Answer: CO2 levels are high in the first half of the year, low in the second half(but increasing on average over time)
SEE BELOW for the rest
Explanation:
concepts
photosynthesis uses light, CO2 and H2O to produce glucose and O2
Respiration uses glucose and O2 to produce CO2 and H2O and energy
Reasoning
this is northern hemisphere data. Winter and colder weather, and winter-deciduous trees reduce removal of CO2 from the atmosphere. The second half of the year is influenced by summer, with high growth rates and high CO2 uptake, reducing atmospheric levels
