Sheep have 54 chromosomes, while goats have 60 chromosomes - HSC - SSCE Biology - Question 9 - 2023 - Paper 1

To determine the correct answer, we first need to calculate the number of chromosomes for the hybrid offspring (geep).

1. Identify the chromosome counts:

   • Sheep have 54 chromosomes (2n = 54, thus n = 27 for the sheep).
   • Goats have 60 chromosomes (2n = 60, thus n = 30 for the goats).

2. Calculate the total chromosomes in a geep:

   • When the sheep's egg (27 chromosomes) is fertilised by the goat's sperm (30 chromosomes), the total number of chromosomes in the geep will be:

   $ext{Total chromosomes} = n_{sheep} + n_{goat} = 27 + 30 = 57$

   Therefore, the diploid number of chromosomes (2n) for the geep is:

   $2n = 57$

3. Choose the correct option:

   • From the options provided, the correct answer is:

   C. 2n = 57 chromosomes.