A supernova is a large explosion that takes place at the end of a star's life cycle. Although supernovas only burn for a short amount of time, they can tell scientists a lot about the universe.

photosynthesis makes the glucose that is used in cellular respiration to make atp. the glucose is then turned back into carbon dioxide, which is used in photosynthesis. while water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water.

1) a giant star is a star with a radius much larger than that of our sun (even hundreds of times bigger). they can be either blue giants or red giants: in the first case, the surface temperature is very high, higher than that of the sun, while in the second case the surface temperature can be lower than that of the sun. the same applies to the mass: blue giants are very massive stars, burning quickly their nuclear fuel, while red giants can have small masses (a little bit bigger than that of our sun).

2) we can find giant stars in the upper part of the hr diagram, blue giants will be on the upper left corner since they have high luminosity and high temperature, while red giants will be on the upper right corner, having high luminosity but low temperature.

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