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Questions and Answers
What is the primary role of carbohydrates in plant growth and metabolism?
Which carbohydrate is primarily responsible for providing immediate energy to plants?
How is starch primarily stored in plants?
What distinguishes amylopectin from amylose in terms of structure?
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What color indicates a positive iodine test for starch?
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Which of the following is NOT a medicinal use of starch?
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What property of amylose allows it to dissolve in water?
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Which starch is primarily utilized as a suspending agent for barium meals in radiography?
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What are ergastic cell contents primarily composed of?
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Which type of metabolites are essential for plant survival?
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What is the main role of secondary metabolites in plants?
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Which of the following compounds are classified as primary metabolites?
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How are carbohydrates characterized in terms of their elemental composition?
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Which of the following is a type of carbohydrate made of a single sugar unit?
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Which carbohydrate derivative is classified as a secondary metabolite?
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What distinguishes secondary metabolites from primary metabolites in terms of necessity for survival?
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What substance plays a protective role by thickening membranes in plants?
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Which of the following substances is classified as a polysaccharide and has medical uses?
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Pectin is primarily obtained from which part of plants?
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What function does pectin serve in the food industry?
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Which drug derived from starch is specifically noted for its use in plasma expansion?
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What are aleurone grains primarily composed of within plant cells?
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Which of the following best describes the role of mucilage in plants?
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Which polysaccharide is used as a suspending agent in pharmaceuticals?
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Study Notes
Ergastic Cell Contents
- Non-living substances present in the cell.
- Can be identified by microscopic examination or chemical and physical tests.
- Found in cytoplasm and vacuole.
Primary Metabolites
- Essential for plant survival
- Organic compounds involved in growth, development, and reproduction of the organism
- Examples include carbohydrates, proteins, lipids
- Absence of primary metabolites would result in immediate death.
Secondary Metabolites
- Not essential for plant survival.
- Often referred to as byproducts of metabolism.
- Examples include alkaloids, volatile oils, tannins, flavonoids.
- Play roles in functions like defense.
Carbohydrates
- Composed of carbon, hydrogen, and oxygen
- Carbon and hydrogen are present in the ratio 2:1, like that of water.
- Classified by number of sugar units:
- Monosaccharides (e.g. glucose)
- Disaccharides (e.g. sucrose)
- Oligosaccharides
- Polysaccharides (e.g. starch, cellulose)
Carbohydrates Role in Plants
- Source of energy: Energy can be stored as starch (storage polysaccharide)
- Structural Function: Example is cellulose in the plant cell wall
- Building blocks: The 5-carbon monosaccharide ribose is a component of coenzymes and the backbone of RNA. Deoxyribose is a component of DNA.
Starch
- Polysaccharide formed of many glucose units
- Source of energy
- Stored in the form of starch grains
- Starch granules are composed of amylose and amylopectin
Amylose vs Amylopectin
- Amylose: Unbranched chain of glucose units, soluble in water, gives blue color with iodine
- Amylopectin: Branched chain of glucose units, insoluble in water, gives bluish black precipitate with iodine
Starch Tests
- General test for carbohydrates: Iodine test: Suspension of starch gives a dark bluish black color
- Molisch's test: Suspension of starch and alcoholic α-naphthol gives violet ring at the interface upon addition of concentrated H2SO4.
Medicinal Uses of Starch
- Topically as dusting powder
- Antidote for iodine poisoning
- Lubricant for surgeons’ gloves
- Tablet disintegrant
- Suspending agent for barium meals
- Nutrient and demulcent properties
Important Starches
- Potato starch
- Maize starch
- Wheat starch
- Rice starch
Starch Grain Features
- Each grain has a hilum, the point of origin of starch deposition.
- Starch is deposited in layers around the hilum.
- Hilum can be located in the center or periphery.
Other Polysaccharides: Mucilage and Gums
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Mucilage: Viscous sticky material
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Plays a protective role in membranes, forming colloidal solution in water.
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Used as demulcent, emollient, and bulk laxatives
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Gives red color with ruthenium red
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Gums: Viscous secretion of trees and shrubs.
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Hardens on drying but is soluble in water.
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Used in pharmaceutical industry in the preparation of emulsions and suspensions.
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Classified as polysaccharides or salts of polysaccharides
Pectin
- Purified carbohydrate obtained from the rind of citrus fruits.
- Source of dietary fiber.
- Structural polysaccharide in plant cell walls.
- Used in food as a gelling agent.
- Used in pharmacy as:
- suspending agent
- in antidiarrheal formulations
Drugs Derived from Starch
- Hetastarch (hydroxyethyl starch): Plasma expander
- Dextrin: Product of partial degradation of starch, used in infant formulas for nutrition, drug delivery, oral disintegrating films
- Dextran: Plasma expander
Proteins
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Classified into:
- Structural proteins in the cell membrane and cell wall
- Storage proteins, mostly in seeds
- Enzymes
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In plants, proteins are stored as amorphous mass called aleurone grains, often containing a crystalloid and a globoid.
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Description
Explore the fascinating world of plant cell composition and metabolism through this quiz. Delve into the differences between ergastic cell contents, primary and secondary metabolites, and carbohydrates. Test your understanding of the vital substances that contribute to plant life and their functions.
