LIFE SCIENCES
SCHOOL BASED ASSESSMENT EXEMPLARS - CAPS
GRADE 12
LEARNER GUIDE

1. Introduction 
Assessment is a continuous, planned process of identifying, gathering and interpreting information about your  performance, using various forms of assessment. It involves four steps:  

• Generating and collecting evidence of achievement
  This is done through the various assessment tasks presented to you by your teacher. 
• Evaluating this evidence
  This is achieved when your teacher marks your answers using a marking guideline to arrive at a mark which  indicates your understanding of the topic(s) covered by the assessment task. 
• Recording the findings
  Not only does your teacher record your marks so as to track your progress through the year, but he/she also  makes a note of aspects that you and other learners in your class answered poorly. 
• Using this information to understand and assist in your development to improve the process of learning and  teaching 
  Using information about poorly answered questions, your teacher may choose to re-teach these aspects and then  provide further opportunities for you and other learners in the class to assess your improvement in the selected  aspects.
  Assessment consists of an informal and a formal component. In both cases regular feedback will be provided for  you to improve your learning. 
• Informal assessment (Assessment for Learning)
  This component is not used for the purpose of progression and promotion. It consists of a number of assessment  tasks presented to you by your teacher on a regular basis. This is usually done within the course of teaching a  topic. It is designed to help you consolidate your learning at each stage of a topic to improve your understanding  of the next stage of the same topic. Giving full attention to informal tasks is guaranteed to prepare you more  adequately for success in the formal component. 
• Formal assessment (Assessment of Learning)
  This component is used for the purpose of progression and promotion. Your teacher will inform you of the number  of tasks, the types of tasks and the dates on which you will undertake these assessment tasks. These tasks cover  the same topics/skills that are covered by the informal assessment tasks. 

Keep track of your progress from the various assessment tasks that you undertake. Make a note of your personal areas  of difficulty and develop a programme that will allow you to address each of these areas. This will guarantee a high quality pass at the end of the year. 
We wish you great success through the year.

2. Programme of formal assessment in Life Sciences 
The table below shows the number and types of assessment tasks required in the Grade 12 year. 

NOTE: The SBA mark must be converted to 25% and the external examination counts 75% of the final mark.
A description of the requirements for each of the different types of assessment tasks follows below.

2.1 Practical tasks 
When designing the practical tasks, the Life Sciences teacher must ensure that: 

• All 7 skills under Specific Aim 2 listed below are covered over the three practical tasks: 
  1. Follow instructions
  2. Handle equipment or apparatus
  3. Make observations
  4. Record information or data
  5. Measure accurately
  6. Interpret information
  7. Design/Plan an investigation
• At least ONE of the practical tasks includes manipulation of apparatus and/or collection of data. 
• Any ONE practical task assesses at least 3 of the 7 skills and must include skill 6 and/or 7.
• 20–40 marks are allocated to a practical task. 

2.2 Research project 
A research project: 

• Is a long-term task (at least 3 weeks of non-contact time) 
• Has a maximum mark of 100  
• Is an investigative task 
• Focuses on accessing knowledge through literature research as well as through primary sources such as people 
• Includes sub-skills such as: 
  • Formulating investigative questions and hypotheses
  • Gathering information from a variety of sources
  • Manipulating and processing information
  • Analysing information
  • Identifying patterns 
  • Evaluating data
  • Drawing valid conclusions
  • Communicating findings 

2.3 Assignment 
The assignment: 

• Is a short-term task (1½–2 hours under controlled conditions) 
• Has a maximum mark of 100  
• Covers Specific Aims 1, 2 and 3 
• Is completed at school and not at home 
• Is completed without the use of any reference materials such as textbooks  
• Is recorded in Term 3 even if it is given and assessed in Term 1 or Term 2 
• Covers a variety of topics 
• Includes as many as possible of the following: 
  • Analysing and interpreting data
  • Making drawings
  • Plotting graphs
  • Drawing tables
  • Performing calculations
  • Justifying conclusions

2.4 Tests and Examinations 

• The test is a minimum of 50 marks. 
• The test in Term 1 covers all work done in that term. 
• The tests in Term 2 and Term 3 cover at least half of the work covered in the respective terms. 
• The mid-year examination covers work completed in Term 1 and Term 2. 
• The trial examinations cover all work completed in Terms 1, 2 and 3, and must include the section on ‘Human  Impact’ from Grade 11. 

The following exemplars have been included in this publication: 

The exemplars provided are meant to show you the format of these tasks as well as the way in which the content and  skills of each topic may be assessed.

3. Assessment tasks 
3.1 Practical Task 1 – Surveying human characteristics 

Task 
Conduct a survey of the occurrence/frequency of dominant and recessive phenotypes for each of three traits/ characteristics (as shown in the pictures below) among the learners in your school. 

• This task must be done individually. 
• This practical must be completed at school. 

Background information 

Many characteristics in humans are controlled by one gene with two alleles, one dominant and one recessive. Three  examples are shown below. 

Method 

1. Select 20 learners that will form part of your sample. 
2. For every learner selected, record the phenotype for each characteristic. 
3. Record the information for each learner in a table. At the end of the table, include the percentage of learners  displaying each phenotype for each of the three characteristics. 
4. Answer the questions set. 

QUESTIONS 

1. List any FOUR planning steps for this investigation.  (4)
2. In terms of the investigation about the type of earlobe (free or attached), name the following:
   2.1 The dependent variable  (1)
   2.2 The independent variable  (1)
3. Formulate a hypothesis for the frequency of tongue-rollers as compared to non-rollers in your school.    (3)
4. Construct a table to show the results obtained in this investigation.   (4)
5. According to the results obtained, would you accept or reject the hypothesis formulated in QUESTION 3?  (1)
6. State TWO ways in which you could make the results of this investigation more reliable. (2)
7. Using the same system of axes, draw a bar graph to represent the percentage of learners displaying each phenotype for each of the three characteristics.  (8)
8. Use the symbols R (tongue-roller) and r (non-roller) to represent the phenotypes and genotypes of  offspring resulting from a cross between two heterozygous individuals.   (6) 

[30]

3.2 Practical Task 2 – Simulating natural selection  

Task 
Simulate ‘natural selection’ using a paper model. 

• This task must be done in pairs but the questions must be answered individually. 
• This practical must be completed at school. 

Background information 
A simulation allows one to demonstrate something that might sometimes be dangerous or that might sometimes require  a lot of time, quickly and in a simple and safe way, using models.  
The different parts that comprise the paper model in this task represent different components in nature. The sheet of  newspaper and the sheet of white paper represent two different environmental conditions. The circles cut from white  paper and from newspaper represent the different appearances/phenotypes of different individuals of the same species. 

Aim 
You are required to investigate the survival of the organisms with the two different phenotypes under different  environmental conditions.  
Materials required 

• A sheet of white paper (preferably A3 size) to use as background 
• A sheet of newspaper (cut to A3 size) to use as background 
• Forceps/tweezers 
• Clock with a second hand/stopwatch 
• Scissors  
• 30 x 2 cm diameter circles cut from another sheet of newspaper 
• 30 x 2 cm diameter circles cut from another sheet of white paper 
• Ruler  

Method 

1. Place the sheet of white paper on the table. 
2. Spread 30 white paper circles and 30 newspaper circles randomly over the surface of the white paper. 
3. Ask your partner to use a pair of forceps/tweezers to pick up as many circles as he/she can in a period of 15  seconds.
4. Count the number of each type of circle that has been picked up. Record this in the table provided.
5. Now repeat steps 1–4 using the sheet of newspaper instead of the sheet of white paper.

Question 1. 

1. Formulate a hypothesis for the above investigation when using the sheet of white paper as  background.  (3)
2. For this investigation, name:
   2.1 The dependent variable  (1)
   2.2 The independent variable  (1)
   2.3 Any TWO fixed variables  (2)
3. Copy and record your results in the following table:   (2)
   
   

   DIFFERENT   BACKGROUNDS	STARTING POPULATION		NUMBER OF CIRCLES   PICKED UP ON DIFFERENT  BACKGROUNDS
   	White paper circles	Newspaper circles	White paper circles	Newspaper circles
   White paper	30	30
   Newspaper	30	30

    

4. Draw a bar graph on the same system of axes to represent the results of your investigation. (8) 

5. Explain the difference in results obtained for the two types of circles when using the sheet of white  paper. (3) 

6. State ONE way in which you could improve the reliability of the results.  (1) 

7. State a conclusion for the above investigation when the newspaper was used as a background. (3)
8. Based on the results obtained, will you accept or reject the hypothesis you formulated in QUESTION  1?   (1)
9. Explain how this investigation and the results of this investigation simulate natural selection as it occurs in the peppered moth. Use the picture below to help you make a comparison.   (5) 
   

[30]

3.3 Assignment 1 – Response to the environment 

Instructions and information  

1. Answer ALL questions.
2. Number the answers correctly according to the numbering system used in this question paper.
3. Draw diagrams and flow charts ONLY when requested to do so.
4. This assignment is to be done under controlled conditions and must be handed in at the end of the session. 

NOTE: If it is not possible to schedule a single 90-minute session for this assignment, then SECTION A can be  done on one day in a 45-minute session and SECTION B the following day in another 45-minute session. 

________________________________________________________________________ 

SECTION A 
QUESTION 1 
An investigation was conducted to study apical dominance in bean plants. Four groups of plants were used. The  diagram below illustrates the process. 

The results are shown in the table below.

1.1 For this investigation, state the: (1) 

1.1.1 Independent variable (1) 
1.1.2 Dependent variable (2) 
1.1.3 Any TWO fixed variables (3)  

1.2 Formulate a possible hypothesis for the above investigation. (4)  
1.3 Explain the difference in results for Groups 3 and 4.  (1) 
1.4 Do the results allow you to accept or reject the hypothesis you formulated in QUESTION 1.2? [12]

QUESTION 2 
The diagrams below show some stages in an investigation involving germinating bean seeds, kept in an evenly warm,  damp environment.  

2.1 What physical stimulus leads to the response above?   (1) 
2.2 Using the information in the diagram and your own knowledge, describe how the tip of the root grows  in the direction that it does after two days.  (6)  
2.3 State TWO functions (other than growth movements and apical dominance) of the hormone  responible for the growth movement illustrated above.   (2)  
2.4 Will the same results be obtained if the investigation is carried out in a dark cupboard?  (1)  
2.5 Explain your answer to QUESTION 2.4. (2) 
2.6 Explain why the cotton wool was kept moist.  (2) 

[14]

QUESTION 3 
Read the passage below and answer the questions that follow. 

The normal plasma glucose level is 100 mg/100 ml. The glucose tolerance test was conducted for three adults and the  plasma glucose level (mg/100 ml) was recorded for two hours at 30-minute intervals. The results are shown below. 

3.1 State how the glucose tolerance response test above is used to decide if a person is suffering from  diabetes.   (2) 
3.2 Adult 1 is not diabetic.  

3.2.1 Describe the changes expected in insulin secretion in Adult 1 during the period 30 minutes to  90 minutes after the glucose drink. 
3.2.2 Explain your answer to QUESTION 3.2.1.   (2)  

3.3 Draw two line graphs on the same set of axes to show the glucose tolerance of Adults 1 and 2. (9) 
3.4 What was the percentage increase in glucose level when the glucose was at its maximum in Adult  2? Show all working.   (3)
3.5 Write down the plasma glucose level of the three adults after two hours as a ratio in simple whole  numbers. Show all working.  (2) 
3.6 Suggest, with reasons, what would happen to insulin secretion for Adult 2: 

3.6.1 If the condition was IDDM (2) 
3.6.2 If the condition was NIDDM  (2) 

[24] 
TOTAL SECTION A: 50

SECTION B 
QUESTION 4 
Read the passage and information below and answer the questions that follow. 

Two learners conducted an investigation in the following way to determine which sense organ sends the message  fastest to the brain: the eye, the ear or the skin (sight, hearing, or touch): 

1. Vusi held a meter stick between his thumb and index finger just above the 100 cm mark, while Mary placed her  thumb and forefinger at the 0 mark on both sides of the stick with just the thumb touching it.
2. As Vusi dropped the meter stick Mary attempted to catch it by closing her thumb and forefinger. The distance on  the meter stick that the stick fell before Mary caught it was recorded and the procedure was repeated three times. 
3. They repeated the investigation to determine hearing and skin responses. For the hearing response, Mary was  blindfolded and reacted to Vusi shouting ‘DROP’ when he let go of the stick. For the skin response, Mary was  blindfolded again. Vusi tapped Mary’s free hand when he let go of the stick.  

The results they obtained are shown in the following table: 

4.1 Name the path that is described in the passage. (2) 
4.2 In relation to this path, what term is used to describe each of the following in terms of the role they  play? 

4.2.1 The muscles  (1) 
4.2.2 Skin sensors  (1) 

4.3 Why should you advise the two learners to repeat the procedure more than three times for each  investigation? (2)
4.4 Identify the following in their investigation: 

4.4.1 The dependent variable  (1) 
4.4.2 The independent variable   (1) 

4.5 Calculate the average distance that the meter stick fell when doing the ‘hearing’ investigation. Show  all working.  (3) 
4.6 Study the graph below showing how the distance on the meter stick can be converted to reaction  time in milliseconds. 

Use the reaction time over distance conversion graph to determine: 

4.6.1 The actual reaction time if the meter stick dropped 9 centimetres (2) 
4.6.2 The distance the ruler will drop for a reaction time of 400 milliseconds  (2) 

 [15]

QUESTION 5 
The graph shows the speed of a nerve impulse along neurons with different diameters, measured in micrometres  (μm). 

5.1 Describe the relationship between the diameter of a neuron and the speed of an impulse travelling  along the neuron.  (2) 
5.2 Use the graph to estimate how fast an impulse would travel along a neuron with a diameter of 5  μm. (2) 
5.3 Name the functional gap found between two neurons across which impulses are transmitted.  (1) 
5.4 Explain the significance of the myelin sheath that covers the neurons. (2) 
5.5 Draw a diagram to illustrate the structure of a motor neuron. Indicate the direction of the impulse by  means of an arrow in the diagram.  (7) 

[14] 

QUESTION 6 
A person sitting in a darkened room covers one eye. A dim electric bulb, positioned at varying distances from the  person, is switched on at one-minute intervals for a period of 9 seconds. During this period the diameter of the pupil of  the eye is measured. The results obtained are shown in the table below. Study the table and answer the questions that  follow.

6.1 Name the structure in the eye that controls the size of the pupil.  (1)
6.2 Between which TWO time intervals did the following changes in the diameter of the pupil occur? 

6.2.1 Smallest increase   (2)
6.2.2 Biggest decrease   (2)

6.3 State why the size of the pupil changes from interval 8 to interval 9.  (2)
6.4 Describe how the size of the pupil changes from interval 8 to interval 9.  (4)
6.5 Why is the response in QUESTION 6.3 referred to as a ‘reflex’?  (1)
6.6 What is the significance of this reflex?  (1)
6.7 At which time interval was the bulb the furthest from the eye?   (1)
6.8 Explain your answer to QUESTION 6.7.   (2)
6.9 State TWO ways in which the investigator could ensure that the results of this investigation are  reliable.   (2)
6.10 State THREE things that must be kept constant in this investigation to ensure that it is valid.  (3)

[21]
TOTAL SECTION B:  50
GRAND TOTAL: 100

3.4 Assignment 2 – Reproduction 

Instructions and information

1. Answer ALL questions.
2. Number the answers correctly according to the numbering system used in this question paper.
3. Draw diagrams and flow charts ONLY when requested to do so.
4. This assignment is to be done under controlled conditions and must be handed in at the end of the session. 

NOTE: If it is not possible to schedule a single 90-minute session for this assignment, then SECTION A can be  done on one day in a 45-minute session and SECTION B the following day in another 45-minute session. 
________________________________________________________________________

SECTION A 
QUESTION 1 
Read the text below and then answer the questions that follow. 

1.1 State the type of fertilisation (external or internal) that occurs in bullfrogs and describe how it occurs.  State whether reproduction in bullfrogs is viviparous, oviparous or ovoviviparous.(3)
1.2 Explain your answer to QUESTION 1.2.  (1)
1.3 Describe TWO characteristics of a frog’s egg.   (2)
1.4 Give TWO reasons suggested in the article for bullfrog eggs to be laid in water.    (2)
1.5 Frog eggs are vulnerable to predators, since there is little or no parental protection.   (2)
1.6  Explain THREE strategies that ensure a good survival rate of tadpoles. 

 [16]

QUESTION 2 
The electron micrograph below is that of the human sperm. Study the micrograph and answer the questions that follow.  

2.1 Draw a labelled line diagram of the human sperm represented in the electron micrograph.   (6) 
2.2 Use the scale line provided to calculate the width of the sperm at its widest point. (4) 
2.3 Explain THREE ways in which the sperm is structurally suited for its role in fertilisation.   (6)   

 [16] 

QUESTION 3 
Records of human fertility for the period 1941 to 1990 have shown changes in the sperm counts of normal men. The  table below summarises the changing percentages of men with high or low sperm counts over a period of 50 years. 

3.1  During which time period was there: 

3.1.1 The highest percentage of men with low sperm counts?  (1) 
3.1.2 The lowest percentage of men with high sperm counts?   (1) 
3.1.3 The greatest difference between men with high sperm counts and men with low sperm counts?  (1) 

3.2 Describe the trend for men with low sperm counts, and compare it with those with high sperm counts  over the period of 50 years.   (2)  
3.3  Calculate the percentage increase in men with low sperm counts from 1971 to 1990. (2) 
3.4  Suggest TWO reasons for the trend described in QUESTION 3.2.  (2) 

[9]

QUESTION 4 
The table below shows the results of a survey on the use of contraceptives by a sample of women in a rural area. 

Draw a pie chart to show the results of the survey. Show all working. [9]

TOTAL SECTION A: 50

SECTION B 
QUESTION 5 
The diagram below shows the changes in the ovary, uterus and level of hormones during a 28-day menstrual cycle.  Study the diagram and answer the questions that follow. 

5.1 Which hormone is responsible for: 

5.1.1 Ovulation (1) 
5.1.2 Primary (first) thickening of the endometrium (1) 

5.2 According to the graph, on which day(s) does each of the following occur: 

5.2.1 Menstruation  (1) 
5.2.2 Ovulation (1) 

5.3 Two structures in the ovaries are responsible for the secretion of two female hormones.

5.3.1 Name the TWO structures and the hormones they secrete. (4) 
5.3.2 Give evidence from the graph to support your answer to QUESTION 5.3.1. 4) 

5.4 Explain the interaction that occurs between the hormones FSH and progesterone and why it is  necessary. (3) 
5.5 Is the female, whose cycle is represented in the diagram, pregnant?  (1) 
5.6 Give TWO reasons from the graph for your answer to QUESTION 5.5.  (2) 

[18]

QUESTION 6 
The table below shows the average human foetal length of males and females over a 40-week gestation period.  

6.1 Draw TWO sets of bar graphs on the same system of axes to compare male and female foetal  length over time.  (9) 
6.2 State TWO conclusions that could be drawn from the results in the graph.  (4) 

[13]

QUESTION 7 
John and Mary have two children. The oldest is Patrick, followed by Anne, a girl. Mary is pregnant again. 
7.1 By representing a genetic cross, show the percentage probability of them having another daughter. (7) 
7.2 Mary and John’s first child is a haemophiliac and they are afraid that their third child may also have  the disorder. Mary is a carrier of haemophilia and John has the normal clotting factor. An ultrasound  scan shows that Mary is expecting a girl. (7) 
Show, using a genetic cross, the percentage probability of their third child having haemophilia. 
7.3 Use the following symbols to construct a simple pedigree diagram showing the inheritance of  haemophilia in this family:  
(5) 

[19] 
TOTAL SECTION B: 50 

3.5 Test – Nucleic acids and meiosis 

Instructions and information

1. Answer ALL questions.
2. Number the answers correctly according to the numbering system used in this question paper.
3. Draw diagrams and flow charts ONLY when requested to do so. 
4. This test is to be done under controlled conditions and must be handed in at the end of the session. 

SECTION A 
QUESTION 1 
1.1 Various possible options are provided as answers to the following questions. Choose the answer  and write only the letter (A–D) next to the question number (1.1.1–1.1.5) in the ANSWER BOOK, for  example 1.1.6 D. 

1.1.1 All nucleic acids are made up of … 

1. deoxyribose sugars, nitrogenous bases and phosphates.
2. sugars, nitrogenous bases and phosphates.
3. ribose sugars, nitrogenous bases and phosphates
4. sugars, nitrogenous bases and sulphates. 

1.1.2 If a DNA molecule contains 20 000 base molecules, of which 20% are cytosine, how  many adenine molecules will be present? 

1. 1 000
2. 2 000
3. 6 000
4. 8 000 

1.1.3 DNA replication ensures that all daughter cells formed as a result of … 

1. mitosis, have identical genetic material.
2. meiosis, have identical genetic material.
3. mitosis, have half the number of chromosomes as the parent cell.
4. meiosis, have half the number of chromosomes as the parent cell.

1.1.4 In individuals with normal haemoglobin, the mRNA for haemoglobin includes the codon  GAA. This sequence is changed in individuals with sickle cell anaemia so that their mRNA  has a codon GUA at the same location. This suggests that the DNA has undergone a  mutation involving a change of base sequence from ... 

1. CAA to TAA.
2. CTT to CAT.
3. CUU to CAT.
4. CTT to CTA. 

1.1.5 The result of profiling various DNA samples in a criminal investigation is shown below.

Which conclusion about the crime could the DNA analyst draw? 

1. Only suspect X was involved.
2. Only suspect Y was involved.
3. Suspects X and Y were both involved.
4. Neither suspect X nor suspect Y was involved. (5 x 2) (10) 

1.2 Give the correct biological term for each of the following descriptions. Write only the term next to the  question number (1.2.1–1.2.4) in the ANSWER BOOK. 

1.2.1 Specific lengths of DNA which carry codes for specific characteristics of organisms
1.2.2 The part of protein synthesis taking place in the nucleus 
1.2.3 The bonds between the two strands of a DNA molecule 
1.2.4 The chromosome condition/ploidy of a somatic cell (4) 

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  number (1.3.1–1.3.3) in the ANSWER BOOK.

(3 x 2) (6) 
TOTAL SECTION A: 20

SECTION B 
QUESTION 2 
Study the diagram below showing a process that takes place in all living cells. 

2.1 Identify the process represented in the above diagram. (1) 
2.2 Name the specific part of the process mentioned in QUESTION 2.1 that occur at the organelle labelled G.   (1) 
2.3 Describe the process named in answer to QUESTION 2.2.  (5) 
2.4 State TWO similarities in structure between molecules B and C. (2) 
2.5 The table below indicates the amino acids that are carried by different tRNAs. 

Identify the amino acids which will be brought to organelle G according to the code provided by the  mRNA found on G. (3) 
2.6 Write down the triplet of DNA bases that correspond to each of the molecules B, F and H, respectively. (3) 

[15]

QUESTION 3 
Study the diagrams below that represent different phases of Meiosis I. 

3.1 Identify the structures labelled B and E.  (2) 
3.2 State TWO functions of the structure labelled F.  (2) 
3.3 Describe the process shown at A in Diagram I.  (2) 
3.4 Tabulate TWO ways in which a cell in the phase shown in Diagram II would differ from a cell in the  same phase in Meiosis II. (5) 
3.5 How many chromosomes will be present in each cell at the end of meiosis? (1) 
3.6 If the above cell division occurred in a human being, describe the events leading to the formation of  an offspring with Down syndrome.  (3) 

[15] 
TOTAL SECTION B:  30 
GRAND TOTAL:  50