The Precambrian era envelopes the major bulk of the history of the Earth, beginning from the creation of the planet approx 4.5 billion years ago and terminating with the origination of composite, multicelled forms of life approximately 4 billion years after.
The Precambrian refers to the earliest of the geologic ages that are signified by the distinct layers of sedimentary rock. The Earth was about more than six hundred million years old when life started. The planet had cooled down from its native molten state, creating a solid crust and oceans formed by water vapor in the atmosphere.
At about three billion years ago, the atmosphere of the Earth was virtually devoid of oxygen. At approximately 2.4 billion years ago, oxygen was discharged from the seas as a waste product of photosynthesis by cyanobacteria. The levels of the gas slowly raised, attaining about 1 percent around two billion years ago.
Approximately 800 million years ago, the levels of oxygen attained about 21 percent and started to breathe life into more composite species. The oxygen-rich ozone layer was also created, protecting the surface of the Earth from the harmful solar radiation.
Answer:
- <u>Huesos:</u> HUMERO, COSTILLAS, TIBIA, CUBITO, VERTEBRAS, CLAVICULA, ROTULA, FEMUR, OMOPLATOS, FALANGES.
- <u>Músculos: </u>DELTOIDES, BICEPS, ADUCTOR, PECTORAL, GEMELOS, DORSAL, CUADRICEPS, IZQUIOTIBIAL, CORAZON, ABDOMINAL.
- <u>Articulaciones: </u>CODO, MUÑECA, CADERA, TOBILLO, HOMBRO, CRANEO.
Explanation:
Los huesos son órganos que tienen la función de dar estructura, protección y soporte al cuerpo. A los huesos se le unen los músculos, los cuales hacen que los huesos se muevan al contraerse estos. Las articulaciones unen los huesos entre sí y permiten junto con los músculos el movimiento del cuerpo y de sus diferentes partes.
Answer:
an experiment
Explanation: Any experiment you do to benefit the world in the name of science
Answer:
A. dihybrid crosses
Explanation:
A dihybrid cross can be defined as a mating experiment between two lines/varieties/organisms that differ in two phenotypic traits. By using pea plants, Mendel performed dihybrid crosses in order to analyze the mode of inheritance of both phenotypic traits at the same time. From these mating experiments, Mendel observed that the inheritance factors (nowadays called genes) sorted independently from one another in the next generation, which is called the principle/law of Independent Assortment.
Answer:
Test Variable (independent variable)
Explanation:
X is always the independent variable/time. Test grades is dependent because it's the outcome. Trust me I took the test.