Biology Basics

Sorted by:  

Animal Movement with Friction and Gravity

Every type of locomotion, movement from one place to another, requires animals to use energy to overcome the forces of friction and gravity that would otherwise hold them to Earth. [more…]

Biology Basics: Bones and Joints

Joints are structures where two bones are attached. Movable or synovial joints allow bones to move relative to each other. In many areas of the body, strong, fibrous connective tissues called [more…]

How Biologists Classify Life

The figure here represents biologists’ current understanding of the tree of life — the phylogenetic tree that shows relationships among all organisms on Earth. Each of the main branches on the family tree [more…]

Action Potential of Neurons

When a neuron is inactive, just waiting for a nerve impulse to come along, the neuron is polarized —that is, the cytoplasm inside the cell has a negative electrical charge, and the fluid outside the cell [more…]

Biology Basics: Phylogenetic Trees

You can interpret the degree of relationship between two organisms by looking at their positions on a phylogenetic tree.

Phylogenetic trees not only show how closely related organisms are but also help [more…]

How Plants Take Elements from the Soil

Plants get all the carbon, hydrogen, and oxygen they need from carbon dioxide and water, which they use to build carbohydrates during photosynthesis. To build other kinds of molecules they also need elements [more…]

Nervous Systems of Animals

Animals are the only living things on Earth with complex nervous systems that first receive and interpret sensory signals from the environment and then send out messages to direct the animal’s response [more…]

Support from Skeletons and Bones

Skeletons give muscles something to pull against; support the body’s weight; store minerals like calcium and phosphorus; and produce blood cells in the bone marrow. However, not all animals have the same [more…]

Animal Ingestion and Digestion

All animals need to break down food molecules into smaller pieces so they can circulate them around their bodies to all their cells. Their cells take in small food molecules and use them as material for [more…]

Biology Basics: Relationships of Organisms

Biologists draw phylogenetic trees to show the relationships of organisms within a group, much like you’d draw a family tree to show the relationships among your parents, grandparents, and other family [more…]

Discover the Power of DNA Technology

At the heart of a revolution in our understanding of life on Earth is the ability to go to the source — DNA — and directly read the genetic code. Over the past 30 years, this revolution has been taking [more…]

How Scientists Cut DNA with Restriction Enzymes

Scientists use restriction enzymes to cut DNA into smaller pieces so they can analyze and manipulate DNA more easily. Each restriction enzyme recognizes and can attach to a certain sequence on DNA called [more…]

How to Define Biological Evolution

Biological evolution refers to the change of living things over time. Charles Darwin introduced the world to this concept in his 1859 work, On the Origin of Species. [more…]

Biology Basics: Natural Selection Outcomes

The two most extreme outcomes of natural selection for species are extinction and speciation. Natural selection may cause populations of species to change, but exactly how they change depends on the specific [more…]

What Evidence Supports the Theory of Evolution?

Since Darwin first proposed his ideas about biological evolution and natural selection, different lines of research from many different branches of science have produced evidence supporting his belief [more…]

Biology Basics: Ecosystems

Life thrives in every environment on Earth, and each of those environments is its own ecosystem, essentially a little machine made up of living and nonliving parts that interact with one another in a particular [more…]

Biology Basics: Population Ecology

Population ecology is the branch of biology that studies the structures of populations and how they change. The unique thing about population ecologists is that they study the relationships within ecosystems [more…]

Biology: How to Track Changes in Populations

Population dynamics are changes in population density over time or in a particular area. Primarily, populations increase because of births (natality) and decrease because of deaths [more…]

Biology Basics: Interaction among Species

Not all the organisms in a given biological community are the same. In fact, they’re often members of different species (organisms that can’t sexually reproduce together and produce fertile offspring). [more…]

Biology Basics: Matter Cycling within Ecosystems

Organisms in biological ecosystems connect to one another through their need for matter as well as energy. Every organism needs molecules like proteins, carbohydrates, and fats to provide the raw building [more…]

How Biologists Read a Gene with DNA Sequencing

DNA sequencing, which determines the order of nucleotides in a DNA strand, allows scientists to read the genetic code so they can study the normal versions of genes. It also allows them to make comparisons [more…]

How Biologists Separate Molecules with Gel Electrophoresis

Scientists use gel electrophoresis to separate molecules based on their size and electrical charge. Gel electrophoresis can separate fragments of DNA that were cut with restriction enzymes, creating a [more…]

Glands and Hormones

In addition to the nervous system’s electrical signals, animals also regulate their bodies with chemical messengers called hormones. Endocrine glands produce the hormones and then release them into the [more…]

Adaptive Immunity

Your adaptive immunity gets its name because it adapts and changes, or adapts, as you go through life and are exposed to specific microbes that your innate defenses can’t fight. Your body’s innate defenses [more…]

Biology Basics: Pulmonary Circulation

Pulmonary circulation, the first pathway of your two-circuit circulatory system, brings blood to your lungs for oxygenation. Following is a rundown of how blood moves during pulmonary circulation. [more…]


Sign Up for RSS Feeds

Education & Languages