Staying Alive

Properties used to determine living vs. nonliving include observable qualities.
Nonliving things can mimic some characteristics of living things but do not possess all.

Require food for growth and energy (carbohydrates as fuel).
Water is essential; about two-thirds of the body is water, crucial for chemical processes.
Other important chemicals: fats (energy storage), proteins (body repair and function), minerals, vitamins.

Living things need appropriate temperature ranges for life processes (homeostasis).

Organisms need sufficient space for resources like air, water, food, and shelter to survive.

Living things exhibit a set of characteristics that differentiate them from nonliving things, which can sometimes mimic these traits.
Properties used to determine living versus nonliving include observable qualities such as growth, reproduction, response to stimuli, and metabolic processes.
Nonliving things do not possess a cellular structure, cannot reproduce or grow autonomously, and lack the ability to carry out metabolic reactions necessary for life.

Made of one or more cells (the basic unit of life): Living organisms can be unicellular (like bacteria) or multicellular (like humans and plants), where complex systems operate through cellular organization.
Require energy: Organisms must obtain energy to sustain life processes; plants do so via photosynthesis, which converts sunlight into chemical energy. Animals, in contrast, obtain energy by consuming other organisms.
Use food and excrete waste: Metabolic processes such as digestion and respiration allow organisms to utilize nutrients and eliminate waste, ensuring the maintenance of internal balance.
Must be adapted to their environment: Adaptations are traits developed over time that enhance an organism’s chances of surviving and reproducing in its specific habitat, reflecting natural selection.
Respond to environmental changes: Living organisms interact with their surroundings and exhibit responses to changes in stimuli, such as light, temperature, and touch, an essential aspect of survival.
Reproduce organisms of their kind: Living organisms can reproduce sexually or asexually to produce offspring, allowing for genetic variation or cloning, respectively.
Grow and develop over a lifespan: All living things undergo growth and development, following specific genetic instructions that guide their transformation from one life stage to another.

Require food for growth and energy: Living organisms need carbohydrates and fats as fuel sources for energy, with carbohydrates typically being the primary source.
Water is essential: About two-thirds of the body's composition is water, critical for various biochemical reactions and maintaining homeostasis. It acts as a solvent for nutrients and waste products.
Other important chemicals: In addition to carbohydrates, fats, and water, organisms require proteins for body repair and function, as well as various minerals and vitamins essential for metabolic processes.

Most organisms require oxygen to survive: Oxygen plays a pivotal role in cellular respiration, where cells convert nutrients into energy.
Oxygen is crucial for energy production: The biochemical pathways that generate ATP (adenosine triphosphate) rely heavily on the availability of oxygen, especially in aerobic organisms.

Living things need appropriate temperature ranges: Each species has a specific range of temperature that it can tolerate, which is vital for maintaining homeostasis and facilitating enzymatic reactions essential for life processes. Extreme temperatures can denature proteins and disrupt metabolic functions.

Organisms need sufficient space for resources: Living entities require enough physical space to ensure access to vital resources such as air, water, food, and shelter, influencing their survival and reproduction in a habitat. Densities that are too high can lead to competition, stress, and decreased survival rates in populations.