What Makes a Thing “Living”? Biology is the many-faceted ✓ Solved

What makes a thing “living”? Biology is the many-faceted study of living things. But what, exactly, is a living thing? Some of our definition comes directly from the work of Pasteur, Mendel, and others. Their work demonstrated that life can come only from other life. This means that all living things must reproduce. They pass genetic information on to their offspring—and all living things do this with DNA. This genetic information helps determine the physical structure of the offspring. As Mendel and Morgan observed, an offspring’s physical structure can vary. This variation, sometimes called diversity, may have fortunate or unfortunate effects for the individual, but it helps the species survive.

If a given population has numerous variations in its gene pool, the population is more likely to have at least some members that can survive an environmental change. Over time, these individual variations accumulate, reshaping the population in new ways. This is the nature of evolution. Because the species can only continue living via reproduction, it is continuous over time. Living things also detect and respond to stimuli. A stimulus is a change, event, or substance that causes an organism to act. In animals and human beings, stimuli can be detected with eyes, ears, nose, touch, or taste buds. For example, you step outside and feel drops of rain on your head. You go back inside and get an umbrella. The raindrops are the stimulus detected by your sense of touch. Pain is another example of a stimulus. If you stub your toe, the pain causes you to move backward or flinch. Drugs, chemicals, and electricity can also be stimuli. The important factor is that stimuli provoke responses.

What else do all living things have in common? For every individual, from a bacterium to a blue whale, life begins and ends. In the stretch of time between those two phenomena, the living thing must, in essence, work to stay alive. Whether it feeds on insects or sunlight, every living thing must consume enough energy that its cells can carry out all their internal processes. These processes include building new cells for growth, removing dead cells and waste matter, and helping the individual reproduce. These processes are chemical; they depend on chemical reactions that can take place only under certain circumstances. Therefore, a living thing’s body must maintain those circumstances, often referred to as the life form’s internal environment. Maintaining that environment—working to live—is called homeostasis.

All living things do the following: they reproduce, pass along their traits through DNA, consume energy sources and expel waste products to maintain homeostasis, respond to their environments, respond to stimuli, change over time, differ as individuals while still being part of a species, and consist of biomolecules arranged into cells with specific internal structures and functions. In more complex life forms, these are organized into tissues and organs with definite structures and functions.

Using these criteria, let's compare a rock and a snail. Both contain large quantities of carbon and change over time—the rock may be weathered by its environment, but it does not respond to stimuli. A snail does respond to stimuli, such as the chemicals that identify the presence of a food source. If a predator is nearby, the rock is unaffected, but the snail’s instincts cause it to react. Similarly, while a rock may break into smaller pieces, it does not reproduce, eat, or produce waste. The snail must consume energy just to exist, as its body works continually to find food, process it into energy, survive environmental changes, and reproduce.

What if we compare the rock to a tree? Like a rock, a tree does not move on its own and does not stalk and eat its prey. However, a tree in the sun is metabolizing sunlight into energy and releasing oxygen as waste to maintain its internal functions. A tree grows or withers depending on its environment and responds to seasonal changes by budding new leaves or shedding the old ones. It also reproduces, hiding seeds in fruit, sending seeds spinning like a maple samara, encasing seeds in a cone like a pine, or sending out roots like an aspen. Thus, trees and snails share many characteristics, unlike rocks.

Biology encompasses an immense variety of life forms. All these life forms live on Earth and are interrelated. Over the past couple of centuries, people have begun recognizing the impact of environmental change on living things. Some environmental changes, like earthquakes or wildfires, are easy to observe, while others, such as chemical changes in oceans or atmospheric shifts, are subtle. A change in one species can cascade into another, as demonstrated when disease in frogs reduces bird populations that prey on them. Human activity also impacts environmental change, leading to discussions on the responsibility to reverse such changes. By observing our neighborhoods, we can note human effects on microclimates—homes providing habitats for spiders and buildings creating warm niches for lichen. These interactions underscore how living organisms shape environments and others' lives.

Paper For Above Instructions

Title: The Criteria of Life - Understanding Living Organisms

To understand what constitutes a living organism, we must define several key characteristics that differentiate living organisms from inanimate objects. As addressed above, living entities must exhibit reproduction, respond to stimuli, consume energy, maintain homeostasis, possess cellular organization, and adapt over time through evolution. This paper evaluates these characteristics in the context of broader biological principles.

The cornerstone of life is its origin and continuous cycle. As established by the works of scientists like Pasteur and Mendel, life perpetuates by reproduction, allowing genetic information to be passed through DNA. This mechanism not only ensures the survival of species but also promotes genetic diversity, which is crucial for adaptation and survival amidst changing environmental conditions.

A critical aspect of living organisms is their ability to respond to stimuli from their environment. For example, organisms detect changes through sensory inputs and respond to them appropriately. This responsiveness is vital for survival; for instance, when prey senses danger, it flees to avoid predation. Furthermore, even unicellular organisms demonstrate this ability, exhibiting movements toward nutrients or away from harmful substances.

Energy consumption is another integral aspect of life. All living things require energy to sustain bodily functions, whether through consumption of organic materials by animals or photosynthesis in plants. This energy sustains metabolic processes necessary for growth, maintenance, and reproduction, highlighting the dependency of life on external energy sources.

The regulation of internal conditions to maintain homeostasis is essential for optimal functioning. Homeostasis involves a variety of physiological processes that keep an organism's internal environment stable, despite external changes. For instance, when temperatures fluctuate, both animals and plants have mechanisms to regulate their internal conditions, ensuring survival during extreme weather.

Cellular organization stands as the basic unit of life. Living organisms are composed of cells—whether they are unicellular organisms like bacteria or multicellular organisms such as plants and animals. These cells work symbiotically, forming tissues, organs, and systems, each with specific functions that contribute to the organism's overall homeostasis and reproduction capabilities.

Additionally, all living organisms have the capacity to evolve over time. Through processes of natural selection, genetic mutations can lead to favorable traits that are passed on to future generations. This adaptability allows species to thrive in changing environments, contributing to biodiversity.

In contrasting living organisms with inanimate objects, it becomes evident that while rocks or minerals may change physically over time due to weathering or erosion, they do not possess the characteristics that define life. For instance, a rock does not replicate, consume energy, or exhibit cellular organization. On the contrary, organisms like snails and trees demonstrate vital responses to stimuli, engage in metabolic processes, and reproduce, underlining their classification as living entities.

Conclusively, characterizing living organisms involves a multi-faceted approach that considers the essential characteristics of life. Understanding these criteria shapes our interpretation of biological phenomena and fosters appreciation for the interdependent web of life surrounding us.

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