|Topics||Cambrian Period, Cell Division, Cytoplasm, Genes, Geologic Time Scale, Health Benefits of Vitamins & Minerals, Kidneys & Bladder, Moon, Secondary Consumers, Weight|
The Cambrian period is one of the most significant geological time periods. Lasting about 53 million years, it marked a dramatic burst of changes in life on Earth known as the Cambrian Explosion. It is from this period that the majority of the history of life on Earth, as documented by fossils, is found. Called the fossil record, the layering of these mineralized imprints of organisms preserved in sedementary rock have allowed geologists to build a historical record of plant and animal life on Earth.
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 nucleus of a eukaryotic cell contains the genetic material of the cell and is surrounded by cytoplasm which contains many organelles. These include:
|endoplasmic reticulum||helps synthesize proteins and fats|
|Golgi apparatus||prepare proteins for use|
|lysosomes||help the cell manage waste|
|centrosomes||guide cell reproduction|
The gene is the base unit of inheritance and is contained within DNA. A gene may come in several varieties (alleles) and there are a pair of alleles for every gene. If the alleles are alike, a person is homozygous for that gene. If the alleles are different, heterozygous.
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.
|Vitamin / Mineral||Sources||Health Benefits|
|Calcium||Dairy products (milk, yogurt, cheese), spinach.||Aids bone growth and repair, muscle function.|
|Iron||Red meat, beans, whole grains.||Allows red blood cells to transfer oxygen to body tissues.|
|Magnesium||Nuts, whole grains, green leafy vegetables.||Muscle, nerve, and enzyme function.|
|Potassium||Bananas, nuts, seeds.||Helps balance fluid levels in the body.|
|Vitamin A||Liver, milk, eggs, carrots.||Vision, immune system, cell growth.|
|Vitamin C||Green and red peppers, citrus fruits, broccoli.||Collagen formation, immune system function, antioxidant (helps protect cells from damage).|
|Vitamin D||Exposure to sunlight.||Helps calcium strengthen bones, muscle, nerve, and immune system function.|
Chemical waste like excess water, minerals, and salt are filtered from the blood by the kidneys and secreted into the urine. Urine is transported from the kidneys to the bladder through ureters.
Tides are caused by the gravitational interaction of Earth and the Moon.
Secondary consumers (carnivores) subsist mainly on primary consumers. Omnivores are secondary consumers that also eat producers. Examples are rats, fish, and chickens.
Weight is a force that describes the attraction of gravity on an object. Force is measured in newtons (N) with 1 N being the force required to impart an acceleration of 1 m/s2 to a mass of 1 kg.