Question

In which animal do haploid cells divide mitotically to produce gametes ?

• A. Male frogs
• B. Male honeybees
• C. Male grasshoppers
• D. Male earthworms

Hint:

Logic Tip: The phenomenon where males develop from unfertilized eggs is called arrhenotoky. Remember: Drones (male bees) have no father and cannot have sons, but they have a grandfather and can have grandsons!

Answer 1

The Correct Option is B

Concept:
Gametes are universally haploid ($n$). In most diploid ($2n$) organisms, gametes are formed through meiosis (reductional division). However, if an adult organism is already haploid ($n$), it cannot undergo meiosis to form gametes. Instead, it must produce gametes through mitosis (equational division).
Step 1:
Frogs are amphibians with standard sexual reproduction. Adult male frogs are diploid ($2n$) and produce haploid sperms via meiosis. This option is incorrect.
Step 2:
Grasshoppers follow the XX-XO sex determination system. Males are XO, meaning they have one less chromosome than females, but they are still essentially diploid organisms that undergo meiosis to produce haploid sperms (some with an X chromosome, some without). This option is incorrect.
Step 3:
Earthworms are hermaphrodites (monoecious) and are typical diploid ($2n$) organisms. They produce both sperm and eggs through standard meiotic division. This option is incorrect.
Step 4:
Honeybees follow a unique haplodiploid sex-determination system. Females (queens and workers) are diploid ($2n=32$) and develop from fertilized eggs. Males (drones) are haploid ($n=16$) because they develop parthenogenetically from unfertilized eggs.
Step 5:
Because male honeybees are already haploid, their cells cannot undergo reductional division. Therefore, their spermatocytes must divide mitotically to produce haploid sperms.
Step 6:
Male honeybees uniquely fit the description, making Option (2) the correct answer.