Classification

The image shows an organism called Euglena gracilis.

Which kingdom does Euglena belong to?

A Animalia

B Plantae

C Prokaryotae

D Protoctista

Bioinformatics, computational biology and synthetic biology are relatively new techniques in biology that have a variety of uses.

This is a preserved thylacine, Thylacinus cynocephalus, a large Australian carnivore that became extinct in 1936.

Many preserved thylacine specimens in museums contain DNA. Scientists have used DNA sequencing, bioinformatics and computational biology to reconstruct the genome of the thylacine. Some scientists hope to be able to use bioinformatics and synthetic biology to produce a living thylacine in the future.

Much of the thylacine DNA present in the museum specimens has broken down. In order to assemble an entire thylacine genome, it is necessary to supplement the thylacine DNA with DNA from a living close relative of the thylacine.

The thylacine belonged to the order Dasyuromorphia. The table shows the classification of the thylacine and some living species of the order Dasyuromorphia.

Name the classification taxon represented by the column headed A.

Using the information in the table, describe the evolutionary and genetic relationships between the species that are listed.

Explain why it is difficult to decide which of the other species would be the most appropriate to use as a source of DNA for constructing a thylacine genome.

All the species in the table belong to the animal kingdom.

Other than the presence or absence of vacuoles, state two features of the cells of these multicellular organisms that would mean they could be classified only in the animal kingdom.

Synthetic biology involves re-designing organisms for useful purposes. One such purpose could be the production of useful proteins.

Proteins can be produced by traditional genetic engineering but the range of proteins available is limited to those that are already produced by a living organism.

Bioinformatics and computational biology can be used in the production of new proteins that are not found anywhere in nature.

* Explain how gene sequencing, bioinformatics and computational biology are used in the production of useful proteins in synthetic biology.

Extra answer space if required.

Suggest why some people might be concerned about the increase of synthetic biology.

The thylacine finally became extinct in 1936 as a result of hunting by humans. However, its population had been in decline for many years before.

Some scientists have concluded that the thylacine was particularly vulnerable to extinction because of low genetic diversity within the species.

The table shows the proportion of heterozygous loci in a range of Australian mammal species together with information about how endangered they are.

Describe the evidence in the table that supports the conclusion that low genetic diversity contributed to the extinction of the thylacine.

Identify one piece of evidence that does not support the conclusion that low genetic diversity contributed to the extinction of the thylacine.

Organisms are named using the binomial system.

What is the correct way to represent the binomial name for domestic dogs?

A Canis familiaris

B Canis familiaris

C canis familiaris

D canis familiaris

Organisms are classified into three domains: Archaea, Bacteria and Eukarya.

Scientists have compared the structures of molecules, such as DNA polymerase and helicase, and organelles in the three domains.

The table shows a comparison of some features of the three domains.

Explain what conclusions can be drawn from the table about which two domains are most closely related.

State the roles of DNA polymerase and helicase in cells.

Evolutionary relationships can be determined by comparing certain biological molecules between species.

Which option is commonly used to determine evolutionary relationships?

A The amino acid sequence of collagen

B The amino acid sequence of messenger RNA

C The base sequence of cytochrome c

D The base sequence of ribosomal RNA

Your answer

Accurate analysis of an ecosystem’s biodiversity requires a detailed classification of organisms.

The spruce pine plant is given the binomial name Pinus glabra.

Place a tick (✓) in the box next to the species most closely related to Pinus glabra.

Explain why Pinus glabra and humans, Homo sapiens, are classified in the same domain but in different kingdoms.

A scientist sampled the species of trees present in two different habitats containing Pinus glabra.

The results of the sampling are shown in Table 5.

Using Simpson’s Index of Diversity, the scientist calculated the biodiversity (D) of Habitat A as 0.71.

Use the formula given to calculate the biodiversity of Habitat B.

Show your working.

State which habitat, A or B, has the greater biodiversity.

D ( Habitat A ) = 0.71

Habitat B was situated beside a lake and showed evidence of ecological succession.

The scientist planned to investigate how the biodiversity changed from the edge of the lake to the other side of habitat B.

State the collective name of the animal and plant populations that are present at the end of primary succession.

Suggest how the scientist could achieve the following during their investigation:

Sample all stages of succession in the habitat........

Minimise sampling bias........

Sample insect biodiversity........

The scientist also measured primary production in both the woodland and lake habitats.

Suggest the units the scientist should use to measure primary production in the two habitats.

The image below shows a European badger, Meles meles, which is a member of the family Mustelidae.

The American badger belongs to a different genus within the same family.

Which of the options, A to D, is the correct binomial name for the American badger?

A Meles leucurus

B mellivora capensis

C mustelidus Everetti

D Taxidea taxus

Your answer

Humans and chimpanzees are currently classified within the same family.

Chimpanzees were once classified separately from humans in the Family Pongidae along with gorillas and orang utans.

Fig. 19.2 shows a human hand and a chimpanzee hand.

Describe two differences between the two images that could have been used to classify humans and chimpanzees in separate families.

Differences between the nucleotide base sequences can be used to estimate the length of time since two species diverged from one another.

The greater the number of differences, the greater the length of time that has elapsed since the two organisms were part of the same species.

Fig. 19.3 shows the line of best fit for the differences in DNA between pairs of primate species plotted against the number of years since the two species diverged from a common ancestor.

Calculate the rate of DNA change using the data in Fig. 19.3.

Give your answer to three significant figures.

........ % per million years

The mutation rate in mammals can vary by as much as 20% between species.

Use Fig. 19.3 to calculate the time since the phylogeny of humans diverged from chimpanzees, and the range over which this estimate may vary.

* Some scientists have suggested that humans and chimpanzees should be reclassified as belonging to the same genus.

Evaluate their suggestion using evidence from Figs. 19.1 to 19.3 and your own knowledge of the scientific basis for the classification of organisms.

One type of gene is known as a homeobox gene.

The base sequences of homeobox genes in humans and chimpanzees are almost identical.

What conclusions about the evolutionary relationship between humans and chimpanzees can be drawn from this piece of evidence?