DNA structure. DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C).
Answer:
compression and rarefaction
Explanation:
This kind of wave is called a longitudinal wave and an example of such a wave is a sound wave. The center of compression can be analogous to the top of a crest of a transverse wave while the center of the rarefaction would be analogous to the bottom of the trough of a transverse wave.
Answer:
chemical change.
Explanation:
There are two types of changes in matter: physical change and chemical change.
physical change- it is a change in matter that alters only its physical properties or its physical appearance. This type of change is reversible. For example- freezing of water, the water turns into solid ice and it can be reversed by melting the ice.
chemical change- it is a change in matter that alter its chemical and thus its physical properties. Most chemical changes are irreversible. for example- burning of paper, results in black soot and ashes- Thus changing both physical and chemical properties.
Messages are slower acting and longer lasting. Plus they are classified as hormones, transported in the blood.
