LIFE SCIENCES GRADE 12 PRACTICAL TASK 1.1 DNA: THE CODE OF LIFE DATE ...

LIFE SCIENCES GRADE 12

PRACTICAL TASK 1.1

DNA: THE CODE OF LIFE

DATE: 15 FEBRUARY 2018

NAME: ___________________________________

TIME: 30 MIN

Total 30

QUESTION 1

Study the following diagrams of different portions of DNA molecules and write the correct term into each of the empty spaces. Numbers 1 to 3 represent labels and numbers 4 to 6 appropriate captions.

1.

2.

4.

nitrogenous base 3.

hydrogen bonds

5.

6.

(6)

Life Sciences Practical Task 1.1

2

Grade 12

FS/February 2018

QUESTION 2

2.1

Below are THREE unzipped strands of DNA molecules ready to be duplicated.

Write the appropriate LETTERS in the spaces provided to build the complementary

strands of DNA X, Y and Z.

X

Y

Z

(3)

2.2

In the DNA "ladders" below, draw the nitrogenous bases from the DNA strands Y

and Z in QUESTION 2.1. Also write down the corresponding numbers of the

nitrogenous bases as indicated by the key. The bases for the first section of DNA

strand X are provided as examples.

KEY: 1 thymine

2 guanine

3 cytosine

4 adenine

X

Y

Z

2

3

1

4

(2)

Life Sciences Practical Task 1.1

3

Grade 12

FS/February 2018

QUESTION 3

The following diagram represents various processes that take place in a cell. The labels A, B and C represent the processes taking place. Write the correct label in each box. .

DNA DNA

A B

mRNA

nuclear membrane

move to cytoplasm

C

anticodon

ribosome (6)

Life Sciences Practical Task 1.1

4

Grade 12

FS/February 2018

QUESTION 4

4.1

Use the decoding wheel to determine the amino acid that corresponds with the

mRNA code given. Read the code from the centre towards the amino acid name

on the edge. Complete the table.

mRNA

AAA GCG GAU CAA

Amino acid

(4)

4.2

Answer the following referring to QUESTION 4.1

4.2.1 Which amino acids have only ONE codon?

________________________________ __________________________ (2)

4.2.2 Which two mRNA codes correspond with histidine?

________________________________ __________________________ (2)

4.2.3 How many different mRNA codes correspond with threonine?

___________

(1)

(5)

Life Sciences Practical Task 1.1

5

Grade 12

FS/February 2018

QUESTION 5

A grocery shop has been robbed. The police arrested two suspects and compared DNA samples from each of them with two hair specimen found at the crime scene. They also took a DNA sample from the owner of the shop in order to exclude him as a suspect.

The results of their investigation are shown below:

Shop owner Suspect 1 Suspect 2 Specimen 1 Specimen 2

5.1 What is the `picture' above called?

_______________________________________

(1)

5.2 How is it possible that the barcodes can be the same for the shop owner and those of specimen 2?

________________________________________________________

________________________________________________________

(2)

5.3 Who committed the crime?

________________________________________________________

(1)

(4)

TOTAL: 30

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