Life - Wikipedia. Life is a characteristic distinguishing physical entities having biological processes, such as signaling and self- sustaining processes, from those that do not, either because such functions have ceased, or because they never had such functions and are classified as inanimate. Various forms of life exist, such as plants, animals, fungi, protists, archaea, and bacteria. The criteria can at times be ambiguous and may or may not define viruses, viroids, or potential artificial life as .
The first part of this book deals with the classification of the fungi. You can certainly ignore chapters 2-7, and move quickly to the more accessible and, to. Biology4Kids.com! This tutorial introduces species taxonomy. Other sections include animal systems, cells, vertebrates, and plants. Welcome to the next post in the A to Z Science series here at Inspiration Laboratories. C is for Classification! Classification or sorting activities are great for.
Biology is the primary science concerned with the study of life, although many other sciences are involved. The definition of life is controversial. The current definition is that organisms maintain homeostasis, are composed of cells, undergo metabolism, can grow, adapt to their environment, respond to stimuli, and reproduce. However, many other biological definitions have been proposed, and there are some borderline cases of life, such as viruses. Throughout history, there have been many attempts to define what is meant by . Modern definitions are more complex, with input from a diversity of scientific disciplines.
Life is a characteristic distinguishing physical entities having biological processes, such as signaling and self-sustaining processes, from those that do not, either.
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Biophysicists have proposed many definitions based on chemical systems; there are also some living systems theories, such as the Gaia hypothesis, the idea that the Earth itself is alive. Another theory is that life is the property of ecological systems, and yet another is elaborated in complex systems biology, a branch or subfield of mathematical biology. Abiogenesis describes the natural process of life arising from non- living matter, such as simple organic compounds. Properties common to all organisms include the need for certain core chemical elements to sustain biochemical functions. Life on Earth first appeared as early as 4. Earth 4. 5. 4 billion years ago. The mechanism by which life began on Earth is unknown, though many hypotheses have been formulated and are often based on the Miller–Urey experiment.
The earliest known life forms are microfossils of bacteria. In July 2. 01. 6, scientists reported identifying a set of 3.
LUCA) of all living organisms. To survive in most ecosystems, life must often adapt to a wide range of conditions.
Some microorganisms, called extremophiles, thrive in physically or geochemically extreme environments that are detrimental to most other life on Earth. Aristotle was the first person to classify organisms. Later, Carl Linnaeus introduced his system of binomial nomenclature for the classification of species. Eventually new groups and categories of life were discovered, such as cells and microorganisms, forcing dramatic revisions of the structure of relationships between living organisms. Cells are sometimes considered the smallest units and . There are two kinds of cells, prokaryotic and eukaryotic, both of which consist of cytoplasm enclosed within a membrane and contain many biomolecules such as proteins and nucleic acids.
Cells reproduce through a process of cell division, in which the parent cell divides into two or more daughter cells. Though currently only known on Earth, life need not be restricted to it, and many scientists believe in the existence of extraterrestrial life. Artificial life is a computer simulation or man- made reconstruction of any aspect of life, which is often used to examine systems related to natural life. Death is the permanent termination of all biological functions which sustain an organism, and as such, is the end of its life. Extinction is the process by which an entire group or taxon, normally a species, dies out. Fossils are the preserved remains or traces of organisms. Definitions. It is a challenge for scientists and philosophers to define life.
Life is considered a characteristic of something that exhibits all or most of the following traits. Living things require energy to maintain internal organization (homeostasis) and to produce the other phenomena associated with life. Growth: maintenance of a higher rate of anabolism than catabolism. A growing organism increases in size in all of its parts, rather than simply accumulating matter. Adaptation: the ability to change over time in response to the environment.
This ability is fundamental to the process of evolution and is determined by the organism's heredity, diet, and external factors. Response to stimuli: a response can take many forms, from the contraction of a unicellular organism to external chemicals, to complex reactions involving all the senses of multicellular organisms. A response is often expressed by motion; for example, the leaves of a plant turning toward the sun (phototropism), and chemotaxis.
Reproduction: the ability to produce new individual organisms, either asexually from a single parent organism or sexually from two parent organisms. These complex processes, called physiological functions, have underlying physical and chemical bases, as well as signaling and control mechanisms that are essential to maintaining life. Alternative definitions. From a physics perspective, living beings are thermodynamic systems with an organized molecular structure that can reproduce itself and evolve as survival dictates. One systemic definition of life is that living things are self- organizing and autopoietic (self- producing).
Variations of this definition include Stuart Kauffman's definition as an autonomous agent or a multi- agent system capable of reproducing itself or themselves, and of completing at least one thermodynamic work cycle. They are most often considered as just replicators rather than forms of life. However, viruses do not metabolize and they require a host cell to make new products. Virus self- assembly within host cells has implications for the study of the origin of life, as it may support the hypothesis that life could have started as self- assembling organic molecules. Biophysicists have commented that living things function on negative entropy. These systems are maintained by flows of information, energy, and matter.
Some scientists have proposed in the last few decades that a general living systems theory is required to explain the nature of life. Instead of examining phenomena by attempting to break things down into components, a general living systems theory explores phenomena in terms of dynamic patterns of the relationships of organisms with their environment.
In 1. 78. 5, he stated that the Earth was a superorganism and that its proper study should be physiology. Hutton is considered the father of geology, but his idea of a living Earth was forgotten in the intense reductionism of the 1. Specifically, he identified the . As Harold J. Morowitz (1. Robert Ulanowicz (2. A closely related approach to CSB and systems biology called relational biology is concerned mainly with understanding life processes in terms of the most important relations, and categories of such relations among the essential functional components of organisms; for multicellular organisms, this has been defined as .
The underlying order- generating process was concluded to be basically similar for both types of systems. Empedocles (4. 30 BC) argued that everything in the universe is made up of a combination of four eternal . All change is explained by the arrangement and rearrangement of these four elements. The various forms of life are caused by an appropriate mixture of elements. Like other ancient writers, he was attempting to explain what makes something a living thing. His explanation was that fiery atoms make a soul in exactly the same way atoms and void account for any other thing. He elaborates on fire because of the apparent connection between life and heat, and because fire moves.
This debate persisted throughout the ancient world. Atomistic mechanism got a shot in the arm from Epicurus .. The choice seems simple: either show how a structured, regular world could arise out of undirected processes, or inject intelligence into the system.
Hankinson, Cause and Explanation in Ancient Greek Thought. The mechanistic materialism that originated in ancient Greece was revived and revised by the French philosopher Ren. In the 1. 9th century, the advances in cell theory in biological science encouraged this view. The evolutionary theory of Charles Darwin (1. The application of hylomorphism to biology was important to Aristotle, and biology is extensively covered in his extant writings. In this view, everything in the material universe has both matter and form, and the form of a living thing is its soul (Greek psyche, Latin anima). There are three kinds of souls: the vegetative soul of plants, which causes them to grow and decay and nourish themselves, but does not cause motion and sensation; the animal soul, which causes animals to move and feel; and the rational soul, which is the source of consciousness and reasoning, which (Aristotle believed) is found only in man.
Aristotle believed that while matter can exist without form, form cannot exist without matter, and that therefore the soul cannot exist without the body. Thus, the whiteness of the polar bear's coat is explained by its purpose of camouflage. The direction of causality (from the future to the past) is in contradiction with the scientific evidence for natural selection, which explains the consequence in terms of a prior cause.
Biological features are explained not by looking at future optimal results, but by looking at the past evolutionary history of a species, which led to the natural selection of the features in question. Typically, the idea was that certain forms such as fleas could arise from inanimate matter such as dust or the supposed seasonal generation of mice and insects from mud or garbage. It was decisively dispelled by the experiments of Louis Pasteur in 1.
Francesco Redi. This originated with Georg Ernst Stahl (1. It appealed to philosophers such as Henri Bergson, Friedrich Nietzsche, and Wilhelm Dilthey. This was disproved in 1. Friedrich W. It is of historical significance because for the first time an organic compound was produced in inorganic reactions.
Can you label the human skeleton? When you've finished move onto the animal skeletons.
Variation - Grouping Do you know which groups living things belong to? Look at the plants and animals as they go past. Can you drag them into the correct groups?
Magnets and Springs Magnets have north poles and south poles. These attract each other. But two north poles will repel each other, as will two south poles. When a spring is stretched or squashed, it creates a force. Earth, Sun and Moon What does a year look like in space? Find out more about the Earth, Moon and Sun.
The Earth travels around the Sun. The Moon travels around the Earth. Day and night are caused by the Earth spinning on its axis. There three sections as follows. Sorting plants and animals into distinct sets. Materials can be changed from one state to another by heating or cooling.
See what happens when you cool and heat water and ice. Try not to blow anything up!
Learn about : Material properties, Metals, Plastics, Glass, Wood and Fabrics. Teeth lesson outline. There are then three different habitats where food chains are constructed from a few of the organisms found there. Food Chains 6a lesson outline.
Changing State 5d lesson outline. There three sections are as follows.
Labelling a life cycle diagram of a flowering plant. Habitats 4b lesson outline. Light and shadows Find out why shadows change angle and size throughout the day.
Our sister site, everyschool. The 1. 70. 0+ links are sorted by subject > key stage > topic. Where possible they try to follow the relevant strategy, framework or scheme of work.