Chapter 5

Imagine that black ash from multiple volcanic eruptions made photosynthesis impossible anywhere on Earth for many years. What would be the consequence to plants? To animals? To microbes?

In some ways, chlorophyll can be thought of as a solar panel like the ones used to generate electricity at power plants. Using terms such as granum, photosystem, \(A T P,\) and chlorophyll, explain this comparison.

Define these terms and arrange them from smallest to largest: thylakoid membrane; photosystem; chloroplast; granum; reaction center.

In the early 1600 s, a Flemish scientist monitored the weight of willow trees and their surrounding soil for 5 years. Because he had applied large amounts of water and the soil had lost little weight, he concluded (incorrectly) that plants grew solely by absorbing water. What is the actual source of the added biomass? Explain your answer.

In \(1771,\) Joseph Priestley found that if he placed a mouse in an enclosed container with a lit candle, the mouse would die. But if he also added a plant to the container, the mouse could live. Explain this observation.

In 1941 , biologists exposed photosynthesizing cells to water containing a heavy oxygen isotope, designated \(^{18}\) O. The "labeled" isotope appeared in the \(\mathrm{O}_{2}\) gas released in photosynthesis, showing that the oxygen came from the water. Where would the 180 have ended up if the researchers had used \(^{18} \mathrm{O}\) -labeled \(\mathrm{CO}_{2}\), instead of \(\mathrm{H}_{2} \mathrm{O} ?\)

Explain how \(C_{4}\) photosynthesis is based on a spatial arrangement of structures, whereas CAM photosynthesis is temporally based.

Listed here are three misconceptions about photosynthesis; explain why each statement is false. (a) Only plants are autotrophs. (b) Plants do not need cellular respiration because they carry out photosynthesis. (c) Chlorophyll is the only photosynthetic pigment.

Considering the requirements for photosynthesis, why can't most plants live on unbroken pavement or in bare sand?