Plant Nutrition Quiz
Questions: 16 · 10 minutes
1. New leaves show yellow tissue between veins while the veins remain relatively green. Which nutrient deficiency is a likely explanation?
Iron
Nitrogen
Magnesium
Phosphorus
2. How do root hairs most directly support mineral nutrition?
They convert mineral ions into sugars before absorption.
They increase the root surface area in contact with soil water and dissolved ions.
They pump atmospheric nitrogen into the root without microbial help.
They transport sugars from leaves to growing tissues.
3. On a standard fertilizer label marked 10-5-8, what do the three numbers usually indicate?
The fertilizer's percentages of elemental carbon, hydrogen, and oxygen
The recommended soil pH, application depth, and watering interval
Percentages by weight of total nitrogen, available phosphate, and soluble potash, in that order
Percentages of calcium, magnesium, and sulfur, in that order
4. Why is magnesium essential to plant nutrition?
It is the main gas incorporated into carbohydrates during photosynthesis.
It is the central atom in chlorophyll and also supports enzyme activity.
It is the principal structural element in plant DNA.
It replaces water as the source of electrons in photosynthesis.
5. What distinguishes an essential plant macronutrient from an essential micronutrient?
Plants require a macronutrient in a larger quantity.
A macronutrient is always absorbed directly from the air.
Only macronutrients take part in plant metabolism.
Micronutrients are beneficial but not essential.
6. A hydroponic solution contains every essential nutrient except calcium. Which result is most likely to appear first?
Distorted young tissues or damaged growing points because calcium moves poorly from older tissue
Uniform yellowing of older leaves because chlorophyll cannot contain calcium
Purple older leaves because calcium is the main component of ATP
Interveinal yellowing of older leaves because calcium is highly mobile
7. A grower applies very high amounts of potassium fertilizer, after which plants develop magnesium-deficiency symptoms. What is the most plausible explanation?
Potassium destroys magnesium atoms in the soil.
Magnesium changes into potassium when fertilizer concentrations rise.
Potassium closes the stomata permanently, preventing magnesium photosynthesis.
Excess potassium can compete with magnesium and reduce its uptake.
8. A plant develops uniform yellowing first on its older leaves, while newer leaves remain greener. Which deficiency best fits this pattern?
Iron deficiency, because iron readily moves from old leaves to new leaves
Calcium deficiency, because calcium is exported from mature leaves
Nitrogen deficiency, because nitrogen can be relocated to younger growth
Boron deficiency, because boron loss begins uniformly in old leaves
9. During drought, a plant closes its stomata. Which nutritional consequence most directly limits photosynthesis?
More nitrate is converted into atmospheric nitrogen.
Phosphorus can no longer be stored in seeds.
Chlorophyll immediately loses its magnesium atoms.
Less carbon dioxide enters the leaf for carbon fixation.
10. Which function is most closely associated with adequate potassium nutrition?
Supporting osmotic balance, stomatal function, and enzyme activation
Serving as the central atom in chlorophyll
Becoming a structural component of DNA bases
Forming the carbon backbone of carbohydrates
11. A hydroponic grower doubles the concentration of every fertilizer salt. Soon, plants wilt even though their roots remain surrounded by solution. What best explains the wilting?
The concentrated solution makes the roots use all available oxygen for photosynthesis.
The extra nutrients cause xylem vessels to transport sugars instead of water.
The concentrated solution lowers external water potential, making water uptake more difficult.
The higher concentration raises the external water potential and forces excess water into roots.
12. How do nitrogen-fixing bacteria in legume root nodules contribute to plant nutrition?
They release nitrogen gas from plant proteins into the atmosphere.
They convert nitrate into phosphorus that roots can absorb.
They enable roots to absorb nitrogen gas directly as nitrate.
They convert atmospheric nitrogen into reduced nitrogen compounds that can enter biological processes.
13. A plant is growing in alkaline soil with a pH near 8 and shows symptoms consistent with iron deficiency, even though the soil contains iron. What is the best explanation?
High pH causes iron to evaporate from the soil.
Alkaline conditions convert iron into nitrogen.
Iron is available only when soil contains no calcium.
High pH can make iron less soluble and less available to roots.
14. Nitrate absorbed by roots must travel to leaves. Which pathway carries most of it upward through the plant?
Phloem transport driven only from roots toward leaves
Xylem transport with the upward water stream
Diffusion through stomata from the atmosphere
Movement through pollen tubes into leaf veins
15. After several days in waterlogged soil, a plant shows poor mineral uptake even though nutrients are present. What is the most direct root-level explanation?
Water permanently washes all ions out of root cells.
Flooding causes roots to stop needing mineral elements.
Low oxygen restricts root respiration and the energy available for active ion uptake.
Excess water prevents nutrients from dissolving around roots.
16. Which description best captures a major nutritional role of phosphorus in plants?
It is the central atom in every chlorophyll molecule.
It is a component of ATP, nucleic acids, and phospholipids.
It is the primary element used to regulate stomatal water balance.
It supplies the carbon skeletons used to make sugars.