Question 1

As light increases, photosynthetic rates increase. The point at which photosynthetic rates level off is called the _______ point.
A) limitation
B) saturation
C) response potential
D) compensation

Accepted Answer

The saturation point is where the rate of photosynthesis no longer increases with additional light, as other factors become limiting.

Question 2

Which of these is the best example of acclimatization to light variation that is accomplished by morphological, rather than physiological means?
A) Plants in different climates have different forms of the same photosynthetic enzymes, according to which form operates best in the plant's particular environment.
B) Spearscale plants grown in different light environments vary in maximum net photosynthesis rate, nighttime respiration values, and light compensation points.
C) Unlike other plants, lichens in the Arctic can photosynthesize at temperatures close to freezing.
D) Golden banner plants adapt to varying light conditions by adjusting their number of chloroplasts and the thickness of their leaves.

Accepted Answer

Golden banner plants adjust their number of chloroplasts and leaf thickness, which are morphological changes, to adapt to varying light conditions.

Question 3

A plant living through a drought keeps most of its stomates closed. This results in a trade-off of physiological processes in which A) photosynthesis increases and energy accumulates in the leaf. B) water is conserved and energy accumulates in the leaf. C) CO₂ uptake and water loss both increase, but leaves are light-damaged. D) CO₂ uptake and water loss both decrease, but photosynthesis increases.

Accepted Answer

Closing stomates conserves water but limits CO2 uptake, reducing photosynthesis and energy accumulation.

Question 4

Refer to the figure showing acclimatization to two different growth temperature regimes from different populations of a shrub occurring in the Mojave Desert and in cool coastal zones in California. The two temperatures regimes used are representative of the two habitats.
 Of the four temperature curves in the two populations, which combination appears least able to acclimate to the given temperature regime?
A) Desert population at the 23°C day/18°C night regime
B) Desert population at the 43°C day/30°C night regime
C) Coastal population at the 23°C day/18°C night regime
D) Coastal population at the 43°C day/30°C night regime

Accepted Answer

The answer of Refer to the figure showing acclimatization to...

Question 5

The bacteria and archaea that inhabited the early Earth oxidized inorganic compounds to obtain energy to fix carbon dioxide. These organisms were probably least likely to oxidize which inorganic compound?
A) carbon.
B) hydrogen.
C) ammonium.
D) methane.

Accepted Answer

Carbon is not typically oxidized by bacteria and archaea to obtain energy, as it is already in a reduced form in organic compounds.

Question 6

In van Helmont's experiment measuring a growing tree, which possible energy source for the tree's growth was he able to rule out?
A) Oxygen
B) Water
C) Carbon dioxide
D) Soil

Accepted Answer

Van Helmont's experiment showed that the mass of the soil barely changed as the tree grew, ruling out soil as the primary source of the tree's mass increase.

Question 7

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?
A) Environment 1
B) Environment 2
C) Environment 3
D) Environment 4

Accepted Answer

The answer of Refer to the table showing the oxygen...

Question 8

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 A) CO₂ uptake increases with increasing O₂ concentration at both CO₂ levels. B) CO₂ uptake decreases with increasing O₂ concentration at both CO₂ levels. C) CO₂ uptake becomes negative by 100% O₂ concentration at both CO₂ levels. D) CO₂ uptake becomes negative by 100% O₂ concentration at high CO₂ levels.

Accepted Answer

The answer of Refer to the figure showing the CO₂...

Question 9

Which hypothesis about the benefits of photorespiration was supported by Kozaki and Takeba's experiment with tobacco plants, in which the plants were genetically altered to elevate and lower their rates of photorespiration? A) Photorespiration takes up the excess O₂ that builds up at high light levels. B) Photorespiration protects the plant's photosynthetic machinery at high light levels. C) Photorespiration cools the plant at high light levels. D) Photorespiration releases CO₂, which in turn increases the rate of photosynthesis.

Accepted Answer

Kozaki and Takeba's experiment showed that altering photorespiration rates affected the plant's ability to protect its photosynthetic machinery, supporting the hypothesis that photorespiration has a protective role at high light levels.

Question 10

Refer to the figure showing results from an experiment by Kozaki and Takeba on genetically altered tobacco plants under conditions that promote damage to photosynthetic membranes.
 Curve _______ represents the plants altered to reduce their photorespiration rates; curve _______ represents plants altered to increase photorespiration rates.
A) A; C
B) B; C
C) C; A
D) A; B

Accepted Answer

The answer of Refer to the figure showing results from...

Question 11

Which two pathways, which provide high concentrations of CO₂ to the Calvin cycle, also substantially reduce photorespiration? A) C₃ and C₄ photosynthetic B) C₄ photosynthetic and ATP C) ATP and CAM D) CAM and C₄ photosynthetic

Accepted Answer

C4 and CAM pathways concentrate CO2 around the Calvin cycle, reducing photorespiration by minimizing oxygen's interaction with RuBisCO.

Question 12

In contrast to C₃ plants, C₄ plants have which structure that keeps the CO₂ concentration high where the Calvin cycle operates? A) Well-differentiated mesophyll cells and bundle sheath tissue with a waxy coating B) A waxy coating around the xylem C) Spongy mesophyll cells D) Stomata in the lower and upper epidermis

Accepted Answer

C₄ plants have well-differentiated mesophyll cells and bundle sheath tissue with a waxy coating that helps maintain high CO₂ concentration for the Calvin cycle.

Question 13

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. A) decrease; increase B) decrease; decrease C) increase; increase D) increase; decrease

Accepted Answer

The answer of As CO₂ concentrations continue to increase in...

Question 14

In the CAM pathway, in contrast to pathways in C₃ and C₄ plants, CO₂ uptake and the Calvin cycle are separated in time, with A) both CO₂ uptake and the Calvin cycle occurring at night. B) both CO₂ uptake and the Calvin cycle occurring during the day. C) CO₂ uptake occurring at night and the Calvin cycle during the day. D) CO₂ uptake occurring during the day and the Calvin cycle at night.

Accepted Answer

In CAM plants, CO2 uptake occurs at night to minimize water loss, and the Calvin cycle occurs during the day when sunlight is available for photosynthesis.

Question 15

Which statement about CAM and C₄ plants is true? A) They both make use of the enzyme PEPcase. B) They both have differentiated mesophyll and bundle sheath tissue separated by a waxy layer. C) They both are typically found in wet climates. D) They both open their stomata during the night.

Accepted Answer

Both CAM and C4 plants utilize the enzyme PEPcase (phosphoenolpyruvate carboxylase) for carbon fixation, although they do so in different ways and at different times.

Question 16

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. A) ‒24 B) ‒3 C) 3 D) 24

Accepted Answer

Delta (δ) is calculated using the formula: δ = [(R_sample/R_standard) - 1] x 1000, where R is the ratio of carbon-13 to carbon-12. Plugging in the values: δ = [(122/125) - 1] x 1000 = -24 per thousand.

Question 17

Refer to the figure showing delta values for plants using three different biochemical pathways for photosynthesis. Which of these types of plants shows the most negative delta value, that is, the greatest discrimination against the uptake of ¹³C? A) C₃ plants only B) C₄ plants only C) C₃ and CAM plants D) C₄ and CAM plants

Accepted Answer

The answer of Refer to the figure showing delta values...

Question 18

When heterotrophs consume food (organic compounds), they convert it to usable chemical energy, primarily in the form of _______, during the process of _______.
A) sugar; glycolysis
B) sugar; the Calvin cycle
C) ATP; glycolysis
D) ATP; the Calvin cycle

Accepted Answer

Heterotrophs convert food into ATP, the usable chemical energy, primarily through glycolysis and other cellular respiration processes.

Question 19

The use of specialized bacteria to help break down a toxic organic pesticide spilled during an industrial accident is an example of
A) the practical application of the CAM pathway.
B) metabolomics.
C) biological control.
D) bioremediation.

Accepted Answer

Bioremediation is the process of using microorganisms to break down and remove pollutants from the environment, such as toxic organic pesticides.

Question 20

Benkman's experiment with five species of birds of the crossbill species complex showed that each species' bill morphology had a positive correlation with its preferred pine cone, which also provided the highest survival rate of each bird type. What major conclusion did Benkman make in response to this evidence?
A) The crossbills' differences are due to past geographical isolation.
B) The crossbills are currently undergoing evolutionary divergence.
C) The crossbills that prefer the most common type of cone will eventually outcompete the others.
D) The crossbills are very flexible in the type of cone they can eat, leading to their success as a species.

Accepted Answer

Benkman concluded that the crossbills are currently undergoing evolutionary divergence, as the correlation between bill morphology and preferred pine cone suggests adaptation to specific ecological niches.

Quiz 5: Coping With Environmental Variation: Energy

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

Which of these is the best example of acclimatization to light variation that is accomplished by morphological, rather than physiological means?

A plant living through a drought keeps most of its stomates closed. This results in a trade-off of physiological processes in which

The bacteria and archaea that inhabited the early Earth oxidized inorganic compounds to obtain energy to fix carbon dioxide. These organisms were probably least likely to oxidize which inorganic compound?

In van Helmont's experiment measuring a growing tree, which possible energy source for the tree's growth was he able to rule out?

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?

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

Which hypothesis about the benefits of photorespiration was supported by Kozaki and Takeba's experiment with tobacco plants, in which the plants were genetically altered to elevate and lower their rates of photorespiration?

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

In contrast to C₃ plants, C₄ plants have which structure that keeps the CO₂ concentration high where the Calvin cycle operates?

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.

In the CAM pathway, in contrast to pathways in C₃ and C₄ plants, CO₂ uptake and the Calvin cycle are separated in time, with

Which statement about CAM and C₄ plants is true?

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.

Refer to the figure showing delta values for plants using three different biochemical pathways for photosynthesis. Which of these types of plants shows the most negative delta value, that is, the greatest discrimination against the uptake of ¹³C?

When heterotrophs consume food (organic compounds) , they convert it to usable chemical energy, primarily in the form of _, during the process of _.

The use of specialized bacteria to help break down a toxic organic pesticide spilled during an industrial accident is an example of

Quiz 5: Coping With Environmental Variation: Energy

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

Which of these is the best example of acclimatization to light variation that is accomplished by morphological, rather than physiological means?

A plant living through a drought keeps most of its stomates closed. This results in a trade-off of physiological processes in which

The bacteria and archaea that inhabited the early Earth oxidized inorganic compounds to obtain energy to fix carbon dioxide. These organisms were probably least likely to oxidize which inorganic compound?

In van Helmont's experiment measuring a growing tree, which possible energy source for the tree's growth was he able to rule out?

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?

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

Which hypothesis about the benefits of photorespiration was supported by Kozaki and Takeba's experiment with tobacco plants, in which the plants were genetically altered to elevate and lower their rates of photorespiration?

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

In contrast to C3 plants, C4 plants have which structure that keeps the CO2 concentration high where the Calvin cycle operates?

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.

In the CAM pathway, in contrast to pathways in C3 and C4 plants, CO2 uptake and the Calvin cycle are separated in time, with

Which statement about CAM and C4 plants is true?

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.

Refer to the figure showing delta values for plants using three different biochemical pathways for photosynthesis. Which of these types of plants shows the most negative delta value, that is, the greatest discrimination against the uptake of 13C?

When heterotrophs consume food (organic compounds) , they convert it to usable chemical energy, primarily in the form of _______, during the process of _______.