Characteristics and Classification of Living Organisms: Question 7
Syllabus 1.2
The domestic cat has the binomial name Felis catus. The first word, Felis, is the genus, and the second word, catus, is the species.
Which of the following shows this binomial name written using the correct convention?
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Worked solution
Step 1: Recall the binomial system
The binomial system is an internationally agreed system in which the scientific name of an organism is made up of two parts: the genus, written first, and the species, written second. Following this system consistently is what allows the same name to be recognised and understood by scientists everywhere.
Step 2: Apply the capitalisation convention
By convention, only the first word, the genus, begins with a capital letter; the second word, the species, is written entirely in lower case. For the domestic cat, this gives Felis catus, with a capital F on “Felis” and a lower-case c on “catus”.
Step 3: Rule out the other options
- “felis Catus” (option B) capitalises the species word instead of the genus word, the reverse of the correct convention.
- “Felis Catus” (option C) capitalises both words, treating the name like an ordinary title rather than following the genus-only capitalisation rule.
- “catus Felis” (option D) reverses the order of the two words, writing the species before the genus, when the genus should always come first.
Final answer
- The correctly written binomial name is Felis catus, option A.