living organisms essay

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Biology library

Course: biology library   >   unit 1.

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What is life?

Introduction, properties of life, 1. organization, 2. metabolism, 3. homeostasis, 5. reproduction, 6. response, 7. evolution, is this the definitive list, separating living and non-living things, what counts as life is still being defined., what do you think, works cited:.

• Eveleth, R. "There Are 37.2 Trillion Cells in Your Body." Smithsonian.com. October 24, 2013. http://www.smithsonianmag.com/smart-news/there-are-372-trillion-cells-in-your-body-4941473/?no-ist .
• Koshland, D. E. "The Seven Pillars of Life." Science 295, no. 5563 (2002): 2215-216. http://dx.doi.org/10.1126/science.1068489 .
• Mullen, L. "Defining Life: Q&A with Scientist Gerald Joyce." Space.com. August 1, 2013. http://www.space.com/22210-life-definition-gerald-joyce-interview.html .

References:

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What makes something living?

All living organisms share several key characteristics or functions: order, sensitivity or response to the environment, reproduction, adaptation, growth and development, homeostasis, energy processing, and evolution. When viewed together, these characteristics serve to define life. Different sources may use slightly different terms to describe these characteristics, but the basic ideas are always present.

Organisms are highly organized, coordinated structures that consist of one or more cells. Even very simple, single-celled organisms are remarkably complex: inside each cell, atoms make up molecules; these in turn make up cell organelles and other cellular inclusions. In multicellular organisms, such as the toad seen in Figure 1, similar cells form tissues. Tissues, in turn, collaborate to create organs (body structures with a distinct function). Organs work together to form organ systems.

In this class, we will be focusing on how cells function, so we will be concentrating on biological molecules, how they make up cells, and how those cells function.

Sensitivity or Response to Stimuli

Organisms respond to diverse stimuli. For example, plants can bend toward a source of light, climb on fences and walls, or respond to touch (Figure 2). Even tiny bacteria can move toward or away from chemicals (a process called chemotaxis ) or light ( phototaxis ).

Reproduction

Single-celled organisms reproduce by first duplicating their DNA, and then dividing it equally as the cell prepares to divide to form two new cells. Multicellular organisms often produce specialized reproductive germline (reproductive) cells that will form new individuals. When reproduction occurs, DNA is passed from the organism to that organism’s offspring. DNA contains the instructions to produce all the physical traits for the organism. This means that because parents and offspring share DNA ensures that the offspring will belong to the same species and will have similar characteristics, such as size and shape.

Growth and Development

All living things increase in size and/or change over their lifespan. For example, a human grows from a baby into an adult and goes through developmental processes such as puberty. Organisms grow and develop following specific instructions coded for by their genes (DNA). These genes provide instructions that will direct cellular growth and development, ensuring that a species’ young will grow up to exhibit many of the same characteristics as its parents, like the puppies seen in Figure 3.

Homeostasis and Regulation

In order to function properly, cells need to have appropriate conditions such as proper temperature, pH, and appropriate concentration of diverse chemicals. These conditions may, however, change from one moment to the next. Organisms are able to maintain internal conditions within a narrow range almost constantly, despite environmental changes, through homeostasis (literally, “steady state”)—the ability of an organism to maintain constant internal conditions. For example, an organism needs to regulate body temperature through a process known as thermoregulation. Organisms that live in cold climates, such as the polar bear (Figure 4), have body structures that help them withstand low temperatures and conserve body heat. Structures that aid in this type of insulation include fur, feathers, blubber, and fat. In hot climates, organisms have methods (such as perspiration in humans or panting in dogs) that help them to shed excess body heat.

Even the smallest organisms are complex and require multiple regulatory mechanisms to coordinate internal functions, respond to stimuli, and cope with environmental stresses. Two examples of internal functions regulated in an organism are nutrient transport and blood flow. Organs (groups of tissues working together) perform specific functions, such as carrying oxygen throughout the body, removing wastes, delivering nutrients to every cell, and cooling the body.

Energy Processing

All organisms use a source of energy for their metabolic activities. Some organisms capture energy from the sun and convert it into chemical energy in food (such as grass and bacteria that can perform photosynthesis); others use chemical energy in molecules they take in as food (such as the condor seen in Figure 5).

Unless otherwise noted, images on this page are licensed under CC-BY 4.0  by  OpenStax .

Text adapted from: OpenStax , Concepts of Biology. OpenStax CNX. May 25, 2017 https://cnx.org/contents/[email protected]:gNLp76vu@13/Themes-and-Concepts-of-Biology

Principles of Biology Copyright © 2017 by Lisa Bartee, Walter Shriner, and Catherine Creech is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.

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Different Ecosystems and Living Things Essay

Introduction, living and nonliving things, types of ecosystems.

An ecosystem is a community of living organisms that interact with nonliving elements in the same environment. Biotic and abiotic components of an ecosystem are interconnected through nutrient cycles and energy exchange. Studying and describing ecosystem processes helps to identify the most important species and expose underlying mechanisms. This essay will emphasize the significance of biodiversity and examine three different ecosystems. The characteristics of living and nonliving things will also be compared and contrasted.

From a biological standpoint, all living things display seven characteristics: movement, respiration, sensitivity, growth, reproduction, excretion, and nutrition (Starr, Taggart, & Evers, 2018). To clarify how these characteristics exactly apply to living organisms, a reference to an earthworm will be given. Earthworms contract circular and longitudinal muscles to move through the soil (movement) and escape the environment that poses a threat to their lives with the help of chemical-sensitive skin cells (sensitivity). This species feeds on manure, compost, fungi, and microorganisms (nutrition) and gets rid of the waste through the last body segment once everything is digested (excretion). The food supplies an earthworm’s body with energy-rich nutrients (respiration) and allows for a gradual growth up to one meter in length (growth). Earthworms are hermaphrodites but still have to mate to lay eggs (reproduction). Nonliving things might possess one or two of these characteristics but never display all of them.

Three notions are instrumental in understanding ecosystems: habitat, population, and community. Habitat is the living environment; the population is all the living organisms within a habitat, and community is the organisms that interact with each other (Starr et al., 2018). The descriptions of the three ecosystems below will focus on describing the habitat and the community. There are many more ecosystems in the world; however, those three were chosen for their striking differences.

Forest ecosystems . A forest is a terrestrial environment dominated by closely spaced trees that grow in a canopy. The members of each forest ecosystem community depend on each other for survival and can be assigned the following roles: producers, primary, secondary, and tertiary consumers, and decomposers. In a forest, producers are plants that can convert solar energy through photosynthesis. They usually grow in four levels (emergent, canopy, understory, and floor) with each level characterized by its access to sunlight. Primary consumers are herbivores and beasts of prey, for instance, for in the Amazon, it could be capybara and red howler monkey. Secondary and tertiary consumers feed on primary consumers and are typical carnivores. For instance, jaguars both prey on the primary (plant-eating birds) and secondary consumers (meat-eating caimans). Lastly, decomposers help dead plants and animals break down, returning the nutrients to the soil and letting plants, the producers, grow and prosper.

Desert ecosystems . Desert ecosystems are somewhat unique since the unusually dry climate made plants and animals evolve to survive in such harsh conditions. The defining factor that impacts relationships between all members and components is the limited amount of rainfall. The plant life is not as luscious as in a forest, but it exists. Such common desert plants as gourds, cacti, and dates store water, which helps primary consumers quench their thirst. Camel is a prime example of a primary consumer, feeding on grasses and low-growing shrubs. Secondary and tertiary consumers are foxes, hawks, snakes, owls, and roadrunners. Large decomposers typically prefer moist areas, so in a desert, this role is primarily played by bacteria.

Marine ecosystems . The marine ecosystem is an aquatic environment with high salt contents. Out of all the types of ecosystems on Earth, marine ecosystems are prevailing. As of now, scientists distinguish between six subtypes of marine ecosystems:

• Open marine ecosystems (open ocean and its upper layer);
• Ocean floor ecosystems;
• Coral reef ecosystems;
• Estuary (sheltered area of a river mouth);
• Saltwater wetland estuary (transition area between land and sea);
• Mangroves (saltwater swamps).

The unity and diversity of an ecosystem will further be explained using the example of coral reef ecosystems. These ecosystems are not homogenous: for instance, the Great Barrier Reef includes as many as fourteen subtypes, so the following statements are generalizations. Producers include zooxanthellae, seaweed, coralline algae, marine worms, algae, plankton, and sponges. Zooplankton, mollusks, starfish, and smaller fish are primary consumers while larger reef fishes such as parrotfish and surgeonfish are secondary consumers. Large organisms such as reef sharks feed on secondary consumers. Fan worms, snails, bristle worms, and bacteria decompose dead bodies to enrich the ocean soil with nutrients.

Ecosystems are interconnected communities within a particular habitat that include both living (growing, reproducing, digesting, excreting, and so on) and nonliving things. Each community is characterized by environmental factors such as climate and food chains consisting of producers, consumers, and decomposers. Regardless of the type, producers are typically plants, consumers are those feeding on plants and herbivore animals, and decomposers are organisms breaking down dead bodies.

Starr, C., Taggart, R., & Evers, C. (2018). Biology: The unity and diversity of life (15th ed.). Boston, MA: Cengage Learning.

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IvyPanda. (2022, January 15). Different Ecosystems and Living Things. https://ivypanda.com/essays/different-ecosystems-and-living-things/

"Different Ecosystems and Living Things." IvyPanda , 15 Jan. 2022, ivypanda.com/essays/different-ecosystems-and-living-things/.

IvyPanda . (2022) 'Different Ecosystems and Living Things'. 15 January.

IvyPanda . 2022. "Different Ecosystems and Living Things." January 15, 2022. https://ivypanda.com/essays/different-ecosystems-and-living-things/.

1. IvyPanda . "Different Ecosystems and Living Things." January 15, 2022. https://ivypanda.com/essays/different-ecosystems-and-living-things/.

Bibliography

IvyPanda . "Different Ecosystems and Living Things." January 15, 2022. https://ivypanda.com/essays/different-ecosystems-and-living-things/.

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1.7: Organization of Living Things

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Organization of Living Things. What does this mean?

We know it all starts with the cell. And for some species it ends with the cell. But for others, the cells come together to form tissues, tissues form organs, organs form organ systems, and organ systems combine to form an organism.

Levels of Organization

The living world can be organized into different levels. For example, many individual organisms can be organized into the following levels:

• Cell : Basic unit of structure and function of all living things.
• Tissue : Group of cells of the same kind.
• Organ : Structure composed of one or more types of tissues. The tissues of an organ work together to perfume a specific function. Human organs include the brain, stomach, kidney, and liver. Plant organs include roots, stems, and leaves.
• Organ system : Group of organs that work together to perform a certain function. Examples of organ systems in a human include the skeletal, nervous, and reproductive systems.
• Organism : Individual living thing that may be made up of one or more organ systems.

Examples of these levels of organization are shown in Figure below .

An individual mouse is made up of several organ systems. The system shown here is the digestive system, which breaks down food into a form that cells can use. One of the organs of the digestive system is the stomach. The stomach, in turn, consists of different types of tissues. Each type of tissue is made up of cells of the same type.

There are also levels of organization above the individual organism. These levels are illustrated in Figure below .

• Organisms of the same species that live in the same area make up a population . For example, all of the goldfish living in the same area make up a goldfish population.
• All of the populations that live in the same area make up a community . The community that includes the goldfish population also includes the populations of other fish , coral, and other organisms.
• An ecosystem consists of all the living things ( biotic factors ) in a given area, together with the nonliving environment ( abiotic factors ). The nonliving environment includes water , sunlight, soil, and other physical factors.
• A group of similar ecosystems with the same general type of physical environment is called a biome .
• The biosphere is the part of Earth where all life exists, including all the land, water , and air where living things can be found. The biosphere consists of many different biomes .

This picture shows the levels of organization in nature, from the individual organism to the biosphere.

Diversity of Life

Life on Earth is very diverse. The diversity of living things is called biodiversity . A measure of Earth’s biodiversity is the number of different species of organisms that live on Earth. At least 10 million different species live on Earth today. They are commonly grouped into six different kingdoms. Examples of organisms within each kingdom are shown in Figure below .

Diversity of life from Archaebacteria to Plants and Animals.

• Many individual organisms can be organized into the following levels: cells, tissues, organs, and organs systems.
• An ecosystem consists of all the populations in a given area, together with the nonliving environment.
• The biosphere is the part of Earth where all life exists.
• The diversity of living things is called biodiversity.

Making Connections

Explore more.

Use this resource to answer the following questions.

• Levels of Organization at utahscience.oremjr.alpine.k12...r/levelorg.htm.
• List the levels of organization, ranging from simplest to most complex.
• What are cells?
• What are tissues? What are the basic tissues in humans?
• What are organ systems?
• How many organ systems are in the human body?
• Organisms can carry out all basic life processes. Explain this sentence.
• Describe the levels of organization of a complex, multicellular organism such as a mouse, starting with the cell.
• Explain how a population differs from a community.
• What is an ecosystem?
• Give three examples of the nonliving environment.
• What is biodiversity?

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