What do all living things maintain

Earthworms have both sperm and eggs within their bodies they are hermaphrodites but they cannot self-fertilise and need to mate with another individual. After mating, a cocoon containing the fertilised eggs is deposited in the soil. Earthworm nutrition comes from a variety of sources, depending on their species. Food types include manure, compost, plant material, fungi, microorganisms and decaying animals.

They take in food through their mouths. Based on the information above, we can confidently categorise earthworms as living things as they carry out all seven life processes. It is now possible to classify them further into a series of hierarchical categories: kingdom, phylum, class, order, family, genus and species. Classifying living things into these categories is an important way for scientists to show how living things are related to each other.

Most scientists classify living things into one of the following six kingdoms. What did you decide? Sometimes people are surprised to find out that earthworms are actually animals — the same kingdom as humans, cats, dogs, dolphins and spiders! Just as living things share a set of common characteristics, animals have key characteristics that can help you to decide whether a living thing is an animal or not.

What are the characteristics of living things? It even fools real ducks. To be classified as a living thing, an object must have all six of the following characteristics:. All living things detect changes in their environment and respond to them. What happens if you step on a rock? But what if you think you are stepping on a rock and actually step on a turtle shell? The turtle is likely to respond by moving—it may even snap at you! All living things grow and develop.

For example, a plant seed may look like a lifeless pebble, but under the right conditions it will grow and develop into a plant. Animals also grow and develop. Look at the animals in Figure below. How will the tadpoles change as they grow and develop into adult frogs? Tadpoles go through many changes to become adult frogs. All living things are capable of reproduction. Reproduction is the process by which living things give rise to offspring. Reproducing may be as simple as a single cell dividing to form two daughter cells.

Generally, however, it is much more complicated. Nonetheless, whether a living thing is a huge whale or a microscopic bacterium, it is capable of reproduction. All living things are able to maintain a more-or-less constant internal environment. However, viruses do not have a cellular structure, do not maintain homeostasis, and cannot reproduce on their own.

Because they lack the ability to maintain homeostasis and lack cellular organization, viruses are not considered cells. Viruses are instead referred to as particles. Virus particles are enclosed within a protein shell called a capsid. Genetic information is contained within the capsid and is needed for viral replication. Viruses cannot replicate themselves. Some viruses, called retroviruses, contain a single strand of RNA instead of DNA and must incorporate their genetic material into the host cell genome in order to reproduce.

Sometimes, pieces of viral genome remain in the host genome after infection. These viruses are known as endogenous retroviruses. Most viruses are small, but some viruses are relatively large, with even more genetic material than bacteria which do have cellular organization. Opinions still differ as to whether viruses are truly alive, and scientists continue to debate whether viruses should be acknowledged as living things.

However, there is little doubt among scientists that viruses are an important part of the microbial biota and that viruses have the ability to affect living organisms on this planet. Indeed, viruses are the most abundant organisms in the ocean and make up most of the genetic diversity. Marine viruses play a major role in biogeochemical cycling in the ocean and can influence the community composition of marine organisms. Most living things are composed of cells that have the ability to perform many different types of functions Fig.

A cell is defined as the basic unit for an organism that is able to maintain homeostasis. One way to understand cells is to compare them to rooms in a house. Every cell has an outer cell membrane that separates it from other cells nearby just as a room has walls to separate it from other rooms inside a house.

Most cells contain genetic information to create an entire new organism and also contain the cellular machinery to reproduce.

Just as some houses have only one room, some organisms are composed of only one cell. Such one-celled organisms are called unicellular or single-celled. They tend to be very small—often only visible through a microscope. The term microbe is also used to describe these single-celled microorganisms.

Figure 6. All molecules, including this DNA molecule, are composed of atoms. Some cells contain aggregates of macromolecules surrounded by membranes; these are called organelles.

Organelles are small structures that exist within cells. Examples of organelles include mitochondria and chloroplasts, which carry out indispensable functions: mitochondria produce energy to power the cell, while chloroplasts enable green plants to utilize the energy in sunlight to make sugars. All living things are made of cells; the cell itself is the smallest fundamental unit of structure and function in living organisms.

This requirement is why viruses are not considered living: they are not made of cells. To make new viruses, they have to invade and hijack the reproductive mechanism of a living cell; only then can they obtain the materials they need to reproduce.

Some organisms consist of a single cell and others are multicellular. Cells are classified as prokaryotic or eukaryotic. Prokaryotes are single-celled or colonial organisms that do not have membrane-bound nuclei or organelles; in contrast, the cells of eukaryotes do have membrane-bound organelles and a membrane-bound nucleus. In larger organisms, cells combine to make tissues , which are groups of similar cells carrying out similar or related functions.

Organs are collections of tissues grouped together performing a common function. Organs are present not only in animals but also in plants. An organ system is a higher level of organization that consists of functionally related organs. Mammals have many organ systems. For instance, the circulatory system transports blood through the body and to and from the lungs; it includes organs such as the heart and blood vessels.

Organisms are individual living entities. For example, each tree in a forest is an organism. Single-celled prokaryotes and single-celled eukaryotes are also considered organisms and are typically referred to as microorganisms.

All the individuals of a species living within a specific area are collectively called a population. For example, a forest may include many pine trees. All of these pine trees represent the population of pine trees in this forest. Different populations may live in the same specific area.