Download 6.4 Mechanisms of inheritance – Further questions and answers Q1

6.4 Mechanisms of inheritance – Further questions and answers
Q1.
Bk Ch6 S6.4 FQ1
Describe the evidence gathered by Watson and Crick that pointed to the complementarity of the
nucleotide bases adenine, guanine, cytosine and thymine.
A1.
Bk Ch6 S6.4 FA1
Watson and Crick observed that the same amount of the nucleotide bases adenine and thymine
occurred in DNA and that the same pattern occurred for cytosine and guanine. They also established
that the DNA molecule is constructed of two DNA strands twisted together to form a double helix.
From this information they hypothesised that the bases adenine and thymine always occurred together,
or were complementary to one another and that the same applied for cytosine and guanine.
Q2.
Bk Ch6 S6.4 FQ2
Use a flow chart to model the process through which the DNA of cells controls the manufacture of
cellular proteins.
A2.
Bk Ch6 S6.4 FA2
1.
2.
3.
4.
5.
6.
7.
8.
DNA contains genes.
Each gene codes for a particular protein.
Genes contain the nucleotide bases that code for the amino acids of which proteins are
constructed.
A nucleotide triplet of bases is called a codon.
Each codon is transcribed onto an mRNA strand in the nucleus.
The mRNA strand moves into the cytoplasm and becomes attached to a ribosome.
At the ribosome tRNA reads the codons on the mRNA and the corresponding anticodon delivers
a particular amino acid.
As amino acids continue to be delivered they become linked to form a polypeptide.
Q3.
Bk Ch6 S6.4 FQ3
Draw a concept map demonstrating your understanding of the factors involved in the process of
evolution. Include sources of variation, natural selection, isolating mechanisms and genetic drift.
A3.
Bk Ch6 S6.4 FA3
6.4 Mechanism of inheritance FQA
Copyright
© Pearson Australia (a division of Pearson Australia Group Pty Ltd)
page 1 of 3
Example concept map:
Q4.
Bk Ch6 S6.4 FQ4
Outline the potential impact on the evolution of living organisms from mutagens released into the
environment by human activity.
A4.
Bk Ch6 S6.4 FA4
Mutagens could potentially cause mutations, which could initially lead to an increase in variation in
species. Some mutations could be favourable but many would reduce the ability to survive and
reproduce, eventually reducing the variation within species.
Q5.
Bk Ch6 S6.4 5
Outline research that led to the development of the ‘one gene, one polypeptide’ hypothesis.
A5.
Bk Ch6 S6.4 FA5
The ‘one gene, one polypeptide’ hypothesis was suggested by Beadle and Tatum following
experiments in which they observed that changes in only one protein altered the phenotype of an
organism. They were able to establish a link between different genes and the proteins they coded for. In
6.4 Mechanism of inheritance FQA
Copyright
© Pearson Australia (a division of Pearson Australia Group Pty Ltd)
page 2 of 3
experiments on bread mould they showed that a series of genetic mutations were co-incidental with
particular positions on the chromosomes of the mould. From this they concluded that each site or gene
was responsible for coding a particular protein, in this case an enzyme. That is, one gene, one
polypeptide.
6.4 Mechanism of inheritance FQA
Copyright
© Pearson Australia (a division of Pearson Australia Group Pty Ltd)
page 3 of 3