How does an atom become a positive ion? A- It loses an electron,
B- It gains an electron,
C- It gains a neutron,
D- It loses a neutron

Which of the following terms describe a liquid molecule that has only single bonds between its carbon atoms

Use the phylogenetic tree to the right to determine which statement below is true. organisms a and f are not related. organism e is more closely related to organism b than organism f. organisms c and d are more closely related than organisms a and b. phylogenetic trees

Which of the following is a reason why early living organisms on earth could not have survived on the surface? 1. the lack of an ozone layer 2. the lack of oxygen in the atmosphere 3. the fact that these organisms were single-celled