Plant Nutrition, Photosynthesis, and Respiration

Comprehensive vocabulary flashcards covering plant nutrition, photosynthesis phases, cellular respiration, plant transport mechanisms, root structure, stomatal function, and essential macro- and micro-minerals from the lecture transcript.

Photosynthesis

An anabolic process in green plants that uses radiant energy from the sun, $CO_2$, and $H_2O$ to make food (glucose) and release $O_2$.

Respiration

A catabolic process in which cells break down glucose using $O_2$ to release energy in the form of $ATP$, producing $CO_2$ and $H_2O$ as waste products.

Anabolic process

A metabolic process involving the building up of complex molecules, such as photosynthesis.

Catabolic process

A metabolic process involving the breaking down of complex molecules to release energy, such as respiration.

Light phase

The light-dependent phase of photosynthesis (also known as Hill's reaction) occurring in the grana of chloroplasts, where chlorophyll absorbs radiant energy to split water ($\text{photolysis}$), produce $ATP$, and reduce $NADP$ to $NADPH$.

Dark phase

The light-independent phase of photosynthesis (also known as the Calvin cycle) taking place in the stroma of chloroplasts, where $CO_2$, $ATP$, and $NADPH$ are used to produce energy-rich glucose.

Photolysis

The splitting of water molecules into oxygen gas and hydrogen ions using radiant energy absorbed by chlorophyll during the light phase of photosynthesis.

Stroma

The colorless liquid medium inside chloroplastids containing floating discs (lamellae), serving as the site for the dark phase (Calvin cycle) of photosynthesis.

Grana

Structures formed by stacked lamellae discs inside chloroplasts where chlorophyll absorbs light energy and the light phase of photosynthesis takes place.

Chlorophyll a

A photosynthetic pigment appearing blue-green, found in all autotrophic organisms, which absorbs light energy in the blue-violet and orange-red regions of the visible spectrum.

Chlorophyll b

A photosynthetic pigment appearing yellow-green that absorbs light energy and transfers it to chlorophyll a.

Chromoplastids

Colored plastids containing red, yellow, and orange pigments found in flower petals and fruits.

Carotenoids

Orange-yellow pigments (such as carotene) that protect plant cells and chlorophyll against photo-oxidation and transfer absorbed light energy to chlorophyll a.

Trellising

A plant manipulation technique of keeping plants off the ground to ensure that fruit-bearing branches have maximum exposure to sunlight for photosynthesis.

Pruning

The removal of tree branches to prevent overshadowing and give plants maximum exposure to sunlight.

Insoluble food storage

The storage of excess sugars as insoluble molecules (like starch) so cell water potential remains unaffected, preventing excessive water uptake by osmosis while keeping food compact within plant cells.

Osmosis

The movement of water molecules from an area of high water potential to an area of low water potential through a permeable membrane.

Diffusion

The movement of molecules from an area of high concentration to an area of low concentration.

Turgor pressure

The internal pressure exerted against the plant cell wall when water moves into the cell via osmosis.

Hypertonic solution

A solution containing a high concentration of dissolved substances, resulting in a low water potential.

Hypotonic solution

A solution containing fewer dissolved substances, resulting in a high water potential.

Cohesion

The attraction force between water molecules created by hydrogen bonds, causing water molecules to stick together in a continuous column.

Adhesion

The attraction force between water molecules and the inner walls of xylem vessels, preventing the column of water from falling back down due to gravity.

Capillary action

The upward movement of water through narrow tubes like xylem vessels, caused by the combined forces of cohesion and adhesion.

Root pressure

The force that develops in the xylem of roots as water moves in by osmosis, pushing water upward through the stem to the leaves.

Transpiration pull

The upward pulling force exerted on the water column inside xylem vessels as water evaporates from the leaves through transpiration.

Suberin

A waxy, corky layer that develops in older regions of the root, blocking water absorption.

Transpiration

The loss of water in the form of water vapor through the stomata of plant leaves, occurring primarily during the day.

Guttation

The loss of water in the form of liquid droplets through hydathodes on leaf edges, occurring mainly at night.

Hydathodes

Specialized openings located on the edges of leaves through which water droplets are lost during guttation.

Guard cells

Specialized paired epidermal cells surrounding each stoma that control its opening and closing depending on their turgor pressure.

Xerophyte

A plant adapted to dry environmental conditions, featuring structural adaptations like sunken stomata, thick cuticles, or rolled leaves to minimize transpiration.

Photosynthates

The chemical products of photosynthesis, including sugars, amino acids, and fatty acids, that are transported throughout the plant.

Translocation

The movement of photosynthates from source cells to sink cells through phloem tubes driven by a pressure gradient.

Macro-minerals

Essential mineral nutrients required by plants in large quantities, such as Nitrogen ($N$), Phosphorus ($P$), Potassium ($K$), Calcium ($Ca$), Magnesium ($Mg$), and Sulphur ($S$).

Micro-minerals

Essential mineral nutrients required by plants in small quantities, such as Iron ($Fe$), Zinc ($Zn$), Copper ($Cu$), and Manganese ($Mn$), which can become toxic if absorbed in excess.

Chlorosis

A plant symptom resulting from nutrient deficiencies (e.g., Magnesium, Nitrogen, or Iron) where leaves turn pale yellow or white due to reduced chlorophyll formation.

Auxins

Plant growth hormones whose precursor synthesis depends on the presence of the micro-element Zinc ($Zn$).