Mady S.

Cell: The smallest structural and functional unit of an organism.

The difference between an animal cell and plant cell is plant cells have a cell wall and animal cells do not. Animal cells are round and irregular in shape while plant cells have fixed, rectangular shapes.

Cell Wall: Provide structure, prevent loss of water, and protection from insects and pathogens.
Chloroplasts: The main role is to conduct photosynthesis.
Vacuoles: Contain wastes and water, and isolate materials that might be harmful or a threat to the cell.

Muscle Cell: Contain protein filaments that producing a contraction that changes both the length and the shape of the cell.
Nerve Cell: Transmit messages from one part of the body to another.
Bone Cell: Cells that help form the bone, mantian the bone, and cover the surface of the bone.

The relationship between tissues and organs is that a group of cells working together is called tissue, and several tissues working together make up an organ, which help carry out life's basic tasks.

The components of the digestive system:
mouth, stomach, liver, gallbladder, esophagus, small and large intestine, pharynx, and pancreas.
The components of the circulatory system:
Heart, blood vessles, veins, arteries and blood.
The components of the respiratory system:
Nose and Vaval cavity, mouth, Pharynx, Larynx,Trachea, bronchi, and lungs.

The Paramecium looks like a cell, but functions on its own because it is a single-celled organisms.