All life has evolved from a single cell, which has since developed into more complex multicellular organisms over time. The biological complexity of an animal can be determined by a number of different characteristics.
Multicellular organisms can be arranged into four different levels of organisation: cells, tissues, organs and organ systems. These range from being the most simple to the most complex.
The cellular level of organisation includes cells, which are the smallest functioning units of an organism, performing a specific function. Porifera are diverse and composed of a loose aggregation of cells. The cell layers of these sponges are not considered to be ‘true’ tissues as there is no basement membrane or intercellular connections – the cells are relatively unspecialised. Sponges are considered to be paraphyletic and to represent the lineage, which is closest to multicellular organisms. This suggests that other animals have evolved and shared a common evolutionary ancestor with sponges.
The tissue level of organisation consists of a group of cells which are similar in function that work together for a specific activity. The higher the complexity of an organism, the more distinctive tissue layers it has. Radiata are an example of a group of organisms which have attained this level of organisation as their highest level. They are characterised by their radial symmetry – they have a top and bottom but no back or front.
The organ level of organisation is composed of
The levels consisted in this system would be a cell, tissue, organ, organ system, organism, and the organization of an organism would be a population, community, ecosystem, and finally to the biosphere. A chipmunk lies in the organism level of this structured system. A chipmunk falls in this category because it is alive and contains an organ system. This means that in the chipmunks body there are sets of organs operating to perform certain tasks. There are many major characteristics of life, and frankly, we share the same ones as chipmunks. A few of the 7 characteristic that we share are the ability to grow and change, reproduction, having a reaction to our environment, and a multitude of more correspondences. All in all, it is remarkable to examine the ways that chipmunks are connected with other organisms in the ecosystem based on their level of organization and characteristics of
2. Define multicellular organism - are those organisms containing more than one cell, and having differentiated cells that perform various functions.
According to Mattias Schleiden and Theodor Schwann the cell is the basic unit of life(Cell Theory- OI). Two common types of cells are the plant and animal cells. Although both kinds of cells share many similar, abundant structures, they also have varying descrepancies from cell to cell. Without a doubt, the nucleus is the most important organelle in the plant cell, even though, the lysosome is the most important structure in the animal cell.
3. Tissue level- Tissue are groups of similar cells that have a common function. The four basic tissue types:
consists of biological systems, that consist of organs, that consist of tissues, that consist of cells
In the Linnaean classification system, all organisms are placed in a ranked hierarchy. His system was one of small groups building into larger ones. The current groupings of organisms from largest to smallest are kingdom, phylum, class, order, family, genus, and species
Others were multicellular, and others had structures or organelles. It was hard to tell which one was which when it came to the
Now that we understand the properties of life and the composition of cells, we can focus on the architecture or formation in terms of basic anatomy and physiology as our second area of exploration. The two types of cells (prokaryotic and eukaryotic) defined before have a few common things such as Plasma membrane (similar to animal cells); Cell wall (similar to plant cells); and Ribosomes, the
Organism level states and organism is made of an organ system. “An organism is any living thing considered as a whole—whether composed of one cell, such as a bacterium, or of trillions of cells, such as a human. The human organism is a complex of organ systems, all mutually dependent on one another.” (Seeley, R., VanPutte, C., Regan, J., & Russo, A.
The cellular level are cells that are made up of molecules. The tissue level are tissues that consist of similar types of cells. The organ level are organ that are made up of different types of tissues. The organ system level which is the organ system that consists of different organs that work together closely. The last level is the organismal level which are human organisms that are made up of many organ systems.
Cells are the basic structural and functional unit of all living organisms. Cells are the smallest form of life of which all forms of life are composed of one or more cells. All cells come from pre-existing cells. Two different of cells exist: Prokaryotes and Eukaryotes. They are structurally and functionally different, but they share some properties.
Organelles are one of the most fascinating aspects of A-Level Biology and are one of the first things that convinced me that Biochemistry is what I wanted to pursue at the challenging level of university. I became interested in the topic of life at a cellular and molecular level during early GCSE studies in year nine. After coming across a detailed diagram of the human cell, which was a contrast to what I was being taught at the time. Detail is something that has always been important to me and is where my desire to understand this concept comes from. After learning in class that mitochondria used to be a separate organism I read "Mitochondria and the Meaning of Life" looking for some answers.
Sponges are considered part of the Animal Kingdom because sponges are multicellular. They are known be diploblastic, which means having two layers of cells. Adult Sponges, may have several cell layers, but originally, they all arise from the two layers that were present in the early embryo (Dawkins 2004). Most sponges are asymmetrical, however some of them show the radial symmetry (Dawkins 2004). Sponges do not have a coelom. A coelom is a cavity within the body in which the heart, intestines, kidney, lungs, etc., they are located, and it is sealed off from the outside world. The body cavity of sponges is large, and it is open to the outside world, also it’s enables the sponge to consume food (Dawkins 2004).
The levels of hierarchy of complexity are organism, organ system, organ, tissue, cells, organelles, molecules, and atoms. An organism is composed of organ systems. Organ systems are composed of organs. Organs are composed of tissues. Tissues are composed of cells. Cells are composed of organelles. Organelles are composed of molecules. Molecules are composed of atoms.
Eukaryotes come in two grades of organization: single-celled (protists) and multicellular (plants, animals, and fungi). The world today is full of complex multicellular plants and animals: how, why, and when did they evolve from protists?