The mass extinctions that occurred 250 million years ago and 65 million years ago may have been due to gradual process or Catastrophic events.
Meiosis creates 4 different cells they are not copied like mitosis
False, each sex cell has one allele so when it combines with the opposing sex cell (depending on the gender) it fills in the gap.
Plants produce oxygen this oxygen gas which is important part of our air is gas that plants and animals must have in order to stay alive when people breeze it's the auction that we take out of the air into our cells and blood is there taking into the alveoli and this is where gas exchange takes place all the o2 available for living organisms come from plants
Answer:
4 valence electrons
Explanation:
Because of the relative stability, these atoms often form covalent bonds rather than ionic bonds that need a charge. One example is Carbon. It has 4 valence electrons, so it can make a 4+ or a 4- charge.
