Soil and Plant Nutrition Flashcards

These flashcards cover the vocabulary and key concepts regarding soil composition, plant nutrition, essential elements, and symbiotic relationships from Chapter 37.

Photoautotrophs

Organisms such as plants, algae, and some prokaryotes that use light energy to produce organic molecules.

Chemoautotrophs

Prokaryotes that generate energy through the oxidation of inorganic chemicals; they are unique to the prokaryotic domain.

Chloroplasts

Organelles containing photosynthetic pigments, enzymes, and other molecules that serve as the major site of photosynthesis.

Photosynthesis

The chemical process represented by the equation $6CO_2 + 6H_2O + \text{sunlight} \rightarrow C_6H_{12}O_6 + 6O_2$, converting water and carbon dioxide into $\text{glucose}$ and oxygen.

Pigment

Any substance that absorbs light; different types absorb light of different wavelengths.

Chlorophyll

The green pigment found in chloroplasts used by photoautotrophs to absorb the sun's energy.

Loam

The most fertile soil type, composed of equal parts sand, silt, and clay.

Topsoil (A horizon)

The uppermost soil horizon consisting of minerals and humus.

Humus

Non-living organic material formed from the decomposition of plants and animals, vital for plant nutrition.

Cation exchange

A process where cations like $K^+$, $Ca^{2+}$, and $Mg^{2+}$ are displaced from negatively charged soil particles by $H^+$.

Salinization

The concentration of salts in soil that occurs as water evaporates, often caused by irrigation from groundwater or aquifers.

Eutrophication

An abundance of nutrients in water (often from fertilizer runoff) that leads to hypoxic zones, or areas with depleted oxygen.

Phytoremediation

The use of plants, such as Thlaspi caerulescens (Alpine pennycress), to remove contaminants or heavy metals from polluted soil.

Essential elements

The 17 elements required for a plant to complete its life cycle and survive.

Macronutrients

Essential elements required by plants in large amounts, such as Nitrogen, Phosphorus, and Potassium.

Micronutrients

Essential elements required by plants in very small amounts, such as Iron ($Fe^{3+}$, $Fe^{2+}$), Zinc ($Zn^{2+}$), and Copper ($Cu^{+}$, $Cu^{2+}$).

Chlorosis

A nutrient deficiency symptom characterized by the yellowing of leaves, often seen between veins or throughout the leaf.

Rhizosphere

The thin layer of soil closely surrounding a plant's roots which contains high microbial activity.

Endophytic bacteria

Rhizobacteria, such as Rhizobium, that live between or within plant cells and help enhance plant growth.

Nitrogen fixation

The conversion of atmospheric nitrogen ($N_2$) into ammonia ($NH_3$) by bacteria, following the formula $N_2 + 8e^- + 8H^+ + 16ATP \rightarrow 2NH_3 + H_2 + 16ADP + 16Pi$.

Nitrification

A two-step process where nitrifying bacteria oxidize ammonia ($NH_3$) to nitrite ($NO_2^-$) and then other bacteria oxidize nitrite to nitrate ($NO_3^-$).

Rhizobium

Endosymbiotic bacteria specifically associated with legume plants that fix nitrogen inside root nodules.

Mycorrhizae

Mutualistic associations between fungi and plant roots where the plant provides sugars and the fungus increases nutrient/water absorption.

Ectomycorrhizae

A type of mycorrhizae where the fungal hyphae form a mantle around the root but do not penetrate the plant cells.

Arbuscular mycorrhizae

Also called endomycorrhizae, these fungi penetrate the cortical cells of the plant root.

Epiphytes

Plants that grow on other plants for physical support but are not parasites, such as staghorn ferns and vanilla orchids.

Parasitic plants

Plants that absorb water, minerals, and sugars from a living host, such as Dodder or Mistletoe.

Carnivorous plants

Plants adapted to low-nutrient soils that trap and digest animals to obtain nitrogen, such as the Venus flytrap or Sundew.