Answer:
mutation and sexual reproduction
Explanation:
Genetic variation within a population occurs via mutation and sexual reproduction, and can be measured using average heterozygosity. Genetic variation between populations is called geographic variation.
The answer is b. This can be remembered if you know that photosynthesis creates oxygen. Just remember that 'phytoplankton' starts with 'ph' just like 'photosynthesis', and you'll know that phytoplakton also create oxygen.
Answer:
Cells need energy or ATP to keep us alive. We also need it to keep our hearts pumping.
Explanation: