Thursday, August 1, 2019

Life Sciences Paper 1

NATIONAL SENIOR CERTIFICATE GRADE 12 LIFE SCIENCES P1 FEBRUARY/MARCH 2011 MARKS: 150 TIME: 2? hours This question paper consists of 14 pages. Copyright reserved Please turn over Life Sciences/P1 2 NSC DBE/Feb. – Mar. 2011 INSTRUCTIONS AND INFORMATION Read the following instructions carefully before answering the questions. 1. Answer ALL the questions. 2. Write ALL the answers in your 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. . Do ALL drawings in pencil and label them in blue or black ink. 7. Draw diagrams 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 may use a non-programmable calculator, protractor and a compass. 11. Write neatly and legibly. Copyright reserved Please turn o ver Life Sciences/P1 3 NSC DBE/Feb. – Mar. 2011 SECTION A QUESTION 1 1. 1 Various options are provided as possible answers to the following questions. Choose the correct answer and write only the letter (A – D) next to the question number (1. 1. 1 – 1. . 6) in the ANSWER BOOK, for example 1. 1. 7 D. 1. 1. 1 The process in which male gametes are formed in humans is called †¦ A B C D 1. 1. 2 When the first child of two parents, without any visible genetic disorder, was born, the child was found to have a serious genetic disorder. The parents were told that a recessive gene had caused the disorder, and that only one pair of genes was involved. If they had a second child this child †¦ A B C D 1. 1. 3 was certain to have the disorder. had a 1 in 2 chance of having the disorder. had a 1 in 4 chance of having the disorder. no chance of having the disorder.Below is a set of steps following fertilisation in humans. Which is the CORRECT order of events? 1. 2. 3. 4. A B C D Copyright reserved vasectomy. spermatogenesis. oogenesis. mitosis. The embryo is embedded in the uterine wall in humans. A zygote is formed in the Fallopian tube. Cell division occurs to form a ball of several hundred cells. The blastocyst remains free for several days in the uterus. 2, 3, 4, 1 2, 1, 3, 4 3, 2, 4, 1 1, 3, 2, 4 Please turn over Life Sciences/P1 4 NSC DBE/Feb. – Mar. 2011 QUESTIONS 1. 1. 4 and 1. 1. 5 refer to the graph below which shows the growth of the follicle and the ovarian hormone levels.Hormonal regulation of the menstrual cycle Growth of follicle B A Ovarian hormone levels 0 1. 1. 4 21 28 Progesterone and LH FSH and LH Oestrogen and progesterone Oestrogen and FSH What is the follicle called after day 14? A B C D 1. 1. 6 14 Which hormones are represented by A and B? A B C D 1. 1. 5 7 Primary follicle Graafian follicle Secondary follicle Corpus luteum A ring of DNA (plasmid) is taken from a bacterial cell to produce insulin. The steps which f ollow are NOT in the correct order below. 1. The gene for insulin is removed from a cell of a human pancreas. 2. The bacteria make clones of themselves and produce nsulin. 3. The insulin gene is put into the plasmid and into a new bacterial cell. 4. The bacterial plasmid is cut using enzymes. The CORRECT order of the steps is †¦ A B C D Copyright reserved 3, 2, 4, 3. 3, 2, 4, 3. 4, 1, 3, 2. 4, 2, 1, 3. (6 x 2) Please turn over (12) Life Sciences/P1 1. 2 5 NSC DBE/Feb. – Mar. 2011 Give the correct biological term for each of the following descriptions. Write only the term next to the question number (1. 2. 1 – 1. 2. 7) in the ANSWER BOOK. 1. 2. 1 1. 2. 2 An arrangement of black bars representing DNA fragments that can be used to determine whether people are related 1. . 3 Structure in the sperm cell containing enzymes that break down the membrane of the ovum 1. 2. 4 The release of an ovum from a follicle 1. 2. 5 The period from fertilisation to birth 1. 2. 6 The tu be that transports the sperm from the testis to the urethra 1. 2. 7 1. 3 All the genes in all the chromosomes of a particular species A hormone produced in females to stimulate milk production (7) Indicate whether each of the statements 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 number (1. 3. 1 – 1. 3. ) in the ANSWER BOOK. COLUMN I 1. 3. 1 Possible ways of improving of fertility 1. 3. 2 Forms the placenta 1. 3. 3 Having a single set of chromosomes 1. 3. 4 Sexually-transmitted disease(s) caused by bacteria 1. 3. 5 Technique used to determine abnormalities of the foetus COLUMN II A: Artificial insemination B: In vitro fertilisation A: Amnion B: Chorion A: Diploid B: Haploid A: Syphilis B: HIV A: Ultrasound B: Amniocentesis (5 x 2) Copyright reserved Please turn over (10) Life Sciences/P1 1. 4 6 NSC DBE/Feb. – Mar. 2011 When a stigma is ripe, it secretes a fluid w hich stimulates pollen grains to grow tubes.The fluid contains sugar. Zama wanted to investigate the following question: How does the concentration of sugar affect the number of pollen grains that germinate/form pollen tubes in flowers? She designed the following investigation. †¢ She took 5 cavity slides. cover slip cavity slide solution with pollen grains †¢ †¢ †¢ †¢ The first slide she filled with distilled water. The second slide she filled with a 5% sugar solution. The third slide she filled with a 10% sugar solution. The fourth slide she filled with a 15% sugar solution. The fifth slide she filled with a 20% sugar solution.She transferred the same number of pollen grains from the anthers of a flower into each cavity of the five slides. A cover slip was gently lowered onto the slide. All five slides were placed in a warm incubator and left for one hour. Each slide was then examined under a microscope and the number of pollen tubes in each slide was coun ted and recorded in the table below. Concentration of sugar solution (%) 0 5 10 15 20 Number of pollen tubes 0 7 11 15 21 1. 4. 1 Explain why Zama used distilled water in the first cavity slide. (2) 1. 4. 2 State THREE ways in which this investigation would be improved to get more reliable results. 3) 1. 4. 3 Copyright reserved Describe a conclusion for the above investigation. (2) (7) Please turn over Life Sciences/P1 1. 5 7 NSC DBE/Feb. – Mar. 2011 The diagram below represents a karyotype of a human cell. 1 6 2 3 7 13 14 19 20 4 8 9 10 15 11 16 21 5 12 17 22 18 23 1. 5. 1 How many chromosomes are present in this karyotype? (1) 1. 5. 2 Is this karyotype that of a man or a woman? (1) 1. 5. 3 Give a reason for your answer to QUESTION 1. 5. 2. (2) 1. 5. 4 Describe how the karyotype of a person with Down's syndrome will be different from the karyotype shown in the diagram above. Copyright reservedPlease turn over (2) (6) Life Sciences/P1 1. 6 8 NSC DBE/Feb. – Mar. 2011 St udy the pedigree diagram of a family where some individuals have haemophilia. Haemophilia is a sex-linked disorder. Use H for normal blood clotting and h for the haemophiliac trait. Peter Andrew Millicent Henry Enid David Priscilla Goliath Key Normal female Anele Male haemophiliac Clarence Normal male 1. 6. 1 1. 6. 2 From the pedigree diagram above, state the relationship between gender and haemophilia. (2) Write down all the possible genotypes of individuals: (a) Peter (b) Enid (c) Clarence (6) (8) TOTAL SECTION A: Copyright reservedPlease turn over 50 Life Sciences/P1 9 NSC DBE/Feb. – Mar. 2011 SECTION B QUESTION 2 2. 1 Study the following diagrams representing different phases of meiosis. A C B Diagram 1 Diagram 2 2. 1. 1 Diagram 4 (3) Label structures A, B and C. 2. 1. 2 Diagram 3 Which phase is represented by: (a) 2. 1. 4 2. 1. 5 Copyright reserved (1) (b) 2. 1. 3 Diagram 1 Diagram 2 (1) Write down the numbers of the diagrams to show the correct sequence in which the pha ses occur. (2) Tabulate THREE differences between the first and second stages of meiosis. (7) Name and explain TWO processes/mechanisms that ensure that he gametes produced at the end of meiosis are genetically different from each other. Please turn over (4) (18) Life Sciences/P1 2. 2 10 NSC DBE/Feb. – Mar. 2011 The diagrams below represent the process of protein synthesis. M O N UC A G G C A C A P Z UGU Q UC AGGCACA R X 2. 2. 1 Identify compound M and organelle R. (2) 2. 2. 2 Write down the sequence of the FIRST THREE nitrogenous bases on the DNA strand that led to the formation of Z. (2) 2. 2. 3 Name the part/stage of protein synthesis that is illustrated in O. (1) 2. 2. 4 The table below shows the base triplets of DNA and the amino acid each codes for.Base triplet of DNA AGT CCG TGT GTA CAA TCC ACA Copyright reserved Amino acid coded for Serine Glycine Threonine Histidine Valine Arginine Cysteine Please turn over Life Sciences/P1 11 NSC DBE/Feb. – Mar. 2011 With ref erence to the diagram in QUESTION 2. 2 and the table above: (a) Name the amino acid labelled P. (2) (b) State the base sequence of the molecule labelled Q. (2) (c) What name is given to the triplet of tRNA bases that codes for each amino acid? (1) (d) Describe how the composition of the protein molecule changes if the base sequence at X is UGU instead of UCA. (2) (12) 30] QUESTION 3 3. 1 The diagram below represents the female reproductive system. X A Y B D C 3. 1. 1 Label structures A, B and C. (3) 3. 1. 2 State THREE functions of D. (3) 3. 1. 3 Fertilisation usually takes place at Y. Why will a blockage at X: (a) Prevent fertilisation at Y (b) Not necessarily lead to infertility Copyright reserved (1) (2) (9) Please turn over Life Sciences/P1 3. 2 12 NSC DBE/Feb. – Mar. 2011 Read the paragraph below and answer the questions that follow. MALE CONTRACEPTIVE CHEMICAL Gossypol is a chemical which is extracted from the seeds of cotton plants.When gossypol was given to rats, mice , dogs and monkeys, it caused a reduction in the fertility of the male animals by reducing their sperm count. Scientists wanted to investigate the idea that gossypol could be used as a human male contraceptive. [Adapted from: Liffen and Liffen, 1987] 3. 2. 1 State a hypothesis for the investigation that scientists wanted to do. (3) 3. 2. 2 State FOUR planning steps that must be followed by researchers before the investigation above is undertaken on humans. (4) 3. 2. 3 In the investigation above, name the following: (a) (1) (b) 3. 2. 4 Dependent variable Independent variable (1)Explain ONE reason why some people might: (a) (2) (b) Copyright reserved Support research on male contraception Object to research on male contraception (2) (13) Please turn over Life Sciences/P1 3. 3 13 NSC DBE/Feb. – Mar. 2011 Study the diagram of a flower below and answer the questions that follow. D A B E C 3. 3. 1 Label parts A, B and D. (3) 3. 3. 2 Describe how the male gamete reaches the ovum aft er pollination. (3) 3. 3. 3 What do the following structures develop into after fertilisation: (a) Structure C (1) (b) Structure E (1) (8) [30] TOTAL SECTION B: Copyright reserved Please turn over 60 Life Sciences/P1 14 NSC DBE/Feb. Mar. 2011 SECTION C QUESTION 4 4. 1 Explain THREE advantages of using genetically modified organisms as food. 4. 2 The table below shows the percentage frequency of human blood groups in the populations of two different cities in South Africa. (6) Human blood groups % frequency in population City 1 City 2 A 25 45 B 20 10 AB 10 5 O 45 40 4. 2. 1 Which blood group has: (a) 4. 3 (1) (b) 4. 2. 2 The highest frequency in City 1 The lowest frequency in City 2 (1) Plot the data in the table as bar graphs on the same system of axes. (10) (12) The diagram below shows a crossing between a homozygous black mouse and a homozygous white mouse.The F1-generation was all black. Male Female P1 X F1 1 2 3 4 Use the symbols B and b for the alleles of fur colour and show di agrammatically a genetic cross between mouse 1 and mouse 3 to show the possible genotypes and phenotypes of the next generation (F2). 4. 4 Clones are a group of genetically identical organisms. Explain THREE advantages and THREE disadvantages with reasons of cloning. Synthesis: NOTE: (12) (3) (15) NO marks will be awarded for answers in the form of flow charts or diagrams. TOTAL SECTION C: GRAND TOTAL: Copyright reserved (7) 40 150

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