CCA INTERNATIONAL COMPREHENSIVE
EXAM 2026 QUESTIONS WITH SOLUTIONS
100% CORRECT
⩥ Which macronutrients are mobile in plants?
Which are not?. Answer: Mobile: nitrogen, phosphorus, potassium,
magnesium
Not mobile: calcium, sulfur
⩥ List the chemical uptake forms of each macronutrient:
N, P, K, Ca, Mg, S. Answer: N: Ammonium ion (NH4+) and Nitrate ion
(NO3-)
P: Phosphate ion (H2PO4- and HPO4 2-)
K: Potassium ion (K+)
Ca: Calcium ion (Ca 2+)
Mg: Magnesium ion (Mg 2+)
S: Sulfate ion (SO4 2-)
⩥ What are the beneficial elements (4) and what do they do?. Answer:
Silicon (Si) - increases cell wall strength, reduces lodging, improves
adaptation to stress (ie drought), improves pest resistance, improves
plant vigor
,Sodium (Na) - improves photosynthesis in C4 plants and may be a
substitute to K in some degree
Cobalt (Co) - essential for N fixation
Selenium (Se) - improves plant growth, essential for animals from feed
⩥ Describe the function of N in plants. Answer: - Used in the synthesis
of amino acids, proteins, enzymes
- Found in chlorophyll (photosynthesis), ADP and ATP (energy transfer)
⩥ Describe the function of P in plants. Answer: - Important component
of energy transfer (ADP, ATP)
- Important to photosynthesis and respiration
- Part of cell nuclear material important to cell division
⩥ Describe the function of K in plants. Answer: - Accelerates growth of
meristematic tissue
- Regulation of stomatal opening (water loss)
- Involved in N and carbohydrate metabolism
- Catalyzes some enzymes
⩥ Describe the function of S in plants. Answer: - Component of several
amino acids (cystine, cysteine, methionine) which are part of many
proteins
- Involved in protein synthesis and enzyme activation
,- Forms flavor compounds in mustard, garlic, and onions
⩥ Define mineralization. Answer: Release of a nutrient when an organic
material (ie OM, manure, etc.) is decomposed by soil microorganisms.
Conversion of a nutrient from the organic to inorganic form.
⩥ Define immobilization. Answer: Reverse of mineralization. Nutrient is
converted from inorganic to organic form.
⩥ What is uptake antagonism between ions?. Answer: Two or more ions
may compete for uptake by various mechanisms. One ion is said to be
antagonistic with regard to the uptake of another ion.
⩥ Describe mass flow.
What nutrients is this important for?. Answer: Nutrients move to a plant
root with the water that is being absorbed by the plant.
Important for N, Ca, and Mg.
⩥ Describe diffusion.
What nutrients is this important for?. Answer: Movement of a nutrient to
a plant root due to a concentration gradient between the soil surface and
the root surface.
Important for P and K.
, ⩥ Describe root interception.
What nutrients is this important for?. Answer: Occurs when a root grows
next to a clay or OM surface and absorbs the nutrients. Actual uptake of
a nutrient at the root surface may be passive or active (by a carrier).
This is usually a minor way nutrients are absorbed.
⩥ Solubility of what nutrients increases in flooded soils?. Answer: Iron
and manganese
⩥ What is ammonification?. Answer: Conversion of organic N to
ammonium (NH4+) by microorganisms as they decompose an organic
material. N rich materials (C:N ratio <15-20:1) exhibit high levels of
ammonification as they are decomposed (ex. manure)
⩥ What is nitrification?
What are the two steps?. Answer: First step: Oxidation of ammonium to
nitrite (NO2-) by Nitrosomonas sp. Oxygen is required. Releases H+
decreasing pH. Nitrification inhibitors slow this first step.
Second step: Oxidation of nitrite (NO2-) to Nitrate (NO3-) by
Nitrobacter sp. This is fairly rapid so nitrite does not commonly
accumulate in soils. This step also requires oxygen.
⩥ What is volatilization?
What conditions favor volatilization?. Answer: - Conversion of
ammonium (NH4+) to ammonia gas (NH3)
EXAM 2026 QUESTIONS WITH SOLUTIONS
100% CORRECT
⩥ Which macronutrients are mobile in plants?
Which are not?. Answer: Mobile: nitrogen, phosphorus, potassium,
magnesium
Not mobile: calcium, sulfur
⩥ List the chemical uptake forms of each macronutrient:
N, P, K, Ca, Mg, S. Answer: N: Ammonium ion (NH4+) and Nitrate ion
(NO3-)
P: Phosphate ion (H2PO4- and HPO4 2-)
K: Potassium ion (K+)
Ca: Calcium ion (Ca 2+)
Mg: Magnesium ion (Mg 2+)
S: Sulfate ion (SO4 2-)
⩥ What are the beneficial elements (4) and what do they do?. Answer:
Silicon (Si) - increases cell wall strength, reduces lodging, improves
adaptation to stress (ie drought), improves pest resistance, improves
plant vigor
,Sodium (Na) - improves photosynthesis in C4 plants and may be a
substitute to K in some degree
Cobalt (Co) - essential for N fixation
Selenium (Se) - improves plant growth, essential for animals from feed
⩥ Describe the function of N in plants. Answer: - Used in the synthesis
of amino acids, proteins, enzymes
- Found in chlorophyll (photosynthesis), ADP and ATP (energy transfer)
⩥ Describe the function of P in plants. Answer: - Important component
of energy transfer (ADP, ATP)
- Important to photosynthesis and respiration
- Part of cell nuclear material important to cell division
⩥ Describe the function of K in plants. Answer: - Accelerates growth of
meristematic tissue
- Regulation of stomatal opening (water loss)
- Involved in N and carbohydrate metabolism
- Catalyzes some enzymes
⩥ Describe the function of S in plants. Answer: - Component of several
amino acids (cystine, cysteine, methionine) which are part of many
proteins
- Involved in protein synthesis and enzyme activation
,- Forms flavor compounds in mustard, garlic, and onions
⩥ Define mineralization. Answer: Release of a nutrient when an organic
material (ie OM, manure, etc.) is decomposed by soil microorganisms.
Conversion of a nutrient from the organic to inorganic form.
⩥ Define immobilization. Answer: Reverse of mineralization. Nutrient is
converted from inorganic to organic form.
⩥ What is uptake antagonism between ions?. Answer: Two or more ions
may compete for uptake by various mechanisms. One ion is said to be
antagonistic with regard to the uptake of another ion.
⩥ Describe mass flow.
What nutrients is this important for?. Answer: Nutrients move to a plant
root with the water that is being absorbed by the plant.
Important for N, Ca, and Mg.
⩥ Describe diffusion.
What nutrients is this important for?. Answer: Movement of a nutrient to
a plant root due to a concentration gradient between the soil surface and
the root surface.
Important for P and K.
, ⩥ Describe root interception.
What nutrients is this important for?. Answer: Occurs when a root grows
next to a clay or OM surface and absorbs the nutrients. Actual uptake of
a nutrient at the root surface may be passive or active (by a carrier).
This is usually a minor way nutrients are absorbed.
⩥ Solubility of what nutrients increases in flooded soils?. Answer: Iron
and manganese
⩥ What is ammonification?. Answer: Conversion of organic N to
ammonium (NH4+) by microorganisms as they decompose an organic
material. N rich materials (C:N ratio <15-20:1) exhibit high levels of
ammonification as they are decomposed (ex. manure)
⩥ What is nitrification?
What are the two steps?. Answer: First step: Oxidation of ammonium to
nitrite (NO2-) by Nitrosomonas sp. Oxygen is required. Releases H+
decreasing pH. Nitrification inhibitors slow this first step.
Second step: Oxidation of nitrite (NO2-) to Nitrate (NO3-) by
Nitrobacter sp. This is fairly rapid so nitrite does not commonly
accumulate in soils. This step also requires oxygen.
⩥ What is volatilization?
What conditions favor volatilization?. Answer: - Conversion of
ammonium (NH4+) to ammonia gas (NH3)
