Question

An organism’s genetic constitution is called
A. Genotype
B. Phenotype
C. Holotype
D. None of the above

Answer 1

Hint: Morphological appearance of an organism is known as the phenotype.

Complete answer: The genetic constituent of an organism is known as the genotype. It is the genetic makeup of an organism.
It is the complete set of chromosomes that the organism inherits from his/her parents, the genotype encodes for genes that further give rise to a particular trait or the phenotype, also known as the morphological appearance of an individual.
While phenotype can be similar for example the height of plants, two plants can be tall morphologically and hence may be termed phenotypically same but yet they may differ in their genotype.
As seen in Mendel's experiments, the genotype for a tall plant may be either be homozygous dominant for the trait (TT) or heterozygous dominant for the trait (Tt), this depicts that even when the genotype Is different, the phenotype may be the same.

Additional information:There are three types of genotypes:
homozygous dominant,
homozygous recessive, and
heterozygous.
1. Genotyping is the process of decoding the genotype of an individual with a biological assay. Also called a genotypic assay, techniques include PCR, DNA fragment analysis, allele-specific oligonucleotide (ASO) probes, DNA sequencing, and nucleic acid hybridization to DNA microarrays.
2. Several genotyping techniques include restriction fragment length polymorphism (RFLP), terminal restriction fragment length polymorphism (t-RFLP),
amplified fragment length polymorphism (AFLP), and
multiplex ligation-dependent probe amplification

So the correct answer is A. Genotype

Note: It should be noted that two organisms having the same phenotype may or may not have the same genetic makeup or genotype. The same was also observed in the case of Mendel's experiments.