Scientists believe that the direction birds go when migrating is guided in part by i) the stars in the night sky ii) the sun during the day iii) the magnetic field of the earth

All of them

Explanation:

answer by yourhope:

hi! : )

in which structure in the nucleus are ribosomes made?

b) nucleolus!

: )

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.