Classification

Describe what is meant by the biological species concept.

Feb/March 2022

Around $2 \times 10^9$ people worldwide are presently infected with the bacterial disease tuberculosis (TB), which is caused by Mycobacterium tuberculosis. Early diagnosis matters because treatment can then start without delay. APOPO is a non-profit organisation that has trained African giant pouched rats, Cricetomys gambianus, to use their sense of smell to find M. tuberculosis. They do this by sniffing a sample of thick mucus from the lungs of people who may have TB. The African giant pouched rats can detect the presence of M. tuberculosis with an accuracy of 87-93%. Fig. 8.1 shows an African giant pouched rat.

Feb/March 2024

Section B. Select one question and respond to it.

May/June 2013

Section B: Answer just one question.

May/June 2014

Most organisms are grouped using a taxonomic hierarchy. Fig. 8.1 shows the hierarchy, but the group names are out of sequence. Complete Table 8.1 by placing the numbers in the correct sequence.

May/June 2020

In 2014, scientists released a phylogenetic (evolutionary) tree diagram that showed how different insect groups arose from ancestral groups and when this happened. To make the diagram, the scientists compared nucleotide and amino acid sequence data from 1478 genes in each of 103 insect species. These 103 species included all 32 orders of the class Insecta. The data were then used to place the species into related groups according to how similar their molecular sequences were, and to follow sequence changes through time.

May/June 2021

Fruit flies in the genus \emph{Bactrocera} are pests that harm fruit crops. Table 3.1 shows the names and geographic distributions of \emph{Bactrocera} fruit flies that had been treated as four different species. In 2014, this classification was revised. All four species were then accepted as a single species, \emph{B. dorsalis}.

May/June 2021

Mantella aurantiaca, the golden mantella, is a small frog that lives on land in Madagascar. Fig. 1.1 shows a golden mantella.

May/June 2022

The moose, Alces alces, is a large deer-family species. It occurs in temperate forests in North America and northern Europe, where snow lies on the ground for much of the year. Fig. 10.1 shows an adult male moose feeding in a lake. The moose feeds on a plant in the lake called watermilfoil, Myriophyllum aquaticum. The moose and the watermilfoil are in the domain Eukarya, which contains the kingdoms Animalia and Plantae.

May/June 2023

A species is placed in one of three domains.

May/June 2025

Living things are grouped into three domains. Eukarya is then split into four kingdoms.

May/June 2025

In California, USA, Ensatina eschscholtzii is a salamander species that inhabits woodland ecosystems. Fig. 6.1 depicts an ensatina salamander.

May/June 2025

Describe the principal features of an organism in the plant kingdom.

Oct/Nov 2013

Lichens occur on trees, walls, rocks and soil. Fig. 9.1 shows a lichen belonging to the genus Usnea. Usnea withstands only low concentrations of sulfur dioxide and cannot grow where the air is polluted with sulfur dioxide. Usnea is made up of a mixture of two cell types: photosynthetic cells, which are placed in the kingdom Protoctista, and fungal cells, which are placed in the kingdom Fungi.

Oct/Nov 2024

Lichens grow on trees, walls, rocks and soil. Fig. 9.1 shows a lichen from the genus Usnea. Usnea can withstand only low concentrations of sulfur dioxide and will not grow where the air contains sulfur dioxide pollution. Usnea consists of a mixture of two cell types: • photosynthetic cells that belong to the kingdom Protoctista • fungal cells that belong to the kingdom Fungi.

Oct/Nov 2024

Exserohilum turcicum is a fungal pathogen. As its mycelium expands, it harms the leaves of maize plants, Zea mays. Damage to the leaves lowers crop yield.

Oct/Nov 2025

Exserohilum turcicum is a fungal pathogen. As the fungus grows, its mycelium harms the leaves of maize plants, Zea mays. This leaf injury lowers crop yield.

Oct/Nov 2025

The kakapo, Strigops habroptila, is a large parrot that is nocturnal, meaning it is active at night, and it occurs only in New Zealand. This bird cannot fly and lives on the ground. On the IUCN Red List of Threatened Species™, the kakapo is classified as critically endangered. Fig. 7.1 shows a kakapo.

Oct/Nov 2025