Plant Nutrition Flashcards

Flashcards based on lecture notes about plant nutrition.

What are the primary nutrients, besides carbon dioxide and water, that plants need for growth?

An array of essential nutrients available as ions dissolved in soil water.

How do plants absorb nutrients?

Via specialized proteins in plasma membranes of root cells, and often through associations with fungi.

What is the role of endodermal cells in nutrient absorption?

To exclude toxins from the xylem or actively transport them into cell vacuoles for storage.

What is the mode of nutrition for autotrophic plants?

They can prepare their own food (all green plants).

What is the mode of nutrition for parasitic plants?

Obtain nutrition from a host plant (e.g., Cuscuta).

What is the mode of nutrition for saprophytic plants?

Obtain nutrition from dead and decaying organisms (e.g., Agaricus).

What is the mode of nutrition for symbiotic plants?

Two organisms sharing mutual benefits (e.g., lichens).

What is the mode of nutrition for insectivorous plants?

Feed on insects to obtain nitrogen (e.g., Pitcher plant).

How do plants obtain essential nutrients?

Soil provides most of these nutrients.

What is an essential nutrient for plants?

An element required for normal growth, reproduction, and specific metabolic functions.

What is the primary source of a growing tree's mass?

Carbon dioxide in the atmosphere.

What are the three essential elements that make up approximately 96% of a plant's dry weight?

Carbon, hydrogen, and oxygen.

Name two macronutrients obtained from soil and their functions.

Nitrogen (component of nucleic acids, ATP, chlorophyll, proteins, hormones, and coenzymes) and Potassium (cofactor for many enzymes; necessary for osmotic adjustment).

Name two micronutrients obtained from soil and their functions.

Iron (necessary for chlorophyll synthesis; component of cytochromes and ferredoxin; enzyme cofactor) and Zinc (involved in synthesis of the plant hormone auxin; maintenance of ribosome structure; enzyme activation).

What are macronutrients?

Building blocks of nucleic acids, proteins, carbohydrates, phospholipids, and other key molecules required in relatively large quantities.

What are limiting nutrients?

Macronutrients that commonly act as limits on plant growth, such as N, P, and K.

What are micronutrients?

Elements that usually function as cofactors for specific enzymes and are required in very small quantities.

What happens when mobile elements like N, P, K, and magnesium are in short supply?

They are transferred to newer leaves, causing deterioration of older leaves.

What happens when immobile nutrients like iron and calcium are in short supply?

Their scarcity is reflected in newer leaves as they remain tied up in older leaves.

What is hydroponic growth?

A method of growing plants using mineral nutrient solutions in water without soil.

What does soil texture refer to?

The proportions of different-sized particles present in the soil.

What are loams?

The best soils, containing roughly equal amounts of sand, silt, and clay along with a high proportion of humus.

What is leaching in the context of soil nutrients?

The loss of nutrients via washing out of the soil by rain.

How does soil pH influence the availability of essential elements?

It affects the solubility and thus the availability of nutrients to plants.

What is cation exchange in soil?

When protons or other cations in soil water bind to negative charges on soil particles, causing bound cations like magnesium or calcium to be released.

Where does most water & nutrient absorption occur in the roots?

At root hairs in the zone of maturation.

How do plant cell walls and plasma membranes differ in permeability?

Plant cell walls are permeable to ions and molecules, while the plasma membrane is highly selective.

What is the role of proton pumps (H+-ATPases) in nutrient uptake?

To move nutrients into the cell against a strong concentration gradient, establishing a proton gradient.

How do plants exclude detrimental ions from the soil?

By either passive or active exclusion.

What is the role of the Casparian strip in ion exclusion?

It forces ions to go through endodermal cells for filtration.

What are metallothioneins?

Small proteins that bind to metal ions, preventing them from acting as poisons within plant cells.

What is the role of the tonoplast in active exclusion of toxins?

It allows plant cells to actively remove toxic substances from the cytosol and store them in the vacuole.

What are epiphytes?

Plants adapted to grow in the absence of soil, absorbing water and nutrients from rainwater and dust.

How do most parasitic plants obtain nutrients?

By tapping into the vascular tissue of their hosts for water and essential nutrients.

Why do carnivorous plants trap insects?

To supplement the nitrogen available in the environment, which is often lacking.

What are mycorrhizae?

Fungi that live in close association with plant roots, providing nitrogen and/or phosphorus in exchange for sugar.

What is nitrogen fixation?

The process by which some bacteria convert atmospheric nitrogen gas (N2) to ammonia, nitrates, and nitrites.

What are nodules on legume roots?

Distinctive structures where nitrogen-fixing rhizobia are found.

What are Nod factors?

Factors produced by rhizobia that bind to the proteins on the membrane surface of the root hair cells triggering morphological changes in the host legume.