Exam 5: Coping With Environmental Variation: Energy

During a dry period, a plant's rates of photosynthesis and transpiration both decrease. This suggests that the plant

Refer to the figure. showing the results of Bjorkman and colleagues' studies of plant responses to different light levels. The plants were reared at three different levels of light intensity: high (red line), medium (blue line), and low (green line). The acclimatized plants were then subjected to various light levels, and their ability to photosynthesize was measured. -What is the light compensation point for those plants that are acclimatized to high-intensity light?

The ratio of carbon-13 to carbon-12 in a sample of material from a C₃ plant is 122:10,000. The same ratio for the reference standard is 125:10,000. Delta (δ) is thus _______ per thousand.

Suppose you are studying a population of herbivores. The traditional food source for these herbivores is a small native plant species. In the last 200 years, the traditional food source of these herbivores was replaced by an invasive grass. The herbivores gained 5 calories of food from every 1 minute of grazing on the native plant, but gain only 3 calories of food from every 1 minute of grazing on the invasive grass. If you compared the current population of herbivores to the historical populations 200 years ago, which change would you be least likely to observe?

In which photosynthetic pathway are carbon dioxide uptake and the Calvin cycle separated in time?

The first organisms on Earth were most likely

As light increases, photosynthetic rates increase. The point at which photosynthetic rates level off is called the _______ point.

When you touch something hot, your hand becomes warm; this is an example of the transfer of which type of energy?

If photosynthesis had not developed on Earth, living organisms would have led a harsher existence because of

Refer to the table showing the oxygen and carbon dioxide concentrations of four different environments. In which environment would we expect photorespiration to be highest?

Which two pathways, which provide high concentrations of CO₂ to the Calvin cycle, also substantially reduce photorespiration?

As CO₂ concentrations continue to increase in our atmosphere, photorespiration rates are likely to _______, a change that should _______ the advantage C₄ plants have over C₃ plants.

Refer to the figure showing the CO₂ uptake in soybean leaves in response to increasing O₂ concentration for soybean leaves exposed to two different CO₂ levels. Based on the figure, the best explanation for the relationship of CO₂ uptake and O₂ concentration is that

To determine where plants obtain the raw materials needed for growth, van Helmont collected data on the growth of a willow tree for over 5 years. He measured the amount of soil in a pot, planted the tree in the soil, and then watered the tree with rainwater. After 5 years, he weighed the soil and the tree. He concluded that the tree did not gain its mass from the soil, but incorrectly concluded that the tree had gained its mass from the water. What are two critical problems with this study design? How could you redesign the study to fix these two study design problems?

Refer to the figure showing the results of Bjorkman and colleagues' studies of plant responses to different light levels. The plants were reared at three different levels of light intensity: high (red line), medium (blue line), and low (green line). The acclimatized plants were then subjected to various light levels, and their ability to photosynthesize was measured. At the light intensity of 500 μmol/m²/s, the plants that are light-limited are those that are acclimatized to

There are three basic photosynthetic pathways: C₃, C₄, and CAM. Briefly explain the likely reasons for the evolution of three different pathways rather than just one.

Suppose that the bottlenose dolphin population in Shark Bay, Australia (as discussed in the textbook) is completely exterminated by an illness. Another population of bottlenose dolphins that have had no contact with the infected individuals eventually moves into the bay. Would you expect these new dolphins to display tool use (use of a sponge)? If they didn't have the behavior would you expect them to display it at some point in the future? Why or why not?

Which of these organisms would be considered a true autotroph?

Refer to the figure. illustrating the effect of tissue temperature on photosynthetic rates in four different plant species. Which plant is most effective in photosynthesizing at tissue temperatures of 15°C?

Would bioremediation through the use of microorganisms be more efficient in cleaning up an oil spill during summer, when water temperatures are warm, or during winter, when water temperatures are cold? Why?