Biology: Characteristics and Organization of Life

• Biology studies living organisms and their environments.

Characteristics of Life

• Living organisms share characteristics such as being organized, acquiring materials and energy, maintaining homeostasis, responding to stimuli, reproducing, growing, and possessing an evolutionary history.

Levels of Organization

• Life is organized in a hierarchy of levels, ordered from smallest to largest/most complex.
• Atoms are the smallest particles of an element exhibiting its properties.
• Molecules consist of two or more atoms bonded together.
• Cells are the fundamental units of life, and the smallest structural and functional units of biological organization.
• Tissues are groups of similar cells performing a specific function.
• Organs are combinations of different tissues performing a common function.
• Organ systems are groups of related organs working together for a common purpose.
• Organisms are individual living things consisting of a collection of organ systems.
• Species include all similarly constructed organisms capable of interbreeding, sharing the same gene pool.
• A population consists of groups of the same species occupying a certain region.
• A community contains populations interacting with one another in the same environment.
• An ecosystem is a biological community together with its associated abiotic or physical environment.
• The biosphere includes the zones of air, land, and water on the Earth's surface where living organisms exist.

Materials and Energy

• All living organisms need materials and energy from an outside source to survive.
• Energy has the ability to do work and exists in potential and kinetic formats.
• Depending on the particular organism, the way that energy is obtained varies; humans and animals consume food.
• Food furnishes molecules of nutrients that can be used to construct larger nutrient compounds or be broken down to generate energy.
• Metabolism emcompasses all the chemical processes taking place within a cell or organism.
• The primary energy source for life on Earth is the energy that comes from the sun.
• Plants, algae, and some strains of bacteria can harness solar energy via photosynthesis to make chemical energy.
• These processes result in products like sugar, which can be used by organisms as food.

Homeostasis

• Homeostasis is the maintenance of stable internal conditions in a cell or organism via self-regulating mechanisms.
• Homeostasis is essential for the correct operation of cells and organisms.

Response to Stimuli

• This involves the capacity to initiate changes due to environmental stimuli, whether internal or external.
• Stimuli include loud noises leading to increased heart rate, increased blood pressure, or food leading to increased blood glucose.
• If a predator is spotted, one may remember the negative feelings and work to reduce the intensity of those feelings while trying to get away.

Reproduction and Development

• All residing organisms come from pre-existing cells/organisms and came from parent organisms.
• Reproduction entails the operations involved in producing new individuals of the exact same type.
• Genetic information gets transmitted to the next generation in this process.
• Growth refers to an increase in cell number and/or cell size.
• Development includes the series of phases in an organism's life, encompassing milestones like adolescence and senescence and potentially including repair after suffering damage.
• DNA is the genetic blueprint of life with instructions to synthesize deoxyribonucleic acid.
• Genes are units of information stored in DNA that specify instructions for particular traits.
• Mutations are variations in DNA sequences and serve as the cornerstone of evolutionary change.

Evolution

• Evolution is the process by which a population changes over time, not each individual organism. Natural selection is the mechanism that allows species to adapt to their surroundings for survival and procreation.
• Adaptation is an organism's structural, functional, or behavioral modification that makes it more suitable in its environment.

Human Relation to other Animals

• All life may be divided into three domains, Bacteria, Archaea, and Eukarya.
• Historically, the Eukarya domain was organized into a "kingdoms” structure, but advances in technology have reclassified the Eukarya based on DNA similarity to one of six supergroups.
• Bacteria and Archaea consist of prokaryotes, which a single celled organism that lacks a nucleus.
• Prokaryotes main characteristics are adaptability to different environments.
• Prokaryotes obtain energy either by absorbing from the environment or by creating it from sunlight and other ingredients.

Eukaryotes

• All cells have a nucleus, and some organisms in the Eukarya are multi-celled.
• The protist kingdom consists of single-celled multi-celled or eukaryote organisms.
• These orgnaisms are the very stem of the subsequent other four.
• Plants are plants, with multi-cellular eukaryote organisms to harness the power of photosynthesis to create energy.
• Fungi are multi-cellular eukaryotes that obtain energy by breaking down living material. Animalia are undergoing multi-cellular eukaryotes development.
• The completion of growth and their final form involves mobile organisms that have muscular and nervoius tissue.
• Some species take energy and ingest organic material.
• Vertebrates species boast the existence of internal support, while a wide collection of invertebrates do not contain such a support structure.
• There are the vertebrates as well, which includes, mammals, fish, etc.
• What sets humans apart from other mammals are factors of how we have incredibly complex brains, as well as ability to use various tools.

Cultural Heritage

• Culture includes inherited behaviors, values and tools/skills shared across a group of individuals.
• Current cultures highlight areas like arts, science and tech.

Humans as Members of the Biosphere

• Humans have interactions with all that involves biological elements and things that occupy it.
• Components include the consumption of plant and animal food.
• Mico-organisms consume and break down waste.
• Ecosystems ensure water intake, crop harvesting, and sustenance.
• Certain items in the ecosystem are used in medicine and drugs, while forests ensure that there is proper flood protection.
• They also create areas for recreational activities.

Science as a Process

• Science involves the constant and never-ending pursuit to understand the natural world.
• It includes observation, and factual information.
• Fat is objective.
• Scientific method entails new understandings, making observations, and hypothesis testing procedures.

Start with an Observation

• The realm entails both measurement and order.
• Natural events or phenomena can be understood via new observations.
• The first stage is observation, collecting insights, so models or hypothesis can be made.
• You often see how observations are influenced by instruments with which we create a hypothesis.

Develop a Hypothesis

• Scientists begin inductive reasoning practices through observations to better isolate a cohesive whole.
• You use logic that can arrive at a hypothesis where you can create experiments as a prediction.

Test the Hypothesis

• One can determine the final hypothesis with careful experimentations.
• Deduction assists as we test through observations and principles.

Data and Analysis

• You can collect results and measure the results, experimenting with the collected data through experiments and metrics.
• Data is put into graphs with some measured amount of control/experimental data.

Statistical Significance

• There has to be accounting of the results with high probability and low statistical significance.
• Often if you are looking results with 5% consideration, one has to consider the significance is on the lower end.

Develop a Conclusion

• The conclusion can derive from an experiment.
• One can test whether there are support structures depending test results and the experiment conclusion can lend itself well to the creation more hypotheses.

Scientific Theory

• Through a collection of observations, conclusions and experiments, various explanations for why the world works in a certain way can be formed.
• Theory are often put in terms of cells for all organisms, gene theory can be inherited, and evolutionary theories have to adapt.
• Often some theories can be supported for 100+ years, evolving to be a principle of law.
• In a controlled study one seeks to create a specific hypothesis, and that requires that it be testable with a specific experimentation design.