cells / tuber); ref. cell wall / membrane; releasing (cell) contents / starch; kills cells / denatures enzymes / stops metabolic reactions; [max 2] (b) amylase / carbohydrase; digests / breaks down / hydrolyses + starch; (to) maltose; [3] (c) (i) fermentation / anaerobic respiration; [1] left hand side of equation glucose / C 6 H 12 O 6 ; right hand side of equation 2C 2 H 5 OH + 2CO 2 / alcohol/ethanol + carbon dioxide; [2] (ii) fungus / yeast ; [1] (d) yeast (cells) + reproduce / increase in number / multiply; (sediment contains) yeast (cells) / bacteria / chewed tuber AW yeast (cells) dead + sugar / food used up / alcohol is toxic AW; [max 2] [Total 11]

15 Page 4 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) (i) (cell 4) - root hair; (cell 5) - sperm(atozoon) / male gamete; [2] (ii) (root hair) increases surface area; (for) absorption / movement (A correct named method of molecular transport) into AW; minerals / ions / salts (or named); water; oxygen; (cell wall) gives mechanical support / allows turgor; [max 3] (b) cell 1 (RBC) F; cell 2 (WBC) K; cell 3 (palisade) G; cell 5 (sperm) J; cell 6 (spongy) H ; [5]

16 Page 5 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) for photosynthesis / to make food/carbohydrate/starch/ glucose/sugar; [1] (b) * limited nitrates / nitrates not topped up; limited protein production; * limited magnesium + for chlorophyll; limited carbon dioxide ; limited photosynthesis / limited production of food/ carbohydrate/starch/glucose/sugar; limited space / volume / area; [max 3] (c) ref. respiration + photosynthesis (occurring in jar); respiration + releases CO 2 ; CO 2 + used for photosynthesis; photosynthesis + releases O 2 ; O 2 + used for respiration; ref. microorganisms / bacteria / fungi / decomposers + in soil; [max 4] (d) water from leaves/transpiration AW / water from soil evaporates; respiration + produces/releases water; *returned to soil / condenses; *absorbed AW / used by plants; [max 3] [Total 11]

17 Page 6 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) food web / food chain / ecosystem / community; [1] (b) natural selection; white animals better suited to environment AW; white not removed/eaten / black removed/eaten AW; (more) white reproduce / (less) black reproduce; ref. allele / gene + inherited / passed on; white become more common / black become less common; [max 3] (c) (i) gene mutation; chromosome mutation; codominance; [max 2] (ii) better adapted (to new condition) / example of better adaptation; protection against hawk/predator / less eaten; [max 2] [Total 8]

18 Page 7 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) loss of water; involves evaporation / as vapour; to the atmosphere / surroundings; cooling effect; through pores AW; in epidermis; both affected by temp / humidity / wind (speed); [max 3] (b) (Accept reverse arguments where relevant) occurs in animals; sweating ref. (loss of) urea / ions / salts / minerals; under nervous control; ref. homeostasis / determined by body temperature; (sweat) glands / ducts; sweat extracted from blood; (from) skin; transpiration from leaves / stems; (helps to) bring ions up stem/xylem / to leaves/cells; (helps to) bring water up stem/xylem / to leaves/cells; consequence of stomata open for photosynthesis; [max 7]

19 Page 8 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) CO 2 / water; from body AW; waste product / toxic material; respiration; metabolic (process); [max 3] (b) homeostasis / osmoregulation; salts / ions / minerals / urea; water; from blood; ref. reabsorption into blood; in varying quantities / excess; depending on food/water intake; and on loss in sweating; tissue fluid therefore at constant concentration; water would otherwise enter or leave cells; osmosis / diffusion; effect on cell appearance (e.g. swell / burst / shrink); affect on enzyme action / metabolism; [max 7]

20 Page 9 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) contains female gamete / female nucleus / egg cell; in ovary; fertilized / fuse; (by the) male gamete / male nucleus; (to form) zygote / embryo; surrounded by integuments/testa; seed + germinates (to form new plant); [max 4] (b) produces haploid; ovum / egg; fertilization + ref. zygote/embryo; oestrogen; progesterone; any two functions of oestrogen (e.g. devpt. of sex organs / secondary sexual characteristics / thickening of uterus lining / stimulates production of LH);; any two function of progesterone (maintains uterus lining / inhibits FSH / inhibits LH AW);; [max 6]

21 Page 10 Mark Scheme Syllabus Paper GCE O LEVEL October/November (a) screening blood; being HIV tested / contact tracing; avoidance of needle/syringe sharing; needle exchange schemes / sterilising needles; condoms / femidoms; limited partners / no intercourse with prostitutes (who may have multiple partners); abstinence; ref. education (about how HIV is spread); take drugs / follow treatment prescribed (to prevent spread within body); [max 4] (b) mosquito (vector); removal of breeding ground AW + drain swamps / prevent stagnation of water AW; kills eggs / larvae / pupae + any two of add insecticide to water / oil on water / put fish/bacteria into ponds;; bite prevention + any two of sleep under nets / screens on windows / wear long-sleeved clothes / insect repellent;; discourage (mosquito) + any two of insect repellent / paint walls white / wear light clothing;; insecticide/pesticide / coils in houses + to kill; release irradiated males + infertile eggs laid ; [max 6]

MARK SCHEME for the October/November 2015 series 5090 BIOLOGY. 5090/21 Paper 2 (Theory), maximum raw mark 80

CAMBRIDGE INTERNATIONAL EXAMINATIONS Cambridge Ordinary Level MARK SCHEME for the October/November 2015 series 5090 BIOLOGY 5090/21 Paper 2 (Theory), maximum raw mark 80 This mark scheme is published as