A section of DNA which codes for a protein is called a _. An enzyme called a _ reads along the DNA and produces mRNA in a process called transcription. Special proteins called _ help this enzyme bind to a segment of DNA called the_. When the correct factors are present in the nucleus, RNA polymerase can begin transcription.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.

the growth of the plants is affected by the heat of the light. what is the student doing?