What is the medullary index for an organism that has a medulla width of 2cm and hair shaft width 4cm? Is this organism human or animal?

a. 1/2 b. The organism is an animal

Explanation:

a. What is the medullary index for an organism that has a medulla width of 2cm and hair shaft width 4cm?

Medullary index = diameter of medulla/diameter of hair.

Given that diameter of medulla = medulla width = 2cm and diameter of hair = hair shaft width = 4cm,

Medullary index = diameter of medulla/diameter of hair = 2 cm/4cm = 1/2

b. Is this organism human or animal?

Since the medullary index = 1/2 > 1/3 (if it is ≤ 1/3 it is human hair and ≥ 1/2 it is animal hair), it is animal hair. So, the organism is an animal.