Core Science Concepts: Earth, Life, and Data
Understanding Statistical Concepts
Scientists refer to a normal distribution or bell curve when data is grouped symmetrically around the mean.
Scientists calculate the mean by adding all the data points and dividing the sum by the number of data points (individuals).
The numerical ratio representing the chance of an event occurring, like winning the lottery, is called probability.
Scientific Models and Decision Making
Types of Scientific Models
Scientists use various types of models, including:
- Physical models
- Graphical models
- Conceptual models
- Mathematical models
Risk is defined as the probability of an unwanted outcome.
Scientific Decision-Making Steps
The steps scientists often use in a decision-making model are:
- Gather information
- Consider values
- Explore consequences
- Make a decision
If an individual makes a decision on an environmental issue based on statistical evidence presented by experts, they are primarily using the scientific value.
Earth’s Structure and Composition
Scientists use seismic waves to learn about the composition and physical properties of the Earth’s interior.
When discussing the crust, mantle, and core, we are referring to the Earth’s compositional layers.
The lithosphere is the rigid outer layer of the Earth, consisting of the crust and the upper part of the mantle.
Magma results from rock melting due to extreme heat, primarily in the lower mantle and upper asthenosphere.
Plate Tectonics and Earthquakes
Tectonic Plate Movement
Tectonic plates move relative to each other in several ways:
- Moving away from each other (divergent boundaries)
- Moving towards each other (convergent boundaries)
- Slipping past each other (transform boundaries)
- Moving over and under each other (subduction zones at convergent boundaries)
Tectonic plates are constantly moving because they rest on the asthenosphere, a semi-molten layer of the upper mantle composed of flowing rock (like very thick liquid magma).
Earthquakes usually occur along faults, which are often located at plate boundaries where plates are sliding relative to each other.
The tremendous forces exerted by the movement of tectonic plates can cause:
- Boundaries to collide or separate
- The formation of mountains
The Atmosphere and Weather Phenomena
A very important component in the atmosphere that serves to trap harmful UV rays from the sun is ozone (O3).
The atmosphere’s two primary components by volume are nitrogen (N2) and oxygen (O2).
Convection currents occur in the atmosphere because warm air is less dense than cooler air, hence it rises, while cooler, denser air sinks.
Energy is transferred from the sun to Earth primarily through radiation.
The two main factors responsible for precipitation falling as snow instead of rain are freezing temperatures (at cloud level and below) and appropriate atmospheric pressure conditions.
Greenhouse Gases
Four significant greenhouse gases include:
- Water vapor (H2O)
- Carbon dioxide (CO2)
- Methane (CH4)
- Nitrous oxide (N2O)
When energy from the sun heats water, causing it to turn into water vapor and rise into the atmosphere, this process is called evaporation.
Ecosystems, Evolution, and Adaptation
The Honey Island Swamp is an example of a complex ecosystem.
Ecosystem Components
Four essential components of most ecosystems are:
- Energy (usually from sunlight)
- Mineral nutrients
- Carbon dioxide
- Water
Charles Darwin was the scientist who proposed that the environment exerts a strong influence over which individuals survive to produce offspring (natural selection).
Natural selection is the process where individual organisms with genetic variations (mutations) that provide survival advantages are more likely to reproduce and pass those advantageous traits to their offspring.
Adaptation is a term describing a trait that increases fitness, often arising through the process of natural selection.
Evolution through natural selection typically occurs over generations; the time frame can vary greatly depending on the organism’s reproductive rate and the strength of selective pressures.
Artificial selection is a type of evolution driven by humans who select specific desirable traits for breeding organisms.
When a new strain of bacteria develops resistance due to repeated exposure to a particular antibiotic, this is referred to as antibiotic resistance.
Classifying Simple Organisms
A unique characteristic often associated with organisms classified as Archaebacteria is their ability to thrive in extreme environments; they are single-celled prokaryotes.
Eubacteria (often simply called bacteria) are among the most commonly found and diverse groups of organisms in the world.