Life Sciences Grade 12 Gauteng June 2025 QP (Eng)

JUNE EXAMINATION GRADE 12 2025 LIFE SCIENCES TIME: 2½ hours MARKS: 150 20 pages Please turn over

LIFE SCIENCES GR12 0625 2 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, flow charts or tables 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 where necessary. 11. Write neatly and legibly. Please turn over

LIFE SCIENCES GR12 0625 3 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 1.1.10) in the ANSWER BOOK, e.g. 1.1.11 D. 1.1.1 In external fertilisation … A a dry environment is required for fertilisation. B sperm cells are released into the female body. C fewer gametes are released. D predation of eggs can easily occur. 1.1.2 Which is NOT a function of the placenta? A It is the point of attachment of the foetus to the mother. B It allows for the diffusion of nutrients from the mother to the foetus. C It allows for the diffusion of oxygen from the mother to the foetus. D It allows for the diffusion of waste from the mother to the foetus. 1.1.3 Into which part of the ear are grommets inserted? A Oval widow B Round window C Tympanic membrane D Cochlea 1.1.4 The microscopic space between two adjacent neurons is a/an … A axon. B synapse. C dendrite. D cell body. Please turn over

LIFE SCIENCES GR12 0625 4 1.1.5 Study the diagram below of the life cycle of a chicken together with the statements that follow. Fertilised egg Embryo Egg Hen Rooster Hatchlings Hen lays eggs [Adapted from Chicken life cycle hi-res stock photography and images – Alamy] i. The embryo develops outside of the female body. ii. The embryo develops inside the female body. iii. The yolk is the primary source of nutrition for the developing embryo. iv. The young receive nutrition from the mother’s body through the placenta. Which combination of descriptions of the reproductive strategy provided above is correct for the life cycle of the chicken? A i and iii B i and iv C ii and iv D ii and iii 1.1.6 Which statement about the body’s structure and its response to changes in speed and direction of body movement is INCORRECT? A The three semi-circular canals are positioned in three different planes (directions). B The endolymph fluid moves in at least one of the semi-circular canals. C The movement of endolymph fluid stimulates the maculae to generate impulses that are sent to the cerebellum. D The cerebellum sends impulses to the skeletal muscles to restore balance. Please turn over

LIFE SCIENCES GR12 0625 5 1.1.7 Study the graph below which predicts the number of people worldwide who will suffer from hearing loss from 2020 to 2050. What is the predicted percentage increase in hearing loss from 2020 to 2030? A 18,37 B 65,38 C 79 D 281 1.1.8 Which part of the amniotic egg stores the waste that is produced by the developing embryo? A Allantois B Yolk sac C Chorion and amnion D Shell Please turn over

LIFE SCIENCES GR12 0625 6 1.1.9 Refer to the diagram below and choose the correct option regarding the hormone production at specific stages of the menstrual cycle. [Source: https://c8.alamy.com/comp/2DHMH1G/menstrual-cycle-chart-increase-and- decrease-of-the-hormones-the-graph-also-depicts-the-growth-of-the-follicle-fluctuation- of-hormones-2DHMH1G.jpg] Day 1 to 6 Day 13 to 15 Day 16 to 28 A FSH Oestrogen LH B FSH LH Progesterone C Oestrogen Progesterone FSH D Progesterone LH Oestrogen Please turn over

LIFE SCIENCES GR12 0625 7 1.1.10 The table below shows the percentage of nitrogenous bases in a DNA sample. The sample contains 17 300 nucleotides. NITROGENOUS BASE SAMPLE A T G C Percentage 19 ? ? ? (%) Which of the following shows the correct number of guanine in this sample? A 31 B 3 287 C 5 363 D 10 726 (10 x 2) (20) Please turn over

LIFE SCIENCES GR12 0625 8 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 1.2.8) in the ANSWER BOOK. 1.2.1 A receptor which receives the stimulus of sound 1.2.2 Photoreceptor cells found in the retina of the eye, which are sensitive to dim light and help with black and white vision 1.2.3 The genetic composition of an organism 1.2.4 A type of dominance where both alleles of a gene are equally dominant 1.2.5 The natural shape of the DNA molecule 1.2.6 The branch of the nervous system responsible for the fight or flight function in emergency situations 1.2.7 The structure responsible for secreting progesterone during the menstrual cycle 1.2.8 The site of meiosis in female animals (8 x 1) (8) 1.3 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 numbers (1.3.1 to 1.3.3) in the ANSWER BOOK. COLUMN I COLUMN II 1.3.1 Hormone levels during A: Low progesterone pregnancy B: High FSH 1.3.2 Significance of meiosis A: To introduce haploid sperm cells into the female B: To maintain a constant number of chromosomes from one generation to the next. 1.3.3 Stimulus picked up in A: Sound the ear B: Change in position of the head relative to gravity (3 x 2) (6) Please turn over

LIFE SCIENCES GR12 0625 9 1.4 Read the extract below and answer the questions that follow. Multiple sclerosis is an autoimmune disease, where the body mistakenly attacks the brain and the spinal cord. It does this by damaging the myelin sheath, which is the protective coating around the nerves. When the myelin sheath is damaged, communication between the brain and the rest of the body is interrupted. The resulting symptoms include extreme tiredness, loss of concentration and memory, numbness, sensitivity to heat and cold, difficulty walking and balancing, spasms, difficulty breathing, dizziness, and mood changes. [Source: www.mayoclinic.org/disease-conditions/multiple-sclerosis/symptoms-causes] 1.4.1 Name TWO structures mentioned in the passage that make up the central nervous system. (2) 1.4.2 State the collective name of the membranous layers that surround the two parts mentioned in QUESTION 1.4.1. (1) 1.4.3 Identify the part of the brain that would be damaged for the following symptom to occur: (a) Memory Loss (1) (b) Difficulty breathing (1) (c) Difficulty with balance (1) 1.4.4 From the passage: (a) Name the category of disease to which multiple sclerosis belongs. (1) (b) Name the part of the neurons that is damaged (1) (8) Please turn over

LIFE SCIENCES GR12 0625 10 1.5 The diagram below shows a genetic engineering process. Study the diagram and answer the questions that follow. [Adapted from DBE Life Sciences P2 Feb-March 2017] 1.5.1 Name the genetic engineering process shown in the diagram above. (1) 1.5.2 Give the letter that represents: (a) The offspring (1) (b) The individual being cloned (1) 1.5.3 Which natural process is imitated from E? (1) (4) 1.6 The diagram below shows an important process occurring in a cell. Study the diagram and answer the questions that follow. [Adapted from DBE Life Sciences P2 Feb-March 2015] 1.6.1 Identify the process shown above. (1) 1.6.2 List THREE organelles where the process mentioned in QUESTION 1.6.1 may take place in a plant. (3) (4) TOTAL SECTION A: 50 Please turn over

LIFE SCIENCES GR12 0625 11 SECTION B QUESTION 2 2.1 The digram below shows the structrure of the human eye. Study the diagram and answer the questions that follow. [Adapted from https://www.bing.com/images/blob?bcid= qHbVluktH. oHY7w8jMPWZzqRcqxJ ...3o] 2.1.1 Explain the structural suitability of part C. (2) 2.1.2 A man was looking at a distant tree and then decided to watch a TikTok video on his phone. Identify the LETTER and NAME of the part of the eye that will be adjusted so that he can see his phone clearly. (2) 2.1.3 The phone brightness setting was high while he was watching the TikTok video. Name and describe the mechanism of the eye that would allow the person to still be able to watch this video despite the brightness setting. (4) 2.1.4 Glaucoma is an eye condition characterised by high pressure in the eye. If left untreated it can damage the part that takes impulses to the brain, which can result in blindness. Give the LETTER and NAME of the part that can be damaged. (2) (10) Please turn over

LIFE SCIENCES GR12 0625 12 2.2 The diagram below shows a portion of an mRNA strand. Study the diagram and answer the questions that follow. [Adapted from DBE Life Sciences P2 May-June 2017] 2.2.1 Write down the complementary DNA base triplet to the molecule shown above, from left to right. (1) 2.2.2 Name and describe the process that led to the production of the molecule above. (5) 2.2.3 State TWO structural differences of DNA nucleotides and RNA nucleotides. (4) 2.2.4 The table below shows the DNA base triplets that code for different amino acids found in human proteins. AMINO ACID BASE TRIPLET IN DNA Leucine GAA Proline GGG Lycine TTT Histidine GTA Serine TCA Methionine TAC Glycine CCC Glutamine GTC During the formation of the molecule in the diagram above, a DNA mutation occurred that changed the nitrogenous bases from AGU to AUG. Using the table above, describe how this would affect the protein that will be formed. (3) (13) Please turn over

LIFE SCIENCES GR12 0625 13 2.3 Haemophilia is a genetic disorder that results in the abnormal clotting of blood. It is caused by a recessive allele carried on the X-chromosome. The allele for normal clotting is XH and the allele for haemophilia is Xh. The inheritance of haemophilia in a family is shown in the diagram below. [Adapted from DBE Life Sciences P2 May-June 2017 Eng] (1) 2.3.1 Name the type of diagram shown above. 2.3.2 Differentiate between the terms gene and allele. (2) 2.3.3 In the diagram above: (a) How many generations are shown? (1) (b) How many females are carriers of haemophilia (heterozygous)? (1) 2.3.4 Provide the possible genotype/s for individuals A and B. (2) 2.3.5 Mother A is expecting a baby girl. Using a genetic cross, show the percentage chance that her daughter will have haemophilia. (6) (13) Please turn over

LIFE SCIENCES GR12 0625 14 2.4 An investigation was conducted to explore the effects of marijuana use on male fertility. Marijuana (Cannabis sativa), commonly called cannabis, is widely used for both recreational and medicinal purposes. However, its impact on male fertility has raised concerns among researchers and healthcare professionals. • A total of 400 men were selected, with two groups of 200 men each. • One group consisted of marijuana users and the second group consisted of men who did not use marijuana. • All 400 men were of the same ethnicity and age group. • The measurements were conducted annually for five years. The data collected is shown in the table below. Parameters Impact on Marijuana Users Non Users (Average) Marijuana Users Semen Volume 2,5 3,0 Decreased (mL) Sperm Concentration 40 60 Decreased (million/mL) Testosterone 400 500 Decreased Levels (ng/dL) Sperm Motility 45 60 Decreased (%) [Adapted from www.cannabisevidence.org] 2.4.1 Identify: (a) The dependent variable (1) (b) The independent variable (1) (c) One variable that was controlled (1) 2.4.2 Identify TWO ways in which the reliability of this investigation was ensured. (2) 2.4.3 Suggest reasons why men who do not smoke were included in this investigation. (2) (7) Please turn over

LIFE SCIENCES GR12 0625 15 2.5 A boy needs a kidney transplant. His biological mother sought help from her three brothers because her kidneys were also dysfunctional. Blood groups and DNA profiles of the boy and his three uncles were used to determine the best match for a kidney donor. The results of the two procedures are shown below. [Adapted from Limpopo Life Sciences P2 Pre-Trial, August 2024] 2.5.1 Name ONE other procedure in which both blood groups and DNA profiling can be used. (1) 2.5.2 Using the information provided, identify which individual is the best match for a kidney donor. (1) 2.5.3 Explain your answer to QUESTION 2.5.2 (3) 2.5.4 If the boy’s maternal grandfather was blood group A, what is/are the possible blood group/s of the maternal grandmother? (2) (7) [50] Please turn over

LIFE SCIENCES GR12 0625 16 QUESTION 3 3.1 The diagram below shows the embryonic development in a female human. Study the diagram and answer the questions that follow. [Adapted from Female reproductory system anatomy chart Stock Vector by ©Sudowoodo 178166266] 3.1.1 Name and describe structure: (a) D (2) (b) E (2) 3.1.2 Name and describe the process that structure E underwent at the uterus so that structure F can be positioned correctly within the uterus. (2) 3.1.3 Draw a fully labelled scientific diagram of the gamete found at A that would have been fertilised. (4) (10) Please turn over

LIFE SCIENCES GR12 0625 17 3.2 The diagram below show THREE different neurons. Study the diagram and answer the questions that follow. [Source: Lesson Explainer: Nerve Cells | Nagwa] 3.2.1 Identify neurons A and C. (2) 3.2.2 Define a reflex action. (2) 3.2.3 Tshepo’s mother had just removed the pot after cooking when he accidentally touched the hot store plate. Describe the pathway that the impulse would take in response to the stimulus, so that he would remove his hand quickly and avoid (5) severe injury. 3.2.4 (1) Name the pathway described in QUESTION 3.2.3 (10) Please turn over

LIFE SCIENCES GR12 0625 18 3.3 Study the information below and answer the questions that follow. Amniocentesis is a test that may be offered during pregnancy to check if a child has a genetic or chromosomal condition, such as Down's syndrome. Guided by an ultrasound (a device that provides an image of the interior of the body), the healthcare provider inserts a thin, hollow needle through the abdominal wall and into the uterus. A small amount of amniotic fluid which contains some foetal cells, is drawn into a syringe. The needle is then removed. [Adapted from https://www.swus.com.au/sites/swus.com.au/files/amnio.jpg] 3.3.1 Using the information given, state the purpose of an amniocentesis. (1) 3.3.2 Name TWO membranes which can rupture that surround the foetus. (2) 3.3.3 State TWO functions of amniotic fluid. (2) 3.3.4 State the difference in the genetic composition of a baby with Down’s syndrome compared to an unaffected baby. (2) (7) Please turn over

LIFE SCIENCES GR12 0625 19 3.4 The diagrams below show two phases of meiosis in a plant cell. Study the diagrams and answer the questions that follow. 3.4.1 Identify parts labelled X, Y and Z respectively. (3) 3.4.2 Tabulate TWO differences between meiosis I and meiosis II. (5) 3.4.3 Describe the term non-disjunction. (2) 3.4.4 Name the phase that will follow immediately after the phase represented by diagram B. (1) 3.4.5 Non-disjunction occurs in the phase mentioned in QUESTION 3.4.4. Compare the number of chromosomes that will be present in each cell at the end of telophase I. (2) (13) Please turn over

LIFE SCIENCES GR12 0625 20 3.5 Bt cotton is a crop that has been genetically modified to be insect-resistant. Scientists conducted an investigation which compared the crop yield of Bt and non-Bt cotton between 1999 and 2007 in a certain country. However, due to unforeseen circumstances the results of the years; 2002, 2003 and 2005 were not recorded. The table below shows the data from the investigation. BT COTTON NON-BT COTTON YEAR (g/m2) (g/m2) 1999 330 350 2000 300 180 2001 340 300 2004 270 170 2006 330 250 2007 290 230 [Adapted from https://www.researchgate.net/publication/235251419] 3.5.1 State the aim of this investigation. (2) 3.5.2 Explain ONE financial benefit that farmers will have when using Bt cotton. (2) 3.5.3 Draw a line graph on the same set of axes to represent the crop yield of Bt and non-Bt cotton from 1999 to 2001. (6) (10) [50] TOTAL SECTION B: 100 TOTAL: 150 END