Plant Physiology: Starch and Metabolic Products

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Questions and Answers

What characterizes the schizogenous method of formation?

Expansion of a cavity through chemical processes

Enclosing a cavity by splitting cells (correct)

Direct growth from a single cell

Formation through cell breakdown

Which type of structure is characterized by the breaking down of cells to form a cavity?

Anastomosing

Schizogenous

Lysigenous (correct)

Schizolysigenous

What are the primary components of latex found in laticiferous structures?

Proteins and carbohydrates

Resins and tannins in an aqueous solution (correct)

Simple sugars and amino acids

Inorganic minerals and salts

Which of the following is an example of a secondary metabolic product?

Volatile oils Signup and view all the answers

Which polysaccharide is formed through the photosynthesis process?

Starch Signup and view all the answers

What is a defining feature of latex vessels?

They can have anastomosing connections Signup and view all the answers

Carbohydrates are composed mainly of which elements?

Carbon, hydrogen, and oxygen Signup and view all the answers

What type of metabolic products are represented by alkaloids and glycosides?

Secondary metabolic products Signup and view all the answers

Which starch has a distinct shape that is described as polyhedral with sharp angles?

Rice starch Signup and view all the answers

What is the main chemical test used to identify starch?

Iodine Test Signup and view all the answers

Which starch is noted for having a large size in its characteristics?

Potato starch Signup and view all the answers

In terms of striation, which starch exhibits an absent feature?

Rice starch Signup and view all the answers

Which starch is described as having mostly simple and few compound aggregates?

Wheat starch Signup and view all the answers

What role does starch play in pharmaceutical applications?

Tablet disintegrant Signup and view all the answers

Which starch has an eccentric pointed hilum?

Potato starch Signup and view all the answers

What is one of the internal uses of starch?

As an antidote for iodine poisoning Signup and view all the answers

What color do hydrolysable tannins produce when tested with ferric chloride?

Blue Signup and view all the answers

What are phlobaphenes resulting from?

Treatment of condensed tannins with acids or enzymes Signup and view all the answers

Which type of tannins do not contain a sugar moiety?

Condensed tannins Signup and view all the answers

What is the main use of calcium oxalate crystals in plants?

Microscopical examination and detection of adulteration Signup and view all the answers

What indicates the presence of tannins in the gold beater's skin test?

A brown or black color on the skin Signup and view all the answers

What is produced as a result of the photosynthesis process in plants?

Glucose and oxygen Signup and view all the answers

What is the primary function of amylose in starch granules?

To form the inner layers of the granule Signup and view all the answers

Which of the following statements about starch is true?

Starch is colored deep blue in the presence of iodine. Signup and view all the answers

What happens to starch granules when heated with water?

They swell and undergo gelatinization. Signup and view all the answers

What is the role of the hilum in starch granules?

It is the starting point of granule formation. Signup and view all the answers

Which of the following describes the macroscopic character of starch?

It occurs as a white powder or irregular masses. Signup and view all the answers

What contributes to the microscopical identification of starch?

Shape and striation of granules. Signup and view all the answers

What happens to starch when treated with concentrated solutions of calcium or zinc chlorides?

It undergoes gelatinization. Signup and view all the answers

What are aleurone grains primarily composed of?

Ground substance, crystalloid, and globoid Signup and view all the answers

Which statement accurately describes the crystalloid in aleurone grains?

It is formed of albumins and is hardly soluble in water. Signup and view all the answers

What color do aleurone grains stain when treated with Millons reagent?

Red Signup and view all the answers

What is the characteristic reaction of most alkaloids when treated with Mayers reagent?

Formation of a yellowish precipitate Signup and view all the answers

Which of the following accurately describes fixed oils?

They are hydrolyzed to produce soap and glycerol. Signup and view all the answers

Glycosides are classified according to which of the following?

Their sugar moiety and the linkage between glycone and aglycone Signup and view all the answers

How are alkaloids typically found in plants?

Either as free bases or as salts of acids Signup and view all the answers

Which of the following statements about volatile oils is true?

They are mixtures of hydrocarbons and oxygenated compounds Signup and view all the answers

What role does osmic acid play in identifying oils microscopically?

It stains oil globules black. Signup and view all the answers

What is a common use of tannins in medicinal applications?

As an astringent in the gastrointestinal tract Signup and view all the answers

What type of fatty acids do fats typically consist of?

Saturated, higher molecular weight Signup and view all the answers

Which type of tannins may be hydrolyzed by acids or enzymes?

Hydrolysable tannins Signup and view all the answers

Which solvent type do free bases of alkaloids typically dissolve in?

Organic solvents only Signup and view all the answers

What is the main therapeutic action of volatile oils?

Antiseptic and carminative Signup and view all the answers

What is the main component of glycosides?

Sugar part (glycone) and non-sugar part (aglycone) Signup and view all the answers

What is observed when tannins react with proteins of animal hides?

They create a protective coat for regeneration Signup and view all the answers

Study Notes

The Cell and Cell Differentiation

A cell is the fundamental unit of living organisms (plants and animals).
Cells consist of a cell wall, nucleus, cytoplasm, and vacuoles.
Cytoplasm contains various organelles like crystals, aleurone grains, mitochondria, Golgi bodies, lysosomes, and plastids.
A tissue is a group of cells with similar form and function.

The Cell Wall

Mature cell walls consist of:
- Middle lamella: An amorphous, colloidal layer composed of pectic substances, acting as an intercellular substance.
- Primary wall (original cambial wall): Composed of cellulose and pectic substances.
- Secondary wall: Formed after cell enlargement, primarily composed of cellulose and polysaccharides. (undergoes modifications with lignin, suberin and cutin deposition)
- Tertiary wall: The innermost layer, typically thin, highly refractive, and composed of cellulose.

Properties of Different Cell Walls

Cellulosic Walls: Primarily composed of cellulose, often accompanied by hemicellulose and pectin.
- Chemical Properties:
  - Turn blue with iodine and sulfuric acid.
  - Turn blue with chloro-zinc-iodine.
  - No color with aniline or phloroglucin and HCl.
  - Dissolve in ammoniacal copper oxide (Cuoxam) and precipitate with dilute sulfuric acid.
Mucilaginous Walls: Certain cellulosic walls can be converted to gums and mucilages (polysaccharides consisting of sugar and uronic acid combined with metals).
- Chemical Properties:
  - Variably stained with ruthenium red, iodine-sulfuric acid, or corallin soda.
Lignified Walls: Lignin (complex phenylpropanoid polymer) strengthens cell walls.
- Chemical Properties:
  - Stain magenta red with phloroglucin and hydrochloric acid.
Suberized and Cutinized Walls: Suberin and cutin are mixtures of polymerized fatty acids and suberic acid.
- Chemical Properties:
  - Stain red with alkanna tincture and Sudan III.
Chitinous Walls: Chitin (polysaccharide derivative containing acetyl and amino groups) forms the skeletal substance of insects and fungi.
- Chemical Properties:
  - Turns deep violet with iodine solution followed by dilute sulfuric acid when heated with 50% potash at 160-170°C.

Cell Differentiation

Parenchymatous Tissues: Fundamental/ground tissues, isodiametric or slightly elongated cells with intercellular spaces. They contain various contents (starch, calcium oxalate crystals). They form major parts of the pith and cortex.
Collenchymatous Tissues: Living mechanical tissue with unevenly thickened, nonlignified cell walls. Common in angles or tangential walls (angular or lamellar collenchyma) of herbaceous stems, petioles, and midribs of leaves.
Sclerenchymatous Tissues: Thick-walled, dead, and lignified cells primarily for mechanical support.
- Sclereids: Small, thick-walled cells, isodiametric or slightly elongated.
- Fibres: Elongated, thick-walled, and lignified cells with tapering ends.

Secretory Tissues

External and Internal: Examples include glandular hairs, secretory cells, cavities, ducts, and laticiferous tissues.
- Secretory Cells: Isolated or in rows, their walls may be suberized. Secrete volatile oils, resin, gum resins, mucilage, enzymes, or tannins.
- Secretory Cavities (Glands): Embedded tissue cavities secreting volatile oils or oleoresin (e.g., savin, clove, buchu, or dictamnus) via Schizogenous, schizolysigenous, or lysigenous.
- Secretory Ducts: Tube-like structures, may extend throughout the organ (e.g., leaf in Pinus) or whole plant, formed schizogenously, lysigenously, or schizolysigenously (e.g., in Capaifera).
Laticiferous Structures: Tube-like cells or vessels with latex (colorless, milky white, yellow, or reddish viscous emulsion). Latex may contain resin, gums, gum-resins, fats, waxes, proteins, alkaloids, tannins, minerals, sugars, and enzymes.

Primary and Secondary Metabolites

Primary Metabolites: Organic compounds directly involved in plant growth and development, such as carbohydrates (starch, sugars), proteins, and lipids.
Secondary Metabolites: Compounds not essential for growth but often provide protection or attractants, including alkaloids, glycosides, volatile oils, tannins (e.g. flavonoids in flowers), or resins.

Starch

Starch is a carbohydrate polymer formed during photosynthesis via condensation of glucose molecules.
Starch granules consist of amylose (interior, soluble in water) and amylopectin (exterior, insoluble in water).
Starch's presence can be confirmed visually with iodine (blue-black color).

Proteins

Proteins are polymers of amino acids, crucial for plant structure and function. Aleurone grains are a common protein storage form in seed tissues.

Lipids

Lipids (fats, oils, waxes) are important for plant structure and energy storage. Fixed oils and fats can be converted to soaps and glycerols by alkalis.

Glycosides

Glycosides are plant compounds composed of a sugar (glycone) moiety and a non-sugar moiety (aglycone), with diverse biological activities.

Volatile Oils

Volatile oils are secreted in oil cells, canals, or glands. Made up of hydrocarbons and oxygenated compounds, characterized by aroma and used in flavoring, perfumery, and as antiseptics.

Tannins

Tannins are water-soluble compounds found in plant extracts. Combine with proteins to prevent putrefaction (e.g. tanning of leather), and have astringent, hemostatic properties, and use as antidotes for poisoning.

Calcium Oxalate

Calcium oxalate is an end product of plant metabolism. Often found in crystalline forms, useful for microscopic identification of plants and detection of adulteration.

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Description

This quiz explores key concepts in plant physiology, focusing on the characteristics of starch, latex structures, and metabolic products. Test your knowledge on the various types of starch, their properties, and their roles in plants and pharmaceuticals.