Ethiopia Grade 12 Biology: Unit 3 Genetics Questions Answers

Ethiopia Grade 12 Biology: Unit 3 Genetics Questions Answers for Ethiopian University Entrance exam. This page contains multiple choice question answers.

Grade 12 Biology: Unit 3 Genetics

  1. Genetic crosses
  2. Molecular genetics
  3. Protein synthesis
  4. Mutations

Ethiopia Grade 12 Biology: Unit 3 Genetics Quiz

0%

Grade 12 Biology: Unit 3 Genetics

Grade 12 Biology: Unit 3 Genetics

1 / 10

In our cells, we have ____ number of chromosomes.

2 / 10

Which of the following type describes the trait or traits determined by a particular genotype?

3 / 10

Where do the chromosomes usually come in pairs called homologous pairs?

4 / 10

Where a large number of genes is stored?

5 / 10

_______the pair of alleles for a particular gene possessed by a organism.

6 / 10

Which of the following is the only physical link between the generations and must pass the genes from one generation to the next?

7 / 10

______ is a section of DNA that determines a specific feature.

8 / 10

Which of the following is a feature of an organism determined by its genes?

9 / 10

Which of the following is a version of a gene that determines a particular trait?

10 / 10

Which of the following allele expressed in a heterozygous organism?

Your score is

The average score is 55%

0%

Grade 12 Biology: Unit 3 Genetics Review Questions Answers

Q1. Two parents of genotype Aa are cross-bred. The alleles do not show codominance. What proportion of the offspring will look
like their parents?

  • A. none
  • B. ¾
  • C. ¼
  • D. ½

Q2. A woman with blood group A and a man with blood group B could potentially have offspring with which of the following blood groups?

  • A. A
  • B. B
  • C. O
  • D. all blood groups

Q3. In an organism of genotype Aa, half the gametes carry the A allele and half carry the a allele. This is due to:

  • A. dominance
  • B. recessiveness
  • C. independent assortment
  • D. segregation

Q4. The genotype of a homozygote could be:

  • A. AA
  • B. aa
  • C. Aa
  • D. XX

Q5. A plant has a genotype AaBb. There is no linkage of the genes. The gametes it will produce are:

  • A. AB and ab
  • B. Aa and Bb
  • C. AA, aa, BB and Bb
  • D. AB, Ab, aB and ab

Q6. A tall pea plant with purple flowers (both determined by dominant alleles) is crossed with a short plant with white flowers. There is no linkage of the genes. If the tall, purple-flowered plant is heterozygous for both traits, the offspring will be:

  • A. 1 purple tall:1 white short
  • B. 3 purple tall:1 white short
  • C. 9 purple tall:3 purple short:3 white tall:1 white short
  • D. 1 purple tall:1 purple short:1 white tall:1 white short

Q7. Cross-breeding results in:

  • A. an increase in heterozygosity
  • B. hybrid vigour
  • C. an increase in the number of dominant alleles
  • D. all of the above

Q8. Which of the following statements concerning multiple allele inheritance is not true?

  • A. A gene has more than two alleles.
  • B. An individual will have more than two alleles of the gene.
  • C. There are more than two alleles in the population.
  • D. The alleles may be dominant, recessive or codominant.

Q9. Which of the following is not true of sex limited traits?

  • A. They are determined by genes on the autosomes.
  • B. They are expressed in only one sex (male or female).
  • C. They are carried on the X chromosome.
  • D. They often result in sexual dimorphism (very different physical appearance in male and female animals).

Q10. It is characteristic of sex-linked traits that they:

  • A. occur more frequently in males than in females
  • B. rarely skip a generation
  • C. are always determined by genes found on the Y chromosome
  • D. none of the above

Q11. DNA consists of two polynucleotide strands in which:

  • A. the percentage of adenine is the same in each strand
  • B. the percentage of adenine is the same as that of thymine in each strand
  • C. the percentage of adenine is the same as that of thymine in the whole molecule
  • D. the percentage of adenine is 50% of that of thymine in the whole molecule

Q12. Ligase is an enzyme that:

  • A cuts DNA molecules, leaving sticky ends
  • B joins sticky ends of DNA fragments
  • C copies DNA fragments
  • D separates DNA fragments

Q13. A gene probe could be:

  • A. a short length of single-stranded DNA that has been made radioactive
  • B. a tRNA molecule that has been made radioactive
  • C. a short length of double-stranded DNA that has been made radioactive
  • D. all of the above

Q14. Viruses and plasmids are examples of:

  • A. vectors
  • B. transformed bacteria
  • C. restriction enzymes
  • D. liposomes

Q15. Which of the following statements about genetic fingerprinting is not accurate?

  • A. Genetic fingerprinting involves the analysis of the DNA to identify an individual.
  • B. Genetic fingerprinting can be used to identify criminals and also the real parents of a child when the identity is in doubt.
  • C. Only coding DNA is used to make a genetic fingerprint.
  • D. Genetic fingerprinting has become faster and more detailed over time.

Q16. In gel electrophoresis of DNA:

  • A. the DNA fragments migrate towards the positive electrode and are separated according to their molecular mass
  • B. the DNA fragments migrate towards the negative electrode and are separated according to their molecular mass
  • C. the DNA fragments migrate towards the negative electrode and are separated according to their electric charge
  • D. the DNA fragments migrate towards the positive electrode and are separated according to their electric charge

Q17. One advantage of genetic engineering over conventional selective breeding is that genetic engineering:

  • A. is quicker
  • B. has fewer side effects
  • C. cannot harm the environment
  • D. none of these

Q18. The best definition of a transgenic organism is:

  • A. a bacterium that contains genes from another organism
  • B. a plant that has been genetically modified
  • C. an animal that has been ‘pharmed’
  • D. any organism that has had a foreign gene added to its genome

Q18. tRNA differs from DNA because it is:

  • A. smaller, single stranded and shows no base pairing
  • B. smaller, single stranded with thymine replaced by uracil
  • C. smaller, single stranded and with deoxyribose instead of ribose
  • D. smaller, single stranded and linear in shape

Q19. The genetic code is:

  • A. a triplet code, degenerate and overlapping
  • B. a doublet code, degenerate and universal
  • C. a doublet code, degenerate and non-overlapping
  • D. a triplet code, degenerate and universal

Q20. The DNA triplet AAT would code for an amino acid carried by tRNA with the anticodon:

  • A. AAU
  • B. TTA
  • C. AAT
  • D. UUA

Q21. In a ribosome, when the two amino acids that are held adjacent to each other form a peptide bond, the tRNA molecules are in
the:

  • A. A and P sites
  • B. A and E sites
  • C. E and P sites
  • D. none of the above

Q22. Post-transcriptional modification of mRNA is carried out in order to:

  • A. remove exons
  • B. remove introns
  • C. alter its shape so that it can bind with a ribosome
  • D. alter its shape so that it can bind with an amino acid

Q23. Which of the following statements about transcription factors is correct?

  • A. They are always produced within cells.
  • B. They bind with promoter sequences of DNA next to the gene.
  • C. They are the same in all cells.
  • D. All of the above.

Q24. Gene silencing by siRNA is referred to as a form of posttranscriptional repression because:

  • A. it stops transcription of genes by RNA polymerase
  • B. it only allows certain genes to be expressed
  • C. it destroys the mRNA formed by transcription of a gene
  • D. none of the above

Q25. Essential amino acids:

  • A. must be taken in as part of our diet
  • B. cannot be synthesised by transamination
  • C. are found in large amounts in quinoa, meat and buckwheat
  • D. all of the above

Q26. When comparing protein synthesis in eukaryotic cells and prokaryotic cells it is correct to say that transcription and translation are:

  • A. separate in both
  • B. coupled in both
  • C. separate in prokaryotes and coupled in eukaryotes
  • D. separate in eukaryotes and coupled in prokaryotes

Q27. Which of the following statements about transcription is correct?

  • A. RNA polymerase assembles DNA nucleotides into a single strand.
  • B. RNA polymerase assembles DNA nucleotides into a double strand.
  • C. RNA polymerase assembles RNA nucleotides into a double strand.
  • D. RNA polymerase assembles RNA nucleotides into a single strand.

Q28. Which of the following is an example of a chromosomal mutation:

  • A. a base duplication
  • B. a base insertion
  • C. a translocation
  • D. none of these

Q29. Which of the following is a frameshift mutation?

  • A. point replacement
  • B. Inversion
  • C. Insertion
  • D. substitution

Q30. The only source of new genetic material during evolution is:

  • A. crossing over
  • B. segregation
  • C. random assortment
  • D. mutation

Q31. The increase in bacterial resistance to penicillin is due to:

  • A. mutation
  • B. natural selection
  • C. the increased use of penicillin
  • D. a combination of all the above

Q32. If a substitution occurs in the DNA of an organism, which of the following will also occur?

  • A. The mRNA will also be altered.
  • B. All the triplets after the mutation will be altered.
  • C. All the triplets before the mutation will be altered.
  • D. A frameshift will occur.