Life Sciences Grade 12 P2 NSC November 2022 QP (Eng)

Downloaded from hlayiso.com GRAAD 12 NATIONAL SENIOR CERTIFICATE GRADE 12 LIFE SCIENCES P2 NOVEMBER 2022 MARKS: 150 TIME: 2½ hours This question paper consists of 15 pages. Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 2 DBE/November 2022 NSC INSTRUCTIONS AND INFORMATION Read the following instructions carefully before answering the questions. 1. Answer ALL the questions. 2. Write ALL the answers in the ANSWER BOOK. 3. Start the answers to EACH question at the top of a NEW page. 4. Number the answers correctly according to the numbering system used in this question paper. 5. Present your answers according to the instructions of each question. 6. Do ALL drawings in pencil and label them in blue or black ink. 7. Draw diagrams, tables or flow charts only when asked to do so. 8. The diagrams in this question paper are NOT necessarily drawn to scale. 9. Do NOT use graph paper. 10. You must use a non-programmable calculator, protractor and a compass, where necessary. 11. Write neatly and legibly. Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 3 DBE/November 2022 NSC SECTION A QUESTION 1 1.1 Various options are provided as possible answers to the following questions. Choose the answer and write only the letter (A–D) next to the question numbers (1.1.1 to 1.1.9) in the ANSWER BOOK, e.g. 1.1.10 D. 1.1.1 The scientist who discovered the fossil 'Karabo' (A. sediba): A Robert Brown B Lee Berger C Raymond Dart D Ronald Clarke 1.1.2 Which ONE of the following is a source of variation that occurs during normal meiosis? A Random mating B Random arrangement of chromosomes C Chromosomal mutations D Cloning 1.1.3 How many sex chromosomes does a normal human female inherit from her mother? A 1 B 2 C 23 D 46 1.1.4 During which phase of meiosis does the nuclear membrane disappear? A Metaphase B Telophase C Prophase D Anaphase 1.1.5 Which ONE of the following is an example of discontinuous variation in humans? A Height B Heart rate C Gender D Weight Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 4 DBE/November 2022 NSC 1.1.6 For a particular characteristic, the offspring inherits … A one allele from the mother and one allele from the father. B both alleles from the father. C both alleles from the mother. D the alleles from either the mother or the father randomly. 1.1.7 Which ONE of the following is CORRECT for speciation through geographic isolation? A The populations undergo phenotypic changes only. B Each population undergoes natural selection independently. C The conditions on each side of the geographic barrier are the same. D The new species formed are genotypically the same as the original species. 1.1.8 Below is a list of events that occur during cell division. (i) Homologous chromosomes line up at the equator of the cell. (ii) Chromatids are pulled to opposite poles of the cell. (iii) Chromosome pairs arrange themselves randomly at the equator of the cell. (iv) Individual chromosomes line up at the equator of the cell. Which ONE of the following combinations occur in both meiosis and mitosis? A (ii), (iii) and (iv) only B (i) and (iv) only C (i), (iii) and (iv) only D (ii) and (iv) only 1.1.9 A short piece of DNA, containing 19 nucleotides in each strand, was analysed. The number of some of the different nitrogenous bases in each strand is shown below. Number of nitrogenous bases A T G C Strand 1 8 - - - Strand 2 - 8 3 4 How many nucleotides containing thymine (T) were present in strand 1? A 8 B 4 C 6 D 2 (9 x 2) (18) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 5 DBE/November 2022 NSC 1.2 Give the correct biological term for each of the following descriptions. Write only the term next to the question numbers (1.2.1 to 1.2.9) in the ANSWER BOOK. 1.2.1 The process of change in the characteristics of biological species over time 1.2.2 The type of bonds between nitrogenous bases in a DNA molecule 1.2.3 The structure that joins two chromatids of a chromosome 1.2.4 The division of the cytoplasm of a cell during cell division 1.2.5 The process during meiosis where there is an exchange of genetic material between chromatids 1.2.6 The structures in animal cells that give rise to spindle fibres during cell division 1.2.7 Similar structures that are inherited from a common ancestor and are modified for different functions 1.2.8 The phase in the cell cycle during which DNA replication takes place 1.2.9 The organelle where translation occurs during protein synthesis (9 x 1) (9) 1.3 Indicate whether each of the descriptions in COLUMN I applies to A ONLY, B ONLY, BOTH A AND B or NONE of the items in COLUMN II. Write A only, B only, both A and B or none next to the question numbers (1.3.1 to 1.3.3) in the ANSWER BOOK. COLUMN I COLUMN II 1.3.1 Type of evolution characterised A: Artificial selection by long periods of little or no B: Punctuated equilibrium change alternating with short periods of rapid change 1.3.2 A plant with white flowers that is A: Incomplete dominance crossed with a plant with red B: Complete dominance flowers and produces offspring with pink flowers 1.3.3 The separation of alleles during A: Law of Dominance gamete formation B: Principle of Segregation (3 x 2) (6) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 6 DBE/November 2022 NSC 1.4 Moyamoya is a disorder caused by a dominant allele (R). This disorder damages the arteries supplying blood to the brain. The pedigree diagram below shows the inheritance of Moyamoya in a family. A B A C D E F G H I J KEY Unaffected male Unaffected female Affected male Affected female 1.4.1 How many generations are represented in the diagram? (1) 1.4.2 Give the: (a) LETTER(S) of unaffected males (1) (b) Genotype of individual A (1) (c) LETTER(S) of individuals not biologically related to A and B (2) (5) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 7 DBE/November 2022 NSC 1.5 The diagram below represents part of an abnormal human karyotype. 21 22 23 1.5.1 How many autosomes are shown in the diagram? (1) 1.5.2 Name the type of chromosomes represented by pair 23. (1) 1.5.3 Name the: (a) Disorder represented in the diagram (1) (b) Process during anaphase of meiosis that resulted in the abnormal number of chromosomes in this karyotype (1) 1.5.4 State the gender of the person represented in this karyotype. (1) (5) 1.6 In rabbits, brown fur (B) is dominant to white fur (b) and long ears (E) is dominant to short ears (e). A rabbit, that is heterozygous for both characteristics, is crossed with a white rabbit with short ears. 1.6.1 Name the type of cross represented. (1) 1.6.2 Give the: (a) Phenotype of a rabbit that is dominant for both characteristics (2) (b) Genotype of the white rabbit with short ears (2) (c) Genotype of the gametes of a heterozygous brown rabbit with short ears (2) (7) TOTAL SECTION A: 50 Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 8 DBE/November 2022 NSC SECTION B QUESTION 2 2.1 The diagram below represents transcription during protein synthesis. Adenine Y X DNA mRNA 2.1.1 Name the part of the cell where this process occurs. (1) 2.1.2 Identify: (a) Sugar X (1) (b) Nitrogenous base Y (1) 2.1.3 Tabulate TWO differences between transcription and DNA replication. (5) (8) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 9 DBE/November 2022 NSC 2.2 A mutation has occurred on a section of an mRNA molecule as shown below. Original sequence AUG GAA AUA CCG CCA GGA Mutated sequence AUG GAA AUA CUG CCA GGA 2.2.1 Name the type of mutation that has occurred. (1) 2.2.2 Give a reason for your answer to QUESTION 2.2.1. (1) 2.2.3 The table below shows some mRNA codons and the amino acids that they code for. mRNA codon Amino acid AUA Isoleucine AUG Methionine CCA Proline CCG Proline CUG Leucine GAA Glutamic acid GGA Glycine (a) State the number of different amino acids coded for by the original sequence of the mRNA molecule given above. (1) (b) Give the anticodon on the tRNA molecule that carries the amino acid isoleucine. (1) (c) Use information in the table to describe the effect of the mutation on the protein formed. (4) (8) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 10 DBE/November 2022 NSC 2.3 The number of chromosomes in the somatic cells of organisms differs from species to species. The graph below shows the number of chromosomes in each somatic cell of THREE different species. The number of chromosomes in the somatic cells of three different species Number of chromosomes 60 50 40 30 20 10 0 Giraffe Mouse Pineapple plant Species 2.3.1 How many chromosomes will be present in: (a) Mouse cells during Telophase II of meiosis (1) (b) A leaf cell of a pineapple plant (1) 2.3.2 Explain why the sperm cell of a giraffe has 15 chromosomes. (4) 2.3.3 Name the phase of meiosis where the halving of the chromosome number begins. (1) 2.3.4 Describe the events in the phase named in QUESTION 2.3.3. (3) (10) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 11 DBE/November 2022 NSC 2.4 The table below shows information about blood groups in a certain population. BLOOD NUMBER OF PERCENTAGE OF GROUP PEOPLE THE POPULATION O 954 000 53 A X 34 B 180 000 10 AB 54 000 3 2.4.1 How many people have the genotype ii? (1) 2.4.2 The population size is 1 800 000. Calculate the value of X. Show ALL working. (3) 2.4.3 Describe how a child inherits the blood group represented by 3 per cent of this population. (3) (7) 2.5 The diagram below represents the DNA profiles of three children and their parents. Only two of the children are their biological children and one is adopted. Mother Father Heila Priya Leo 2.5.1 Identify the TWO biological children. (2) 2.5.2 Explain your answer to QUESTION 2.5.1. (2) 2.5.3 State THREE other uses of DNA profiling. (3) (7) 2.6 Brown enamel of the teeth is a sex-linked trait. A dominant allele on the X chromosome causes brown teeth in humans. 2.6.1 Explain why more males than females have white teeth. (4) 2.6.2 A man with brown teeth married a woman with white teeth. Use a genetic cross to show the possible phenotypic ratios of their children. Use XB for brown teeth and Xb for white teeth. (6) (10) [50] Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 12 DBE/November 2022 NSC QUESTION 3 3.1 Read the extract below. When a child is born, the umbilical cord is cut and stem cells can be obtained from it. Many people think that the stem cells for treating human conditions should be obtained from umbilical cords, rather than from human embryos. Recently, stem cells have also been obtained from bone marrow. These stem cells are used to treat conditions such as heart disease and spinal injuries. 3.1.1 Name THREE sources of stem cells mentioned in the extract. (3) 3.1.2 Explain why the characteristics of stem cells make them useful for treating some disorders. (2) 3.1.3 Name ONE condition in the extract that can be treated with stem cells. (1) (6) 3.2 Read the extract below. Samango and vervet are two species of monkeys that occupy the same habitat. Researchers have recently discovered that a population of samango monkeys were able to interbreed with vervet monkeys to produce offspring. These offspring were infertile. 3.2.1 Define the term population. (3) 3.2.2 Give ONE reason why samango and vervet monkeys are considered to be two different species. (1) 3.2.3 List THREE mechanisms of reproductive isolation that are NOT mentioned above. (3) (7) 3.3 Scientists find evidence for human evolution by comparing humans to other hominids. The upper limbs of humans and African apes show similar characteristics, whereas there are differences between the dentition (teeth) of the two. 3.3.1 Why do scientists look for similarities between humans and African apes? (1) 3.3.2 Explain the importance of the positioning of the thumbs for humans and African apes. (2) 3.3.3 State ONE difference between the teeth of humans and African apes. (2) (5) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 13 DBE/November 2022 NSC 3.4 The diagram below represents one model of the evolution of some hominids. Most recent Homo sapiens Homo neanderthalensis Homo florensiensis Homo heidelbergensis Homo naledi Homo erectus Species X (used stone tools) Homo rudolfensis Earliest Australopithecus africanus 3.4.1 Identify the type of diagram shown. (1) 3.4.2 How many genera are represented by the diagram? (1) 3.4.3 Name the species: (a) Represented by X on the diagram (1) (b) That shares a common ancestor with Homo erectus (1) 3.4.4 Which species of the genus Homo is the only one in existence today? (1) 3.4.5 Name TWO forms of evidence that would have been used to support the information in the diagram. (2) 3.4.6 The average cranial capacity of Homo sapiens is 1 500 cm3 compared to 520 cm3 in Australopithecus africanus. Explain the significance of the difference in cranial capacity. (3) 3.4.7 Explain how the fossils of Australopithecus africanus, Species X and Homo erectus are used to support the 'Out of Africa' hypothesis. (4) (14) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 14 DBE/November 2022 NSC 3.5 Modern-day whales are aquatic mammals, spending their entire lives in the ocean. They are thought to have evolved from four-legged ancestors, as represented below. SPECIES EXISTENCE CHARACTERISTICS ON EARTH Pakicetus 50 mya Quadrupedal carnivore Ambulocetus 48 mya Flipper-like large feet and tail for swimming Dorudon 40 mya Large flippers in front and very small hind limbs Balaena (Blue whale) Present day Non-functioning pelvis and large flippers in front 3.5.1 Which ancestor of whales most likely lived both in water and on land? (1) 3.5.2 Give ONE reason for your answer to QUESTION 3.5.1. (2) 3.5.3 Explain why Ambulocetus and Dorudon may be considered as transitional species in the evolution of whales. (2) 3.5.4 Explain, according to Lamarck, why modern-day whales do not have legs. (3) (8) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 15 DBE/November 2022 NSC 3.6 Patients infected with the HI virus (HIV) are treated with antiretroviral drugs. When they miss their treatment, it can increase the chances (probability) of the virus developing resistance to the drug. Scientists conducted an investigation to determine the effect of the number of missed treatments on the probability of the HI virus developing resistance to antiretroviral drugs. The results are shown in the table below. Number of missed Probability of the HI virus treatments developing resistance to (in days) antiretroviral drugs (%) 2 0 7 20 14 35 21 40 37 60 3.6.1 State the following for this investigation: (a) The dependent variable (1) (b) The independent variable (1) 3.6.2 Based on the results, state ONE precaution for patients receiving antiretroviral treatment. (1) 3.6.3 State a conclusion for this investigation. (2) 3.6.4 Describe the evolution of resistance to antiretroviral medication in the HI virus. (5) (10) [50] TOTAL SECTION B: 100 GRAND TOTAL: 150 Copyright reserved