UNIVERSITY OF MALTA SECONDARY EDUCATION CERTIFICATE SEC BIOLOGY. May 2013 EXAMINERS REPORT

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1 UNIVERSITY OF MALTA SECONDARY EDUCATION CERTIFICATE SEC BIOLOGY May 2013 EXAMINERS REPORT MATRICULATION AND SECONDARY EDUCATION CERTIFICATE EXAMINATIONS BOARD

2 SEC Biology May 2013 Session Examiners Report Part 1: Statistical Information The Table below shows the istribution of graes for the May 2013 session. GRADE U ABS TOTAL PAPER A PAPER B TOTAL % OF TOTAL Part 2: Comments regaring caniate s performance 1. Although caniates are being irecte accoring to previous SEC Biology Examination Reports, the following misconceptions nee to be aresse: a) the improper use of breathing, respiration an gaseous exchange; b) igestion occurring in the pancreas (possibly ue to the name of pancreatic juice). 2. A larger number of caniates answere the question on Genetics correctly. 3. Caniates o not keep to the inicate lines when answering the questions in Paper I. 4. Compare to other questions, caniates performance is poor when they answer the question on experimental esign in paper II. Paper I Compare with previous years, caniates i well in the genetics question. A large number of caniates are still unaware that the marks allotte to each question inicate the amount of etail expecte in their answers. Question 1 a. Most caniates i well. Incorrect use of prepositions often change meaning to answers completely e.g. on the skin vs in the skin have completely ifferent meanings. When escribing the location of the ureter, a number of caniates incorrectly referre to the penis an / or vagina. b. Caniates i better in 1a than 1b. Some caniates wrote the function instea of the exact location of the structure in question. Question 2 a i Most were correct. Incorrect answers inclue starch an glucagon. Most answers were correct. b i Incorrect answers inclue the pituitary glan an Islets of Langerhans. Some caniates i not specify the type of cell an answere animal cell or just name an unrelate example. 2

3 c Only a minority of caniates obtaine full marks. Many just escribe the function of bloo. i Incorrect answers for this question inclue fainting, iabetes or reference to bloo pressure. Most caniates knew that glucose is use by cells to harvest energy but only a hanful inicate the maintenance of water potential relationships between bloo an tissue flui. Question 3 a A large number of caniates were penalise as they i not unerline the term Trachinus. b i Most caniates faile to link the fact that preators attack the Great Weever from above as it lives at the bottom of the sea. A small amount of caniates mentione the presence of gills an many caniates introuce breathing rather than gaseous exchange. c Most answers were correct, inicating the proper wor camouflage. Another correct answer was blen well. Most answers were correct. The most common incorrect answer was preator-prey relationship. e i Most answers were correct but some caniates misspelt the term Crustacea. Most answers were correct. Incorrect answers inclue ifferent characteristics an ifferent scientific name, rather than making irect reference to 3 ifferent genera. Question 4 a i Most caniates replie correctly. The iea of variables was often not mentione. At times caniates mentione precautions which are not relate to Biology, example place apparatus on a flat surface; to ensure accurate results. b i Most caniates answere correctly an even name the proper term enature. Only a hanful of caniates were aware full marks, as only few mentione the active site an what happens after. Many caniates once again repeate enaturation, that is the answer to question bi. c i The term emulsification was use correctly by the majority of caniates. Some caniates mentione the increase in surface area of the lipi roplets but faile to mention the interactions between the substrate an the enzyme. For this reason, only one mark was aware to most of the caniates. Question 5 a i Most caniates either got i, an i all wrong or all correct. At times the lines that were rawn to show the location, were unclear, particularly when labelling the iastema. As above i As above b Most answers inclue the absence of a iastema an/ or a horny pa. Caniates often note the presence of canines in the lion but faile to inicate that they were large an pointe. c Most answers were correct. Incorrect answers inclue kiney, stomach an intestines. e Most caniates answere this question well. f Incorrect answers inclue physical features such as eyesight, night vision an entition. These were only a minority as most caniates answere running fast, hunting in packs an catching sick an vulnerable prey. g i Most answers were correct. The most common mistake was to mention the iploi number of human chromosomes, that is 46. Most answers were correct. The most common mistake was to mention the haploi 3

4 h number of human chromosomes, that is 23. The most common answer inclue there is more haemoglobin to carry oxygen. Degeneration or lack of nucleus was very scarcely mentione. Question 6 a i The term relate to the molecular unit of hereity was frequently cite correctly, however some incorrect terms inclue trait or genetic. The term mutation was frequently correctly mentione. However incorrect written terms inclue Usher Synrome an genetic isorer. b i Caniates often wrote the genotype correctly. Caniates often wrote the genotype correctly c Caniates generally performe well in this question. Still a number of caniates lost most of the marks since they worke the genetic iagram in a sex linke manner. Similarly in this question, a number of caniates incorrectly worke out the question in a sex linke manner. Question 7 a Caniates correctly mentione the phylum to which amphibians belong. b i However caniates mentione incorrect internal structural characteristics present in a caecilian. Incorrect characteristics inclue presence of legs, lungs, igestive system, skeleton, an spinal cor. The comparison between the skin surface of a caecilian an that of a snake was generally aequate. Most answers referre to the smooth moist skin in caecilians an the ry scaly skin in snakes. C Caniates often faile to link correctly the presence of caecilians in moist habitats to the nee to return to water to lay eggs or to retar water loss. Some caniates mentione to nee of caecilians to conuct gas exchange over skin surface. Some common incorrect explanations inclue since they are col blooe, or without water they ry out an ie. i Caniates score well in the last part of the question relate to the mammals group of animals that give live birth to live young. Furthermore caniates explaine correctly that fertilise eggs insie the mother s boy are protecte from preators. Some also mentione the avantage of nutrients supply to the eveloping young. Question 8 a The ovary glan that secretes oestrogen an progesterone was often confuse with the pituitary glan. b Caniates generally labelle the progesterone an oestrogen levels aequately. c Caniates often wrote incorrect escriptions of the progesterone levels in pregnant females inee most caniates simply mentione that progesterone increases rather than that progesterone levels remains high or increases an remains constant. The pituitary glan was generally correctly mentione. e i The efinition of the zygote was generally correct an reference to the iploi cell forme after sperm fertilizes ovum was evient. The name of the organ that provies the foetus with its requirements was often incorrectly liste as the umbilical cor instea of the placenta. f Frequently the cite example of the birth control metho/s use by females to prevent entry of sperm inclue the femiom or iaphragm. Some incorrect examples inclue the coil an birth control pills. g The escription of the temperature metho an Billing s metho referre to the changes in temperature an type of mucus. 4

5 Question 9 a i Generally caniates are still encountering ifficulties to answer questions of the give a biological explanation type. Inee caniates lost marks primarily because of lack of etail an focus. In the car pool poster caniates often referre to the avantage of less traffic without highlighting the reuction in fumes/exhaust/air pollution. Only a minority of caniates mentione specific air pollutants. Similarly in the canvas bag poster caniates often referre to the prouction of bags instea of the limite use of plastic/paper bags when compare to the reusability factor of canvas bags. Only a limite number of caniates referre to the increase in litter with the use of plastic/paper bags. i The saving lan poster was often linke to urbanisation an the estruction of habitats caniates faile to link the process to increase in numbers of enangere/extinct species. b Caniates often cite plausible ways of preventing umbing rubbish in the countrysie. Most caniates inclue recycling, re-using, repairing items, bulk refuse service, law enforcement an CCTV cameras as possible ways to prevent umbing of rubbish. Question 10 a i Very often caniates istinguishe clearly between iffusion an active transport. Caniates faile to istinguish clearly between transpiration an translocation. The answers inicate that caniates have a misconception about the translocation process. i Caniates often istinguishe clearly between interspecific an intraspecific competition. b i The commonly cite similarities between mitosis an meiosis referre to the cell ivision aspect an the prouction of new cells. The ifferences mentione inclue the site of the ifferent processes, the number of chromosomes, the ifference between clones in mitosis an iverse cells in meiosis. Paper 2A Question 1 a. Most caniates answere this question correctly. Some caniates use the phrase internal fertilisation to refer to gestation in utero. b i The majority of caniates i not answer this question correctly. Most caniates efine species as a group of organisms sharing similar characteristics. Several caniates efine species as being the last taxonomical category. Most caniates answere this question correctly. c i Many caniates sai that sloths have a slow acting stomach so that foo may be igeste slowly so that energy may be release graually. Others sai that the iet of the sloth oes not provie enough energy for the stomach to act more rapily. Some caniates sai that the foo sloths eat is ifficult to igest but mae no reference to cellulose in plant cell walls. The majority of caniates quote the text in the passage an sai that the bacteria prouce enzymes that help to break own the tough leaves. i The majority of caniates sai that a low calorie iet yiels less energy an hence cannot permit a high metabolic rate. This woul ensure that the little energy available is not use too quickly. The majority of caniates answere this question correctly although some sai that sloths exhibit slow movement in orer to conserve energy. 5

6 e Many caniates sai that sloths on t move to prevent an increase in their boy temperature. Question 2 a b c The majority of caniates rew the bar chart correctly although some rew the bar chart on the square paper while others superimpose the two graphs. Many caniates i not inclue a title. The majority of caniates got the subtraction part of the calculation correct. Several caniates however faile to work out the percentage correctly. The majority of caniates answere this question correctly. Many however sai the avantage of using pesticies is that they can kill bacteria. Some liste the fact that pesticies coul harm the fish as the main isavantage. i The majority of caniates answere this question correctly. The majority of caniates answere this question correctly. Question 3 a i The majority of caniates answere this question correctly. The majority of caniates answere this question correctly. i The majority of caniates answere this question correctly although many sai that water makes the bloo flui an thus prevents clotting. b i The majority of caniates answere this question correctly. The majority of caniates faile to escribe an aequate metho for comparing the rate of water uptake. Very few caniates referre to the fact that the shoots shoul have a similar surface area. No reference to acclimatisation was mae. Many caniates referre to the introuction of an air bubble in the capillary tube an that reaings shoul inclue a measurement of the istance move by the bubble. Many caniates sai that the apparatus shoul be set up in a humi environment without escribing how a humi environment coul be create. c i Many caniates sai that mineral ions are absorbe along with water by osmosis. The majority of caniates answere this question correctly. The majority of caniates answere this question correctly. Some caniates sai that plants aapte for living in ry habitats have a waxy cuticle without emphasizing that this is thick. e i The majority of caniates referre to the fact that the walls of capillaries are thin/only one cell thick. The majority of caniates referre to the fact that capillaries have a large surface area. The majority of caniates sai that tissue flui allows the exchange of material between the capillaries an the tissues. i The majority of caniates sai that oxygen moves from capillaries to muscle tissue because the latter requires oxygen for respiration an that carbon ioxie moves from the tissue to the bloo to be eventually exhale from the lungs. Few referre to the relative concentrations of oxygen an carbon ioxie in the tissues an capillaries. Question 4 a i The majority of caniates sai that carbohyrate igestion starts in the mouth while protein igestion starts in the stomach. Many caniates went on to say that igestion continues in the intestines. A consierable number of caniates sai that igestion continues in the ileum. Several caniates mae correct reference to the enzymes involve in the igestion of carbohyrates an proteins. 6

7 Few caniates referre to the fact that ifferent enzymes have ifferent optimal ph values. The majority of caniates referre to the various functions of the liver an sai that the liver has a ifferent bloo supply compare to other organs because of its important role. Few caniates referre to the hepatic artery or the hepatic portal vein. i The majority of caniates answere this question correctly. iv The majority of caniates answere this question correctly. b i The majority of caniates answere this question correctly. The majority of caniates answere this question correctly. i The majority of caniates answere this question correctly. However some caniates incorrectly suggeste that ientical twins arise when two sperm cells fuse with a single ovum. Question 5 a The efinition for the term ecosystem was generally incomplete. In many cases the answer was totally incorrect. Many caniates omitte to refer to the interaction between the biotic an the abiotic component. Many more omitte to mention the iea of energy flow an cycling of matter. b i Generally correct an in line with the marking scheme. Marks were principally lost when caniate faile to mention the leaching/seeping of nitrates through the groun until they reach the groun water. Generally correct. One nees to point out the fact that in many cases the language an expressions use were inicative of very poor comman of both English an Scientific language. Caniates seem to prefer using animals go rather than animals migrate to mention one. In the opinion of the examiner the ability of expression is getting weaker by the year. i Generally correct even though in many cases incomplete. Marks were lost when caniates faile to link together precipitation/evaporation with the changes in salinity. Worryingly a significant number of caniates referre to salinity as a factor which changes of its own accor an omit the strong corresponence with water levels. Another point of concern is again the general inability to use simple phrases with the correct scientific terms in place an instea use expressions like the sun evaporates water or the sun absorbs or takes water which are totally unacceptable. c i A significant proportion of marks was instea lost in this part. Very few caniates linke properly the ecrease in carbon ioxie levels with photosynthesis an the increase in plant growth. The biological processes an thinking use were generally poor an of low stanar inee. Only a hanful of caniates manage to link photosynthesis, prouction of glucose an its use in respiration to provie energy necessary for growth or for the prouction of new tissue. It seems that caniates are still very easily taken aback by questions involving a certain egree of application. Generally incomplete as most caniates faile to mention that ecomposition releases carbon ioxie. The examples given in response to organisms responsible for ecomposition were generally correct. i Generally incomplete. The examiner was asking for a escription an not merely a mention of one activity. Hence a complete answer is combustion of fossil fuels an not simply use of fossil fuels. A significant portion of the caniates mae reference to riving a car, harly an acceptable answer as it shows an inability to link fossil fuels with release of carbon ioxie. 7

8 Generally incorrect. Very few caniates obtaine half or full marks in this part. It seems that the majority of the caniates is uner the incorrect impression that an effect of the thinning of the ozone layer is an increase in global warming. The scientific reasoning behin this statement is totally incorrect. The thinning of the ozone layer allows more UV light to reach the planet s surface causing mutations, cataracts, melanoma an other skin conitions etc. Global warming is mainly concerne with the trapping or IR raiation in the atmosphere leaing to an overall increase in temperature with all its consequences. The ozone layer oes not affect in any way the IR levels whether it is intact or not. Question 6 a i Generally correct with a significant proportion of caniates omitting some parts to the answer. The examiner points out however the incorrect reference in a worrying number of scripts about the movement of neurons rather that the transmission of a nervous impulse. Very few caniates mae reference to the spee of impulse transmission. Even fewer mentione the quick synaptic transmission between neurons as the major reasons behin the short time lapse between the stimulus an the response. The answers given were not in the least anywhere close to the marking scheme. i Very few caniates mentione that the enocrine glans are effectors. The majority mae reference to the secretion of hormones as a response awaring them half the marks allotte. The correct an proper use of terminology is imperative in the scientific formation of the caniates. b i Very few caniates linke together the evaporation of sweat from the skin surface with the absorption of heat energy from the boy thus provng a cooling effect. Many answere incompletely by stating that sweat evaporates cooling the boy, omitting the proper reason. Generally correct. No major points to comment about. i Generally incomplete. Caniates gave a possible effect: hypothermia or hyperthermia, but faile to explain clearly the anger of these in the enaturation or eactivation of enzymes (epening on the effect) an thus the lowering of metabolic activity, etc. c i Generally correct. Caniates failing to obtain full marks, gave incomplete answers Question 7 as they i not clearly escribe the changes occurring insie the shoot. The examiner woul like to point out, once again, the general inability to use proper terms involving the movement of molecules: molecules migrate or are transporte, but efinitely molecules o not move or walk or go anywhere! Another point is that plants grow towar or away from a stimulus an o not go or flee from it. Very few caniates mae a reference to an equal istribution of auxin in all areas of the shoot. The majority of caniates were aware one mark for the irection of growth (upwars) only. Oly enough caniates scoring goo marks in the previous part coul not relate an link the knowlege with this secon part an hence lost a significant proportion here. i Generally incomplete. It seems that the majority of the caniates faile to unerstan the question correctly. Many explaine why chlorophyll is important whereas the question is also about the relevance of the observation reporte in it. Very few caniates state that chlorophyll prouction is stimulate by the presence of light. iv Many caniates faile to realise that the question ha two parts: 1) about the type of response an 2) the give a reason. Shockingly a number of caniates gave the answer in terms of the shoot rather than the root. a i Generally correct. No major points to comment about. Generally correct. i Generally correct for the insect, the myriapo an the arachni. The reason for choosing crustacean for organism D were in the majority of cases incorrect as the feature mentione was not typically crustacean, like the presence of the 8

9 exoskeleton (the answer aopte by the majority). b i Generally incorrect as the majority mae reference to hibernation. Generally correct. No major points to comment about. c i Generally incomplete an partially incorrect. Caniates mae reference to breathing which is typically mammalian ue to the presence of lungs. Many referre to the spiracles as the respiratory surface or the site of gaseous exchange; clearly incorrect. Very few mentione that they are the openings of the tracheal system or that they close to prevent water loss or that they allow the entry an exit of oxygen an carbon ioxie respectively. Generally incomplete with respect to the boy parts where spiracles are situate. Caniates omitte either the thorax or the abomen Generally incorrect in ientifying the exact place, that is both sies of the above mentione boy parts. Many sai uner the wings, on the legs, on the hea, etc i Generally correct. iv Generally correct. PAPER 2B comments General Comments: Caniates were unable to express themselves properly mainly ue to their poor comman of the English language. This was strongly evient in answers where caniates were expecte to write a short paragraph such as in question 4. Question 1 a. Several caniates i not keep to criteria suggeste by question i.e the use of graph paper an the labelling of axes an bars. Some caniates rew a histogram rather than a bar chart. b Most caniates were unable to ientify the enotherm classes from the list of vertebrates given. c i Mainly correct. Answers to this questions were either incorrect or incomplete with caniates simply stating the change in the amount of oxygen in water without giving a reason why. i Several caniates escribe the organisms foun in the first trophic levels as autotrophs/proucers however many where unable to explain properly why proucers occupy this trophic level in a foo chain. e f Question 2 i Too basic an answer was given to this question. Mainly correct. A large number of caniates i not match the trophic level to the primary/seconary consumer in their answer but simply wrote own secon an thir trophic level. Few caniates gave complete correct answers to this classic question. Several gave one correct way of why energy is reuce from one trophic level to another. a i Mainly correct for naming kingom. Several incorrect answers with caniates giving mammals as their reply for phylum of sloths. The term mammals was referre to in the initial text of the question. A variety of correct characteristics were given by caniates the most common being having hair or fur. b i Most caniates attempting question 2 i not answer this question. There were very few partially correct answers. Caniates copie correctly the relevant portion of text of question b. c i Some caniates still efine a habitat as the place where an animal lives. Mainly correct although some caniates gave a general answer such as trees. 9

10 i A number of caniates were able to apply their knowlege of herbivore igestion to this question an answer correctly. Few caniates gave etaile replies. Many suggeste that this is a mechanism to facilitate the igestion of foo. e Very few full answers. The majority of caniates gave few carbohyrates igeste as their answer. f i There were a large number of incorrect answers to this question. Caniates were unable to ifferentiate between behavioural an physiological methos of temperature control. Question 3 a i Mainly incorrect. Several caniates inaccurately gave the function of water in cytoplasm for cell turgty. Again some caniates erroneously state that water in bloo plasma liquefies bloo. b i Most caniates wrote a vague proceure without referring to the correct metho. Practical precaution of attaching capillary tubing uner water was harly mentione by caniates. Several caniates correctly state that win increases the rate of transpiration but very few caniates gave a vali reason for this answer. c i Some caniates name an explaine well the process by which mineral salts are absorbe from soil. Few escribe the passage of ions in the plant. Mainly correct. Several caniates were able to give at least one suitable answer to this question. e i Some correct answers. Several caniates i not attempt this question. Mainly incorrect. Several caniates inaccurately gave the function of water in cytoplasm for cell turgty. Question 4 a i Several caniates mentione the change into puberty as the boy evelops. Few explaine that the growth of facial hair is a seconary sexual characteristic. Many caniates explaine correctly the ifference in the characteristic spee of nervous an enocrine messages. Only a small number of caniates gave vali reasons why there is a ifference in spee. i Answers highlighte misunerstoo concepts of the origin of ientical an fraternal twins. b i Many caniates i answer that carbohyrate igestion starts in the mouth but faile to mention the importance of salivary amylase an that this type of igestion continues in the uoenum. Certain caniates state the presence of uct glans in the human boy. Very few gave examples. i Some caniates gave at least one factor affecting photosynthesis other than the intensity of light. Question 5 a i Most caniates were aware that the binomial system is universal an thus avois confusion. Reference to evolutionary relationships was never encountere. Often correct. The iea of segments, jointe boy an presence of exoskeleton was often known amongst the caniates. i Some caniates confuse the arthropo group with the actual names of organisms. The most confuse characteristic was that of crustaceans where the majority of caniates answere har exoskeleton. b i Most common answer: to breathe. Often caniates faile to explain the gas exchange process i.e. the mentioning of O 2 an CO 2. Prevention of water loss was rarely mentione an a reference to the tracheal system was rare in Paper B. 10

11 i Often correct. Sometimes correct. Question 6 a i Reference to the use of fertilisers (an sometimes sewage) was often one. Some caniates though, faile to escribe HOW these nitrates en up in groun water i.e. the run-off an seeping through rocks. Often correct. b i Often correct though lacke etaile an 1 mark was eucte for this. Eg. Have beak (omitte toothless), have wings (omitte forelimbs moifie), lay eggs (omitte har shelle). Parallel veins often correct. Often fibrous an tap roots were confuse. Aventitious roots never mentione, scattere vascular bunles very rarely observe. i Often incorrect as the caniates faile to realise that the question was about the flower of monocots an icots. c i Breakown of ea organic matter often correct. Nearly always, the release of CO 2 was omitte. Use of cars was common answer in paper B. This was consiere incorrect when no reference to fossil fuels was mae. i Glucose often mentione. Very confuse ieas emerge. A escription of a greenhouse was consiere incorrect. i Climate change with reference to the melting of the polar ice caps was the most common answer encountere. Increase risk of skin cancer was also a common answer. It is suggeste that caniates are expose to other environmental issues relate to the thinning of the ozone layer. Question 7 a i Very often the escriptions are incorrect because caniates fin ifficulty in escribing an giving the necessary etail. For example receptors; where the stimulus is foun. Sometimes caniates provie rawing of a reflex arc but faile to give a escription as require by the question. involuntary action is most often given b i Sweat evaporates from the skin is often known but that heat energy is carrie away from the boy is often omitte. Vasoilation rarely mentione. Hairs relax is sometimes given. i Often caniates explaine that heat is trappe by the fat in the skin. This is not an accurate escription. c i Shoots ben towars the light often correct but the term phototropism often is omitte. The mechanism of auxins very often unknown. i Correct Sometimes chloroplasts an chlorophyll are exchange. Question 8 a i - i b i - i c i - i Win see ispersal was sometimes correct though confusion with win pollination was often encountere. A escription of the way sees are move by the win an their abunance was never encountere. However, the iea of competition was sometimes mentione. The term shivering was not often mentione by the caniates. The term vegetative propagation was never encountere. More often caniates referre to cloning. This was not consiere correct. However, often the caniates referre to the asexual process of reprouction. 11

12 i - i e i - i Very confusing answers were encountere here. The term geotropism was very rarely encountere. Hunting was commonly observe in this question. Very often caniates explaine that the preator hunts for the prey to get foo. This was aware marks. However, the relationship between preator an prey an their populations were never encountere. Chairperson 2013 Examination Panel 12