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Bota 111:General Genetics Question Paper
Bota 111:General Genetics
Course:Bachelor Of Science In Animal Production
Institution: Chuka University question papers
Exam Year:2011
INSTRUCTIONS:
Answer ALL questions in Sections A & B, and ANY TWO in Section C.
SECTION A (30 MARKS)
1. If an organism has a segment of one or more chromosomes duplicated, then a part of its genome is said to be
(a) dipliploid (b) hyperploid (c) euploid (d) autoploid [½ mark]
2. In domestic chicken, mating an individual bearing the “Rose” comb with another bearing the “Pea” comb shape produces F1 progeny bearing walnut combs. A cross between two walnuts produces individuals bearing the comb shapes “Pea”, “Rose”, walnut and single. This type of gene interaction is known as
(a) nonallelism (b) atavism (c) epistasis (d) concealment [½ mark]
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3. Anticodons are associated with
(a) tRNA (b) rRNA (c) mRNA (d) most RNAs [½ mark]
4. Which is the correct karyotype for the cri-du-chats syndrome?
(a) 46 (5p-) (b) 45 (5q-) (c) 45 (5p-) (d) 47, (X+ 5p) [½ mark]
5. A man and a woman are heterozygous for a certain gene. If they marry and plan to have three (3) children, what is the probability that all three children will be heterozygous for that gene?
(a) ¼ (b) 4 3 (c) 8 1 (d) 16 1 [½ mark]
6. Which of these is not found in animal cells?
(a) lysosome (b) ribosome (c) nucleoplasm (d) dictyosome [½ mark]
7. A monohybrid
(a) has one set of chromosomes and alleles (b) is heterozygous for one pair of alleles (c) is homozygous for one pair of alleles (d) is result of a self-fertilized individual [½ mark]
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8. Which of the following statements is not true about lethal genes?
(a) If the lethal gene is dominant and immediate in expression, all individuals carrying the gene will die.
(b) The presence of a lethal gene will hinder fertilization.
(c) Some lethal genes have a delayed effect so that the organism lives for a time.
(d) Lethal genes are altered genes or mutations [½mark]
9. The process of protein synthesis takes place in the
(a) lysosome (b) smooth ER (c) ribosome (d) nucleolus [½ mark]
10. The process of karyotyping is one in which
(a) locations of genes on the chromosomes are determined. (b) chromosome pictures are spread, cut and aligned according to homologous pairs. (c) DNA is removed from the chromosomes and analyzed. (d) chromosomes are labeled with isotopes for analysis. [½ mark]
11. Sickle-cell anemia is due to a mutation that leads to
(a) substitution of a base-pair (b) a delition of one or more base-pairs (c) a duplication of one or more base-pairs (d) a trisomy involving one of the chromosomes. [½ mark]
12. Among animals, plants and microorganisms, meiosis does not occur in
(a) somatic cells (b) spores (c) zygotes (d) all the above [½ mark]
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13. In certain sheep, the following phenotypes are common in animals whose genotypes are as follows:
Genotype Male Female
h+h+ horned horned h+h horned hornless hh hornless hornless [½ mark]
The allele of the gene involved here is said to
(a) have sex expression and variation (b) be sex-limited (c) have sex-influenced dominance (d) have male dominant influence [½ mark]
14. The following are all genetic diseases except
(a) cancers (b) rickets (c) hemophilia (d) Huntington disease [½ mark]
15. The DNA of one species differs from that of another species in its
(a) hydrogen bonds (b) phosphate group (c) pentose sugar (d) base sequence [½ mark]
16. Which of the following is considered the replication enzyme?
(a) the endonucleases (b) polymerase I (c) polymerase II (d) polynucleotide ligase [½ mark]
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17 If a husband and wife of normal skin colour, and who have two sons of normal skin colour, have their third baby who is albino, the best explanation for this is that
(a) the wife and not the husband must be a heterozygote (b) the husband and not the wife must be a homozygote (c) the husband and the wife must be both heterozygotes (d) there must have occurred a new mutation in one of them. [½ mark]
18. If 50% of the progeny resulting from a testcross of an organism are found to show the recessive trait, then the organism in question is (a) homozygous recessive (b) homozygous dominant (c) a mutant (d) heterozygous [½ mark]
19. The two pyrimidine bases present in DNA are
(a) adenine and guanine (b) cystosine and thymine (c) adenine and thymine (d) cystosine and guanine [½ mark]
20. Certain genes, when present will not allow the expression of other genes, and thus alter phenotypic ratios. Such genes are termed
(a) modifier genes (b) hypostatic genes (c) epistatic genes (d) linked genes [½ mark]
21. The normal segment of a certain organism chromosome is 123.456789, where the dot (.) represents the centromere. Chromosomes were observed in that organism that had the following structures:
(a) 123.476589 (b) 123.46789 (c) 1654.2789 (d) 123.4566789
In each case, give the name of arrangement. [5 marks]
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22. Upon completion of your course, you are called upon to assist in a dispensary where blood transfusion is in progress. Blood matching must be done accurately before transfusion. Use your knowledge to match donor blood to potential recipients. Let the matching, i.e. nonagglutination be represented by a tick (v) and where there is no matching, i.e. agglutination by a cross (X) in the table below.
DONOR BLOOD
RECIPIENT
A B AB O A B AB O
[5 marks]
23. Outline the factors that can cause changes in genes and genotype frequencies in a population that is at the Hardy-Weinberg equilibrium. [5 marks]
24. Define the following terms:
(a) allele [1 mark] (b) genotype [1 mark] (c) single-factor cross [1 mark] (d) atavism [1 mark] (e) aneuploidy [1 mark]
SECTION B (40 MARKS)
25. If you were to make crosses using Pisum sativum and in one of your dihybrid crosses obtained the following F2 counts:
Plant with round seeds, yellow flowers = 608 “ “ wrinkled seeds, yellow flowers = 202 “ “ round seeds, green flowers = 210 “ “ wrinkled seeds, green flowers = 64
Using the appropriate statistical test, accept or reject the hypothesis that your results fit the 9:3:3:1 phenotypic ratio. [20 marks]
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26. Explain the structure of DNA and RNA with respect to their chemical subunits. [20 marks]
27. Write notes on:
(i) Turner syndrome (ii) Down syndrome (iii) Klinefelter syndrome (iv) cri-du-chats syndrome [20 marks]
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