If a haploid organism has 20 chromosomes, how many will be present in the body cells?
Chromosomes are bundles of DNA that are typically found in the nucleus of eukaryotic cells. They are a means of organizing the DNA and facilitating access to it during transcription and replication.
Haploid is the term used for a cell that contains a single copy of each unique chromosome normally present in that organism. The majority of sexually reproducing species use haploid cells during reproduction, combining one from each parent to form a zygote. The zygote, and all subsequent body cells, are called diploid cells, because they have two copies of each chromosome, one from each parent's haploid cell.
Another term for body cells is "somatic" cells - deriving from the root word "soma" meaning body. Thus, any body, aka somatic cell, will have twice the number of chromosomes that we would normally expect to find in a haploid cell coming from the same organism.
In this case, if the haploid cell contains 20 chromosomes, then the diploid cell should contain 40.