The base sequence of a different section of mitochondrial DNA (mtDNA) were analysed to determine the differences between giant panda and red panda DNA. In total, there were eight differences between the mtDNA of the two species.
Mitochondrial DNA is estimated to mutate at a rate of 1.87 x 10-7 mutations site-1 year-1. Use the information given to calculate how long ago the giant panda and the red panda evolved from a common ancestor. Show your working and round your answer to three significant figures.
Cetaceans is an order of carnivorous aquatic mammals which include dolphins, whales and porpoises. The following diagram shows two proposals that have been put forward regarding the closest living relative of the cetaceans, represented by diagrams R and S.
Compare and contrast the information in diagrams R and S.
Casein is a protein found in the milk of most mammals. Scientists investigated the differences in the DNA base sequence of the gene coding for casein in the mammals shown in diagrams R and S. The following table shows their results.
Scientists concluded that diagram S best represents the currently accepted theory regarding the evolutionary origin of cetacean.
Based on the information provided, evaluate this conclusion.
More recently, scientists decided to merge the order Cetacea and Artiodactyla into a single order called Cetartiodactyla based on new sequencing results.
Explain the importance of classifying organisms correctly according to their clade.
Based on the information provided in part a), deduce four other taxonomic groupings/levels of classification that would be similar for dolphins and whales.
DNA hybridisation is a technique used to determine the genetic similarity between species. The double stranded DNA of two different species is mixed and then heated until the strands separate. This provides an opportunity for hybridisation between the different DNA strands to occur. The mixture is then cooled in order to allow new hybrid double stranded DNA molecules to form. The greater the degree of hybridisation, the more genetically similar the two species are.
Scientists investigated the genetic similarity between four species of bacteria (A to D) by allowing their DNA to hybridise with each other. The results of this investigation are shown in the table below.
i)
Identify the species of bacteria that is most closely related to the other bacterial species.
The group of scientists also investigated the similarity of the protein molecules that make up peptidoglycan in the cell walls of the bacterial species. The amino acid sequence of species A was compared to those of species B to D.
The results are shown in the table below:
Bacterial species
Percentage similarity
A
100
B
99.4
C
98.7
D
97.8
Based on the information provided and your knowledge of protein synthesis, explain the reason why the bacterial species show such a high level of similarity between the protein molecules, even though there are differences in their DNA.
The following diagram shows a cladogram that indicates the evolutionary relationship of plants. Note that different taxonomic groups are represented in the cladogram.
Identify the plant phyla which are the most closely related.
Bryophyta are found in a variety of environments and are typically very small in size. Filicinophyta are able to grow to much larger sizes than Bryophyta.
Using your knowledge of plant phyla characteristics, explain the difference in size between Bryophyta and Filicinophyta.
