Atmospheric levels of carbon dioxide have increased from $300$ parts per million (ppm) to almost $355$ ppm in recent years. What will be the effect of this increase on photosynthesis and growth in $C_3$ plants? In $C_4$ plants?

Are the light reactions necessary in the mesophyll cells of $C_4$ plants? Explain the reasons for your answer.

What are the products of the light reactions, and how are they used?

What is the relationship between the light reactions and the carbon dioxide–fixing reactions of photosynthesis?

Describe the location and function of the two systems of carbon dioxide fixation in $C_4$ plants.

How do chemoautotrophs obtain organic nutrients?

The curve in Figure $4.16$ shows the effect of temperature increase on the rate of photosynthesis in a typical $C_3$ plant. Construct and explain a curve showing the response of a $C_4$ plant to the same increase in temperature.

Completa esta parte del diálogo entre Julia y Luisa con la forma correcta del presente del verbo indicado.

• Julia: ¿(Navegar) ________ en la internet?

In what ways is photosynthesis important to humans?

How is light used in photosynthesis?

Describe the process of photorespiration. What is its effect on the rate of photosynthesis?

Why are chemoautotrophs rare among familiar organisms?

Develop a concept map showing how the environment influences the rate of photosynthesis.

Does the Calvin cycle operate in the dark? Explain.