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UNIVERSITY
OF
KWAZUlU~NATAl
SCHOOL OF SCIENCE, MATHEMATICS & TECHNOLOGY
EDUCATION (Edgewood Campus)
BACHELOR OF EDUCATION
EXAMINATIONS - JUNE 2011
Module Title
Biological Science for
Educators 410
Code
EDBS410 E 1
Duration
3 Hours
Marks
150
Internal
Examiner
Dr. M. Stears
External
Examiner
Ms M Doidge
Write legibly
Answer all questions
This paper consists of'1 pages
QUESTION 1
1.1.
The diagram depicts Hershey and Chase's experiment.
virus particle
J;i
l.
I,i
4:,.
(~_~~':!-)
--(--------=) --C~,)
.~\
labeled with 35S
'"
" I'
•.. ' ... ~
.~ "
a
virus particle ----,
labeled with 32p
\
i,.
~li
\--~)-L
b
4:,
)-c.__
)
1.1.1 What were these scientists trying to find out?
(2)
1.1.2. In the experiment depicted in row a, the bacteriophage contains radio-active
sulphur. The bacteriophage in row b contains radio active phosphorus.
Explain what the result was in each experiment as well as the conclusions the researchers
drew from the results.
(8)
1.2.
A fly has the following percentage ofnucleotides in its DNA: 27,3%Adenine, 27,6%
Thymine, 22,5% Guanine and 22,5% Cytosine.
How do these numbers demonstrate Chargaff' s rules?
(3)
/13/
QUESTION 2
2.1.
The template strand of a gene contains the sequence 3' - TTCAGTCGT -5'.
Draw the non-template sequence of the DNA as well as the mRNA sequence,
indicating 5' and 3' ends of each. How do the two sequences differ?
(6)
2.2
Imagine the non-template sequence in question 2.1 was transcribed instead of the
template sequence. Draw the mRNA sequence and translate it using the genetic code
below.
(4)
2.3.
Predict how well the protein synthesized from the non-template strand would function, if
at all.
(4)
u
G
C
A
,phenylalanine
serine
tyrosine
cysteine
phenylalanine
serine
tyrosine
cysteine
~,C
leucine
serine
STOP
STOP
A
leucine
' serine
STOP
tryptophan
G
leucine
proline
histidine
ar.9inine
U
leucine
proline
histidine
arginine
C
,
i
-;
U
U (,
~'
"
C
r
A
leucine
proline
glutamine
arginine
A
leucine
proline
glutamine
arginine
G
isoleucine
threonine
asparagine
serine
U
isoleucine
threonine
asparagine
serine
C
isoleucine
threonine
lysine
arginine
A
i
threonine
lysine
arginine
G
I
alanine
aspartate
glycine
"U
valine
alanine
aspartate
glycine
C
valine
alanine
glutamate
glycine
A
alanine
glutamate
glycine
G
methionine
(or START)
-
valine
G
,
~,
I
valine
-
i
/14/
2
/14/
QUESTION 3
3.1
There are a number of controls that influence whether, when and how a gene in
eukaryotic DNA will be expressed. One such control is mRNA degradation control.
Explain what this means.
(3)
3.2
The diagram shows the spindle which is formed during cell division. The microtubules
play an important role in this process. Describe the two mechanisms by which the
daughter chromosomes move to opposite poles.
(4)
3.3
Assume that a cell entering
you expect at the following
3.3.l. At the end of the 'S'
3.3.2. If the cell undergoes
answer.
the cell cycle has X amount of DNA. How much DNA would
stages?
interval? Explain your answer.
(2)
meiosis,at the end of Telephase II in each cell? Explain your
(2)
/11/
QUESTION 4
4.1.
You notice several duck species in the same lake habitat, with no physical barriers
hampering the ducks' movements. All the females of the various species look quite
similar to one another. But the males differ in the patterning and colouration of their
feathers. Which form of reproductive isolation may be keeping each species apart? (3)
4.2.
Read the experiment conducted on guppies on page 4
3
Predator: Killifish; preys mainly -;) ...'.'" .
on juvenile guppies (which do
_~
not express the color genes)
<~/
~!
POOI~;h~
I
killifish,
but no guppies
prior to transplant
Guppies: Adult males have
brighter colors than those
in"pike-cichlid
pools"
~~~
EXPERIMENT,·.
".' '.
J 0 h n En dl er,o f t h e U·ruversrty
.
0f C a lif
I ornia
Santa Barbara, studied wild guppies in the Aripo River system' on
the Caribbean island of Trinidad, He transplanted 200 guppies
from pools containing pike-cichlids, intense guppy predators, to
pools containing
killifish, less active predators of guppies, He
tracked the number of bright-colored spots and the total area of
those spots on male guppies in each generation,
RESUL1$0};"".
.
- '-',
~.=""' ,,', Aft er 22 mont h s ( 15 generations),
the number
and total area of colored spots on male guppies in the transplanted population had increased compared to those of males in
the source population,
12
'"
10
~ ~
8
00
E~
6
Zov
4
~ 0
2
Predator: Pike-cichlid;
.
I
L-._.,.,...-
~~
preys mainly on adult guppies
Guppies: Adult males are more drab in color
than those in "killifish pools"
•
I
Source
population
Transplanted
population
o
Source
population
I
~
4.2,1. Which one of the following phenomena is depicted here? Select the correct answer
A. Genetic drift
B. Natural selection
C. Reproductive isolation
D. Allopatric speciation
4,2.2 Explain the results of the experiment
(2)
(4)
4.2.3 What would happen if, after 22 months, guppies from the transplanted population
were returned to the source pool?
(2)
4.3.
Three different types of rock A,B and C were dated, using radiometric dating of Uranium
235. U235 decays into Pb207
In rock A the ratio ofU235: Pb207 was 19:6
In rock B the ratio ofU235:Pb 207 was 13:2
4
Transplanted
population
In rock C the ratio
ofU235: Pb207 was 9:2
The half-life ofU235 is logarithmically plotted on the graph below. Use the graph to
determine the age of each of the rocks A, Band C. Show your calculations in each case.
Half -life of U-235
~~~~~~~=.
1~~~'
~===r===t==3E==t===E=~===t===l
-- -.. -_.....
60-J---;·,--+O;;::;::"d---+--i---t·.--~
40 f-,---"--4---+----+-~;;::.".,.d--_I__,-
-1---,,_.
--~, .--"'_
.. ---~-
30 1-.----;,.--+-...........j------+----tI'......I--~, -~"'''. ..--_.'--21J
..•••.••..
~
~-.--".
-=
eo:
'6iJ
..
I.
e
~
e
=
.
~
~
,
I~
~
3~--+--~~~-~--~~--+--+--+---1
2
(12)
/23/
Millions of years
QUESTION 5
5.l.
It is important to remember that the evolutionary history of humans is best reconstructed
as a bush where there were often several related species in existence at anyone time.
Nevertheless, a number of trends characterise human evolution.
These trends include:
5.1.1. Bipedalism
5.1.2. Trends in cranial capacity
5.1.3. Trends in general morphology of the skull
Describe the nature of these trends, and in each case describe the characteristics of the
ancestor hominid as well
(15)
5.2.
At the end of your backbone is a coccyx, a few small, fused-together bones. Is this human
coccyx a vestigial structure- all that is left of the tail of some distant vertebrate ancestors?
Or is it the start of some newly evolving structure? Explain your answer.
(4)
/19/
5
QUESTION 6
6.1.
Explain why scientists use mostly bacteria and most often, E. coli to clone DNA.
(4)
6.2.
Describe the process of gene cloning using bacteria.
(6)
6.3
Give two uses of gene cloning. Explain your answer
(6)
/16/
QUESTION 7 (Show your calculations for all questions)
7.1
A black goat crossed with an albino goat produced 12 black offspring. When the albino
was crossed with a second black one, 7 blacks and 5 albinos were obtained. What is the
best explanation for this genetic situation? Write genotypes for the parents, gametes and
offspring.
(8)
7.2
In cheetahs, a recessive allele causes an absence of dark patches in the fur making such
animals uniformly light brown. Another recessive allele on the same chromosome causes
pointed ears, instead of rounded ears .. If two phenotypically normal cheetahs that are
heterozygous at these loci are mated, what percentage of their offspring will have pointed
ears? What percentage of the pointed ear cheetahs will be uniformly brown ?(8)
7.3.
Colour patterns in a species of tern is determined by one gene with three alleles. Alleles
(M) and (U) are dominant and allele (i) is recessive to both. How many genotypes are
possible in a flock of terns that contains all the possible combinations of these three
alleles?
(3)
7.4.
In a certain strain of rice, a dominant allele K inhibits grain colour, while the recessive
allele (k) permits colour when homozygous. At a different locus, the dominant allele G,
causes green grain colour, while the homozygous recessive genotype gg causes brown
grain kernels. If plants heterozygous for both loci are crossed, what will the phenotypic
ratio of the offspring be?
(8)
7.5.
In a certain species of beetle, the long antennae condition (L) is dominant to the short
antennae condition (1), and the normal leg condition (D) is dominant to the hairy leg
condition (d). Antennae length and leg texture are inherited independently
Determine the genotypes for the two parents for all possible matings producing the
following offspring:
6
a) 318 long antennae, normal; 98 long antennae, hairy legs
b) 401 long antennae, normal
(4)
(2)
/33/
QUESTION 8
8.1.
Niven and Nyna each have a sibling with a rare blood disorder caused by a recessive
gene. Neither Nyna, Niven, nor any of their parents has the disease, and none of them
has been tested to reveal the trait. Based on this incomplete information, calculate the
probability that if this couple has a child, the child will have this blood disorder.
(8)
8.2.
Under what circumstances is it possible for both father and his son to be haemophiliacs?
(2)
8.3.
A woman has six fingers on each hand and six toes on each foot. Her husband and their
daughter have the normal number of digits. Extra digits is a dominant trait. What fraction
of this couple's children would be expected to have extra digits?
(5)
8.4.
Assume , in humans, that the difference in skin colour is due primarily to two pairs of
genes which segregate independently: BBCC is black, bbcc is white, any three of the
genes in black produce dark skin, any two medium skin, and anyone produces light skin
colour. Give the genotypes of parents who are:
a) Both medium, but have one black and one white child
b) Both medium and can have only medium children
c) Medium and light and have a large number of children: % medium, % light, Vs
dark and Vs white
(6)
/21/
TOTAL: 150
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