Pharmacognosy I: Cell Structure and Organelles

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Questions and Answers

What is the primary function of the cuticle in plants?

To enhance photosynthesis

To control water loss from underlying cells (correct)

To facilitate gas exchange

To provide structural support

Where are stomata primarily located on a leaf?

On the lower surface of the leaf (correct)

Only at the leaf's edge

Evenly distributed on both surfaces

On the upper surface of the leaf

What is true about the impermeability of cutin?

It retains moisture within the plant (correct)

It allows for easy gas exchange

It prevents oxygen diffusion

It facilitates nutrient uptake from the soil

How do stomata contribute to a plant's survival?

By regulating gas exchange Signup and view all the answers

What characteristic of cutin makes it essential for plant health?

It is impermeable to water and gases Signup and view all the answers

What is true regarding the nature of epidermal cells?

Epidermal cells are living and form a continuous layer. Signup and view all the answers

Which of the following statements about intercellular spaces in epidermal cells is accurate?

Intercellular spaces are found predominantly in certain regions like leaves and green stems. Signup and view all the answers

What are the primary regions in plants responsible for the production of new cells called?

Meristems Signup and view all the answers

In which areas are stomal pores typically found, according to the information provided?

On leaves and green stems Signup and view all the answers

Which part of the starch structure is characterized by striations?

Grains Signup and view all the answers

What is the primary characteristic of the layer formed by epidermal cells?

It consists of living cells with no spaces between them. Signup and view all the answers

Which statement correctly identifies the role of meristems in plant biology?

They produce new plant cells. Signup and view all the answers

In the context of plant cell theory, what is the significance of meristems?

They are sites for cell division and differentiation. Signup and view all the answers

How do the characteristics of epidermal cells affect their function in plants?

Absence of intercellular spaces allows for efficient gas exchange. Signup and view all the answers

What is the term for the center point in the starch grain structure known as the hilum?

It is where striations converge. Signup and view all the answers

What does the nuclear envelope contain?

Proteins and genetic information Signup and view all the answers

What are vacuoles primarily filled with?

Cell sap Signup and view all the answers

What term is used for the materials present in vacuoles?

Ergastic substances Signup and view all the answers

Which of the following statements is true regarding the contents of vacuoles?

They are filled with ergastic substances. Signup and view all the answers

Which of these options describes a function of the nuclear envelope?

Controls the entrance and exit of materials Signup and view all the answers

What classifies the dermal tissue in plants?

It forms the outer protective covering of the plant. Signup and view all the answers

Which of the following is NOT one of the four systems of tissues in plants?

The connective Signup and view all the answers

Which system of tissues primarily provides structural support in plants?

The ground tissues Signup and view all the answers

In the classification of plant tissues, which tissue system is primarily involved in transport?

The vascular tissues Signup and view all the answers

Which of these options best describes the role of secretory tissues in plants?

They accumulate and secrete substances like resins. Signup and view all the answers

What is the primary source of waste products in plant cells?

Metabolic activities of protoplasm Signup and view all the answers

Which best describes the nature of waste products in plant cells?

By-products of metabolic activities Signup and view all the answers

Waste products in plants originate from what biological component?

Protoplasm Signup and view all the answers

What process in plant cells can lead to the formation of waste products?

Metabolic processes Signup and view all the answers

What function do waste products serve in plant metabolism?

They are by-products of metabolism rather than functional components Signup and view all the answers

Study Notes

Lecture 2: Pharmacognosy I

Cell Wall Components:
- Middle lamella: Composed of calcium and magnesium pectate
- Primary cell wall: Primarily cellulose, capable of extension
- Secondary cell wall: Formed when cells stop enlarging, made of cellulose, and increases cell area
- Cytoplasm strands (plasmodesmata): Connect protoplasm of adjacent cells
Cell Organelles:
- Plasma membrane: Phospholipid bilayer, selectively permeable, and involved in sensory transduction.
- Nucleus: Controls all cellular activities and transmits hereditary characteristics.
- Endoplasmic Reticulum (ER):
  - Smooth ER: No ribosomes; produces proteins used in the cell
  - Rough ER: Contains ribosomes, synthesizes proteins destined for export.
- Ribosomes: Minute spherical bodies, responsible for high protein synthesis and cell division.
- Golgi apparatus: Processes proteins from the ER, sorts and packages them for various destinations, and involved in cell wall formation.
- Mitochondria: Powerhouse of the cell, produces necessary energy.
- Plastids:
  - Leucoplasts: Colorless plastids
  - Chloroplasts: Contain chlorophyll and are involved in photosynthesis
  - Chromoplasts: Contain carotenoid pigments.
- Lysosomes: Contains digestive enzymes, performs intracellular digestion.
- Vacuoles: Filled with cell sap (tonoplast), and contain pigments like anthocyanin.
Quiz Matching:
- Rough Endoplasmic Reticulum: Attached by ribosomes
- Plasmodesmata: Small strands of cytoplasm connecting adjacent cells
- Cystolith: Outgrowth of the cell impregnated with calcium carbonate
- Mitochondria: Powerhouse of the cell.
True or False (1-4):
- 1. Primary cell wall are thicker and stronger, deposited when cell enlargement is complete: True.
- 1. Chromoplasts: non-pigmented plastids, some which can synthesize starch: False
- 1. Nucleus is a Central leader of the cell, contains directions to make proteins and genetic information (DNA/RNA): True
- 1. Vacuoles are membrane-bound organelles filled with cell sap: True
Ergastic Substances (Cell Inclusions):
- Materials present in vacuoles, either reserve substances utilized for cellular activities, or metabolic products.
- Two types:
  - Food storage products: Carbohydrates, proteins, and fats.
  - Waste products: Results from metabolic activities of the protoplasm.
Food Storage Products (Carbohydrates):
- Cellulose: Main component of cell walls; composed of long chains of glucose units.
- Starch: Stored as granules with various shapes, plant type dependent for identification; produces glucose with hydrolysis and maltose.
Plant Cell Structures (Simple, Semi-Compound, Compound grains):
- Simple: Composed of layers around a point (hilum)
- Semi-compound: Made from two or more individual grains with a common surrounding layer
- Compound: Aggregated individual grains without shared layers
Maize Starch and Potato Starch Characteristics: (Descriptions of the various types of starch)
Tests for Identity:
- Microscopic examination: Distinguishes sources (e.g., maize, rice, potato, wheat) of starch.
- Iodine test: Starch turns blue with iodine solution
Proteins (B-Protein):
- Stored as aleurone grains, polypeptides linked by peptide linkages.
- Stained red with Millon reagent, yellowish brown with iodine solution, and yellow with picric acid.
Fats (C-Fats):
- Mixtures of esters of fatty acids and glycerol (glycerides).
- Two types:
  - Solid: Wax, suberin, fat, and cutin
  - Liquid: Fixed oils
Waste Products:
- Calcium carbonate crystals: Formed within epidermal cells (cystoliths).
Calcium Oxalate Crystals:
- Common in plants, deter herbivores/pests.
- Types: Prisms, Raphides, Clusters, Druses, Rosettes, Clusters.
How to Differentiate CaCO3 and CaOx:
- CaCO3: Dissolves with effervescence in dilute acids.
- CaOx: Insoluble in acetic acid, but dissolves without effervescence in hydrochloric and sulfuric acid.
Plant Tissues:
- Meristematic tissues: Actively dividing cells. Example (Apical, Intercalary, Lateral meristems)
- Permanent tissues: Non-dividing cells with specific functions. Example (Dermal, Ground, Vascular, Secretory)
Dermal Tissue: Forms the outer protective layer (epidermis) -Stomata- Regulation gas exchange

-Components of stomata
- Guard cells (kidney-shaped in dicots, dumbbell-shaped in monocots)
- Subsidiary cells -Types of stomata (paracytic, diacytic, anisocytic, anomocytic.
Epidermal Modifications:
- Trichomes: Hairs; classified into glandular and non-glandular types

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Description

This quiz covers key concepts from Pharmacognosy I related to cell wall components and organelles. Explore the intricacies of the plasma membrane, nucleus, endoplasmic reticulum, ribosomes, and Golgi apparatus. Test your knowledge on how these structures contribute to cell function and organization.