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Life Sciences P2 1 FS/September 2016 Grade 12 Prep. Exam.

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PREPARATORY EXAMINATION

GRADE 12

LIFE SCIENCES P2

SEPTEMBER 2016

MARKS: 150

TIME: 2½ HOURS

This question paper consists of 17 pages.



INSTRUCTIONS AND INFORMATION

Read the following instructions carefully before answering the questions. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

Answer ALL the questions. Write ALL the answers in the ANSWER BOOK. Start the answers to EACH question at the top of a NEW page. Number the answers correctly according to the numbering system used in this question paper. Present your answers according to the instructions of each question. ALL drawings must be done in pencil and labelled in blue or black ink. Draw diagrams, tables or flow charts only when asked to do so. The diagrams in this question paper are NOT necessarily drawn to scale. Do NOT use graph paper. You must use a non-programmable calculator, protractor and compass, where necessary. Write neatly and legibly.



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 to D) next to the question number (1.1.1 to 1.10) in the ANSWER BOOK, for example 1.1.11 D.

1.1.1 Two individuals are most likely members of the same

species if they …

A B C D

have a different number of chromosomes. can mate and produce fertile offspring. breed at different times during the year. are phenotypically different .

1.1.2 Which ONE of the following is most likely the chromosome

complement of a person with Down syndrome?

A B C D

46 + XX 46 + XY 45 + XX 44 + XY

1.1.3 Which of the following correctly identifies the relationship

between alleles, chromosomes, and genes?

A B C D

Genes contain chromosomes and alleles Chromosomes contain genes but not alleles Alleles are found in chromosomes but not in genes Alleles are different forms of genes found in chromosomes

1.1.4 During meiosis II in humans ...

A B C D

homologous pairs of chromosomes separate. chromosomes arrange singly at the equator. only the sex chromosomes separate. DNA replication takes place.

1.1.5 RNA differs from DNA in that RNA ...

A B C D

has deoxyribose sugar and uracil. has thymine and a phosphate group. has uracil and a ribose sugar. is a double-stranded molecule.



1.1.6 If the mother has blood group AB and the father blood

group O the possible blood groups of the offspring will be ...

A B C D

A or B only. AB only. O only. A, B, AB or O.

1.1.7 Which of the following shows the process of DNA

replication in the correct sequence?

A B C D

DNA helix unwinds strand unzips complementary bases pair two identical DNA strands form. Two DNA helixes unwind strand unzips complementary bases pair one DNA strand form. DNA helix unzip strands unwinds complementary bases pair one DNA strand form. DNA helix unwinds strand unzips complementary bases pair – one DNA strand form.

1.1.8 In humans the ability of the tongue to roll is a dominant trait.

The inability to roll the tongue is recessive. If two individuals who are homozygous recessive for this trait have a child, the chance that the child will be able to roll his/her tongue, is …

A B C D

75%. 100%. 0%. 50%.

1.1.9 Which ONE of the following monohybrid crosses of

complete dominance will result in a phenotypic ratio of 3:1? A cross where …

A B C D

both parents are heterozygous. one parent is heterozygous and the other is homozygous recessive. both parent are homozygous for the dominant characteristic. one parent is heterozygous and the other is homozygous dominant.

1.1.10 The molecules that are involved in transcription are ...

A B C D

mRNA and amino acids. DNA and tRNA. DNA and mRNA. tRNA and mRNA. (10 x 2)

(20)



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 1.2.8) in the ANSWER BOOK.

1.2.1 1.2.2 1.2.3 1.2.4 1.2.5 1.2.6 1.2.7 1.2.8

An allele that influences the phenotype whether in the homozygous or heterozygous combination

Bonds by which the base pairs are linked in DNA

Point of overlap of chromatids during crossing over

Opening in the skull through which spinal cord enters

Group of organisms of the same species occupying the same habitat

Tangled network of chromosomes located in the nucleus Openings in the nuclear membrane that allow mRNA to leave the nucleus

The type of nucleic acid on which the anti-codon for protein synthesis is located

(8) 1.3 Indicate whether each of the descriptions 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 to 1.3.3) in the ANSWER BOOK.

COLUMN I COLUMN II

1.3.1

Produced the first X-ray pictures of DNA

A: B:

Watson Franklin

1.3.2

All the genes in all the chromosomes of a species

A: B:

Genome Genotype

1.3.3 The chromosome number of a cell formed by meiosis

A: B:

Diploid Haploid

(3 x 2) (6)



1.4 The following represents a possible phylogenetic tree of

Australopithecus and Homo species.

0

Appearance of art

35 000

Homo sapiens

First burials

100 000

Homo neanderthalensis

Moved out of Africa

500 000 Homo erectus

Control of fire

1000 000

Homo habilis

Use of tools

3 000 000

Australopithecus africanus

Australopithecus afarensis

Bipedal hominids

6 000 000

Ardipithecus ramidus

[Adapted from: m.ivyroses.com/Human evolution]

1.4.1 1.4.2 1.4.3

How many years ago did Homo neanderthalensis disappear from earth?

According to the phylogenetic tree:

(a) Which was the first group to use tools?

(b) Which TWO Australopithecus species co-existed? (c) Which species moved out of Africa?

Name ONE fossil of Australopithecus found in South Africa.

(1)

(1)

(2)

(1)

(1) (6)

Yea

rs a

go



1.5 Three ladies each gave birth to a baby boy in a large hospital. The

babies were accidentally swopped. The most accurate way to correctly match each baby with his parents was by using DNA profiles. The DNA profiles are shown below.

SMITH STEVENS JONES BABY

MR MRS MR MRS MR MRS 1 2 3

1.5.1 1.5.2

Which baby (1, 2 or 3) belongs to the: (a) Smith's? (b) Jones'? State THREE other uses for DNA profiling.

(1)

(1)

(3) (5)



1.6 The diagram below shows two phases of meiosis. 1.6.1

1.6.2 1.6.3

Provide labels for A and B.

Identify the phase represented by diagram I.

State the functions of A and C.

TOTAL SECTION A:

(2)

(1)

(2) (5)

50

A

B

Diagram I Diagram II

C



SECTION B QUESTION 2 2.1 The diagram below shows one stage of protein synthesis.

2.1.1 2.1.2 2.1.3 2.1.4

Name:

(a) organelle X (b) structure Y

(c) the stage of protein synthesis shown in the diagram

Name and describe the process that occurs in the nucleus to produce mRNA. The table below shows the mRNA codons that code for different amino acids. Using the information in the table and the diagram above, write down the sequence of the amino acids that are represented by numbers 2 and 4.

Give the base sequence on DNA that codes for the amino acid leucine.

CODON OF mRNA AMINO ACID

CUU Proline

GUA Leucine

CCA Glycine

GGA Glutamic acid

GAA Valine

(1)

(1)

(1)

(5)

(2)

(1) (11)

X

mRNA

1 2 3 4

Y

C C U C U U G U A

amino acid

G G A C C U C A U G A A



2.2 In humans eyebrows are either connected or not connected to each other.

Study the family tree shown below that shows the inheritance of connected and not connected eyebrows over four generations.

Key:

Male with eyebrows not connected

Male with eyebrows connected

Pedigree diagram showing inheritance of connected or not connected eyebrows.

2.2.1

2.2.2 2.2.3 2.2.4 2.2.5

Which type of eyebrows is controlled by the dominant allele?

Give a reason for your answer to QUESTION 2.2.1 using evidence from the pedigree above.

Persons E and F are twins. Did they develop from a single fertilised egg or from two fertilised eggs? Give TWO reasons based on their phenotypes to support your answer to QUESTION 2.2.3. What percentage of females in the pedigree diagram's eyebrows are connected?

(1)

(2)

(1)

(2)

(2) (8)

Eye brows not connected Eye brows connected

F

Female with eyebrows not connected Female with eyebrow connected

C D

A B

E



2.3 In humans brown tooth enamel is inherited as a sex-linked recessive trait. A man who carries the recessive allele will have brown tooth enamel. A man with brown tooth enamel marries a woman with white teeth, but whose father had brown tooth enamel. Use XB for white teeth enamel and Xb for brown tooth enamel.

2.3.1 2.3.2

Explain why the woman is heterozygous for tooth enamel colour. Use a genetic cross to show the possible ratio of the phenotypes of their children.

(4)

(6) (10)

2.4 Read the extract and answer the questions that follow.

2.4.1 2.4.2 2.4.3

Name TWO functions of non-coding DNA. According to Dr Carolyn Hancock, what percentage of DNA is called 'junk DNA'? List characteristics shared by DNA and RNA.

(2)

(1)

(3) (6)

Mysterious DNA

The genome is made up of all DNA in a human. The human genome has 20 000–25 000 genes and the average gene has about 3 000 bases. The genes make up only 2% of the human genome and the rest of the DNA consists of non-coding regions. Some of them are used for regulating chromosomal structure and the quantity and quality of proteins made. The function of 50% of the DNA, made up of repeated sequences and known as 'junk DNA', is not yet known. Some scientists differ from the above view. According to Dr Carolyn Hancock, genes make up 5% of the human genome.

[Adapted from: http://dnaproject.co.za]



2.5 In rats the allele for a black coat colour (B) is dominant over the allele

for a white coat colour (b). The allele for a long hair (L) is dominant over the allele for a short hair (l).

2.5.1

Two rats were crossed. The genotypes of their offspring are represented in the Punnett diagram below, except at (i) and (ii).

BL Bl bL bl

Bl BBLl BBll BbLl (i)

bl BbLl Bbll (ii) bbll

2.5.2

Give the: (a) Genotype of the offspring at (i) (b) Phenotype of the offspring at (ii) If rats produce offspring all with the genotype BbLl and the female genotype is bbll, state the only possible genotype of the male.

(1)

(2)

(2) (5)

[40]



QUESTION 3

3.1 The diagrams below show the skeletons of two hominids.

3.1.1 3.1.2 3.1.3 3.1.4

State TWO advantages of bipedalism.

Identify TWO similarities in the forelimbs of organism 1 and organism 2.

Explain the significance of the change of the pelvis towards bipedalism.

State TWO advantages of the larger cranial capacity of organism 2.

(2)

(2)

(4)

(2) (10)

Organism 1 Organism 2



3.2 Earth originally existed as one large land mass that later drifted apart

and formed the continents as we know it today. The following two pictures are those of baobab trees found on the continent of Africa (Diagram I) and found on the continent of Australia (Diagram II).

Explain how the two species of baobab trees shown above might

have formed.

(6)

DIAGRAM II DIAGRAM I



3.3

An investigation was done by grade 12 learners to compare the speed of left-handed persons and right-handed persons in mirror writing. Mirror writing is writing in the opposite direction to what is considered normal writing. This is the writing seen in front of ambulances so that drivers in front of the ambulance can read the text in their rear-view mirrors. The following steps were carried out:

Twenty learners were selected, ten left-handed and ten right-handed.

A simple text sentence was given to them to change into mirror writing.

A stopwatch was used to measure the time taken for each learner to finish the task.

The recording of their task was done in seconds. The results of the investigation are shown in the table below.

TIME TAKEN TO PERFORM MIRROR WRITING IN SECONDS

LEARNERS 1 2 3 4 5 6 7 8 9 10 Average Time

LEFT-HANDERS 129 135 147 127 119 164 129 138 147 153 138.8

RIGHT-HANDERS 165 187 196 175 159 172 219 193 167 188 182.1

3.3.1

3.3.2 3.3.3 3.3.4 3.3.5

Formulate a hypothesis for this investigation. State the independent variable in this investigation. Identify TWO variables which were kept constant in this investigation other than the one given in the investigation. What conclusion can be drawn from this investigation? Draw a bar graph to show the average time taken for left-handers and right-handers to write the sentence.

(2)

(1)

(2)

(2)

(6) (13)



3.4 In 1971, ten wall lizards (Podarcis sicula) were introduced to an

island from a neighboring island. After being left for some decades they where compared by scientists to the colony from which they were taken originally. The Island on which they were released had very few insects and more vegetation. They were found to have changed from an insectivorous diet to a vegetarian diet. This diet change seemed to have brought visible changes in the wall lizards.

THE EVOLUTION OF THE WALL LIZARD

[Adapted from www.suria.org.uk]

3.4.1 List THREE characteristics other than head size that changed in Podarcis sicula. (3) 3.4.2 Explain how the change in diet can account for the larger

body size. (2) 3.4.2 Use your knowledge of natural selection to explain the changes in

size of the head of the wall lizard. (6) (11) [40]

TOTAL SECTION B: 80

Original lizard Lizard after decades

Head larger with

more bite force for

chewing leaves

Head smaller for

eating insects

with less bite force

Body larger

Tail thicker

http://www.suria.org.uk/



SECTION C QUESTION 4 The characteristics of organisms can be changed through selective breeding and genetic engineering. Use an example to describe selective breeding and also describe the similarities and the differences between natural selection, selective breeding and genetic engineering.

Content: Synthesis:

(17) (3)

(20)

NOTE: NO marks will be awarded for answers in the form of flow charts or diagrams.

TOTAL SECTION C: GRAND TOTAL:

20 150

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