If the haploid number for a plant species is 4, how many chromosomes are found in a member of the species that has one of the following characteristics? Explain your reasoning in each case.
Pentaploidy

Verified step by step guidance

1. Understand the concept of haploid number: The haploid number (n) represents the number of chromosomes in a single set of the organism's genome. For this plant species, the haploid number is given as 4 (n = 4).
2. Define pentaploidy: Pentaploidy refers to an organism having five sets of chromosomes (5n). This is a type of polyploidy, where the chromosome number is a multiple of the haploid number.
3. Calculate the total number of chromosomes: Multiply the haploid number (n = 4) by the number of sets in pentaploidy (5). The formula is: $5\times 4$.
4. Explain the reasoning: Since pentaploidy means five complete sets of chromosomes, the total chromosome count is the result of multiplying the haploid number by 5. This ensures the organism has five times the genetic material of a haploid cell.
5. Verify the concept: Double-check that the calculation aligns with the definition of pentaploidy and the given haploid number. This step ensures the understanding of polyploidy and chromosome multiplication is correct.

Key Concepts

Haploid and Diploid Numbers

The haploid number (n) refers to the number of chromosomes in a gamete, which is half the total number of chromosomes in a diploid organism. In this case, if the haploid number for the plant species is 4, the diploid number (2n) would be 8, representing the total chromosomes in somatic cells.

Polyploidy

Polyploidy is a condition in which an organism has more than two complete sets of chromosomes. Pentaploidy, specifically, means that the organism has five sets of chromosomes. This can occur through processes such as hybridization or errors in cell division, leading to increased genetic variation.

Calculating Chromosome Number in Polyploids

To determine the total number of chromosomes in a polyploid organism, multiply the haploid number by the number of chromosome sets. For a pentaploid organism with a haploid number of 4, the total chromosome count would be 4 (haploid) x 5 (sets) = 20 chromosomes.