The independent variable is the only factor that a scientist
varies for different groups in an experiment.
measures in an experiment.
keeps constant for each group in an experiment.
records throughout an experiment.

eukarya because is is like alche and b is bacteria and d is animals

explanation:

when it is at an intermediate population density

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.

answer >   yes we do, women; have three holes, urethral opening(pee hole, vagina, and the women pee/girls pee out of the urethra like the men do; only they have a single opening to pee/ejaculate.   (sorry if i'm too forward with this, but this is for a biology class, isn't it? )

hope that !         : )