Module 6 Organism Classification and the Linnaean System

According to the study guide, why do scientists classify organisms? Choose the best reason that captures the overall purpose described.

• To give every organism a unique common name

• To organize diversity, group by shared traits, and study relationships using evidence

• To eliminate the need for scientists to communicate with one another

• To prove that all organisms are unrelated

Answer explanation

Scientists classify organisms to organize the vast diversity of life, group them by shared traits, and study their relationships using evidence. This approach enhances understanding of biological connections.

Tags

NGSS.MS-LS4-2

NGSS.MS-LS4-4

Which sequence correctly shows the taxonomic hierarchy in the Linnaean system from broadest to most specific, as stated in the guide?

• Kingdom → Domain → Phylum → Class → Order → Family → Genus → Species

• Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species

• Phylum → Class → Order → Family → Genus → Species → Domain → Kingdom

• Domain → Phylum → Kingdom → Class → Order → Family → Genus → Species

Answer explanation

The correct sequence in the Linnaean taxonomic hierarchy is Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species, starting from the broadest category to the most specific.

The modern classification system combines Linnaeus’s hierarchy with the concept of three domains. Which list correctly names these domains?

• Bacteria, Protista, Animalia

• Bacteria, Archaea, Eukarya

• Archaea, Plantae, Fungi

• Eukarya, Animalia, Monera

Answer explanation

The correct domains in the modern classification system are Bacteria, Archaea, and Eukarya. These domains represent the three major branches of life, distinguishing between prokaryotic and eukaryotic organisms.

A scientist is deciding whether a newly discovered microorganism belongs in Bacteria or Archaea. Based on the guide, which type of evidence would be most appropriate to use?

• Color of the organism under visible light

• Genetic evidence and cell type characteristics

• How fast the organism moves in water

• The number of organisms living in the same habitat

Answer explanation

The most appropriate evidence to classify the microorganism is genetic evidence and cell type characteristics, as these provide definitive insights into its classification within Bacteria or Archaea, unlike the other options.

Which statement best explains how evolution relates to classification in the guide’s description?

• Classification ignores evolution because traits never change

• Classification is based on the idea that life forms share traits due to evolution and evidence

• Evolution only affects species names, not groupings

• Evolution is mentioned as a historical idea but does not influence modern classification

Answer explanation

The correct choice highlights that classification is rooted in the concept of shared traits among life forms, which arise from evolutionary processes and evidence, emphasizing the connection between evolution and classification.

Tags

NGSS.MS-LS4-2

Use the stated hierarchy to reason about group membership. If two organisms are in the same Family but different Genus, what else must be true according to the Linnaean sequence?

• They must also be in the same Species and Order

• They share the same Domain, Kingdom, Phylum, Class, and Order

• They are in different Kingdoms but the same Class

• They must have identical genetic sequences

Answer explanation

If two organisms are in the same Family but different Genus, they must share the same Domain, Kingdom, Phylum, Class, and Order according to the Linnaean hierarchy, making this the correct choice.

Scientists today classify organisms using cell type, complexity, and genetic evidence. Which scenario shows strategic use of these criteria to plan a classification?

• Comparing common names to decide the Kingdom

• Measuring cell nuclei, assessing multicellularity, and analyzing DNA to determine the Domain

• Counting how many individuals live in a population to assign the Phylum

• Observing behavior alone to decide the Species

Answer explanation

The correct choice involves measuring cell nuclei, assessing multicellularity, and analyzing DNA, which directly aligns with the criteria of cell type, complexity, and genetic evidence for classification.

Tags

NGSS.MS-LS4-4

A scientist finds a single-celled organism without a nucleus living in a freshwater pond. Based on the characteristics listed, which domain most likely includes this organism?

• Domain Bacteria

• Domain Archaea

• Domain Eukarya

• Protists

Answer explanation

The organism is single-celled and lacks a nucleus, indicating it is prokaryotic. This characteristic aligns with Domain Bacteria, as Archaea also includes prokaryotes but typically inhabit extreme environments, unlike freshwater ponds.

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NGSS.MS-LS4-2

Which statement best distinguishes Domain Archaea from Domain Bacteria according to the characteristics provided?

• Archaea are multicellular while Bacteria are single-celled.

• Archaea live in extreme environments while Bacteria are found almost everywhere.

• Archaea have a nucleus while Bacteria do not.

• Archaea include plants and animals while Bacteria include fungi.

Answer explanation

The correct choice highlights that Archaea thrive in extreme environments, such as hot springs and salt lakes, while Bacteria are ubiquitous, found in diverse habitats. This distinction is key in understanding their ecological roles.

An organism is eukaryotic and can be either unicellular or multicellular. Which domain does it belong to based on the listed traits?

• Domain Bacteria

• Domain Archaea

• Domain Eukarya

• Domain Protista

Answer explanation

The organism is eukaryotic, which means it belongs to Domain Eukarya. This domain includes all organisms with complex cells, whether unicellular or multicellular, distinguishing it from Bacteria and Archaea.