Life Sciences Grade 12 P1 Gauteng Mock 2021 QP (Eng)

Downloaded from hlayiso.com GAUTENG DEPARTMENT OF EDUCATION PREPARATORY EXAMINATION 2021 10831 LIFE SCIENCES PAPER 1 TIME: 2½ hours MARKS: 150 17 pages P.T.O.

Downloaded from hlayiso.com LIFE SCIENCES 2 (Paper 1) 10831/21 INSTRUCTIONS AND INFORMATION 1. Answer ALL the questions. 2. Write ALL the answers in the ANSWER BOOK. 3. Start the answers to EACH question on 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. Make 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. P.T.O.

Downloaded from hlayiso.com LIFE SCIENCES 3 (Paper 1) 10831/21 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 to 1.1.8) in the ANSWER BOOK, for example 1.1.9 D. 1.1.1 Which part of a neuron transmits an impulse towards the cell body? A Dendrite B Cytoplasm C Axon D Nucleus 1.1.2 What is the gland that secretes insulin called? A Thyroid B Hypothalamus C Pituitary/Hypophysis D Pancreas 1.1.3 Which of the following structures in an amniotic egg protects the developing embryo from physical injury? A Yolk sac B Chorion C Allantois D Shell P.T.O.

Downloaded from hlayiso.com LIFE SCIENCES 4 (Paper 1) 10831/21 1.1.4 Which labelled structures indicate the place where fertilization and implantation occur? A A and D B A and B C B and C D B and D 1.1.5 Study the following factors related to reproduction in females: (i) When progesterone levels peak, FSH and LH levels are low. (ii) Ovulation occurs at around day 14. (iii) When fertilization occurs, FSH levels remain high. (iv) Oestrogen and progesterone produced by the ovaries during the ovarian cycle influence the uterine cycle. The correct statements are ... A (i), (ii), (iii) and (iv). B (i), (iii) and (iv). C (i), (ii) and (iii). D (i), (ii) and (iv). P.T.O.

Downloaded from hlayiso.com LIFE SCIENCES 5 (Paper 1) 10831/21 1.1.6 Which of the following represents the correct sequence of development, after fertilization has taken place? A Ovum → Zygote → Blastocyst → Morula → Foetus B Zygote → Morula → Blastocyst → Foetus C Ovum → Zygote → Morula → Blastocyst → Foetus D Zygote → Blastocyst → Morula → Foetus Use the diagram below to answer the QUESTION 1.1.7 and QUESTION 1.1.8. Middle Piece Head A B C D 1.1.7 The only part of the sperm cell that enters the ovum during fertilization is … A part D. B part C. C part B. D part A. 1.1.8 The parts of the sperm cell that assist the sperm with movement are … A parts A, B and C. B parts, A and D. C parts A and B. D parts A, B and D. (8 x 2) (16) P.T.O.

Downloaded from hlayiso.com LIFE SCIENCES 6 (Paper 1) 10831/21 1.2 Give the correct biological term for each of the following descriptions. Write only the term next to the question number (1.2.1 to 1.2.5) in the ANSWER BOOK. 1.2.1 A condition caused by the lens of the eye becoming cloudy 1.2.2 The part of the nervous system that responds when a person gets a fright 1.2.3 A phenomenon where the main central stem displays more growth than the side stems, at the tip of a tree 1.2.4 A type of development where young birds are born with their eyes closed and with no feathers 1.2.5 The structure that provides nutrients to the developing embryo in ovoviviparous animals (5 x 1) (5) 1.3 Indicate whether each of the statements in COLUMN I apply 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 to 1.3.3) in the ANSWER BOOK. COLUMN I COLUMN II 1.3.1 Hormone responsible for the falling off of A Abscisic acid ripe fruit B Gibberellins 1.3.2 Function/s of the allantois in an amniotic A Involved in gaseous egg exchange B Stores excretory waste from the developing embryo 1.3.3 A fish, laying eggs prior to fertilization A External fertilization B Ovipary (3 x 2) (6) P.T.O.

Downloaded from hlayiso.com LIFE SCIENCES 7 (Paper 1) 10831/21 1.4 The diagram below represents the human male reproductive system. A B C H D E G F 1.4.1 Give the LETTER of the part that is associated with each of the following statements: (a) Temporarily stores sperm (1) (b) If cut, semen will not contain sperm cells (1) (c) Transports both urine and semen (1) (d) Assists in optimum sperm production at a temperature lower than body temperature (1) (e) Produces testosterone (1) (f) Secretes alkaline fluid which neutralises the acidity of the vagina, which would kill sperm (1) (6) P.T.O.

Downloaded from hlayiso.com LIFE SCIENCES 8 (Paper 1) 10831/21 1.5 A young seedling was removed from the soil and placed on its side. Once placed on its side, the shoot excluding the tip, was exposed to light from all directions (indicated by the arrows), to prevent phototropism. F A E B C D AFTER 1.5.1 Name the hormone which stimulates seed germination. (1) 1.5.2 Name the tropic movement that will be observed in the seedling above, after it was placed on its side. (1) 1.5.3 Give the LETTER/S of the area/s where: (a) The seedling had the highest concentration of auxins BEFORE being placed on its side (2) (b) The seedling would have the highest concentration of auxins AFTER being placed on its side (2) (c) Cell elongation would be inhibited in the shoot (2) 1.5.4 Name TWO defence mechanisms used by plants to stop herbivores from eating them. (2) (10) P.T.O.

Downloaded from hlayiso.com LIFE SCIENCES 9 (Paper 1) 10831/21 1.6 The diagram below shows different glands, the hormones they release and their target organs. A B D C Kidney 1.6.1 Identify each of the following: (a) The glands labelled A and B (2) (b) The hormones labelled C and D (2) 1.6.2 Which substance in the body is regulated by hormone C? (1) 1.6.3 Name ONE other hormone released by gland B. (1) 1.6.4 Give the term used to describe the regulation of a constant internal balance, even if the internal or external environment changes. (1) (7) TOTAL SECTION A: 50 P.T.O.

Downloaded from hlayiso.com LIFE SCIENCES 10 (Paper 1) 10831/21 SECTION B QUESTION 2 2.1 The graph below shows changes in the diameter of the pupil under different luminances. Luminances refer to how bright the light is. The diameter of the pupil ranges from approximately 2 mm to 8 mm. Diameter of the pupil at different luminances 9 7.7 Diameter of the pupil (mm) 7.5 8 6.9 7 A 6 4.9 5 3.8 4 B 2.5 3 2.1 2 1 0 0.0001 0.001 0.01 0.1 1 10 100 1000 10000 Luminance (cd/m2) 2.1.1 Give the diameter of the pupil at point A. (1) 2.1.2 Calculate the average diameter of the pupil using only the points indicated between A and B on the graph. (Show all working.) (3) 2.1.3 Describe the relationship between luminance and the diameter of the pupil from point A to point B. (2) 2.1.4 Explain the role that pupillary reflex plays in changing the diameter of the pupil from point A to point B. (3) 2.1.5 Define each of the following: (a) Luminance (1) (b) A reflex action (2) 2.1.6 The beam of light from a laser pointer has a high enough luminance to burn any receptor cell in the retina in about 10 seconds. Explain how shining a laser pointer directly onto the retina for more than 10 seconds, will affect your eyesight. (3) (15) P.T.O.

Downloaded from hlayiso.com LIFE SCIENCES 11 (Paper 1) 10831/21 2.2 The diagram below shows the internal structure of the eye. A B Optic nerve 2.2.1 Identify the structures labelled A and B. (2) 2.2.2 The optic nerve is a sensory neuron. Tabulate TWO differences between a sensory neuron and a motor neuron. (5) 2.2.3 Name the part of the nervous system which is composed of cranial and spinal nerves. (1) 2.2.4 Describe how structures A and B enable the ability to focus on objects further than 6 m away. (4) (12) P.T.O.

Downloaded from hlayiso.com LIFE SCIENCES 12 (Paper 1) 10831/21 2.3 The diagram below shows a section through the human brain. Cerebrum Corpus callosum Pons Cerebellum Spinal cord Medulla oblongata 2.3.1 Give ONE function for each of the following: (a) The corpus callosum (b) The cerebrum (c) The spinal cord (3) 2.3.2 Draw a labelled diagram of a simple reflex arc and indicate the direction in which the impulse travels. (5) (8) P.T.O.

Downloaded from hlayiso.com LIFE SCIENCES 13 (Paper 1) 10831/21 2.4 The diagram below shows the internal structure of the ear. A B C D F E 2.4.1 Give the LETTER and NAME of the part of the ear that: (a) Allows air to move between the middle ear and the throat (2) (b) Contains receptors for hearing (2) (c) Is a membrane separating the outer ear from the middle ear (2) (d) Is the first of three ossicles (2) (e) Conducts sound waves from the pinna to the structure labelled E (2) 2.4.2 In a soccer match the goalkeeper dived to save a goal from being scored by the opposing team. Describe the role of the semi-circular canals in maintaining balance as the goalkeeper dived. (5) (15) [50] P.T.O.

Downloaded from hlayiso.com LIFE SCIENCES 14 (Paper 1) 10831/21 QUESTION 3 3.1 Read the extract below and answer the questions that follow. The Comrades Marathon is an ultra-marathon of approximately 89 kilometres which is run annually in the KwaZulu-Natal province between the cities of Durban and Pietermaritzburg. It is the world’s largest and oldest ultra- marathon race. Athletes run up to 12 hours continually to complete the race. Runners train for many months and they carbo-load (consume a diet high in carbohydrates such as pastas and grains) in preparation for this race. 3.1.1 While running, an athlete’s body temperature increases. Describe the negative feedback mechanism that will restore the athlete’s body temperature to normal. (6) 3.1.2 Explain the effect of running for long periods of time on each of the following: (a) Water levels in the blood (2) (b) Carbon dioxide levels in the blood (2) 3.1.3 Explain how carbo-loading before the race assists athletes to have enough energy during the race. (6) (16) P.T.O.

Downloaded from hlayiso.com LIFE SCIENCES 15 (Paper 1) 10831/21 3.2 Read the extract below and answer the questions that follow. Tshepang read a WhatsApp message which stated: “Wearing a facemask increases the carbon dioxide levels in the blood and could lead to sickness.” He decided to conduct an investigation to determine whether wearing a facemask increases the carbon dioxide levels in the blood.  He could not afford a device that measures the carbon dioxide levels in the blood, so he decided to measure the pulse rate (indicates heart rate) and the breathing rate.  He chose 10 classmates for the investigation.  The breathing rate and pulse rate of each classmate was measured, after 4 hours of not wearing a facemask and again after 4 hours of wearing a facemask. 3.2.1 Identify the dependent variable in this investigation. (1) 3.2.2 State TWO variables which relate to the classmates and should be kept constant in order to ensure the validity of this investigation. (2) 3.2.3 Give TWO planning steps that Tshepang needed to consider before conducting his investigation. (2) 3.2.4 Explain how the breathing rate can be used to show an increase in the carbon dioxide levels in the blood. (4) (9) P.T.O.

Downloaded from hlayiso.com LIFE SCIENCES 16 (Paper 1) 10831/21 3.3 Read the extract below and answer the questions that follow. How to optimise the chances of conception It is estimated that one in five couples in South Africa are suffering from infertility and are experiencing difficulty in conceiving. Research has shown that conception (fertilization) is more likely to happen when intercourse takes place in the 3 or 4 days leading up to ovulation. Recent evidence has also shown that many women have a poor understanding of their menstrual cycle and the process of ovulation. Incorrect timing of intercourse is therefore thought to be a common, but easily correctable cause of difficulty in conceiving. The introduction of home-based hormonal digital ovulation tests (DOTs) has at least provided a simple solution for women wishing to optimise the timing of intercourse when trying to conceive. 3.3.1 Give TWO reasons according to the passage, why women may have difficulty conceiving. (2) 3.3.2 The digital ovulation test monitors an increase in a specific hormone. Name this hormone. (1) 3.3.3 Name the gland that produces the hormone mentioned in QUESTION 3.3.2. (1) 3.3.4 Name the gland that releases a hormone which triggers ovulation. (1) 3.3.5 Give ONE reason why intercourse should take place 3 to 4 days before ovulation. (1) 3.3.6 Explain why the secretion of too little progesterone can pose an additional problem to a female trying to fall pregnant. (2) (8) P.T.O.

Downloaded from hlayiso.com LIFE SCIENCES 17 (Paper 1) 10831/21 3.4 An ultrasound (sonogram) is an imaging technique that uses sound waves to produce images of the foetus in the uterus. Dr Mkhize monitored the development of the foetus in one of her patients during pregnancy by measuring the foetal head circumference. She also monitored the blood flow along the umbilical cord. The results are shown in the table below. Time (weeks) Head circumference (cm) 14 12 18 16 22 20 26 24 30 28 34 31 38 33 40 36 3.4.1 Give the correct biological term for pregnancy. (1) 3.4.2 Use the information in the table above to plot a line graph. (6) 3.4.3 Give THREE functions of the amniotic fluid that surrounds the foetus during pregnancy. (3) 3.4.4 List TWO structures through which the foetus will pass during natural birth. (2) 3.4.5 While doing the ultrasound, the doctor noticed that the umbilical arteries were blocked but there was normal blood flow through the umbilical vein. Explain the effect that this will have on the developing foetus. (5) (17) [50] TOTAL SECTION B: 100 TOTAL: 150 END