Both. You can use it as singular or plural.
Answers: 1 .The difference in the brightness of two stars with the same surface temperature is attributable to their sizes.( last choice)
2.Most responsible for the formation of a star is gravitational force.(second choice )
3. Blue ( last choice)
4.
A spinning neutron star that appears to give off radio wave pulses is called a pulsar ( third choice)
5.Greater redshifts in the spectra of galaxies indicate faster speeds ( first choice)
Rapid environmental changes can cause:
1) Species can become vulnerable to extinction.
2) A decrease or increase of populations.
3) Diversity of species.
Answer: amino acids
A mutation is a single or multiple event which brings a change in a genetic material of the organisms. A mutation will alter a DNA base pair that causes deletion or substitution of one amino acid in a protein encoded by a gene.
The precambrian era makes up about 90% of the earths history, but there was little to no living organisms at the time other than microscopic ones. The first eukaryotes were found in the cambrian period after the precambrian period, not only that but at the end of the precambrian era in the Proterozoic era there was a mass extinction of about 70-80% of all living organisms
