An Aspen tree is an example of which level of organization? (cell, issue, organ, organ system or organism?)

How does pregnancy begin? a) a placenta forms in the uterus b) a sperm reaches an egg in the fallopian tubec) the blastocyst differentiates into two cell types d) contractions begin in the uterine wallapex

Which of the following cell structures is significantly different between gram- positive and gram-negative bacteria?

Which is a kingdom? protistachordataprokarya mammalia