Photosynthetic Mechanisms Quiz

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What is the key enzyme involved in the photosynthetic process?

Rubicon, which is crucial for water uptake

Rubisco, which is very N-expensive (correct)

ATP synthase, which generates energy from light

Enolase, which is essential for CO2 fixation

What is the primary function of the Calvin Cycle in photosynthesis?

To regulate water loss through transpiration

To reduce and fix CO2 into organic molecules (correct)

To capture light energy and release oxygen

To generate energy from ATP synthesis

What factor influences conductance in the photosynthetic process?

Soil pH levels

Temperature fluctuations

Leaf coloration

Stomata opening and closing (correct)

What represents a positive carbon balance in plant physiology?

Addition of carbon as carbohydrates Signup and view all the answers

In the context of photosynthesis, what does LCP stand for?

Light Compensation Point Signup and view all the answers

How is the carbon exchange rate calculated in photosynthesis?

(Net Photosynthesis / Conductance) x (Cair - Cinternal) Signup and view all the answers

Why is it mentioned that small Sugar Maple saplings in forest shade can be decades old?

To illustrate their slow growth and suppression of reproduction in shade Signup and view all the answers

What is the significance of low light compensation points (LCP) for plant survival?

Plants with low LCP require less light to meet their respiratory needs Signup and view all the answers

What does the text suggest about the relationship between light availability and growth in forest plants?

Sunflecks and canopy gaps provide opportunities for rapid growth in forest plants Signup and view all the answers

Why do late successional dominant plants have lower LCP according to the text?

For better shade tolerance at the cost of slower growth Signup and view all the answers

How do holes in the forest canopy created by dead trees impact understorey plant growth?

The holes create a high-light environment, favoring rapid growth in understorey plants Signup and view all the answers

Why do deciduous forest species often have the ability to adapt to seasonally changing light availability according to the text?

As a result of their low LCP allowing them to meet their respiratory needs in low light conditions Signup and view all the answers

What is the primary problem associated with the RUBISCO enzyme in C3 photosynthesis?

Consumes O2 to release CO2 Signup and view all the answers

Which photosynthetic mechanism is characterized by a spatial separation of CO2 uptake and carbohydrate production?

C4 photosynthesis Signup and view all the answers

Why are C4 plants more water-efficient compared to C3 plants?

Less need for stomata to be open Signup and view all the answers

In which type of environment do C3 grasses predominate?

Cooler months with rainfall Signup and view all the answers

What is a key disadvantage of CAM photosynthesis compared to C3 photosynthesis?

Temporal separation of CO2 uptake and Calvin cycle Signup and view all the answers

What is the main advantage of PEP carboxylase in the context of photosynthesis?

Inhibits photorespiration Signup and view all the answers

Why does CAM photosynthesis save water compared to other mechanisms?

Stomata open at cooler, humid night times Signup and view all the answers

Which type of grasses show higher productivity in hotter, drier environments?

C4 grasses Signup and view all the answers

What is the primary limitation on the growth and photosynthetic rates of CAM plants?

Temporal separation between CO2 uptake and Calvin cycle Signup and view all the answers

Why do C3 grasses predominate in habitats with rainfall in cooler months?

Rainfall availability matching growth requirements Signup and view all the answers

How do plants generally absorb nutrients from the soil?

As dissolved inorganic ions Signup and view all the answers

What is the primary source of nitrogen (N) for plants in the soil?

NH4+ and NO3- ions from dead organic material Signup and view all the answers

Why is the C:N ratio important for determining soil fertility?

It affects the competition between plants and microbes for nutrients Signup and view all the answers

How do plants ensure the uptake of minerals against concentration gradients in the roots?

Active transport using specialized uptake mechanisms Signup and view all the answers

Why is it important for plants to have specialized ion channels for nutrient uptake?

To facilitate movement of nutrients against concentration gradients Signup and view all the answers

In what forms do plants primarily absorb most mineral nutrients from the soil water?

Inorganic ions like NO3-, NH4+, and H2PO4- Signup and view all the answers

What is the primary function of arbuscular mycorrhizal (AM) fungi in relation to plants?

Enhancing water uptake and conservation in plants Signup and view all the answers

How do orchids like Coralroots and Indian Pipes depend on mycorrhizae for survival?

By using mycorrhizae as seedlings due to a lack of storage tissues Signup and view all the answers

What is a drawback mentioned in the text regarding the use of mycorrhizae in nutrient-rich soils?

Potential negative effects due to wrong fungal-plant combinations Signup and view all the answers

Why are mycorrhizae considered most useful in nutrient-poor soils?

To aid in nutrient uptake when soils lack nutrients Signup and view all the answers

What ecological role do insects play in relation to carnivorous plants mentioned in the text?

Providing essential nutrients to the plants Signup and view all the answers

How does cryptic parasitism by AM fungi impact plant-fungi relationships?

Raises concerns about having the wrong combination of fungi and plant Signup and view all the answers

What happens when the C:N ratio of dead leaf litter drops below 25 in the soil?

Decomposers start to free more N than they can use. Signup and view all the answers

Which type of decomposers degrade cellulose in wood?

Brown Rots Signup and view all the answers

What is the main reason for the failure of peatlands, leading to peat accumulation and reduced nutrient release?

Low water movement Signup and view all the answers

What is the primary result of anaerobic respiration due to low O2 levels in peatlands?

Reduced decomposition Signup and view all the answers

Which type of mycorrhizae is largely host-specific and surrounds the root?

(ECM) Ectomycorrhizae Signup and view all the answers

Why do litter from conifers decay slower than litter from deciduous plants?

Higher lignin content Signup and view all the answers

What is a key characteristic of Arbuscular mycorrhizae in terms of host specificity?

They are non-host-specific Signup and view all the answers

What is the primary source of N for plants in the soil?

Decomposition of dead organic material Signup and view all the answers

Why are organic molecules in soil useless for most plants?

They are too large to be absorbed by roots Signup and view all the answers

How do plants generally absorb most mineral nutrients from soil water?

As dissolved inorganic ions through the roots Signup and view all the answers

Why is the C:N Ratio important for determining soil fertility?

It indicates the balance between carbon and nitrogen in organic matter Signup and view all the answers

What is a key reason why herbivory is damaging to plants?

Reduction in nutrient recycling within plant systems Signup and view all the answers

How does mineralization of organic matter contribute to nutrient availability for plants?

Converts large organic molecules into forms that plants can absorb Signup and view all the answers

In what way do orchid seeds, like Coralroots and Indian Pipes, depend on mycorrhizae for survival?

By obtaining carbohydrates for energy Signup and view all the answers

Why are mycorrhizae considered more beneficial in nutrient-poor soils compared to rich soils?

As they are more profitable in such conditions Signup and view all the answers

What is the primary role of ectomycorrhizae in relation to plant protection?

Protecting from pathogens Signup and view all the answers

What characteristic distinguishes coralroots and Indian Pipes as 'cheaters' in the context of plant-fungi relationships?

Their parasitic behavior even in maturity Signup and view all the answers

What potential impact can incorrect combinations of fungi and plants have on plant growth?

Negatively affect nutrient uptake Signup and view all the answers

What is the significance of insects in the context of carnivorous plants mentioned in the text?

Insects serve as a rich source of nitrogen Signup and view all the answers

What is the primary reason for reduced microbial activity in peatlands?

Low pH caused by acidic fermentation Signup and view all the answers

Why does the decomposition rate of wood depend on its quality?

High cellulose content Signup and view all the answers

What is the significance of the C:N ratio in soil for decomposers?

C:N ratio above 25 limits decomposer growth Signup and view all the answers

What does excess inorganic nitrogen being lost to the soil signify?

Nitrogen becoming overabundant Signup and view all the answers

Why do decomposers start freeing more nitrogen than they can use when the C:N ratio drops below 25?

Nitrogen abundance in the soil Signup and view all the answers

What is the impact of lignin content on the decomposition of leaf litter?

Slows down decomposition Signup and view all the answers

Why are peatlands characterized by very low available nutrients?

Excessive water and poor drainage Signup and view all the answers

How does the C:N ratio of dead leaf litter change over time during decomposition?

Drops below 25 as microbes respire away CO2 Signup and view all the answers

What is one main reason for the accumulation of peat in failed systems like peatlands?

Reduced microbial activity from low oxygen, leading to incomplete decomposition Signup and view all the answers

How does the form of carbon affect decomposers' growth in soils?

Easy-to-break-down forms inhibit nutrient cycling Signup and view all the answers