Unit 5 Living Things
LIVING THINGS
All living things are made up of very small parts called cells. They are so small that they can only be seen using a microscope.
Animals and plants are made up of billions of cells. Living things made up of more than one cell are called multicellular.
There are also living things that are made up of a single cell. They are called unicellular and can only be seen under a microscope.
THE VITAL FUNCTIONS
All living things perform three vital functions
Nutrition. Cells get the substances they need to grow and get energy.
Relationship. Cells receive information from the environment around them and can react to it.
Reproduction. The cells divide and form daughter cells. All cells always come from other cells that already exist.
The cells within our body are alive because they perform all three vital functions. However, each of the cells alone cannot be considered living things since they need the other cells to stay alive.
CELLS STRUCTURE
The smallest unit that exists that is part of a living thing is the cell. The cells of animals and plants have the following parts:
- The nucleus controls the functions of the cell, such as reproduction.
- The cell membrane is a covering that separates the inside of the cell from the outside.
- Cytoplasm is a gelatinous substance where different chemical reactions take place. It is mainly made up of water and numerous dissolved substances.
- Vacuoles contain water and minerals necessary for the body to grow.
Apart from these elements that are shared by animal and plant cells, plant cells also have:
- A strong cell wall, which provides protection and gives it its shape. Plant cells are polygonal in shape while animals are more rounded.
- Chloroplasts containing chlorophyll necessary for photosynthesis.
HOW ARE THE CELLS?
The cells are very small, but they have different sizes. In our body, for example, the cells of the brain, the neurons, are much larger than those of the blood, the red blood cells. Furthermore, different types of cells have different shapes: spherical, prismatic, starry, flat ...
People, like the rest of living beings, are made up of cells. Our body is made up of billions of cells of different shapes and sizes.
THE LEVELS OF ORGANIZATION
Multicellular beings are made up of many cells. Those cells are not arranged in any way, but are organized. In living beings, various levels of organization can be distinguished.
Tissues
Cells that are of the same type are grouped into tissues. The cells of a tissue perform a common function.
The cells of the bone tissue form the bones that support our body.
The epidermal tissue protects the surface of the leaves.
Organs
The union of several tissues that are organized to work together gives rise to an organ.
The tongue is an animal organ that is made up of various tissues: muscle tissue; the epithelial tissue, which forms the overlying skin; and the nervous tissue, which forms the nerves that transmit flavors, among other tissues.
Systems and apparatus
A system is made up of several organs of the same type that perform the same function.
The muscular system is made up of muscles. The skeletal system is made up of bones.
An apparatus is made up of different organs or various systems that work in coordination to perform work.
The locomotor system is an apparatus made up of the muscular system and the skeletal system. Both work together to produce movements and displacements.
organisms
The union of all the devices and systems of place to an organism, that is, a complete living thing.
In multicellular organisms we can distinguish cells, tissues, organs, systems, apparatus, and the entire living being. For the body to function, all levels must work in coordination, from cells to apparatus.
Single-celled living things, like bacteria (being made up of a single cell) remain at the first level of organization, the cell. Your cell must perform all the vital functions of the living being.