Question

levels of organization
least complex

most complex
cardiac
tissue
heart
muscle
cells
circulatory
system

Explanation:

Step1: Recall biological organization levels

In biology, the levels of organization from least to most complex are: cells, tissues, organs, organ systems. Here, muscle cells (cells) → cardiac tissue (tissue) → heart (organ) → circulatory system (organ system).

Step2: Assign to each level

• Least complex (top box): muscle cells (cells level)
• Next: cardiac tissue (tissue level)
• Next: heart (organ level)
• Most complex (bottom box): circulatory system (organ system level)

Answer:

From top (least complex) to bottom (most complex): muscle cells, cardiac tissue, heart, circulatory system