Stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime. Depending on the mass of the star, this lifetime ranges from only a few million years (for the most massive) to trillions of years (for the less massive), considerably more than the age of the universe. ^
Small, relatively cold, low mass red dwarfs burn hydrogen slowly and will burn for hundreds of billions of years
Massive hot supergiants will live for just a few million years.
A mid-sized star like the Sun will remain on the main sequence for about 10 billion years. Hope tis helps!!
Answer: it is difficult because it is necessary to understand some concepts used in a system. For example what is a boundary, and environment which can be positive or negative, etc. A sample could be the course OpenLearn that provides an example of Computing & IT.
Explanation:
Answer:
Na+ only
Explanation:
Depolarisation of membrane refers to the change in the resting membrane potential of the membrane of a cell which is usually -70mv to a more positive value.
This value changes when the positive ions move inside the cell which increases the positive charge inside the cell.
In the myocardial cell, the sodium ions move inside the cell which changes the potential towards the more positive side as a result of which the signals for contraction arises.
Thus, Na+ only is correct.
Answer:
B. similar to the cells just treated with the dye - 0% dead
Explanation:
According to this question, an experiment was set up in which kidney cells were treated with a chemical for different amounts of time. Hence, the independent/manipulable variable is the CHEMICAL.
Based on the observation of the group of cells, a cell that has been damaged by the chemical will appear pink when treated with dye while a cell treated with only due but no chemical will not appear pink.
A NEGATIVE CONTROL is the group in an experiment that is not treated with the independent variable i.e. doesn't receive experimental treatment. Since the independent variable in this experiment is the CHEMICAL, the negative control will be the group that doesn't receive the chemical treatment. Hence, the negative control is similar to the cells just treated with the dye - 0% dead
