Some simpler animals lack what type of embryonic tissue?

The organelle pictured is found in cells of and is theorized to have once been an independent organism.

Which of the following describes the difference in stimuli required to detect a difference between the stimuli? a. just noticeableb. signal detectionc. subliminald. top down

What do we call an individual that has inherited two identical alleles for the same trait? a. homozygous b. heterozygous c. monozzygous