Question: 176: Which of the following are true about the taxonomical aid ‘key’?
(a) Keys are based on the similarities and dissimilarities.
(b) Key is analytical in nature.
(c) Keys are based on the contrasting characters in pair called couplet.
(d) Same key can be used for all taxonomic categories.
(e) Each statement in the key is called Lead.
Choose the most appropriate answer from the options given below :
(1) (a), (b) and (c) only
(2) (b), (c) and (d) only
(3) (a), (b), (c) and (e) only
(4) (a), (c), (d) and (e) only
Answer: Option (3)
Explanation:
A taxonomical key is a tool used for the identification of organisms based on their characteristics.
Keys are constructed by considering similarities and dissimilarities among organisms,
so statement (a) is correct.
A key is analytical in nature because it helps in step-by-step identification by analysis of characters,
hence statement (b) is correct.
Keys are based on contrasting characters arranged in pairs known as couplets,
making statement (c) correct.
Each statement within a couplet is called a lead, so statement (e) is also correct.
A single key cannot be used for all taxonomic categories because different groups require different keys, hence statement (d) is incorrect.
Therefore, the correct set of statements is
(a), (b), (c), and (e), corresponding to option (3).