Answer:
A rock is a collection of minerals. In a cooling lava, mineral crystals do not have time to form and are very small. The chemical composition will be the same as if the magma cooled slowly. Existing rocks may be heated enough so that the molecules are released from their structure and can move around.
Explanation:
Answer:
Mitotic phase
Explanation:
Cell cycle is composed of interphase and mitotic phase. Interphase is aphase of cell preparation. It is subdivided into:
- G1 (gap 1 phase)-the cell grows and becomes larger
- S phase- replication of DNA, duplication of centrosomes
- G2 (gap 2 phase)-proteins and oranelles are made
Mitotic phase is phase of cell division, chromosomes are separated, daughter cell get identical sets of chromosomes. It is followed by cytokinesis-separation of cytoplasm. Stages of mitosis are:
- prophase-condensation of chromatin into chromosomes, the nuclear envelope breaks down, mitotic spindle formation
- metaphase-the chromosmes line up (metaphase plate)
- anaphase-the siste chromatides move toward opposite cell poles
- telophase-the nuclear envelope forms again, cell division is almost complete
Answer:
Graptolites lived from the Cambrian Period, about 510 million years ago, disappearing in the Carboniferous Period, around 320 million years ago.
hope this helps!
The Hertzsprung-Russell diagram is one of the most important tools in the study of stellar evolution. Developed independently in the early 1900's by Ejnar Hertzsprung and Henry Norris Russell, it plots the temperature of stars against their luminosity (the theoretical HR diagram), or the color of stars against their absolute magnitude
Depending on its initial mass, every star goes through specific evolutionary stages dictated by its internal structure and how it produces energy. Each of these stages corresponds to a change in the temperature and luminosity of the star, which can be seen to move to different regions on the HR diagram as it evolves. This reveals the true power of the HR diagram – astronomers can know a star’s internal structure and evolutionary stage simply by determining its position in the diagram.
The Hertzsprung-Russell diagram the various stages of stellar evolution. By far the most prominent feature is the main sequence (grey), which runs from the upper left (hot, luminous stars) to the bottom right (cool, faint stars) of the diagram. The giant branch and supergiant stars lie above the main sequence, and white dwarfs are found below it.