The genetic make-up of an organism is described as

1. Analyze the question The question asks for the term that describes the genetic make-up of an organism. That means the set of genes it carries, not how it looks.

2. Explain the concept

• Allele: one of the alternative forms of a gene, such as T (tall) or t (short). It is a single version of a gene, not the whole genetic make-up.
• Chromosome: a thread-like structure in the nucleus that carries genes. It is a physical structure, not a description of the genetic make-up.
• Phenotype: the observable or physical characteristics of an organism, such as height, colour or blood group. It is the result of the genes plus the environment.
• Genotype: the combination of alleles an organism has for a trait, which is its genetic make-up, such as TT, Tt or tt.

3. Solution

• "Genetic make-up" means the genes and alleles an organism inherits.
• That is the genotype.
• Example: two pea plants can both look tall (the same phenotype), but one may be TT and the other Tt (different genotypes).

4. Answer The correct option is D. Genotype.

5. Exam tip Remember the sound link: Genotype = Genes (what is inside), Phenotype = Physical appearance (what you see). JAMB often tests this pair, so keep them apart.