What is the difference between haploidy and monoploidy?

Haploidy and monoploidy are both terms used in genetics to describe the number of sets of chromosomes in a cell or organism. While they are similar concepts, there is a subtle distinction between them:

Haploidy: Haploidy refers to a condition where a cell or organism has a single set of chromosomes. In other words, the number of chromosomes is reduced to half the normal diploid number. In a diploid organism, such as humans, the somatic cells contain two sets of chromosomes (2n), while the reproductive cells (gametes) are haploid (n) and contain one set of chromosomes. Haploidy is a characteristic of gametes and certain specialized cells, such as pollen or eggs.

Monoploidy: Monoploidy, on the other hand, refers specifically to an organism or cell having only one complete set of chromosomes. It is a condition where an organism has a single copy of each chromosome, rather than the usual two copies in diploid organisms. Monoploidy can occur naturally in some organisms, but it is relatively rare. In most cases, monoploidy is a result of a genetic abnormality or an error during cell division.

To summarize, haploidy generally refers to the state of having a single set of chromosomes, which is characteristic of gametes, while monoploidy specifically denotes the presence of only one complete set of chromosomes in an organism or cell.