Look at the image of a synapse. which letter correctly labels the synapse?

Which statement best describes the relationship between an allele and a gene? question 1 options: an allele is a variation of a gene that can be expressed as a phenotype. an allele is the part of a gene that attaches to messenger rna molecules. an allele is a segment of a dna molecule that controls replication of a gene.

Some substances but not other can cross the (blank) membrane of a cell

How has biodiversity on earth changed over time?