Life Sciences Grade 12 KZN March 2019 Paper & Memo

MARKS: 60 TIME: 1 hour Downloaded from hlayiso.com education Department: Education PROVINCE OF KWAZULU-NATAL NATIONAL SENIOR CERTIFICATE GRADE 12 LIFE SCIENCES " COMMON TEST " MARCH 2019 : This question paper consists of 9 pages.

Downloaded from hlayiso.com Life Sciences 2 March 2019 Common Test NSC INSTRUCTIONS AND INFORMATION Read the following instructions carefully before answering the questions. 1, 2. 10. 11. Answer ALL the questions. Write ALL the answers in the ANSWER BOOK. Start the answers to each question at the top of a NEW page. Number the answers correctly according to the numbering system used in this question paper. Present your answers according to the instructions of each question. Do ALL drawings in pencil and label them in blue or black ink. Draw diagrams, tables or flow charts only when asked to do so. The diagrams in this question paper are NOT necessarily drawn to scale. Do NOT use graph paper. You may use a non-programmable calculator, protractor and a compass. Write neatly and legibly. Copyright reserved Please Turn Over MI

Downloaded from hlayiso.com Life Sciences 3 March 2019 Common Test NSc SECTION A QUESTION 1 11 Various options are provided as possible answers to the following questions. Choose the answer and write only the letter (A to D) next to the question number (1.1.1. to 1.1.3) in the ANSWER BOOK, for example 1.1.4 A. 1.1.1 Two complimentary bases in a DNA strand are held together ... A __ by strong nitrogen bonds. B by weak hydrogen bonds. C because they are coiled around each other. D by weak nitrogen bonds. 1.1.2 Which of the following statements about species that use external fertilisation are correct? (i) | Most young survive to maturity (ii) Water is needed for fertilization (iii) Produce a small number of eggs (iv) Produce a large number of eggs (i) and (ii) only (i), (ii) and (iv) only (ii) and (iii) only (ii) and (iv) only GUOWD 1.1.3. Which of the following distinguishes prophase 1 of meiosis from prophase of mitosis? Nucleolus and nuclear membrane disappear Homologous chromosomes pair up Nuclear membrane breaks down Chromosomes become visible voOw> (3x2) (6) Copyright reserved Please Turn Over MY

Downloaded from hlayiso.com Life Sciences 4 March 2019 Common Test NSC 1.2 Indicate whether each of the descriptions in COLUMN | applies to A ONLY, B ONLY, BOTH A AND B or NONE of the items in COLUMN Il. Write A only, B only, both A and B, or none next to the question number (1.2.1 to 1.2.2) in the ANSWER BOOK. COLUMN | COLUMN II 1.2.4 The development in some A. -Precocial birds where the hatchlings are |B - Altricial able to feed on their own 1.2.2 Holds together chromatids A Chiasma ‘ B Centromere (2x2) (4) TOTAL SECTION A: 10 Copyright reserved Please Turn Over MI

Downloaded from hlayiso.com Life Sciences 5 March 2019 Common Test NSC SECTION B QUESTION 2 2.1 The diagram below represents cell division. {*) 2.1.1 Name the type of cell division represented in the diagram. (1) 2.1.2 State where in the human male body does the type cell division mentioned in QUESTION 2.1.1 takes place. (1) 2.1.3 How many chromosomes are present in cell A? (1) 2.1.4 Explain what the effect will be, if the crossing over did not take place during the type cell division named in QUESTION 2.1.1 above. (2) 2.1.5 In the human karyotype the first 22 pairs of chromosomes are referred to as ... (1) (6) Copyright reserved ne Please Turn Over

Downloaded from hlayiso.com Life Sciences 6 March 2019 Commen Test NSC 2.2 The diagram below represents the stages of the menstrual cycle. Hormone Y A Emon ©) rb Gland X 9 ¢ « Progesterone NN wae Menstrual cycle 2.2.1 Identify: (a) Gland X (b) Hormone B 2.2.2 Give TWO visible reasons from the diagram indicating that fertilisation did not take place during this menstrual cycle. 2.2.3 State the effect of hormone Y on the lining of the uterus. 2.2.4 Explain the effect of the disintegrating corpus luteum on the menstrual cycle. Copyright reserved MI Please Turn Over (1) (1) (2) (4) (9) [15]

Downloaded from hlayiso.com Life Sciences 7 March 2019 Common Test NSC QUESTION 3 3.1 The diagram below shows the part of a stage in protein synthesis. Molecule R 3.1.1 Identify organelle A. 3.1.2 How many codons are shown altogether in the molecule R? 3.1.3 Give the DNA base triplet for the amino acid Asp. 3.1.4 Name and describe the stage of protein synthesis shown in the Copyright reserved diagram above Please Turn Over MI (1) (1) (1) (6) (9)

Downloaded from hlayiso.com Life Sciences 8 March 2019 Common Test NSC 3.2 Pregnancy is problematic in females aged between 17 and 35 years. The females aged between 40 and 45 years struggle to get pregnant. Scientists conducted an investigation to establish the relationship between the maternal age, the pregnancy and the infertility rate percentage. The investigation was conducted in one of the hospitals in Durban. He conducted the investigation with a small sample size. The females between ages 20 and 50 years were investigated from 2007 to 2017, Their findings are summarised in the graph below. Relationship between the maternal age, infertility and pregnancy rate (%) 100 = ° 2 a: ~ “em 78 4 ie 63 69 ~ Key fess 52 ne WA -@ Pregnancy Ss 8 infertility 2 So | » ° = hn \e . a YS ‘ Q »--. 20-25 25-29 30-34 35-39 40-44 4549 50+ Maternal age (yr) Pregnancy & infertility rate (%) yn ° ° w wo co A 3.2.1 Identify the: (a) Dependent variable (1) (b) Independent variable (1) 3.2.2 Refer to the passage above and state ONE way in which the = (1) scientists failed to ensure the reliability during this investigation. 3.2.3 Describe the relationship shown in the graph by the maternal age, the pregnancy and inferiility rate percentage. (3) (6) (15) TOTAL SECTION B: 30 Copyright reserved Please Turn Over AML?

Downloaded from hlayiso.com Life Sciences 9 March 2019 Common Test NSC SECTION C QUESTION 4 Describe the DNA replication and the process of oogenesis as it takes place in the ovary. Also describe how abnormal meiosis may results in an egg cell with one chromosome less. Content: (17) Synthesis: (3) (20) NOTE: NO marks will be awarded for answers in the form of tables, flow charts or diagrams. TOTAL SECTION C: 20 GRAND TOTAL: 60 Copyright reserved Atl

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE GRADE 12 LIFE SCIENCES MARCH 2019 COMMON TEST MEMORANDUM MARKS: 60 This memorandum consists of 4 pages.

Downloaded from hlayiso.com Life Sciences 2 March 2019 Grade 12 - Memorandum SECTION A QUESTION 1 1.1 1.1.1 BPP 1.1.2 B / DPP 1.1.3 BPP (3 x 2) (6) 1.2 1.2.1 A onlyPP 1.2.2 B onlyPP (2 x 2) (4) TOTAL SECTION A: 10 SECTION B QUESTION 2 2.1 2.1.1 MeiosisP (1) 2.1.2 TestisP/Seminiferous tubules (1) 2.1.3 6P (1) 2.1.4 - No exchange of genetic materialü between homologous chromosomes - resulting in a decreased variationPin offspring (2) 2.1.5 Autosomesü (1) (6) 2.2 2.2.1 (a) Pituitary glandP/hypophysis (1) (1) (b) Luteinising hormoneP/ LH 2.2.2 - Corpus luteum is degeneratingP/disintegrating - Progesterone is decreasingP (2) (Mark first TWO only) 2.2.3 Hormone Y/oestrogen thickens the endometriumP (1) 2.2.4 - Progesterone level will decreaseü in the blood - Menstruation will take placeü/ endometrium breaks down - No inhibition of pituitary glandü/Hypophysis - from producing FSHü - The follicle will developü - leading to ovulationü (4) Any 4 (9) [15] Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences 3 March 2019 Grade 12 - Memorandum QUESTION 3 3.1 3.1.1 Ribosomeü (1) 3.1.2 8ü (1) 3.1.3 CTAü (1) 3.1.4 Translation*ü - Each t-RNA picks up a specific amino acidü - When the anticodon on the tRNAü - Matches the codon of the mRNAü - Then tRNA brings the required amino acid to the ribosomeü - Amino acids become attached by peptide bondsü - to form required proteinü * compulsory mark+ any 5 (6) (9) 3.2 3.2.1 (a) – Percentage infertility - Pregnancy (1) (b) Maternal ageü (1) 3.2.2 - Small sample size was usedü/ investigation was conducted in only one hospital. (1) Mark first ONE only 3.2.3 - As the maternal age increasesü - the infertility increasesü - and the pregnancy decreasesü (3) (6) (15) TOTAL SECTION B: 30 Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences 4 March 2019 Grade 12 - Memorandum SECTION C QUESTION 4 DNA replication - Occurs during interphaseü - DNA molecule unwindsü - Weak hydrogen bonds between nitrogenous bases breakü - DNA unzipsü/DNA strands separate from each other - Both DNA strands serve as templatesü - to form a complementary DNA strandsü / A-T and G-C - using free DNA nucleotides from the nucleoplasmü - The process is catalysed by enzymesü Any 7 (7) Oogenesis - Under the influence of FSHü - diploid cellsü/ germinal epithelial cells in the ovary - divide by mitosisü - forming many folliclesü - One cell inside a follicle enlarges and undergoes meiosisü - to produce four haploid cellsü - One cell survives to form a mature haploid ovumü Any 6 Abnormal meiosis (6) - Mutations/errors may occurü during meiosis - Chromosomes may fail to separateü/non-disjunction - During anaphaseü 1/2 - this may result in an unequal distribution of chromosomesü (4) Content: (17) Synthesis: (3) (20) ASSESSING THE PRESENTATION OF THE ESSAY Relevance Logic sequence Comprehensive All information provided is Ideas arranged in a logical Answered all aspects relevant to the question cause-effect sequence required by the essay in sufficient detail All the information provided is All the information regarding At least the following points relevant to the: the: should be included: - DNA replication - DNA replication - DNA replication 5/7 - Oogenesis - Oogenesis - Oogenesis 4/6 - Abnormal meiosis - Abnormal meiosis in a - Abnormal meiosis 2/4 There is NO irrelevant logical sequence information 1 mark 1 mark 1 mark TOTAL SECTION C: 20 GRAND TOTAL: 60 Copyright reserved Please turn over