Introduction to Biology

Now, I'm making this page after a couple of pages even though I probably should've made it first. No hate please guys im sorry 😓

But anyway, let's start this lesson.

Biology is the study of life. But what is considered living in the first place? Living things are all so different - so how can we find similarities between every species on Earth? It might seem mindblowing, but all living things have seven shared characteristics:

• Order: All living things are highly organized. For example, cells are organized into tissues. Tissues are organized into organs. Organs are organized into organ systems.

• Response to environment: All living things respond to changes in their environments.

• Adapt to the environment: All living things adapt to their environment.

• Growth and development: All living things grow and develop.

• Reproduction: All living things must be able to reproduce.

• Energy use: All living things require energy to survive.

• Regulation (homeostasis): All living things have mechanisms in place to ensure their internal temperature stays constant.

Life is organized in many ways. Scientists need ways to put living creatures in categories so they can find patterns and links to species. The highest level of this organization is called domains. All life on Earth fits within three domains: bacteria, archaea, and eukaryota.

Bacteria are microorganisms. They are further divided into eubacteria and cyanobacteria.

Archaea are unicellular microorganisms that are commonly extremophiles, meaning they live in extreme conditions.

Both bacteria and archaea are prokaryotic. This means that their cells do not have nuclei inside them. I will explain nuclei in the cell organelles page, so be sure to check that one out.

Eukaryotes can be unicellular or multicellular. They are further divided into four kingdoms: animalia, fungi, protista, and plantae. Animalia consists of multicellular organisms, or well, animals (thats pretty wild). Fungi can either be unicellular or multicellular, but all fungi decompose dead organisms. Plantae consists of organisms that produce energy using photosynthesis. Protista is a kingdom of unicellular and multicellular organisms that don't really fit into any other categories 💀

Biology is a huge field, and it is super complex at all of its levels. Thus, the hierarchy of organization helps organize life into categories by scale. These categories are the following:

• Biosphere: All life and places where life exists on Earth. Ex) Anywhere you look that has life.

• Ecosystem: All living and nonliving components of an area. Ex) A rainforest.

• Community: All organisms in an ecosystem. Ex) A cherry tree with hummingbirds, insects, and microorganisms.

• Population: All individual organisms in a certain species. Ex) 45 catfish living in a pond.

• Organism: An individual living thing. Ex) A koi fish.

• Organs and Organ Systems: Body parts mean to perform a specific function. Several organs can collaborate in an organ system. Ex) The heart (organ) is part of the circulatory system (organ system).

• Tissue: A group of cells performing a function. Ex) Muscles are made of tissues.

• Cell: The fundamental unit of life. Ex) Many bacteria are made of only one cell.

• Organelle: A functional structure in a cell that is enclosed with a membrane. Ex) The nucleus.

• Molecule: A chemical structure consisting of 2 or more atoms. Ex) DNA.

Biology itself is also centered around five themes that are interwoven with each other:

1. Evolution: Evolution is "the process of change that has transforming life on Earth from its earliest forms to the vast array of organisms living today," according to the textbook I cited on the welcome page (PLEASE go buy it for yourself if you're interested - it's a truly amazing textbook). This is the core theme of biology. All living things evolve to their environments in order to survive successfully. This process occurs via natural selection, which I have explained a little later in this page.

2. Information Flow: Life depends on the flow of genetic information in your body to successfully create and maneuver living things, or even use signaling information to communicate between cells about internal regulation. This information is written in the form of deoxyribonucleic acid, or DNA (I have gone into more detail about DNA on the macromolecules page, so please check that out when you can), which provides all the instructions for all of a cell's functions. Long story short, by using four nucleotides (A, C, T, G) and putting them in specific orders, DNA is able to encode the precise information the body needs in genes - the discrete unit of inheritance. The genome is all of the genetic material in an organism, consisting of DNA, genes, and other elements that control the activity of those genes. This might seem confusing, so try to remember it like this: genes are segments of DNA, and all the DNA in an organism is the genome.

3. Relationship of Structure and Function: In order to successfully survive and reproduce, living things must have structures that enable them to perform the functions they need to perform. An example of a structure and function relationship is the wrist of the red panda. There is a structure called a false thumb that allows for the function of holding bamboo. If all of our structures had no function, they could get in the way and would be useless to our survival - hence the need for them to actually do useful things. I think adaptations, which I will talk about in a minute or so, are a great example of this and a factor in evolution.

4. Transfer and Transformation of Energy and Matter: Life depends on the energy and matter transfer and transformations between living creatures, nonliving things, and within living creatures in order to survive. For example, in an ecosystem, everyone has a role - they can either be producers or consumers. Producers use sunlight to create their own food while consumer get their energy from eating producers or other consumers. Energy changes from light energy to chemical energy, is transferred from producers to consumers, and transformed into thermal energy and released into the environment as heat. Matter, on the other hand, cycles through an ecosystem instead of escaping it. It goes from the air and soil to producers, from producers to consumers, from consumers to other consumers, from other consumers to decomposers, and then goes back to the air and soil.

5. Interactions Between and Within Systems: Living things depend on the organized interactions within themselves (in their cells, tissues and organs, and between their muscles and organ systems) and among themselves (food chains, evolution, etc) to effectively survive. Two fields of biology that branch from this theme are ecology and systems biology, which I will explain a little later in this page.

Evolution, the core theme, occurs through the process of natural selection, in which only the successful traits of species are passed down to their offspring. For example, (this is my favorite example, since I grew up hearing it), a long time ago, there was an ecosystem of birch trees and moths. The moths came in two colors - brown and white. However, since the trees were birch trees, most of the moths were white. But a factory was built nearby, and the smoke from its spires stained the birch trees black. Because the white moths were more visible to birds, tthey were all eaten, and only the brown moths could live long enough to reproduce. Soon, the whole species consisted of mostly brown moths - natural selection at its finest.

For a species to survive through natural selection and reproduce, it must have adaptations - or, body parts, abilities, and traits that animals have that give them an advantage to help them better survive in their environment. Adaptations vary slightly from individual to individual, and they can be passed down to offspring. Because of this, the animals with more successful adaptations are the ones that are able to pass them down, which is exactly what natural selection is: survival of the fittest. That implies that you would not survive, unfortunately... you're not Dwayne The Rock Johnson. Humble yourself.

Artificial selection is the manmade version of natural selection. It is a process by which humans control evolution in organisms by selectively choosing which ones to breed. Some examples of this are:

1. Only breeding pigs with long ears to ensure that more pigs with long ears are born.

2. Desiring thick, juicy corn, and therefore only breeding the most thick corn for this results.

3. Noting that people prefer brighter snakes as pets and only breeding the brightest snakes.

Hey, if you're interested in this stuff, you should study ecology. Ecology is the study of organisms and how they interact with their environments. For example, food chains are interactions between organisms within their environment. 

Systems biology is another field one might be interested in. Systems biology is an approach to scientists that helps them model the behavior of biological systems by analyzing the interactions between them. For example, there is a map of the interactions between over 2000 proteins in a fruit fly cell. If you're curious, you might end up making one like it yourself.

Oh well, that's all I have to say in this page. I'm looking forward to working more! Please check out the welcome page to see which pages are complete and which ones are in progress. I hope to see you in the next one!