1. What biological molecules are most useful to investigate genetic diversity between species ?
Answer
DNA, mRNA and proteins.
2. Explain why is it practically easier for scientists to isolate mRNA for a given gene from a cell than from DNA.
Answer
mRNA is located in the cytoplasm of the cell, so easier to access.
3. Scientists select areas at random to sample organisms when carrying out a diversity investigation. Why is it important to select areas to sample at random ?
Answer
To remove bias.
4. Give the evolutionary relationship between the horse, chicken and shark.
Answer
The horse is most closely related to the chicken. It is least closely related to the shark. The horse has the most similar amino acid sequence to the chicken.
5. The table below shows the comparison of base sequence of a section of mitochondrial DNA in five different species. Draw a phylogenetic tree based on this information.
Answer
6. Explain why biological molecules are useful in investigating genetic diversity.
Answer
Biological molecules are useful in investigating genetic diversity because the DNA code is universal. Examining DNA and the proteins it encodes provides a reliable way to measure evolutionary changes, since proteins are directly determined by DNA sequences.
7. All species of anole lizards that inhabit these three habitats are found on all the islands of the Caribbean, including Cuba, Jamaica, Hispaniola and Puerto Rico. At one time the islands were interlinked by land. Scientists have offered two different explanations about how these species have evolved:
Explanation 1: Each group of Anoles evolved before the separation of the islands took place. After this evolution took place, they migrated to different islands and then the islands separated.
Explanation 2: The islands separated before any evolution of the lizards took place. The lizards then evolved independently on each island to inhabit the different niches.
In order to investigate which of these hypotheses was correct, scientists compared the DNA sequences from a large number of species of anoles from the different Caribbean anoles. From this, they drew a phylogenetic tree.
The table below shows which island each species inhabits.
Using this information to explain which of the two hypotheses is most likely to be correct.
Answer
They each evolved on separate islands because those with a more recent common ancestor, and therefore more closely related, inhabit the same islands. For example, at least two anoles from the same island are A. ophiolepis and A. sagrei.
8. When scientists collect quantitative data in diversity investigations, they calculate means and standard deviations. Standard deviation provides a more reliable way of comparing variation in populations than range. Explain why.
Answer
Standard deviation shows the spread of data around the mean. It can be used to observe whether there is an overlap between standard deviations, which indicates whether there is a significant difference between the means. Means can be distorted by outliers if one value is extreme.