Answer and Explanation:
From the given statements, the correct ones are B and C.
Here's an explanation of each statement:
A. The E. coli genome is approximately 10^6 base pairs in size.
This statement is incorrect. The genome of Escherichia coli (E. coli) is around 4.6 million base pairs in size, not 1 million.
B. In the human genome, approximately 20% of the nuclear DNA codes for proteins.
This statement is correct. Roughly 20% of the human genome consists of protein-coding genes. The remaining portion includes non-coding DNA sequences, regulatory regions, and other functional elements.
C. In the human genome, almost 60% of the nuclear DNA is repetitive.
This statement is correct. The human genome contains a significant amount of repetitive DNA sequences, such as transposons and tandem repeats. These repetitive sequences make up a substantial portion, estimated to be around 60% of the nuclear DNA.
D. The nuclear genome of the fruit fly has fewer base pairs than the nuclear genome of a mouse.
This statement is incorrect. The nuclear genome of the fruit fly (Drosophila melanogaster) contains approximately 180 million base pairs, while the nuclear genome of a mouse (Mus musculus) is around 2.6 billion base pairs. Therefore, the mouse genome is significantly larger than the fruit fly genome.
E. The organism with the largest haploid genome, in base pairs, is a plant.
This statement is not addressed by the options provided. However, it is generally true that many plants have larger genomes compared to animals. For example, some species of lilies and ferns have exceptionally large genomes. Nevertheless, without specific options to choose from, we cannot determine if this statement is correct based on the given options.
In summary, the correct statements from the given options are B and C. The human genome has approximately 20% of its nuclear DNA coding for proteins, and nearly 60% of the nuclear DNA is composed of repetitive sequences.