SCSA Biology Heredity
5 sample questions with marking guides and sample answers · Avg. score: 53.1%
Which of the following are broken as a normal part of DNA replication?
hydrogen bonds between complementary bases
nitrogen bonds between complementary bases
phosphodiester bonds between adjacent nucleotides
phosphate bonds between adjacent nucleotides
Muscular dystrophy in golden retriever dogs is caused by a mutation of the dystrophin gene. It is much more common in male golden retrievers than females. On this basis, what type of condition is muscular dystrophy in golden retrievers?
sex-linked dominant
sex-linked recessive
autosomal dominant
autosomal recessive
Proteins are present in all living organisms and are essential to cell structure and function.
Describe the roles of DNA, messenger RNA (mRNA) and transfer RNA (tRNA) in protein synthesis.
Life on earth is very old.
Describe four characteristics of the oldest known life forms and explain how the fossil record and comparative genomics have helped to determine the characteristics of early life forms.
The Montara oil spill, which occurred off the northwest coast of Western Australia in August 2009, is classed as one of the worse oil disasters in Australian waters. Oil spills are initially treated with detergents (to disperse the spill) and fire, but genetically-modified bacteria that can digest the oil are sometimes also used.
Describe how recombinant DNA technology is used to genetically modify bacteria to digest oil and discuss two advantages and two disadvantages of using a genetically-modified microorganism for environmental conservation.
Gene pools are dynamic, with changes in allele frequencies being caused by several factors, including mutation and genetic drift.
Describe how mutation and genetic drift change the frequency of alleles in a population and explain the significance of these changes.
Fleece colour in sheep is determined by the alleles at an autosomal gene, where a dominant
allele (T) gives white fleece, and a recessive allele (t) gives black fleece.
Two white sheep are mated. They produce offspring with white fleece and with black fleece.
Distinguish between a dominant and a recessive allele.
Distinguish between autosomal and sex-linked alleles.
Calculate the probability of these sheep producing an offspring with black fleece. Explain
your answer.
Spider lamb syndrome (SLS) is an inherited condition in sheep. Affected animals have
abnormal spines and long, often splayed (spread out) legs. SLS is caused by a recessive
SLS allele at an autosomal gene. Outline an approach that can be used to determine
whether an unaffected individual has the SLS allele without breeding the sheep.
Body size in sheep is a polygenic trait. Explain what a polygenic trait is.
A group of biologists want to produce a line of sheep with increased resistance to fleece
rot. They could do this either by artificial selection or by transgenesis. Outline one
advantage and one disadvantage of producing this line of sheep by artificial selection
rather than transgenesis.