|Topics||Capillaries, Cell Division, Cerebrum, Compound, Convection, Geologic Time Scale, Minerals, Respiration, Stratosphere, Stratus Clouds|
Capillaries are small thin-walled vessels that permit the exchange of oxygen, carbon dioxide, nutrients, and waste between blood and the body's cells. This process of exchange is called diffusion.
Cell division is the process by which cells replicate genetic material in the nucleus. Cell division consists of several phases:
|interphase||chromosomes replicate into chromatids and the cell grows|
|prophase||chromatids pair up|
|metaphase||paired chromatids move to opposite sides of the cell|
|anaphase||cell elongates and nucleus begins to separate|
|telophase||separation of nucleus is complete resulting in two new nuclei|
|cytokinesis||cytoplasm and cell membranes complete their separation resulting in two separate cells|
The cerebrum is the major part of the brain and is responsible for the main senses (thinking, hearing, seeing).
A compound is a substance containing two or more different chemical elements bound together by a chemical bond. In covalent compounds, electrons are shared between atoms. In ionic compounds, one atom borrows an electron from another atom resulting in two ions (electrically charged atoms) of opposite polarities that then become bonded electrostatically.
Convection is the transfer of heat by the circulation or movement of the heated parts of a liquid or gas. Examples of heat transfer by convection include water coming to a boil on a stove, ice melting, and steam from a cup of coffee.
The Earth is approximately 4.6 billion years old and its history is divided into time periods based on the events that took place and the forms of life that were dominant during those periods. The largest graduation of time is the eon and each eon is subdivided into eras, eras into periods, periods into epochs, and epochs into ages.
Small quantities of certain minerals like iron, calcium, magnesium, and salt are important for nutrition and health.
The respiratory system manages respiration which is the process by which blood cells absorb oxygen and eliminate carbon dioxide.
The stratosphere is just above the troposphere and is stratified in temperature with warmer layers higher and cooler layers closer to Earth. This increase in temperature is a result of absorption of the Sun's radiation by the ozone layer.
Clouds are categorized based on their shape, size, and altitude. Stratus clouds are low-altitude clouds characterized by horizontal layering with a broad flat base. When stratus clouds occur on the ground the result is fog.