Which definition is correct? A. a physical change creates a new substance because bonds are broken or formed
B. a physical change can happen without changing any characteristics of the substance
C. a chemical change occurs when the substance remains the same but the shape, or other physical characteristics change
D. a chemical change produces a new substance by breaking and forming new bonds

Whereas a change that causes change in chemical composition of a substance is known as chemical change. For example, A new substance is always formed in a chemical change. Thus, we can conclude that the definition a chemical change produces a new substance by breaking and forming new bonds, is correct.

the offspring would all be white. if the parents are both white flowers then they have the genotype rr, which when crossed results in an all white punnet square.

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.