Plant Nutrition: Processes, Sap Movement, and Key Structures

Nutrition Defined

Nutrition is the set of processes by which living organisms transform energy and substances from their environment into their own organic molecules.

Types of Nutrition

• Autotrophs

  Organisms that are able to convert the sun's energy and mineral substances from water and soil into biomolecules.

• Heterotrophs

  Organisms in which nutrition occurs in living organisms that cannot capture the sun's energy, obtaining nutrients by consuming other organisms.

Nutritional Processes

1. Water ascends from roots to leaves through the xylem, which transports water, providing hydrogen.
2. Mineral salts dissolved from the soil provide essential elements like nitrogen, phosphorus, potassium, chloride, iron, magnesium, etc.
3. Carbon dioxide from the air provides the carbon necessary for plants.

Sap Movement in Plants

Crude Sap (Xylem Sap)

Crude sap (water and mineral salts) rises through the xylem tissue, which is a conductor in the form of hollow tubes. It ranges from roots to leaves and other parts of the plant where photosynthesis occurs.

Prepared Sap (Phloem Sap)

Prepared sap (biomolecules dissolved in liquid) moves through the phloem. It goes both upward and downward.

How Crude Sap Ascends

Transpiration

Transpiration is the continued loss of water through the stomata of the leaves. This phenomenon creates a vacuum, which causes the suction of the xylem sap, causing it to flow from roots to leaves.

Capillarity

Capillarity refers to the cohesive forces that aid in sap movement.

Key Plant Structures and Components

Stomata

Small pores located in the epidermis of leaves where gas exchange and water loss occur through transpiration.

Leaf Lamina (Blade)

The broad, flat part of a leaf.

Petiole

The stalk that connects the leaf blade to the stem.

Cuticle

A thin, waterproof layer covering the epidermis of leaves and stems.

Epidermis

The outermost layer of cells, typically single-celled, located beneath the cuticle.

Chloroplasts

Organelles responsible for photosynthesis, containing chlorophyll, which gives leaves and green parts of plants their color.

Chlorophyll

The green pigment in plants that captures the sun's energy, enabling the conversion of inorganic substances into biomolecules through photosynthesis.

Photosynthesis

Photosynthesis is a process where the sun's energy captured by chlorophyll is converted into chemical energy. It produces glucose, which is the first product obtained in photosynthesis.

Cellular Respiration

Cellular respiration occurs in the mitochondria of the cell and involves the oxidation of organic nutrients to extract the energy they contain.

Utility of Organic Molecules

• Energy Use (Cellular Respiration)

  Glucose is used for energy.

• Transportation

  Sucrose is transported throughout the plant.

• Storage

  Glucose is stored as starch grains in seeds and tubers.

• Biosynthesis of Other Molecules

  From glucose, other biomolecules like proteins, cellulose, and lipids are synthesized.