Which of the following must happen first in order for DNA replication to occur?
DNA polymerase binds to the leading strand
DNA is unwound
Hydrogen bonds form between bases
chromosomes condense

DNA is unwound.

Explanation:

DNA replication is the process where by two identical DNA copies are produced from a double stranded DNA molecule.

Before DNA will replicates, the double helix length of the DNA to be copied must be unwound, the two strands are separated and the hydrogen bond that link the paired bases are broken. Once the are unwound, they are held apart to expose the new bases so that hydrogen bond can link the nucleotides. The enzyme polymerase then join the new nucleotides into a new DNA strand that is complementary to the template.

not the best question format lol but what i think might as scale color is controlled by a single gene with two alleles, the green allele and the yellow allele. when moths that are homozygous for green scales are mated with moths that are homozygous for yellow scales, 100% of the offspring have green scales.

weathering - colorado river carves land in arizona to form the grand canyon. cracks form in a sandstone wall surrounding a house. a marble statue near the science museum is changing color due to rainfall

erosion - after a rainstorm, soil and rock piees litter the roadways. the sand dunes in the sahara desert are changing shape.

here's your answer.