.."" ,,4. 1. UNIVERSITY KWAZUlU~NATAl BACHELOR OF EDUCATION EXAMINATIONS - JUNE Code EDBS410 E 1. Marks External Examiner 4:,.

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1 .."",,4. 1. UNIVERSITY OF KWAZUlUNATAl SCHOOL OF SCIENCE, MATHEMATICS & TECHNOLOGY EDUCATION (Edgewood Campus) BACHELOR OF EDUCATION EXAMINATIONS - JUNE 2011 Module Title Duration Internal Examiner Biological Science for Educators Hours Dr. M. Stears Code EDBS410 E 1 Marks External Examiner 150 Ms M Doidge Write legibly Answer all questions This paper consists of'1 pages QUESTION The diagram depicts Hershey and Chase's experiment. virus particle.\ I,i labeled with 35S J;i a l. '" 4:,... "'... I'. " (_':!-) --( =) --C,) virus particle ----, \ labeled with 32p i,. li 4:, \--)-L )-c. ) b

2 ' What were these scientists trying to find out? (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 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 indicating 5' and 3' ends of each. How do the two sequences differ? sequence, (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 C A, G i,phenylalanine serine tyrosine cysteine -; U (, phenylalanine serine tyrosine cysteine,c U leucine serine STOP STOP A leucine ' serine STOP tryptophan G leucine proline histidine ar.9inine U C leucine proline histidine arginine " C,, leucine proline glutamine arginine A r leucine proline glutamine arginine G isoleucine threonine asparagine serine U A G - isoleucine threonine asparagine serine C isoleucine threonine lysine arginine A i i methionine (or START) threonine lysine arginine G I valine alanine aspartate glycine "U I valine alanine aspartate glycine C valine alanine glutamate glycine A valine alanine glutamate glycine G - /14/ 2

3 /14/ QUESTION 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 the cell cycle has X amount of DNA. How much DNA would you expect at the following stages? 3.3.l. At the end of the 'S' interval? Explain your answer. (2) If the cell undergoes meiosis,at the end of Telephase II in each cell? Explain your answer. (2) /11/ QUESTION 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

4 Predator: Killifish; preys mainly -;)...'.'". on juvenile guppies (which do _ not express the color genes) </ Guppies: Adult males have brighter colors than those in"pike-cichlid pools"! POOI;h killifish, I but no guppies prior to transplant EXPERIMENT,. J h E dl f h U. f C lif ".' '. 0 n n er,o t e ruversrty 0 a 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 22 h (. - '-',.=""',,', er mont s 15 generations), the number and total area of colored spots on male guppies in the transplanted had increased compared to those of males in the source, 12 '" IL-._.,.,...- Predator: Pike-cichlid; preys mainly on adult guppies. Guppies: Adult males are more drab in color I than those in "killifish pools" I Source Transplanted E 6 0 Zo 4 v 2 o Source Transplanted 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 (2) 4,2.2 Explain the results of the experiment (4) What would happen if, after 22 months, guppies from the transplanted were returned to the source pool? (2) 4.3. Three different types of rock A,B and C were dated, using radiometric 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 dating of Uranium 4

5 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. 1'=. Half -life of U-235 ===r===t==3e==t===e====t===l 60-J---;,--+O;;::;::"d---+--i---t _ ,,_. 40 f-,---" ;;::.".,.d--_i,- --,.--"'_ ;, j tI'...I--, -"'''...--_.' ". 21J..... '6iJ =.. -eo: I. e e =. -, I QUESTION 5 5.l. Millions of years 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: Bipedalism Trends in cranial capacity 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) /23/ (12) /19/ 5

6 QUESTION 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. 6.3 Give two uses of gene cloning. Explain your answer /16/ (6) (6) 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

7 a) 318 long antennae, normal; 98 long antennae, hairy legs b) 401 long antennae, normal (4) (2) /33/ QUESTION 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 7