1. An amoeba is a unicellular organism.
What characteristics?

Some things consist of only one cell. They are called unicellular organisms. One of the simplest living things, an amoeba, is made of only one cell. Amoebas (sometimes spelled amoebas or amoebae) are too small to be seen without a microscope, but they are commonly found in ponds and lakes.

i don't know. if i were you, i would search it up online : d

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]