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.
Octaploidy

Verified step by step guidance

1. Step 1: Understand the concept of haploid number. The haploid number (n) represents the number of chromosomes in a single set of the genome. For this plant species, the haploid number is given as 4 (n = 4).
2. Step 2: Define octaploidy. Octaploidy refers to an organism having eight sets of chromosomes (8n). This is a type of polyploidy, where the chromosome number is a multiple of the haploid number.
3. Step 3: Calculate the total number of chromosomes in an octaploid individual. Multiply the haploid number (n = 4) by the number of sets (8n). The formula is: $8\times 4$.
4. Step 4: Explain the reasoning. Since octaploidy means eight complete sets of chromosomes, the total chromosome count is the product of the haploid number and the number of sets. This ensures the organism has eight times the genetic material of a haploid cell.
5. Step 5: Conclude the calculation process. The total chromosome count for an octaploid individual is determined by the multiplication performed in Step 3. This value represents the number of chromosomes in the organism.

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. Octaploidy, specifically, means that the organism has eight sets of chromosomes. This can occur through processes such as whole-genome duplication, which is common in plants and can lead to increased size and vigor.

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 octaploidy, with a haploid number of 4, the total chromosome count would be 4 (haploid) x 8 (sets) = 32 chromosomes in the octaploid plant.