COMPETENCY TEST FOR GRADE 12 MARKERS LIFE SCIENCES …€¦ · Various options are provided as possible answers to the following questions. Choose the correct answer and write only

1

Copyright reserved Please turn over

MARKS: 120 TIME: 2 hours

This competency test consists of 13 pages and an answer book of 9 pages.

NAME: ……………………………………………..SURNAME…………………………….. NAME OF SCHOOL: …………………………………………………………………………. ID NR:……………………………………………………………………………………………

LIFE SCIENCES PAPER 2

MAY 2015

COMPETENCY TEST FOR GRADE 12 MARKERS

2 Life Sciences Paper 2 Competency test WCED/May 2015


COMPETENCY TEST INSTRUCTIONS AND INFORMATION Read the following instructions carefully before answering the questions. 1. Answer ALL the questions in the ANSWER BOOK attached. Section A: Answer the series of questions in the ANSWER BOOK attached. Section B: Mark examples of learners’ answers in the ANSWER BOOK attached. 2. Present your answers according to the instructions of each question. 3. ALL drawings should be done in pencil and labelled in blue or black ink. 4. Only draw diagrams or flow charts when asked to do so. 5. The diagrams in this question paper are NOT all drawn to scale. 6. Do NOT use graph paper. 7. Non-programmable calculators, protractors and compasses may be used. 8. Write neatly and legibly. 9. Make sure that your name is on both the question paper and answer book. 10. DO NOT REMOVE THE QUESTION PAPER OR THE ANSWER BOOK FROM THE ROOM. IF YOU DO YOU WILL BE DISQUALIFIED FROM THE TEST.



SECTION A Write your answers in the table in your ANSWER BOOK provided. QUESTION 1 Various options are provided as possible answers to the following questions. Choose the correct answer and write only the correct letter (A to D) on your ANSWER BOOK.. 1.1 A white cow is bred with a red bull. Each offspring’s coat colour is roan. This is an example of ... A a dihybrid cross

B incomplete dominance C co-dominance D Mendel’s law of independent assortment

1.2 The following are characteristics of the different types of DNA:

1 Codes for proteins 2 Forms together with proteins the large sub-unit of ribosome 3 Some of their functions are still unknown 4 Has regulatory functions 5 Codes mRNA

1.2 Which of the following combinations are true about non-coding DNA? A 1, 2, 3, 4, 5 B Only 2, 3 and 4 C Only 2, 3, 4 and 5 D Only 3 and 4

1.3 How many chromosomes are present in a somatic cell of a child with

Down syndrome?

A 23 B 27 C 46 D 47

1.4 Four different phenotypes are possible in the F1-generation if the

parents’ blood types are …

A B and B B A and B C O and AB D AB and AB



1.5 Which of the following are used as evidence for evolution?

I. Homologous structures II. Biogeography III. Genetics

A Only I and II B Only I and III C Only II and III D I, II and III 1.6 Larmark’s theory of evolution is usually known as … A natural selection. B descent with change. C inheritance of acquired characteristics.

D artificial selection.

1.7 The distribution of organisms is known as …. A biochemistry. B biogeography. C archaeology. D palaeontology. 1.8 Which one of the following serves as evidence of cultural evolution

in early Homo species? A Remains of animals close to a Homo skeleton B Remains of ancient tools C Male and female skeletons in the same area D A large number of Homo skeletons in an area (8 x 2) = 16

TOTAL QUESTION 1: [16]



QUESTION 2 2.1 Describe how abnormal meiosis can lead to the disorder where a person has three number 23 chromosomes. Also name the process in meiosis. [8] 2.2 In a certain species of plant, Acer rubrum (red maple), tallness (T) is

dominant over shortness (t) and red (R) fruit colour is dominant over yellow (r) fruit colour.

2.2.1 A plant that is homozygous for both tallness and red fruit colour, is crossed

with a plant homozygous for both shortness and yellow fruit colour.

List the phenotypes and genotypes of

(i) P1 generation. (2) (ii) F1 generation. (2)

2.2.2 If the F1 generation in QUESTION 2.2.1 were interbred, what are the

chances of the offspring being short with yellow fruit? (2)

2.2.3 Explain why colour blindness, a sex-linked disease, is more often found in men than in women. (3)

[9] 2.3 Read the extract below and the information in the graph and answer

the questions that follow. Antibiotic peptides occur naturally on the surface of human skin. There is a concern that peptides could damage living human cells. One form of damage is the fragmentation (breaking down) of DNA. Human cells were incubated for 16 hours with each peptide extract A, B, C and D at varying concentrations (2µmol dm-3, 6µmol dm-3, 20µmol dm-3 and 80µmol dm-3 respectively). The amount of DNA fragmentation was then measured and represented in the graph below.



2.3.1 Identify the peptide extract that causes the least damage to DNA. (1) 2.3.2 Calculate the percentage increase in DNA damage that results when the peptide concentration of A increases from 2 µmol dm -3 to 6 µmol dm -3.

Show ALL working. (3) 2.3.3 What is the highest amount of fragmentation that occurred in the peptide extract C? (1) [5] 2.4 The diagram below shows one stage of protein synthesis.

The table below shows five codons and their corresponding amino acids.

Codon Amino acid CUU Leucine GGA Glycine CAA Glutamic acid GUA Valine CCU Proline

2.4.1 Identify the stage of protein synthesis represented in the diagram above. (1) 2.4.2 Describe the stage of protein synthesis that is NOT shown in the diagram above. (6) 2.4.3 Use the information in the table to identify the amino acids numbered 1

and 4 respectively. (2) [9]



2.5 The diagram below represents a nucleic acid molecule. Study the diagram

and answer the questions that follow.

2.5.1 Identify the molecule represented in the diagram. (1) 2.5.2 Give two observable reasons for the choice of your answer to

QUESTION 2.5.1. (2)

2.5.3 Explain the importance of the following (a) the strong bond between the sugar and phosphate (2) (b) the weak bonds between the nitrogenous basis (2)

2.5.4 Describe how the molecule mentioned in QUESTION 2.5.1 is able to make copies of itself. (6) [13]



2.6 Since 1972, biologists have studied finch populations in the Galapagos

islands. The graph below shows the change to the number of finches, the rainfall and the number of small seeds over a period of seven years on one island (Daphne Major). Small seeds are abundant in rainy seasons and large seeds are drought resistant

2.6.1 In which year was the finch population the highest? (1) 2.6.2 Briefly describe the trend in the finch population from 1977 to 1980. (2) 2.6.3 Name the environmental factor that caused the changes in the finch

population described in QUESTION 2.6.2. (1) 2.6.4 Use Darwin’s theory of natural selection to explain how seed-eating

finches with large beaks evolved on Daphne Major island over many generations. (6)

[10]

2.7 Describe how the genus Proteus probably evolved into different species in South Africa and in Australia. [12]

2.8 An investigation was carried out to determine the effect of an antibiotic (X) on two strains of bacteria (A and B) that cause TB. The diagram below shows the result of the antibiotic (X) treatment after Day 1 and Day 2 of a five day course to treat TB infection. The bacteria (strains A and B) were cultured in a petri dish at a temperature of 37,5°C.



2.8.1 Formulate a hypothesis for the above investigation. (3) 2.8.2 Which factors in the above investigation represent the (a) independent variable? (1) (b) dependant variable? (1) 2.8.3 Which bacteria, A or B, is resistant to the antibiotic? (1) 2.8.4 Explain the effect that the antibiotic had on the bacteria after

the first and second day of treatment. (2)

2.8.5 Name the process that leads to the difference in the population size of bacteria A and bacteria B. (1) 2.8.6 Predict the consequence should a person fail to complete the

antibiotic course. (2)

2.8.7 Why must the bacteria be cultured at 37,5° C? (2) 2.8.8 State TWO precautions that must be taken to ensure that the results

of the investigation are valid. (2) [15]



2.9 The diagrams below show the upper jaw and skull of organisms A and B.

Study the diagrams and answer the questions that follow.

2.9.1 Mention ONE visible difference between the palate shape and teeth (dentition) of organisms A and B. (4)

2.9.2 Identify the organism (A or B) which is more likely to be bipedal and explain your answer. (3)

[7]

TOTAL FOR SECTION A: 104

SECTION B QUESTION 3 Instructions You have to mark the learners’ answers in the ANSWER BOOK. The following are provided:

1. Questions and the memoranda for these questions below, and 2. Answers from different learners to be marked in the ANSWER BOOK.

Mark these learners’ answers in the ANSWER BOOK as follows: Use a red pen to …

1. Allocate a tick () close to the correct answer/key word, 2. Give a sub-maximum mark for each sub-section of the question (see memorandum), 3. Make comments such as max., not applicable, mark first TWO only, etc.



QUESTION 3 3.1 Tablulate TWO differences between a DNA molecule and a RNA molecule. (5) MEMORANDUM FOR QUESTION 3.1

DNA RNA 1 Contains Deoxyribose sugar 1 Contains Ribose sugar 2 Double strands 2 Single strand 3 Contains the nitrogenous bases A, T, C & G / A is proportional to T and G is proportional to C

3 Contains the nitrogenous bases A, U, C & G / Different relative numbers of A, U, C and G

4 Double helix structure 4 Different flat structures such as folded loops or single strands

5 Complementary base pairs 5 Bases not in pairs/ no complementary pairs

(Mark first TWO only) any 2 x 2

+ 1 for presenting a table (1)

(5) 6 marks are allocated to the marking of this question.

3.2 The table below shows the results obtained by crossing a pure-bred black

furred mouse with a brown furred mouse. The gene for black fur is dominant over the gene for brown fur. Offspring from the F1 generation were used as parents (consisting of 4 breeding pairs) of the F2 generation.

Draw bar graphs on the same system of axes to represent the phenotypic results of the F2 generation offspring of each breeding pair shown in the table above. (7)

Number of black mice

Number of brown mice

Parents 1 1 F1 generation 8 0 F2 generation Offspring of 1st breeding pair Offspring of 2nd breeding pair Offspring of 3rd breeding pair Offspring of 4th breeding pair

8 7 5 4

0 1 3 4



MEMORANDUM FOR QUESTION 3.2

NOTE: If the wrong type of graph is drawn: - Marks are forfeited for ‘correct type of graph’ ; ‘drawing of graph’ If graphs are not drawn on the same system of axes:

- Mark the first graph only using the given criteria – Candidates will lose 2 marks for the incorrect drawing of the pair of bars

Mark allocation of the graph Correct type of graph (T) 1 Caption for graph 1 Correct label for X-axis 1 Graphs labelled/key provided for 2 graphs

1

Correct label and scale for Y-axis 1 Drawing of bars (D)

1 mark if 2 to 3 pairs of bars plotted correctly 2 marks if all 4 pairs of bars are plotted correctly

(7)

7 marks are allocated to the marking of this question.

T D

Results of the number of different colour/phenotypes of offspring per breeding pair

0123456789

1 2 3 4Breeding pairs

Nu

mb

er

of

off

sp

rin

g

Key: Black - Brown -



3.3 Colour blindness is a sex-linked disease caused by the presence of a recessive

allele (Xd). A normal father and heterozygous mother have children. Represent a genetic cross to determine the possible genotypes and phenotypes of the children of the parents. (7)

Memorandum for 3.3 Father Mother P1/parent phenotype Normal x Normal genotype XDY x XDXd

Meiosis Fertilisation F1/offspring

2 normal daughters, 1 normal son, 1 colour-blind son

P1 and F1/Parents and offspring Meiosis and fertilisation

(7)

3 marks are allocated to the marking of this question.

TOTAL SECTION B: (16) GRAND TOTAL: 120

Gametes XD Xd XD XD XD XD Xd Y XDY Xd Y

1 mark for correct gametes 1 mark for correct genotypes

Documents

COMPETENCY TEST FOR GRADE 12 MARKERS LIFE SCIENCES …€¦ · Various options are provided as possible answers to the following questions. Choose the correct answer and write only