Which organ contain lots of vessicle

When listening the levels of orginization in orginisims from the smallest to most complex , which level is just below organs in complexity

How do water’s relative densities as a solid and a liquid differ from that of most other substances? water’s solid and liquid forms have different densities, while most other substances have solid and liquid forms with similar densities. water’s solid and liquid forms have similar densities, while most other substances have solid and liquid forms with different densities. water’s liquid form is less dense than its solid form, while the opposite is true of most other substances. water’s solid form is less dense than its liquid form, while the opposite is true of most other substances.

Closing romer’s gap. what is the significance of the new fossil evidence found in scotland? answer in claim evidence and reasoning