Classification & Biodiversity — Practice · Grade 10 Science

Chapter: Evolution, Ancestry & Biodiversity

What this practice covers

By the end of Classification & Biodiversity you should be able to:

10 questions, multiple choice, written answer and numeric, each with a worked explanation.

Vocabulary used: taxonomy, binomial nomenclature, domain, cladogram, shared derived trait, biodiversity.

Problem 1

In binomial nomenclature, an organism's two-part scientific name is made of its
  1. domain and kingdom
  2. family and order
  3. genus and species
  4. kingdom and phylum
Answer and explanation

genus and species

Binomial ('two-name') nomenclature combines the genus (first, capitalized) and the species (second), as in Homo sapiens.

Problem 2

The three domains into which all life is classified are
  1. Plants, Animals, and Fungi
  2. Producers, Consumers, and Decomposers
  3. Prokaryotes, Protists, and Vertebrates
  4. Bacteria, Archaea, and Eukarya
Answer and explanation

Bacteria, Archaea, and Eukarya

Based on Carl Woese's molecular work, all life is divided into three domains: Bacteria, Archaea, and Eukarya (which contains all organisms with complex cells).

Problem 3

Explain what a shared derived trait is and how it helps you group organisms on a cladogram.
Answer and explanation

A shared derived trait is a feature that first evolved in a common ancestor and was inherited by all of its descendants. On a cladogram, all the organisms that share that trait form a group (clade) branching from that ancestor, so shared derived traits let you identify which organisms are more closely related.

Problem 4

On a cladogram, salamanders and turtles branch from a common ancestor that is more recent than the ancestor either shares with sharks. What can you conclude?
  1. Salamanders and turtles are more closely related to each other than either is to sharks
  2. Sharks are more closely related to turtles than salamanders are
  3. All three are equally related
  4. Branch points on a cladogram carry no information about relatedness
Answer and explanation

Salamanders and turtles are more closely related to each other than either is to sharks

A more recent shared branch point means a closer relationship, so salamanders and turtles are more closely related to each other than either is to sharks.

Problem 5

A region originally had 800 native species. Habitat loss has driven 120 of them to extinction. What percentage of the region's native species has been lost?
Answer and explanation

15 %

120 / 800 = 0.15 = 15%.

Problem 6

Two communities each contain five species, but one is dominated by a single species. Are their diversity patterns identical? Explain the reasoning in your own words.
Answer and explanation

No; equal richness does not establish equal biodiversity patterns.

Species richness matches at five.

Relative abundances differ, so evenness and ecological structure can differ.

Response criteria

  • Use the stated conditions.
  • Show the evidence or calculation.
  • Explain the conclusion and any stated limitation.

Problem 7

Why can a classification change after DNA evidence is added? Show the reasoning, not just the conclusion.
Hints

State which measure is being compared.

Answer and explanation

New evidence can revise the inferred evolutionary relationships represented by groups.

Problem 8

Can a local identification key classify every species worldwide?
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

No. Its choices and species coverage are limited to its intended scope.

Problem 9

A key identifies a specimen within its stated scopeA key identifies a specimen within its stated scopeFeature present?Follow defined option AFollow defined option BAn identification key is a decision tool, not an ancestry timeline.
Original paired-choice tool, not a field key for handling unknown organisms.
Interpret the supplied visual. Does arriving at the same key choice prove two organisms are closest evolutionary relatives?
Answer and explanation

No. A key sorts using selected identifying traits; ancestry requires appropriate relationship evidence.

A dichotomous key offers paired choices using defined characters. Reliable use requires visible or measured features, applicable life stage and the set of organisms the key covers. A wrong early choice can send the user to a plausible-looking wrong endpoint. Identification differs from an ancestry explanation: a practical key can use conspicuous traits without turning every choice into an evolutionary branching event. Report uncertainty when a specimen lacks a required feature or falls outside the key’s scope.

No. A key sorts using selected identifying traits; ancestry requires appropriate relationship evidence.

Response criteria

  • Read the structures, axes, directions and units correctly.
  • Connect the evidence with the biological mechanism.
  • Respect stated model assumptions and distinguish an observation from a further inference.

Problem 10

Two equal-effort samples each contain five species. Counts are 8,8,8,8,8 versus 36,1,1,1,1. Compare richness and evenness and name one sampling limitation.
Answer and explanation

Both have richness five and total 40, but the first is more even. Detection, area, timing and effort can affect observed richness; unobserved species are not automatically absent.

Both have richness five and total 40, but the first is more even. Detection, area, timing and effort can affect observed richness; unobserved species are not automatically absent.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the biological mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

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