Answer Key And Markscheme - NTK Academic Group

Chapter 6 Human physiology Multiple-choice questions 1. C 2. A 3. D 4. B 5. C 6. B 7. A 8. C 9. A 10. A Structured question Question 1 (a) Award [1] for each of the following structures clearly drawn and labelled. type I pneumocyte; type II pneumocyte; film of moisture / surfactant; capillary wall / endothelium; plasma / blood; [4 max] red blood cell / erythrocyte; Film of moisture Type I pneumocyte Capillary wall Plasma Erythrocyte Type II pneumocyte (b) sodium ion; potassium ion; proteins; [2 max] glucose; Accept other appropriate answers. 2016 NTK Publishing Limited 12

(c) e.g. minerals active transport / diffusion (without digestion); e.g. proteins active transport / diffusion after digestion (into amino acids); e.g. glucose active transport / co-transport with sodium ion / diffusion; [2 max] Award [1 max] for each nutrient named in (b). (d) liver; [1] 13 2016 NTK Publishing Limited

Chapter 7 Nucleic acids Multiple-choice questions 1. B 2. C 3. C 4. B 5. B 6. A 7. C 8. B 9. A 10. B Structured question Question 1 (a) primary structure; [1] (b) DNA replication in vitro / outside cell; using dideoxyribonucleic acid nucleotides / dideoxyribonucleoside triphosphates / ddNTPs; deoxyribonucleic acid nucleotides / deoxyribonucleoside triphosphates / dNTPs / (Taq) DNA polymerase; using polymerase chain reaction / PCR technique; random termination of DNA synthesis; produce DNA fragments of different lengths / sizes; separate DNA fragments by gel electrophoresis; [5 max] length of fragments used to deduce position of base; (c) regulators of gene expression / promoter / other named examples; introns; telomeres; genes for tRNA; tandem repeats / satellite DNA / highly repetitive sequences; 2016 NTK Publishing Limited 14 [2 max]

(d) RNA polymerase binds to DNA; at promoter; RNA polymerase unwinds double helix; mRNA synthesized from 5’ to 3’; using antisense DNA strand (as template); transcription stops at terminator; splicing removes introns from mRNA in eukaryotes; mRNA binds to (small subunit of) ribosome; ribosome arrives at start codon / initiation; ribosome moves along the mRNA / translocation from 5’ to 3’; tRNA carries amino acids to ribosome; anticodons on tRNA pair with codons on mRNA; complementary base pairing / A pairs with U, G pairs with C; amino acids attached to tRNA by tRNA-activating enzymes; [8 max] peptide bonds form between amino acids; 15 2016 NTK Publishing Limited

Chapter 8 Metabolism, cell respiration and photosynthesis Multiple-choice questions 1. D 2. B 3. A 4. B 5. C 6. B 7. C 8. B 9. A 10. C Structured question Question 1 (a) loss of hydrogen (ion) / H / H ; [1] Reject reference to oxygen or electrons. (b) 2; (c) [1] Krebs cycle Calvin cycle oxidation of substrate / intermediate formation of ATP / ADP Pi reduction of substrate / intermediate; ATP hydrolysis of ATP / ATP ADP Pi; reduction of NAD / NAD / hydrogen / electron carrier oxidation of reduced NADP / NADPH H / NADPH / NADPH2 / hydrogen / electron carrier; production of carbon dioxide / decarboxylation fixation of carbon dioxide / carbon fixation / carboxylation; occur in matrix / mitochondrion occur in stroma / chloroplast; Award [1] for each correct row. A table is not required but the difference between Krebs cycle and Calvin cycle must be made clear. 2016 NTK Publishing Limited 16 [3 max]

(d) (chlorophyll in) photosystem II absorbs light; electrons excited from (chlorophyll in) photosystem II; excited electrons captured by electron carriers; electrons passed through electron transport chain / ETC; on thylakoid membrane; energy released from reduction-oxidation / redox reactions (of electron carriers); to pump protons / hydrogen ions; from stroma to intermembrane space of thylakoid / thylakoid space; proton gradient created across thylakoid membrane / high concentration of protons / hydrogen ions in thylakoid space / intermembrane space; protons / hydrogen ions diffuse from intermembrane space / thylakoid space to stroma; through ATP synthase / synthetase; formation of ATP from (condensation of) ADP and Pi / ADP Pi ATP; (non-cyclic) photophosphorylation; electrons excited from photosystem I enters ETC; [8 max] in cyclic photophosphorylation; Reject ATPase. (e) oxygen binds to active site of rubisco / ribulose bisphosphate carboxylase(/oxygenase); less glycerate 3-phosphate / GP formed; [2 max] competitive inhibition; 17 2016 NTK Publishing Limited

Chapter 9 Plant biology Multiple-choice questions 1. C 2. D 3. B 4. D 5. A 6. C 7. C 8. B 9. B 10. C Structured question Question 1 (a) (apical) meristem; [1] (b) form new cells by mitosis; elongation of root; indeterminate growth; deep / long root system allows access to groundwater / increase surface area; [3 max] (c) starch converted to glucose; glucose and fructose condense to form sucrose; sucrose loaded into sieve tubes at source; by active transport / co-transport with protons / hydrogen ions; by companion cell; increase solute concentration at source; water flows into sieve tubes (at source); by osmosis; high hydrostatic pressure at source; unloading of sucrose at sink; reduce solute concentration at sink; water flows out of sieve tubes (at sink); low hydrostatic pressure at sink; water flows down hydrostatic pressure gradient (from source to sink); [9 max] pressure-flow model / mass flow model; Award [1] for conversion from starch to sucrose. 2016 NTK Publishing Limited 18

(d) auxin / indoleacetic acid / IAA produced by shoot / root tip; auxin / indoleacetic acid / IAA diffuses along shoot / root; differential distribution of auxin / indoleacetic acid / IAA; by auxin efflux pumps; response to light / gravity / other appropriate named stimuli; auxin / indoleacetic acid / IAA stimulates shoot growth / inhibit root growth; in region of elongation; [4 max] tropism is growth response to a directional stimulus; 19 2016 NTK Publishing Limited

Chapter 10 Genetics and evolution Multiple-choice questions 1. A 2. D 3. A 4. A 5. D 6. A 7. B 8. C 9. B 10. D Structured questions Question 1 (a) Award [4 max] for description of gene linkage. genes on the same chromosome; tend to be inherited by the same daughter cell / gamete / nucleus / do not segregate independently; produce non-Mendelian ratio / not 9 : 3 : 3 : 1 / 1 : 1 : 1 : 1; recombination caused by crossing over / chiasmata formation; in prophase I / metaphase I (of meiosis); Award [4 max] for an example of genetic cross. definition of alleles; parental genotypes and phenotypes; genotypes and phenotypes of offspring; [8 max] parental and recombinant offspring labelled; Reject examples not illustrating gene linkage. (b) homologous chromosomes pair up / form bivalents / undergo synapsis; crossing over / formation of chiasmata; in prophase I / metaphase I; exchange / recombination of alleles between non-sister chromatids (of homologous chromosomes); random orientation of (homologous) chromosome pairs in metaphase I; random orientation of sister chromatids in metaphase II; 2n combinations of chromosomes; [5 max] non-disjunction changes chromosome number; Award [1 max] for random orientation if phase / division not specified. 2016 NTK Publishing Limited 20

(c) skin colour controlled by multiple genes / is polygenic; alleles of each gene lead to production / no production of melanin / skin pigments; alleles are co-dominant; individuals inherit different combinations of alleles; different frequency of melanin- / pigment-producing alleles; [4 max] a range of phenotypes / from light skin colour to dark skin colour; Question 2 (a) Award [1 max] for the following structures clearly drawn and labelled. homologous chromosomes — drawn as a tetrad; sister chromatids — joined at the centromere; centromere — same position on both chromosomes; [3 max] chiasma — labelled at the point of crossing; (b) crossing red-eyed male flies with white-eyed female flies; red eye is dominant / white eye is recessive; expected ratio (red : white) 3 : 1 (according to Mendelian genetics); all male offspring had white eyes, all female offspring had red eyes; exception / discrepancy to Mendelian ratio; [4 max] discovery of sex linkage / genes located on X chromosome; Accept use of other crosses that illustrate sex linage of eye colour in fruit flies (Drosophila melanogaster). Reject “wild type” and “mutant” without reference to dominance. Accept appropriate description of gene linkage. (c) speciation is the formation of new species; speciation requires (reproductive) isolation of populations / gene pools; isolation prevents gene flow / interbreeding / hybridization; geographical isolation and example e.g. separation by mountains; temporal isolation and example e.g. different flowering times; behavioural isolation and example e.g. different courtship behaviours; genetic isolation and example e.g. polyploidy; different selection pressures on isolated populations / gene pools; populations no longer able to interbreed / produce fertile offspring; [7 max] speciation can be allopatric or sympatric; Accept other appropriate types of isolation mechanisms. Ignore classifying isolation mechanisms as prezygotic or postzygotic. 21 2016 NTK Publishing Limited

Chapter 11 Animal physiology Multiple-choice questions 1. D 2. A 3. C 4. D 5. D 6. B 7. C 8. C 9. D 10. C Structured questions Question 1 (a) sperms move to oviduct (through cervix and uterus); receptors on plasma membrane of sperms bind to proteins on egg / zona pellucida / vitelline membrane; acrosome releases (hydrolytic) enzymes; digestion of zona pellucida / vitelline membrane / corona radiata; plasma membrane of sperm and egg / secondary oocyte fuse; fusion of male and female gametes / sperm and egg / secondary oocyte / fertilization; release / exocytosis of cortical granules into zona pellucida; to prevent polyspermy; male / sperm nucleus enters egg / secondary oocyte; secondary oocyte completes meiosis II; male and female nuclei fuse / a zygote is formed; zygote divides by mitosis (to form embryo); cleavage of embryo; formation of blastocyst / blastulation; embedment / attachment of blastocyst onto endometrium; [8 max] Reject “uterine lining”. (b) monoclonal antibodies specific to human chorionic gonadotropin / HCG; HCG secreted by embryo; test for HCG in urine; [2 max] colour change if HCG is detected; (c) estrogen level increases; progesterone level decreases; increased sensitivity of uterus / uterine wall to oxytocin; oxytocin stimulates muscle contraction (of uterine wall); muscle contraction forms positive feedback with oxytocin; 2016 NTK Publishing Limited 22 [4 max]

(d) antidiuretic hormone; effect: increase permeability of collecting duct to water; stimulate cells to express more aquaporins (on plasma membrane); [2 max] Award [1 max] for effects of ADH. Question 2 (a) similarities: osmoregulation associated with excretion (of nitrogenous wastes); reabsorption of water controlled by salt concentration; involve removal of water from body fluid / blood / hemolymph and reabsorption; involve behavioural responses / example of behavioural response; involve active transport of salts; differences: Osmoregulation in humans Osmoregulation in insects occur in kidneys occur in Malpighian tubules; occur in specialized organ associated with digestive system; involve hormonal / endocrine control no hormonal / endocrine control; [6 max] Award [1 max] for each correct row of differences. A table is not required by the difference between osmoregulation in humans and insects must be made clear. Award [6 max] only if answer contains both similarities and differences. (b) contraction of flexor bends joint; contraction of extensor straightens joint; flexor and extensor are antagonistic; joint formed by (pieces of) exoskeleton; muscle action coordinated by nervous system; [4 max] muscle contraction stimulated by nerve impulses; (c) higher chance / success of fertilization; prevent dehydration of gametes; higher gamete survival; fewer gametes are required / wasted / less energy required for producing gametes; [2 max] Accept other appropriate answers. 23 2016 NTK Publishing Limited

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MARKSCHEME BIOLOGY Standard Level Practice Test Paper 1 25 2016 NTK Publishing Limited

1. D 11. A 21. C 2. B 12. B 22. A 3. B 13. C 23. A 4. C 14. D 24. A 5. C 15. B 25. B 6. C 16. B 26. D 7. A 17. B 27. D 8. B 18. A 28. A 9. A 19. C 29. A 10. C 20. C 30. D 2016 NTK Publishing Limited 26

MARKSCHEME BIOLOGY Standard Level Practice Test Paper 2 27 2016 NTK Publishing Limited

Mark Allocation Candidates are required to answer all questions in Section A and one out of two questions in Section B. Maximum total 50 marks. 1. Each row in the “Question” column relates to the smallest subpart of the question. 2. The maximum mark for each question subpart is indicated in the “Total” column. 3. Each marking point in the “Answers” column is shown by means of a tick ( ) at the end of the marking point. 4. A question subpart may have more marking points than the total allows. This will be indicated by “max” written after the mark in the “Total” column. The related rubric, if necessary, will be outlined in the “Notes” column. 5. An alternative wording is indicated in the “Answers” column by a slash (/). Either wording can be accepted. 6. An alternative answer is indicated in the “Answers” column by “OR” on the line between the alternatives. Either answer can be accepted. 7. An alternative markscheme is indicated in the “Answers” column under heading ALTERNATIVE 1 etc. Either answer can be accepted. 8. Words inside chevrons « » in the “Answers” column are not necessary to gain the mark. 9. Words that are underlined are essential for the mark. 10. The order of marking points does not have to be as in the “Answers” column, unless stated otherwise in the “Notes” column. 11. If the candidate’s answer has the same “meaning” or can be clearly interpreted as being of equivalent significance, detail and validity as that in the “Answers” column then award the mark. Where this point is considered to be particularly relevant in a question it is emphasized by OWTTE (or words to that effect) in the “Notes” column. 12. Remember that many candidates are writing in a second language. Effective communication is more important than grammatical accuracy. 13. Occasionally, a part of a question may require an answer that is required for subsequent marking points. If an error is made in the first marking point then it should be penalized. However, if the incorrect answer is used correctly in subsequent marking points then follow through marks should be awarded. When marking, indicate this by adding ECF (error carried forward) on the script. “ECF acceptable” will be displayed in the “Notes” column. 14. Do not penalize candidates for errors in units or significant figures, unless it is specifically referred to in the “Notes” column. 2016 NTK Publishing Limited 28

Section B Extended response questions – quality mark Extended response questions for HLP2 each carry a mark total of [16]. Of these marks, [15] are awarded for content and [1] for the quality of the answer. [1] quality mark is to be awarded when: the candidate’s answers are clear enough to be understood without re-reading the candidate has answered the question succinctly with little or no repetition or irrelevant material. It is important to judge this on the overall answer, taking into account the answers to all parts of the question. Although, the part with the largest number of marks is likely to provide the most evidence. Candidates that score very highly on the content marks need not necessarily automatically gain [1] mark for quality (and vice versa). 29 2016 NTK Publishing Limited

Section A Question 1. Answers a presence of three homologous chromosomes «in a nucleus / cell» b a. meiosis I Notes 1 b.  total number of Down syndrome cases caused by error in meiosis I is larger than that in meiosis II c Total Accept appropriate use of data from table. Accept use of maternal data instead of total. Reject comparison between different parental origins. 2 a. more cases of Down syndrome caused by error in maternal meiosis b. «mean» maternal age higher in cases of Down syndrome than control 3 c. «mean» paternal age lower in cases of Down syndrome than control d a. 7 100% 118 2 b. 5.9% e a. 0.1 10 / Award [2] for correct answer. 0.1 1000 1 100 b. 29 Allow any number between 28 and 30. 2 Award [2] for correct answer. f Accept other appropriate answers. a. recorded prevalence is lower «than curve / trend» b. inaccurate data due to low birth rate / natality / fertility in older mothers c.  diseased fetuses / embryos have higher chance of miscarriage / death during pregnancy 2016 NTK Publishing Limited 30 2 max

Question 2. Answers a 4.5 cm 562.5 80 μm b a. eukaryotic Notes Accept any number between 550 and 575. 1 2 b.  presence of membrane-bound organelles / named membrane-bound organelle / internal membrane system c Total a. mitochondrion is site of aerobic respiration Reject “energy”. b. provide ATP 2 max c. for muscle contraction / growth / repair 31 2016 NTK Publishing Limited

Question 3. Answers Notes a chlorophyll b plants utilize more red light and blue light for photosynthesis / cannot utilize green light for photosynthesis effectively c a. split into oxygen and hydrogen «ions» «and electrons» Total 1 Allow use of correct wavelengths of visible light. 1 b. oxygen is a by-product c. electrons used to produce ATP «in electron transport chain / ETC» d. hydrogen «ions» «and electrons» used to produce / reduce organic compounds e. in light-independen

Chapter 7 Nucleic acids 14 Chapter 8 Metabolism, cell respiration and photosynthesis 16 Chapter 9 Plant biology 18 Chapter 10 Genetics and evolution 20 Chapter 11 Animal physiology 22 Practice test markscheme Practice Test (Standard Level) Paper 1 25 Practice Test (Standard Level) Paper 2 27 Practice Test (Higher Level) Paper 1 45 Practice Test .