Biology 11 - Unit 1 Questions

Explain the benefit of classification systems.

Classification systems create clear universal communication and discussion about biological creatures. Classification systems also create biological meaning with the use of taxa for biological creatures, meaning that each group of animals will have something common or similar, whether it be distant or recent characteristics.

Describe two characteristics of a good classification system.

A good classification system creates universally accepted names.

A good classification system has biological meaning behind the groups. For example, grouping organisms that have similar characteristics.

List the two rules of binomial nomenclature that allow people to recognize the scientific names of various species.

The genus (capitalized) name of the animal is listed first, followed by the species (lowercased). On typed-out work, the scientific name for an animal is italicized. On handwritten work, the name is underlined with a single line.

Describe two problems associated with the naming systems that existed before Linnaeus’ time.

Biological names were created by describing the physical characteristics of the organism with the use of Latin or Greek words that were supposedly known among many scientists. The two problems were that the names would get too long and that scientists and botanists would often choose to describe different characteristics of the same organism, defeating the purpose of universal agreement.

Name Linnaeus’ seven taxa and describe the relationships between them.

The seven taxa defined by Linnaeus are: Kingdom, Phylum, Class, Order, Family, Genus, and Species. These seven taxa represent a hierarchal classification system, with each subsequent taxon representing a more specific grouping of organisms, where Kingdom is the broadest taxa and species is the most specific.

Explain how taxonomists use homologous and analogous structures found in adult anatomy, embryos, and fossils to group organisms according to evolutionary relationships.

According to the evolutionary theory, species today have all evolved from earlier organisms. With that theory in mind, organisms with homologous structures are grouped together because they show the evolution of a common ancestor. However, with analogous structures, structures that serve the same purpose but are structurally developed differently, do not share the same common ancestor, and therefore, are not grouped together.

Explain how taxonomists use biochemicals, such as DNA and the protein molecule cytochrome c, to reveal evolutionary relationships among organisms.

Using the evolutionary theory, organisms and their DNA will be similar to the DNA of their ancestors. Using this information, we can say that different organisms may have similar genes, leading to similar phenotypes or genotypes. 

Cytochrome c differs slightly in each organism. These differences were developed through mutations that occurred after a common ancestor diverged into different organisms. More recent mutations will mean their cytochrome c will differ less. But if two species diverged way earlier, there would have been more time for the two different organisms to fully mutate, making their cytochrome c differ more. Scientists can compare DNA and RNA nucleotide sequences or amino acid sequences to find out how recent the ancestor is or find out how far back the divergence of an organism happened.

Explain two reasons why Linnaeus’ original two-kingdom system is now a five-kingdom system.

Carolus Linnaeus’ two-kingdom system was not sufficient because there were many other organisms, specifically microorganisms, that were only discovered after the invention of microscopes. These microorganisms have been proven to be very different from most animals and plants, therefore putting them into a separate kingdom: Monera. It is also true that unicellular eukaryotes behave differently compared to multicellular eukaryotes, thus putting them into a separate kingdom: protista. It is also true that moulds and yeasts are proven to be different from plants, thus putting them into a separate kingdom: Fungi.