What must happen to a chromosome before a cell starts mitosis? What must happen to a chromosome before a cell starts mitosis? A. The two chromatids of the chromosome must become attached to each other. B. Both molecules of DNA in the chromosome must be replicated. C. The chromatin of the chromosome must be completely condensed. D. The single DNA molecule in the chromosome must be replicated.

The DNA must be replicated first to be a whole chromosome since at the previous division it was only a set of two "half" chromosomes.

Explanation:

Mitosis never replicates DNA which is split in half in a set pattern every replication to prevent mutations.

answer; i believe the correct answer is ( proteins );

d concave shape of wave rock

explanation:

the concave shape of wave rock is a very good evidence that supports the evolution of earth due to chemical weathering. if we talk about structure of   wave rock, studies have estimated that it is around 2.7 billion years old. it also serves as the foundation of evidence that it was the place where australian continent began to form.

how the structure of wave rock was created?

studies suggest that structure of wave rock was created when the surrounded area was started to weather due to which deposition of material started on the part of land which now contains wave rock.

the structure of wave rock is considered to be one of the best-known landforms in australia. at the height of around 15 cm, there can be found flared slopes which formulate the margins of hyden rock. it is now assumed by geologists that wave rock was created by subsurface water-induced weathering and not by glaciers, waves or wind.

due to deposition of material over the period of long time, the wave rock became tougher and tougher due to weathering from surrounding terrain. this makes it a physical evidence that supports   the evolution of earth due to chemical weathering.

hope it !