Frogs essays

Frogs essays A Frog is a small, tail less animal that has bulging eyes. Almost all frogs have long back legs. The strong hind legs make the frog able to leap farther than the length of its body. Frogs live on every continent except Antarctica, but tropical regions have the greatest number of species. Frogs are classified as amphibians. Most amphibians, including most frogs, spend part of their life as a water animal and part as a land animal. Frogs are related to toads, but are different from them in a few ways. The giant frog of west-central Africa ranks as the largest frog. It measures nearly a foot (30 centimeters) long. The smallest species grow only 1/2 inch (1.3 centimeters) long. Frogs also differ in color. Most kinds are green or brown, but some have colorful markings. Although different species may vary in size or color, almost all frogs have the same basic body structure. They have large hind legs, short front legs, and a flat head and body with no neck. Adult frogs have no tail, though one North American species has a short, tail like structure. Most frogs have a sticky tongue attached to the front part of the mouth. They can rapidly flip out the tongue to capture prey. Frogs have such internal organs as a heart, liver, lungs, and kidneys. Some of the internal organs differ from those of higher animals. A frog's heart has three chambers instead of four. And although adult frogs breathe by means of lungs, they also breathe through their skin. The eggs of different species vary in size, color, and shape. A jelly like substance covers frog eggs, providing a protective coating. This jelly also differs from species to species. Some species of frogs lay several thousand eggs at a time. But only a few of these eggs develop into adult frogs. Ducks, fish, insects, and other water creatures eat many of the eggs. Even if the eggs hatch, the tadpoles also face the danger of being eaten by larger wat...

The 7 Base Units of the Metric System

The 7 Base Units of the Metric System The metric system is a framework of units of measurement that has grown from its 1874 birth in a diplomatic treaty to the more modern General Conference on Weights and Measures, or CGPM (Conferà ©rence Gà ©nà ©rale des Poids et Measures). The modern system is properly called the International System of Units, or SI, an abbreviation from the French Le Systà ¨me International dUnità ©s. Today, most people use the names metric and SI interchangeably. The 7 Base Metric Units The metric system is the main system of measurement units used in science. Each unit is considered to be dimensionally independent of the others. These dimensions are measurements of length, mass, time, electric current, temperature, amount of a substance, and luminous intensity. Here are definitions of the seven base units: Length: Meter (m) The meter is the metric unit of length. Its defined as the length of the path light travels in a vacuum during 1/299,792,458 of a second.Mass: Kilogram (kg) The kilogram is the metric unit of mass. Its the mass of the international prototype of the kilogram: a standard platinum/iridium 1 kg mass housed near Paris at the International Bureau of Weights and Measures (BIPM).Time: Second (s) The basic unit of time is the second. The second is defined as the duration of 9,192,631,770 oscillations of radiation corresponding to the transition between the two hyperfine levels of cesium-133.Electric current: Ampere (A) The basic unit of electric current is the ampere. The ampere is defined as the constant current that, if maintained in two infinitely long straight parallel conductors with a negligible circular cross-section and placed 1 m apart in a vacuum, would produce a force between the conductors equal to 2 x 10-7 newtons per meter of length.Temperature: Kelvin (K) The Kelvin is the unit of thermodynamic temperature. It is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. The Kelvin scale is an absolute scale, so there is no degree.​ Amount of a Substance: Mole (mol) The mole is defined as the amount of a substance that contains as many entities as there are atoms in 0.012 kilograms of carbon-12. When the mole unit is used, the entities must be specified. For example, the entities may be atoms, molecules, ions, electrons, cows, houses, or anything else.Luminous Intensity: candela (cd) The unit of luminous intensity, or light, is the candela. The candela is the luminous intensity, in a given direction, of a source emitting monochromatic radiation of frequency 540 x 1012 hertz with radiant intensity in that direction of 1/683 watt per steradian. These definitions are actually methods to realize the unit. Each realization was created with a unique, sound theoretical base to generate reproducible and accurate results. Other Important Metric Units In addition to the seven base units, other metric units are commonly used: Liter (L) While the metric unit of volume is the cubic meter, m3, the most commonly used unit is the liter. A liter is equal in volume to one cubic decimeter, dm 3, which is a cube that is 0.1 m on each side.Angstrom (Ã…) One angstrom equals 10-8 cm or 10-10 m. Named for Anders Jonas Ã…ngstrom, the unit is used to measure the chemical bond length and electromagnetic radiation wavelength.Cubic centimeter (cm3) A cubic centimeter is a common unit  used to measure solid volume. The corresponding unit for liquid volume is the milliliter (mL), which is equal to one cubic centimeter.