Life Sciences Grade 12 IEB Paper 2 2017 Memo

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE EXAMINATION NOVEMBER 2017 LIFE SCIENCES: PAPER II MARKING GUIDELINES Time: 2 hours 100 marks These marking guidelines are prepared for use by examiners and sub-examiners, all of whom are required to attend a standardisation meeting to ensure that the guidelines are consistently interpreted and applied in the marking of candidates' scripts. The IEB will not enter into any discussions or correspondence about any marking guidelines. It is acknowledged that there may be different views about some matters of emphasis or detail in the guidelines. It is also recognised that, without the benefit of attendance at a standardisation meeting, there may be different interpretations of the application of the marking guidelines. IEB Copyright © 2017 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 2 of 10 SECTION A QUESTION 1 1.1 Correct terms 1.1.1 Parental care – option 1 1.1.2 Allopatric speciation – option 2 1.1.3 Convergent evolution – option 2 1.1.4 Continental drift – option 2 1.2 1.2.1 500–600 (accept range) 1.2.2 2 050–2 250 (accept range) 1.3 morphological characteristics can evolve at an incredibly uneven pace sometimes completely out of step with genetic changes/speciation seems to occur in bouts and not steadily over time/speciation has been record breaking 1 550 species in relatively short time (10 million years). 1.4 1.4.1 • Cichlids possess two sets of jaws • one in the mouth, (to suck, scrape or bite off bits of food) • the second set of jaws are adapted in the throat • to crush, slice or pierce the food • greater feeding options • the two sets of jaws are finely adapted to a type of food/very versatile/adaptable • allows each species to occupy its own very specific ecological niche; (4 optional facts) • hundreds of species can coexist without directly competing/if these cichlids had tried to exploit the same food resources, most would have been driven to extinction 1.4.2 Summary of piscivorous cichlids and the types of food they eat Type/group Feeding Type of food Type of food of cichlids specialisation Piscivores Whole fish Consume whole fish – Scales Eat scales from sides Approach from behind and Scale Eaters of other cichlids grab mouthful of scales Eggs or young Dislodge young from Ram mouth of mouth Paedophages of mouth mouth brooders and brooder and dislodge eggs brooders eat their eggs or young and young Carnivorous Insects and Eating insects and – cichlids shrimp shrimp Small and Crush and process Large molars to crush Crushers thin-shelled small and thin-shelled shells molluscs molluscs Heading = column headings = 5 groups of piscivorous cichlids = linked to correct type of food (sliding scale: 5 correct =; 4 correct =; 3 correct = ; 2 to 1 correct =) Alt answer: Heading = column headings = Max 3 correct =; 2 to 1 correct =) (4) IEB Copyright © 2017 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 3 of 10 1.5 Cichlids in Lake Victoria are genetically very close to one another; evolutionary adaptations can and did evolve many times; independently of one another; example of convergent evolution; mtDNA indicates relatedness 1.6 Survival of the fittest example: Bower builders (nest-builders) – many male African cichlid fish build a pit or sand castle on a lake bottom; to attract females; females pick the largest nest/bower; strongest males can move most stones; males compete with one another to fertilise the most eggs; carry on their genes in offspring. Not survival of the fittest example: Bright colouration of males; owing to preferences of the females; female cichlids are often a drab grey or brown; example of sexual selection; rather than pressure for physical survival/survival of the strongest; the different colours of otherwise identical fish serve as a barrier; separating distinct species; e.g. a female of a species that prefers yellow males will not mate with a red one. 1.7 1.7.1 inbreeding/selective breeding/artificial selection/cross breeding 1.7.2 decrease in gene pool/genetic diversity/decrease in homozygosity; increase in genetic abnormalities/less resistant to disease (Relate to term given 1.7.1.) QUESTION 2 2.1 State whether the following statements are True or False. 2.1.1 True 2.1.2 False 2.1.3 False 2.1.4 True 2.1.5 False 2.2 H. naledi braincases were tiny/560 cubic centimetres for the males/465 for the females far less than H. erectus's average of 900 cubic centimetres bigger brain in H. erectus indicates closer to modern humans/more evolved species/greater cognitive/thinking ability (2 facts for comparison + 1 for evolutionary implication ) 2.3 Berger invited many scientists from different countries; many were young scientists; usually only scientists closest collaborators are given access to the bones; to help him analyse the bones of H. naledi quickly; could take years, even decades to investigate the findings; Berger's team spent 6 weeks; would let him be known in his field; give all scientists access to the newest discovery; mystery of human origins so important to unravel that all scientists need new information. (How = + Why =) IEB Copyright © 2017 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 4 of 10 2.4 primitive above, modern below = mixture of more advanced Homo features and more primitive Australopithecine features Primitive above: H. naledi's hand displays curved fingers, a clue that the species had retained an ability to climb in trees and on rocks; the shoulders were apish too; the widely flaring blades of the pelvis were as primitive as Lucy's; proportionately long arms; small braincase. Modern below: the bottom of the pelvis looked like a modern human's; The feet are virtually indistinguishable from modern humans longer legs; ridges for strong muscle attachment. (Accept other relevant structural differences (1 = explanation + 2 = primitive above + 2 = modern below)) 2.5 2.5.1 C A B (1) 2.5.2 Toes are all in line in H.naledi and human foot – no divergent big toe as in Little Foot (accept other relevant answers) 2.5.3 Enabled upright posture; freed hands; to manipulate objects/ environment/make tools; allowed walking/running gait/over long distances; less surface area exposed to sun therefore cooler. (Other suitable advantages of bipedalism) 2.6 Australopithecus africanus 2,3-million-year-old fossil Homo naledi (unknown- closer to humans than H. erectus) (H. erectus + 2 mya – 100 000 years) Australopithecus sediba two million years ago Homo sapiens o mya 3 m.y.a. 2 m.y.a. 1 m.y.a. Today A. Sediba H. Sapiens A. africanus H. naledi Heading Timeline correct (3 m.y.a → today) Placing of: A. africanus A. sediba H. naledi H. sapiens IEB Copyright © 2017 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 5 of 10 SECTION B QUESTION 3 ESSAY The rapid evolution of antibiotic resistance in bacteria will lead to the extinction of modern Homo sapiens (humans). Summary of facts contained in sources to develop argument. Antibiotic resistance will Antibiotic resistance will lead to extinction of modern NOT lead to extinction of humans modern humans A Blog = not • Bacteria continually evolve A reliable/valid, to adapt to new antibiotics. etc. B • Developing antibiotics to B • New antibiotics developed combat disease all the time. inadvertently leads to • Scientists understand how bacterial resistance. bacteria evolve. • Bacteria evolve very quickly. • Magic bullet (penicillin) analogy no longer holds; need magic shotgun = much more effective treatment. C • Not even on to human trials C • Shu Lam, a 25-year-old yet, only mice. PhD student, has • UN declared resistant developed a polymer that bacteria threat to global can kill six different health. superbug strains without • Hospital superbugs. antibiotics, simply by • Gonorrhoea. ripping apart their cell walls. • "A breakthrough that could change the face of modern medicine". • Antibiotics, which "poison" bacteria, can also affect healthy cells in the area. • The polymers that Lam has designed don't seem to affect healthy cells at all. IEB Copyright © 2017 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 6 of 10 D Credible = BBC • Drug resistant infections D Medical will kill an extra 10 million correspondent people a year worldwide. • More than currently die from cancer. • Huge population decrease by 2050 unless action is taken. • Drug resistant infections are currently implicated in 700,000 deaths each year. • The costs would spiral to $100trillion. • Overuse of antibiotics causes resistance to spread through communities. E • Sweden acknowledged E • Sweden has urgent threat of antibiotic acknowledged the urgent resistant bacteria. threat to public health of • Methods only successful in antibiotic resistance and 0–4 yrs. implemented effective programs. • For many years has worked hard to reduce the impact of antibiotic overuse. • Antibiotic use in Sweden has been reduced by 50% in children under the age of four. • Clear link between antibiotic resistance and consumption made Sweden draw up national treatment recommendations on how and when to use antibiotics. IEB Copyright © 2017 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 7 of 10 F • The development of new F • Six new drugs approved in antibiotics by the 2014. pharmaceutical industry has essentially stalled due to economic obstacles. • Of the 18 largest pharmaceutical companies, 15 abandoned the antibiotic field. • Antibiotic research has been scaled back as a result of funding cuts due to the economic crisis. • Antibiotic development is no longer considered to be an economically wise investment for the pharmaceutical industry. • Because antibiotics are used for relatively short periods and are often curative, antibiotics are not as profitable as drugs that treat chronic conditions. • Decline in development and approval for antibiotic development in last 30 years. G • Trials not yet started for G • Bacteriophages control the resistant bacteria. number of bacteria and • Clinical trials very recent. maintain ecological balances in nature. • Each bacteriophage infects only a few bacterial species or types, potentially making them real precision-guided "smart weapons" in the battle against bacterial infections. • They can be used against antibiotic-resistant bacteria. • First clinical trials with phage therapy have recently been carried out. • Bacteriophages were identified already in 1896 and were studied closely in the 1920s. IEB Copyright © 2017 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 8 of 10 • At that time, phage therapy was used to treat both animal and human infections – such as cholera and bubonic plague in India, often with good results so promising research. H • Only potential sources; will H • New antibiotic teixobactin. take years to develop. • Prevent some bacterial resistance up to 30 years. • Natural microbes in environment may provide new drugs. Own Knowledge • Colistinin example • Nature of evolution – • XDR TB survival of the fittest • Hospital superbug difficult humans will outpace to combat evolving bacteria. • CRISPR-CAS 9 can destroy resistant bacteria or reprogram bacteria to not have resistance to antibiotics. • Natural population control mechanisms to reduce humans to carrying capacity, not all humans will die. Total: 100 marks IEB Copyright © 2017 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 9 of 10 Note: Essay should be 2½ to 3 pages in length. Time allocation suggestion: Reading of sources 10 min.; Planning 10 min.; Writing essay 40 min. Possible mark 1 mark 2 marks 3 marks 4 marks (40) • Decision given • Decision given • Decision given • Key points present for • Key points developed for • Key points developed for Planning and against the and against the and against the argument argument argument 6 ×2 • Source references identified (e.g. Source A/own information) • Vague • Clear decision made Decision • Changed position within 2 essay • Up to ¼ of potential • Up to ½ of potential • Up to ¾ of potential • Source detail – very Use of knowledge detail in sources used to detail in sources used to detail in sources used to close to full potential from sources 8 support argument support argument support argument used to support ×2 argument • Some facts given • Many facts given beyond • Some facts given • Many facts given beyond beyond the source to the source to support beyond the source to the source to support Use of own support argument argument support argument argument 4 knowledge • Facts integrated into the • Facts integrated into the argument argument • Repetition mostly • Repetition mostly avoided avoided • Some minor digression • Some minor digression Content Relevance • Supporting argument • Supporting argument 2 relevant relevant • Quality of source extracts acknowledged IEB Copyright © 2017 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 10 of 10 • Writing consists of facts • Maximum if no clear • Supports the position • Strongly supports a clear with little linkage or decision in support • Reasoning is clear position reasoning • Reasoning correct, but • Minor errors in flow • Reasoning is very clear Quality of argument • Reasoning incorrect hard to follow • Linkage sometimes and succinct supporting • Ordinary: some linkage missed • Flow is logical 8 decision ×2 evident • Compelling with regular linkage • Well-integrated argument Possible mark 1 mark 2 marks 3 marks 4 marks (40) • One to two counter • Three to four counter • Integration of one to two • Integration of three to Fairness – counter opinions given from the opinions given from the counter opinions from four counter opinions opinions to 4 sources sources the sources into from the sources into decision argument argument • Writing is almost • Tone, language, • Tone is consistent and • Tone is mature and unintelligible terminology weak suited to scientific suited to scientific • Tone, language, • Introduction and language language terminology unscientific conclusion present • Good and appropriate • Excellent and and very weak language and appropriate language Presentation 4 • Introduction and/or terminology and terminology conclusion not present • Mostly appropriate • Correct paragraphing paragraphing with good transitions • Introduction and • Interesting introduction, conclusion have merit satisfying conclusion Scientific merit Essay shows academic rigour, accurate reasoning, insight and cohesiveness. 2 IEB Copyright © 2017