It grows at temperatures above 212 °F (100 °C). Animals are sometimes called metazoans, which thus distinguishes them from the protozoans, which are single-celled. The first of these is that they are comprised of cells. These layers are covered and protected by two sheets of clear cellulose that is very tough. Living things include many kinds of organisms, from the plants, animals, fungi, and algae that can be readily seen in nature to the multitude of tiny creatures known as protozoa, bacteria, and archaea that can be seen only with a microscope. Plants called legumes can make proteins by taking up nitrogen provided by bacteria that live in nodules in the plant’s roots. For centuries scientists divided living things into two kingdoms—plants and animals. The surface of the amoeba’s cell is a clear, tough membrane which covers and protects the cytoplasm of the cell. For example, the cell wall of archaea does not contain peptidoglycan, and the way archaea process DNA is more complex. The reason behind this is that they sleep for about 14 – 15 hours a day and rest of the time they just sit, eat and sleep. Other such extremophile species of archaea live in pools of highly acidic or salty water. But note that an engine does not use coal or oil to make itself larger or mend parts, as living things do with food. The activities of the cells are controlled by the cell’s genetic material—its DNA. Vascular plants include the flowering plants, the trees, and most familiar terrestrial plants. Thus living things must have a way to dispose of waste matter. Scientists still do not agree that viruses are actually living things, since these entities cannot sustain life on their own. Like animals, fungi must digest their food before absorbing it, but unlike animals, fungi digest their food outside of their bodies. All living organisms create waste products via the processes of living. Air and light also are critical needs for some organisms. Another kind of tissue, the blood, nourishes them. There are many kinds of single-celled organisms that are not prokaryotes. The organisms classified in the Kingdom Animalia are multicellular eukaryotes. This is true even of the simplest microorganisms, which may reproduce by simply dividing into two parts. Take a minute to check out all the enhancements! After translating an article, all tools except font up/font down will be disabled. Although abundant numbers of archaea live in a great variety of habitats, including in the oceans and in soil, a notable characteristic of certain species is that they can thrive in environments that are deadly to other kinds of organisms. Special fibers that work like nerves control the cilia and flagella. In this way it builds up protoplasm and cellulose. All living organisms must be capable of releasing energy stored in food molecules through a chemical process known as cellular respiration. Accessible across all of today's devices: phones, tablets, and desktops. Much waste comes from food. As a group, bacteria are highly diverse. The protists are commonly divided into the animal-like protozoa, most of which are heterotrophic; the plantlike algae, which are autotrophic; and the funguslike slime molds and water molds, which are saprophagous.