Final answer:
The statement that seedless watermelons have 33 chromosomes is true; they are sterile triploid hybrids. Chromosome number variations, such as in watermelons, strawberries, and kiwis, can affect the DNA content in fruit cell nuclei. The DNA isolation technique aids in studying these genetic materials.
Step-by-step explanation:
The statement that seedless watermelons have 33 chromosomes is true. Seedless watermelons are indeed sterile hybrids and typically have an odd number of chromosomes which prevents them from producing viable seeds. This is because seedless watermelon varieties are usually triploid, having three sets of chromosomes (3n), as a result of cross-breeding a diploid (2n) with a tetraploid (4n) watermelon. In the case of a normal watermelon, which is diploid, it would have two sets of chromosomes, therefore having 22 chromosomes. However, in seedless watermelons, the offspring have three sets, leading to a total of 33 chromosomes.
To understand the relation between chromosome number and the DNA content, consider different ploidy levels in plants like the common strawberry, which is octoploid (8n), and the cultivated kiwi, which is hexaploid (6n). This variation can influence the total amount of DNA in a fruit's cell nucleus. Factors contributing to the total DNA amount include not only the number of chromosome sets but also the size and number of genes within those chromosomes. The DNA isolation technique is a protocol to extract and purify DNA from cells, which involves various steps that help release and then precipitate the DNA out of the solution.
It is important to correct the misconception stated in part c., where it mentions somatic cells are haploid with 46 chromosomes, which is incorrect. Somatic cells are diploid and contain two sets of chromosomes, while gametes, which are used for sexual reproduction, are haploid with half the number of chromosomes present in somatic cells.