Optometry Admission Test (OAT) Practice

What defines a haploid cell?

1. A cell containing one set of chromosomes

2. A cell containing two sets of chromosomes

3. A cell that is genetically identical to another

4. A cell that can undergo mitosis

The correct answer is: A cell containing one set of chromosomes

A haploid cell is defined as a cell that contains one set of chromosomes, which is a foundational concept in genetics. In organisms that reproduce sexually, such as humans, haploid cells are typically gametes—sperm and egg cells. These cells are produced through the process of meiosis, which reduces the chromosome number by half, ensuring that when fertilization occurs, the resulting zygote has the appropriate diploid number, combining genetic material from both parents. This one set of chromosomes is crucial for maintaining the correct chromosome number across generations, as it allows for genetic diversity while preventing an excess of chromosome material from accumulating in a species. Other options relate to different cell types and processes. For instance, a cell containing two sets of chromosomes refers to diploid cells, which are common in somatic cells. A cell that is genetically identical to another refers to clones, which can occur in processes like asexual reproduction or mitosis, but this doesn't define haploidy. Lastly, a cell that can undergo mitosis does not exclusively denote haploid cells; both haploid and diploid cells can undergo this process. Thus, the unique characteristic of having one set of chromosomes distinctly identifies a haploid cell.