Chapter 3 Flashcards
The main environmental challenge faced by all warm-desert animals is dissipating excess heat in
an environment where water is scarce.
A) True
B) False
A) True
Which of the following represents adaptation(s) of the kangaroo rat to life in a desert
environment?
A) gathering water each morning from the dew that forms on leaf surfaces
B) spending daytime hours in a relatively cool, comfortable burrow
C) migrating north during the summer months
D) all of the above
B) spending daytime hours in a relatively cool, comfortable burrow
Which of the following traits is of particular significance in enabling the camel to function well
in its extreme desert environment?
A) The camel can extract water from the desert atmosphere.
B) The camel requires very little water to eliminate wastes.
C) The camel’s large body has a low surface-to-volume ratio and thus heats up relatively slowly
during the day.
D) The camel is equipped with sweat glands that enable it to exploit evaporative cooling.
C) The camel’s large body has a low surface-to-volume ratio and thus heats up relatively slowly
during the day.
Which part of the electromagnetic spectrum exists between the wavelengths of 400 and 700 nm?
A) infrared radiation B) visible light C) ultraviolet radiation D) x-rays
B) visible light
The energy content of electromagnetic radiation is related inversely to its wavelength. Which of
the following kinds of electromagnetic radiation has the highest energy?
A) infrared radiation B) red light C) violet light D) ultraviolet radiation
D) ultraviolet radiation
The highest recorded albedo, or proportion of light reflected by a particular surface, is found in: A) snow and clouds B) sand, dry soils, and deserts C) savannas, meadows, and most crops D) forests and water surfaces
A) snow and clouds
We perceive water in small amounts to be transparent to visible light. This observation is
deceptive, however. The amount of visible light penetrating to 10 m depth in pure seawater is
actually __________ percent.
A) 1 B) 10 C) 50 D) 90
C) 50
Some algae living at shallow depths in the ocean (the green alga Ulva is an example) have
photosynthetic pigments much like those of terrestrial plants, absorbing strongly in the red and
blue parts of the visible spectrum and reflecting in the green part of the spectrum. However,
algae living deeper in the ocean (the alga Porphyra is an example) have specialized pigments
that enable them to absorb __________ light.
A) violet B) orange C) green D) brown
C) green
During photosynthesis, oxygen in water serves as an electron donor for reduction of carbon. In
this process, oxygen is:
A) reduced from its form in water to its molecular form, O2.
B) oxidized from its form in water to its molecular form, O2.
B) oxidized from its form in water to its molecular form, O2.
Why is the enzyme RuBP carboxylase-oxidase (Rubisco) so important in photosynthetic
assimilation of carbon?
A) This enzyme is responsible for the conversion of organic acids into glucose.
B) This enzyme is responsible for the conversion of energy contained in light into energy stored
in ATP and NADPH.
C) This enzyme is responsible for the conversion of glucose into sucrose.
D) This enzyme is responsible for the incorporation of carbon (from the atmosphere or water)
into an organic compound (glyceraldehyde 3-phosphate or G3P) available for Calvin-Benson
cycle synthesis of glucose.
D) This enzyme is responsible for the incorporation of carbon (from the atmosphere or water)
into an organic compound (glyceraldehyde 3-phosphate or G3P) available for Calvin-Benson
cycle synthesis of glucose.
When Rubisco binds oxygen, the net result is a reversal of the light reactions, leading to the
production of CO2 and ribulose bisphosphate (RuBP). What is this process called?
A) photorespiration
B) photoreduction
C) photosensitization
Chapter 3: Adaptations to the Physical Environment: Light, Energy, and Heat
4
D) photoreversal
A) photorespiration
Which of the following types of plants solves the problem of photorespiration by supplying the
Calvin-Benson cycle with high concentrations of carbon dioxide?
A) C3 plants B) C4 plants
B) C4 plants
Which of the following statements is false?
A) C4 plants devote less leaf tissue to photosynthesis itself than do C3 plants and thus lose their
advantage under conditions where C3 photosynthesis functions efficiently.
B) C4 photosynthesis confers several advantages on plants, including greater efficiency of
carbon assimilation and greater water-use efficiency.
C) C4 plants physically separate the first step of photosynthetic carbon assimilation (in
mesophyll cells) from the other steps of photosynthesis (in bundle sheath cells).
D) The first chemical product of photosynthetic carbon fixation in C4 plants is glyceraldehyde
3-phosphate (G3P), a 3-carbon molecule.
D) The first chemical product of photosynthetic carbon fixation in C4 plants is glyceraldehyde
3-phosphate (G3P), a 3-carbon molecule.
Plants with crassulacean acid metabolism (CAM) exhibit a temporal separation of carbon
fixation (carried on at night) from the rest of the photosynthetic process (carried on during
daylight hours). Otherwise, however, CAM plants are most similar to which of the following in
their photosynthetic chemistry?
A) C3 plants B) C4 Plants
B) C4 Plants
A dense layer of spines or hairs assists plants of cool deserts by:
A) reducing attacks by herbivorous insects.
B) attracting pollinators and other beneficial insects.
C) minimizing absorption of direct sunlight and reducing evaporation of water.
D) reducing wind resistance during periods of high winds.
C) minimizing absorption of direct sunlight and reducing evaporation of water.
A dense layer of spines or hairs creates a thick “boundary layer” of still air adjacent to a plant’s
surface. This boundary layer would have deleterious effects in a hot desert environment because
it would:
A) foster the development of fungi and bacteria.
B) make the plant attractive to herbivores.
C) retard heat loss.
D) shed rainwater that might be absorbed directly by the plant.
C) retard heat loss.
Which of the following represent(s) plant adaptations that minimize transpiration (and thus water
loss) in arid environments?
A) dense spines and hairs C) recessed stomates
B) thick, waxy cuticle D) all of the above
D) all of the above
Although the concentration of carbon dioxide in air and in most aquatic systems is similar,
aquatic systems have an additional, more abundant, source of inorganic carbon that is lacking in
the atmosphere. In the pH range typical of most natural bodies of water (6–9), which of the
following represents this “additional” reservoir of inorganic carbon?
A) bicarbonate ion, HCO3
−
B) carbonate ion, CO3
2−
C) carbide ion, C2
2−
D) glyceraldehyde 3-phosphate (G3P)
A) bicarbonate ion, HCO3
−
Inorganic carbon is abundant in water, but this does not necessarily mean that aquatic plants have
ready access to carbon. In particular, what attribute of the water adjacent to the plant surface
might limit diffusion of inorganic carbon molecules from the water into the plant?
A) the boundary layer of unstirred water adjacent to the plant surface
B) the much higher temperature of water adjacent to the plant surface
C) the much higher salinity of water adjacent to the plant surface
D) the much higher acidity of water adjacent to the plant surface
A) the boundary layer of unstirred water adjacent to the plant surface
The availability (concentration) of oxygen in water is far less than that in the atmosphere. Why is
this so?
A) Oxygen has low solubility in water.
B) Oxygen diffuses slowly through water.
C) Below the photic zone, there is no production of oxygen by photosynthesis.
D) all of the above
D) all of the above
