AQA · A-Level · Biology

    Course version: 7402 · Version from Sept 2016

    One hierarchy comprises the taxa: domain, kingdom, phylum, class, order,…

    Full specification wording

    Species and taxonomy: One hierarchy comprises the taxa: domain, kingdom, phylum, class, order, family, genus and species.

    The order runs domain, kingdom, phylum, class, order, family, genus, species, from the largest and most inclusive group down to the smallest.

    Checked against the AQA 7402 specification (opens in a new tab) on .

    • Point 7 of 9
    • 4 key terms

    Study notes

    From the checked teaching notes for this specification point.

    The idea

    The order runs domain, kingdom, phylum, class, order, family, genus, species, from the largest and most inclusive group down to the smallest. Learn the eight names in sequence, because classification tables may ask you to fill gaps. In such a table each column is one organism and each row one level, so a missing entry is found by reading across the row to see which level you are in and down the column to keep the organism consistent. The domain sits above kingdom and was added when sequence data showed that prokaryotes fall into two deeply separated groups. The last two levels, genus and species, are the ones used in the organism's name, so a column that ends with a genus and a species name has ended in the right place.

    What earns the marks

    • Give the levels in the correct sequence from the largest group down to the species: domain, kingdom, phylum, class, order, family, genus, species.
    • Complete a classification table by reading across the row to identify the level and down the column to keep the organism consistent.
    • Give the genus and species names together as the binomial in the species row.
    • Keep every entry within a column referring to the same organism.
    • Identify which level of the hierarchy a given group name belongs to, and name the levels immediately above and below it.

    Common mistakes and how to put them right

    • Swapping class and order, the two levels most often transposed.

      Put it right: The sequence is class then order.

    • Putting both the genus name and the species name in the genus row of a table.

      Put it right: The binomial belongs in the species row.

    • Omitting domain and starting the hierarchy at kingdom.

      Put it right: Domain is the largest group and comes first.

    • Inventing extra ranks such as sub-phylum, which are not required by this specification.

      Put it right: Use only the eight levels listed.

    • Filling gaps by copying the pattern of a neighbouring column instead of reading the level from the row.

      Put it right: Read across the row to identify the level.

    Exam tips

    • Write the eight levels down the margin as soon as a classification table appears, then fill the table from your list.
    • In a completion table, check each entry against both its row and its column before moving on.
    • If you have to write the binomial in the species row, give both words; the species word alone is not the binomial.

    Try the lesson

    The start of the Species and taxonomy: One hierarchy comprises the taxa: domain, kingdom, phylum, class, order, family, genus and species. lesson, made from checked teaching notes for this specification point.

    Have a go first

    Which taxon in the hierarchy domain, kingdom, phylum, class, order, family, genus and species contains the largest number of organisms?

    Listen

    The order runs domain, kingdom, phylum, class, order, family, genus, species, from the largest and most inclusive group down to the smallest. Learn the eight names in sequence, because classification tables may ask you to fill gaps. In such a table each column is one organism and each row one level, so a missing entry is found by reading across the row to see which level you are in and down the column to keep the organism consistent. The domain sits above kingdom and was added when sequence data showed that prokaryotes fall into two deeply separated groups. The last two levels, genus and species, are the ones used in the organism's name, so a column that ends with a genus and a species name has ended in the right place. A strong answer earns marks for these points. Give the levels in the correct sequence from the largest group down to the species: domain, kingdom, phylum, class, order, family, genus, species. Complete a classification table by reading across the row to identify the level and down the column to keep the organism consistent. Give the genus and species names together as the binomial in the species row. Keep every entry within a column referring to the same organism. A common slip: Swapping class and order, the two levels most often transposed. Instead, the sequence is class then order. Exam tip: Write the eight levels down the margin as soon as a classification table appears, then fill the table from your list.

    See it

    A vertical flowchart of eight boxes joined by downward arrows. The top box is labelled Domain, which points down to Kingdom, which points down to Phylum, which points down to Class, which points down to Order, which points down to Family, which points down to Genus, which points down to Species at the bottom. The order runs from the largest and most inclusive group at the top to the smallest at the bottom.
    It shows the eight taxa of the hierarchy in sequence from the largest and most inclusive group, domain, down to the smallest, species.

    Put it in order

    Put these steps in the order they happen.

    1. 1. Order
    2. 2. Species
    3. 3. Family
    4. 4. Domain
    5. 5. Kingdom
    6. 6. Genus
    7. 7. Phylum
    8. 8. Class

    Key words

    Say what each word means before you turn the card.

    eight taxonomic levels

    Try answering aloud or in your head before turning the card.

    domain to species

    Try answering aloud or in your head before turning the card.

    classification tables

    Try answering aloud or in your head before turning the card.

    genus and species

    Try answering aloud or in your head before turning the card.

    See every definition
    eight taxonomic levels
    The hierarchy comprises domain, kingdom, phylum, class, order, family, genus and species, from the largest and most inclusive group down to the smallest.
    domain to species
    The order runs domain, kingdom, phylum, class, order, family, genus, species, and the eight names must be learned in sequence.
    classification tables
    In such a table each column is one organism and each row one level, so a missing entry is found by reading across the row and down the column.
    genus and species
    The last two levels are the ones used in the organism's name, so a column ending with a genus and a species name has ended in the right place.

    Label the diagram

    Some boxes have lost their names. Pick the right name for each number.

    The diagram again, with 3 boxes numbered instead of named. A vertical flowchart of eight boxes joined by downward arrows. The top box is labelled Domain, which points down to Kingdom, which points down to Phylum, which points down to Class, which points down to Order, which points down to Family, which points down to Genus, which points down to Species at the bottom. The order runs from the largest and most inclusive group at the top to the smallest at the bottom.

    • 1Box 1

    • 2Box 2

    • 3Box 3

    0 of 3 labelled

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