Biology 1108 Exam 2 Review Questions

gases that diffuse into and out of plants through stomata

CO2 and water vapor

Plants use which of the following as the main building block to create biomass (leaves, stems, roots)?

CO2 in the air

Which of the following is false?

CO2 is a high energy molecule

Match each plant line with the plant it represents. Remember - WUE is positively correlated with drought tolerance CAM Plants C3 Plants C4 Plants

CAM Plants - Purple Stars C3 Plants - Red Stars C4 Plants - Blue Stars

Which plants use the most amount of energy for photosynthesis/other cellular activities? The biggest gray slice?

CAM plants

Describe how C3 and CAM plants differ. When/where do the light reactions occur? When/where does the Calvin cycle happen? What enzyme does the Calvin cycle use? Which enzymes are used to fix atmospheric CO2 when it enters a leaf? When is atmospheric CO2 fixed?

CAM plants change the C-fixation time of when CO2 is initially fixed while C3 plants can't. The light reactions occur in the Mesophyll. The Calvin Cycle is happening during the day within the Mesophyll. The PEP Carboxylase is used to fix the atmospheric CO2 when it enters a leaf. The Rubisco is used to fix the atmospheric CO2.

Which of the following statements are true? Select 2 options.

CAM plants fix atmospheric CO2 at night. In CAM plants, the initial fixation of atmospheric CO2 and the Calvin cycle both occur in the mesophyll cells.

Step 1 - PSII absorbing photons of light Step 2 - Splitting of water to replace the e- donated by PSII, release of O2 gas Step 3 - the e-transport chain pumping H+ into the thylakoid Step 4 - PSI absorbing photons of light Step 5 - PSI donating high energy e- to NADP+ reductase which produces NADPH Step 6 - The e-transport chain donating an electron to PSI to replace the one it donated to NADP+

Continue

Step 7 - Build up of H+ ions inside of the thylakoid, creation of a H+ proton gradient across the thylakoid membrane Step 8 - ATP production

Stop or slow to almost nothing

Water use efficiency (WUE) is best defined as:

The amount of carbon assimilated as biomass or grain produced per unit of water used by a plant

Select the TRUE statement below.

The electron donated by PSII is replaced by an electron that is released when H2O is split.

What would happen if instead of receiving the entire spectrum of visible light, plants were only exposed to orange and red light?

The rate of photosynthesis would decrease by more than half.

Which of the following statements is true?

The reduction of 3-PGA to form G3P is endergonic

Ecological niche

the functional position and role of an organism within its environment

Realized niche

the set of conditions used by an organism after including interactions with other species (where it does live), the actual habitat that is occupied by an organism in the presence of competing species

What is the possible downside of resource partitioning?

The downside of resource partitioning is that in interspecific competition can exist because of the fact the when the partitioning happens one species can expand and take over the other species and its resources.

Rubisco catalyzes the reaction that combines CO2 with ribulose bisphosphate (RuBP) to create 3-PGA.

C-fixation

Which of the following statements is false?

The e-transport chain absorbs light energy from the sun.

Of the solar energy available to plants how much is unusable, reflected or lost to photochemical inefficiencies/thermodynamics? Hint - this is the same for all plants (C3, C4, and CAM plants).

76.6%

Rank C3, C4, and CAM plants from highest (1) to lowest (4) based on their overall efficiency to use energy to make biomass.

1. C3 Plants (<30C) 2. C4 Plants 3. C3 Plants (>30C) 4. CAM Plants

Rank C3, C4, and CAM Plants from highest (1) to lowest (3) based on their WUE

1. CAM Plants 2. C4 Plants 3. C3 Plants

Match each reaction with its type Oxidation Reduction 1. Step A 2. Step B

1. Reduction 2. Oxidation

Match the cross-sections with the type of plant that CAM Plants C4 Plants C3 Plants

2. CAM Plants 2. C4 Plants 1. C3 Plants

What is the equation for photosynthesis?

6CO2 + 6H2O ------> C6H12O6 + 6O2

A proton gradient results from the unequal distribution of H+ protons (ions) on opposites sides of the thylakoid membrane. The proton gradient is created by which of the following?

A) splitting of water, which releases 2 H+ protons B) the e- transport chain

Which of the following correctly describe the Sonoran desert?

A) Although it is a desert with temperatures that routinely exceed 100F, the Sonoran desert is home to C3, C4 and CAM plants B) Summer monsoons occur in July and August, they are infrequent and unpredictable but when they do come the amount of precipitation that falls is more than what is received during any other time of the year. C) In the winter months Dec-February, rainfall is more frequent and more reliable but the amount of precipitation is very small.

The light dependent reactions involve 2 separate photosystems (PSII and PSI). Select the most accurate statement below.

A) Both PSII and PSI are embedded in the thylakoid membrane. B) Both PSII and PSI contain chlorophyll and both absorb photons of light. C) Both PSII and PSI donate electrons

Select the most accurate statement below.

A) Chloroplasts have both an inner and outer membrane (a double membrane) and circular DNA B) Photosynthesis is thought to have first evolved more than 3 billion years ago when CO2 was more abundant in the atmosphere than oxygen.

Which of the following correctly describe leaf area ratio (LAR)?

A) Leaf area ratio is the photosynthetic surface area (leaves) per unit dry weight of a plant (leaves + stems + roots). B) Leaf area is a measure of the efficiency with which a plant can acquire CO2 and light for photosynthesis C) A plant with an equal ratio of leaves and roots has a higher leaf area ratio than a plant that has fewer leaves and more roots.

Photosynthesis can be divided into two steps: the light-dependent reactions and the Calvin cycle (light-independent reactions). Select the most accurate statement below.

A) The light-dependent reactions take place in the thylakoid and the Calvin cycle (light independent reactions) take place in the stroma (the liquid part inside of the chloroplast). B) The light-dependent reactions convert light energy and water into chemical energy (ATP and NADPH) and the Calvin cycle (light independent reactions) convert CO2 and chemical energy (ATP and NADPH) into sugars. C) O2 is a byproduct of the light-dependent reactions

Based on the reading which of the following are true? Select all that apply. Part 1

Atmospheric concentrations of carbon dioxide have been steadily rising, from approximately 315 ppm (parts per million) in 1959 to a current atmospheric average of ~410 ppm. Photosynthetic organisms, plants and algae, are autotrophs; they introduce energy and fixed C into food webs/ecosystems In the last 30 years the rise in CO2 levels has caused a noticeable greening of the earth especially in the deserts, which are turning into grasslands; this is an example of a positive feedback look that is amplifying global warming

Which statement is the most accurate?

B) Air has a very strongly negative water potential (-13MPa to -100MPa) vs. roots which have a very weakly negative water potential (-0.4MPa); water moves towards areas the are more negative. C) Transpiration, adhesion and cohesion all affect how water moves in a plant.

Bet hedging in the desert is a common strategy, but not all plants use this approach. Which species STMI or PERE is likely to use this strategy and why?

Bet hedging is likely to be used by the STMI species due to the fact that they're uncertain in their reproduction which allows them to use this strategy.

What type of light is best for plant growth? Hint - think about why leaves appear green to the human eye.

Blue and Orange/Red Light

Absorb photons of light Embedded in the thylakoid membrane

Both PSII and PSI

Which pair of words best completes the following sentence? WUE is a way to compare different ____________ strategies and LAR (leaf area ratio) is way to compare different ___________ strategies.

C-acquisition, Allocation

Which plants use the least amount of energy for photosynthesis/other cellular activities? Which have the smallest gray slice?

C3 plants

Of the energy available for photosynthesis (23.4% of the energy from the sun), which plants use the most for making biomass? Which plants are the most efficient? Which use the biggest slice of the pie for biomass (green)?

C3 plants (<30C)

Which adaptation makes CAM plants more WUE (more drought tolerant) than C4 plants?

C4 and CAM strategies require less water but they use more energy (are less efficient) than C3 plants.

Based on the reading which of the following are true? Select all that apply. Part 4

C4 plants fix atmospheric CO2 with PEP carboxylase, which has a low affinity for O2. C4 plants are in general relatively unresponsive to increased CO2 levels above the current ambient levels. C4 plants in general decrease their stomatal conductance under elevated CO2 levels

C4 plants are able to drastically reduce photorespiration compared to C3 plants. Which of the following explains why C4 plants are able to do this? Select 2 options.

C4 plants use PEP-carboxylase (an enzyme with high affinity for CO2 and low affinity for O2) to initially fix atmospheric CO2. The Calvin cycle in C4 plants occurs in the bundle sheath cells, it is physically separated from the light dependent reactions (which produce O2) and the initial fixation of atmospheric CO2, which both occur in the mesophyll cells.

Saguaro cacti have thick, hard-walled, succulent stems - when it rains, water is stored in them. The inside of the stem is either spongy or hollow (depending on the cactus). A thick, waxy coating keeps the water inside the cactus from evaporating. They lack true leaves but their stems are photosynthetic. They practice CAM photosynthesis. Select all of the true statements below.

Cacti like the saguaro cacti, which don't have leaves, lose less water through evaporation than C3 plants that have true leaves. Cacti like saguaro cacti that employ CAM photosynthesis are less efficient at fixing carbon and photosynthesizing than C3 plants when water is plentiful.

the attraction of molecules for other molecules of the same kind

Cohesion

the attraction of molecules of one kind for molecules of a different kind

Cohesion

At the same time chlorophylls are being broken down new pigments (anthocyanins) are also being made. Anthocyanins are a second example of a protector pigment, but unlike carotenoids which are present in leaves all year, anthocyanins are made in the fall. Based on what you know about pigments, which of the 2 curves do you think is the absorption curve for anthocyanins?

Curve A (solid line)

Reduction

Gain of electrons Gain of hydrogen Loss of Oxygen

Oxidation

Gain of oxygen Loss of electrons Loss of hydrogens

Which of the following statements correctly summarize your understanding of the relationship between seed germination strategies and drought tolerance in C3 annuals adapted to living in the desert. (Hint there are two correct statements)

For C3 annuals adapted to living in the desert the % of seeds that germinate under suitable conditions is positively correlated with drought tolerance The incidence of bet-hedging in C3 annuals adapted to living in the desert is negatively correlated with drought tolerance

Based on the figure above, which term best completes the following sentence. The _____________ of species 1 includes the space between the high and low tide marks.

Fundamental Niche

What might happen if a second species of barnacle (species 2), which shares some or all of the fundamental niche with species 1, is introduced? I can think of four possible responses.

If a second species of barnacle (species 2) shares some or all of the fundamental niche with species 1 it will create 2 realized niches in which the species will share or take all of each others resources. They can use principle such as competitive exclusion: one species uses the resources more efficiently, driving the other species to local extinction. They can use principle such as resource partitioning: Both species alter their use of the habitat to divide resources between them (i.e. niche separation, niche partitioning).

Which statements below are true? Select all that apply.

In C4 and CAM plants the initial fixation of atmospheric CO2 occurs at night to limit water loss. In C4 and CAM plants atmospheric CO2 is fixed by PEP carboxylase.

Based on the reading which of the following are true? Select all that apply. Part 2

In general plants grow faster under elevated CO2 levels Under elevated CO2 concentrations, plants use less water during photosynthesis

In regular (C3) plants where do the light dependent reactions occur? What do they produce? Where does the Calvin cycle occur? What enzyme is used to fix atmospheric CO2?

In regular (C3) plants the light dependent reactions occur within the mesophyll. They produce O2, ATP, and NADH. Rubisco is used to fix the atmospheric CO2.

Why are regular plants called C3 plants and C4 plants called C4 plants?

In regular C3 plants the product produced when atmospheric CO2 is fixed is a 3C molecule (3-PGA). In C4 plants the product produced when atmospheric CO2 is fixed is a 4C molecule (oxaloacetate).

Which of the following explains what happens to oxygen produced by the light-dependent reactions?

It is released into the atmosphere.

Based on the reading which of the following are true? Select all that apply. Part 5

Legumes show greater enhancement of photosynthesis and growth by elevated CO2 without a corresponding decrease in the N in their tissues. Legumes create excess carbohydrates under elevated CO2 levels, which they send to the bacteria living in their root nodules.

Based on the reading which of the following are true? Select all that apply. Part 3

None of the statements are true

Its donated electron is replaced by an e- from the e-transport chain Donates an excited e- to NADP+ reductase

PSI

Donates an excited e- to the e-transport chain Its donated electron is replaced with an e- from H2O

PSII

Which of the following statements regarding photorespiration is true?

Photorespiration is likely to occur when oxygen levels are high and carbon dioxide levels are low in the leaf, this happens when stomata are closed to conserve water.

Describe 3 ways photosynthesis is important at an ecosystem or global level. Use the figures provided to help you brainstorm.

Photosynthesis is important an ecosystem as it provides the first form of energy in the long extensive food chains in the ecosystem. Also it provides much needed carbon dioxide as a simple byproduct helping the homeostasis of all gases.

STMI (rabbit) and PERE (tortoise) are both C3 annuals. Which strategy listed below differentiates them?

Photosynthesis/growth vs. water acquisition

In 1-2 brief sentences/phrases describe why species with high LAR can achieve high relative growth rates. Try to use words like allocate, surface area, interception, (resources or energy or fixed C).

Plant species with high LAR allocate more resources/energy/fixed C towards producing leaves, they have more surface area for intercepting light for photosynthesis/growth, when resources (water/nutrients/light) are unlimited/not limiting they can achieve high rates of growth

Which line best illustrates the relationship between water use efficiency and drought tolerance?

Positive correlation between WUE and drought tolerance

Although the light-independent reactions don't involve light directly they do require the ATP and NADPH made by the light-dependent reactions. Which stages of the Calvin cycle use ATP or NADPH?

Reduction stage Regeneration stage

3-PGA is converted into glyceraldehyde-3-phosphate (G3P).

Reduction stage

G3P is used to make glucose in a process called gluconeogenesis AND RuBP is regenerated.

Regeneration stage

Forgetting what we know from the first example, what is the easiest way an ecologist could test whether species 2 is occupying all of its fundamental niche or only a portion of it (i.e., its realized niche)? Hint - what causes a species to occupy its realized niche vs. its fundamental niche?Hint - what is the limiting resource in this example?

Remove species 1 and observe if species 2 expands its range.

Using the two graphs provided match where STMI and PERE would be located

STMI is located in the middle of the graph which is B and E while PERE is located at C and F.

In the Sonoran desert there are two distinct rainy seasons; one during the winter starting in December running through March and the second in the middle of the summer. Which annual species (STMI/rabbit vs. PERE/tortoise) is likely found during these different seasons? Why?

STMI/rabbit are likely to be found in the summer when rainfall is large & frequent due to being a fast grower while in PERE/tortoise is likely to be found in the winter when rainfall is small and frequent as they're a slow grower.

In 1-2 brief sentences/phrases describe why species with high LAR ratio (STMI) are less drought tolerant than species with low LAR ratio (PERE). Full credit for answers using fixed budget, allocate, (resources or energy or fixed C)

Species with high LAR ratio are less drought tolerant due to the fact that they as they efficiently use their fixed budgets unlike low LAR ratio (PERE).

Describe the type of growth STMI (a species with high LAR) experiences when grown under low water conditions. Based on this description can you add something to your answer to the previous question.

Teriences slowed growth among their growth.

What are the benefits of resource partitioning at the species level? What are the benefits of resource partitioning at the ecosystem level?

The benefits of resource partitioning at a species level is that it can help reduce competition by sharing a limited resource through placement in different places. Another benefit is that at separate times species can go and consume the resource so no competition will be apparent.

Why do leaves change color in the fall?

The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible and give the leaves part of their fall splendor. At the same time other chemical changes may occur, which form additional colors through the development of red anthocyanin pigments.

Why do leaves change color BEFORE falling off of the tree? Why do you think chlorophyll is broken down and carotenoids aren't (2 reasons)? Hint - how do these 2 pigments differ in what they do in a leaf (i.e., their primary role) and how do they differ chemically?

The leaves change color before falling of the trees due to the fact that certain molecules are needed to maintain the color and when non-existed it helps in the makeup of changing color. The role of chlorophyll is to help in the process of photosynthesis. The role of carotenoid is to protect the photosynthesis process and dissipate heat from the light energy.

Describe how C3 and C4 plants differ. Where do the light reactions occur? Where does the Calvin cycle happen? What enzyme does the Calvin cycle use? Which enzymes are used to fix atmospheric CO2 when it enters a leaf?

The main difference between C3 and C4 plants is that C4 plants change location where the Calvin Cycle occurs from while C3 doesn't do this process. The Calvin Cycle uses Rubisco. The enzyme that is used to fix atmospheric CO2 when it enters the leaf is PEP carboxylase.

How do plants use glucose? Select all that apply.

To make amino acids/proteins To make starch (i.e., stored energy) As an energy source for respiration - yes plants have mitochondria and yes they respire 😊 To make cellulose - the main building block of biomass which provides the structure of a plant To make fats and oils (i.e., stored energy in seeds)

the evaporation of water vapor from leaves through stomata

Transpiration

pressure exerted by fluid in a cell that presses the cell membrane against the cell wall; this gives plant their structure

Turgor pressure

Which adaptations make C4 and CAM plants more WUE than C3 plants?

When stomata close during hot/dry conditions to reduce water loss, ([02] >[C02]) in the mesophyll cells: In C3 plants, Rubisco switches from C-fixation to photorespiration. In C4/CAM plants atmospheric CO2 is initially fixed by PEP carboxylase to form a 4C intermediate, PEP carboxylase has high affinity for CO2 and a low/no affinity for 02. In C4 plants malate is then moved into bundle sheath cells where the Calvin cycle/Rubisco occurs, physically separated from the 02 produced by the light dependent rxns. In CAM plants atmospheric CO2 is fixed at night (when it is more humid) and malate is stored in the vacuole overnight, in the AM malate is broken down to CO2 which is used by the Calvin cycle/Rubisco, stomata remain closed during the day.

Match each species with the traits they are expected to demonstrate. ____ Low WUE ____ High WUE ____ Low relative growth rate ____ Low leaf area ratio (LAR) ____ High relative growth rate ____ High leaf area ratio (LAR) 1.STMI: Stylocline micropoides 2.PERE: Pectocarya recurvata

__1__ Low WUE __2__ High WUE __2__ Low relative growth rate __2__ Low leaf area ratio (LAR) __1__ High relative growth rate __1__ High leaf area ratio (LAR)

Compare the leaf area increase = growth between species 1 and species 2, what happens after exposure to a low amount of water? what happens after a high amount of water? Which species is STMI/rabbit vs. PERE/tortoise? ____ PERE ____ STMI 1. Black bars (some growth under both low and high water conditions) 2. Gray bars (very little growth under low water conditions, high growth under high water conditions)

__1__ PERE __2__ STMI

Match the traits to the two figures. ____ Low leaf area ratio (LAR) ____ Low relative growth rate ____ High leaf area ratio (LAR) ____ High relative growth rate ____ High WUE ____ Low WUE 1. 2.

__2__ Low leaf area ratio (LAR) __2__ Low relative growth rate __1__ High leaf area ratio (LAR) __1__ High relative growth rate __2__ High WUE __1__ Low WUE

Using the graph provided match where C3, C4, and CAM plants would be located. ____ CAM plants ____ C3 plants ____ C4 plants 1. A 2. B 3. C

__3__ CAM plants __1__ C3 plants __2__ C4 plants

Match each example with the type of tradeoff it represents. ____ Succulent leaves/stems/roots ____ C3/C4/CAM photosynthesis ____ Ocotillo shedding its leaves under hot dry conditions ____ High or low LAR = leaf area/plant biomass 1. C-acquisition strategy that balances water loss and C-acquisition 2. Allocation strategy that balances water loss and photosynthesis/growth 3. Allocation strategy that balances water storage vs. photosynthesis/growth 4. Allocation strategy that balances water acquisition vs. photosynthesis/growth

__3__ Succulent leaves/stems/roots __1__ C3/C4/CAM photosynthesis __2__ Ocotillo shedding its leaves under hot dry conditions __4__ High or low LAR = leaf area/plant biomass

Match the 3 lines with the plant species it is demonstrating. ____ this plant species has lower WUE, more water is being lost per C gained, it is less drought tolerant ____ this plant species has higher WUE, less water is being lost per C gained, it is more drought tolerant ____ this plant species evenly balances water lost to the C it gains. 1. Blue stars 2. Yellow stars 3. Red stars

__3__ this plant species has lower WUE, more water is being lost per C gained, it is less drought tolerant __1__ this plant species has higher WUE, less water is being lost per C gained, it is more drought tolerant __2__ this plant species evenly balances water lost to the C it gains.

The figure provided shows the steps of the Calvin cycle. Match each letter with the compound found there. 1. A 2. B 3. C 4.D 5. E 6. F 7. G 8. H 9. I

__9__ NADP+ and Pi __1__ CO2 __3__ 3-PGA __8__ NADPH __4__ G3P __7__ ADP + Pi __5__ 1/2 glucose __2__ RuBP __6__ ATP

Which word or word best completes the following sentence? Drought tolerance/WUE is negatively correlated with relative growth rate. When relative growth rates go down, the drought tolerance of the plant __________

goes up

Which word or word best completes the following sentence? LAR is positively correlated with relative growth rate. When values of LAR go up the relative growth rate of the plant __________

increases

Fish living around the Aleutian Islands eating prey species either in shallow waters near the shore vs. the deeper locations just off shore in the Bering Sea. Giraffes using their incredibly long necks and tough, prehensile tongues to expertly remove acacia leaves from the top branches of trees.

resource partitioning by space

Spring flowering bulbs like daffodils and tulips flowering before most trees leaf out. Bats collecting nectar from plants at night

resource partitioning by time

Fundamental niche

the entire set of conditions under which an organism can survive and reproduce (where it could live), the theoretical habitat in the absence of competitors