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Anatomy of Flowering Plants - Anatomy and functions of different tissues

Grade 11CBSEBiology

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Meristematic Tissues: These are groups of cells that have the capability to divide. They are classified into Apical (primary growth), Intercalary (between mature tissues), and Lateral (secondary growth like vascular cambium and cork cambium).

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Simple Permanent Tissues: Composed of similar cells. Parenchyma (thin-walled, cellulosecellulose walls, for storage), Collenchyma (thickened at corners with cellulosecellulose, hemicellulosehemicellulose, and pectinpectin for flexibility), and Sclerenchyma (dead, lignified walls for mechanical support).

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Complex Permanent Tissues: Xylem and Phloem. Xylem transports H2OH_2O and minerals via tracheids, vessels, xylem parenchyma, and xylem fibres. Phloem transports organic solutes (food) via sieve tubes, companion cells, phloem parenchyma, and phloem fibres.

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Vascular Bundles: Based on arrangement, they are classified as Radial (Xylem and Phloem on different radii, as in roots) or Conjoint (Xylem and Phloem on the same radius).

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Open vs. Closed Bundles: Open bundles possess cambium (characteristic of DicotDicot stems for secondary growth), while Closed bundles lack cambium (characteristic of MonocotMonocot stems).

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Stomatal Apparatus: Consists of the stomatal aperture, guard cells, and surrounding subsidiary cells. Guard cells in DicotsDicots are bean-shaped, while in grasses (MonocotsMonocots), they are dumb-bell shaped.

📐Formulae

Total Plant Surface Area∝Rate of H2O Transpiration\text{Total Plant Surface Area} \propto \text{Rate of } H_2O \text{ Transpiration}

Primary Growth=Apical Meristem+Intercalary Meristem\text{Primary Growth} = \text{Apical Meristem} + \text{Intercalary Meristem}

Secondary Growth≈Activity of Vascular Cambium+Cork Cambium\text{Secondary Growth} \approx \text{Activity of Vascular Cambium} + \text{Cork Cambium}

Composition of Cell Wall=(C6H10O5)n (Cellulose)\text{Composition of Cell Wall} = (C_6H_{10}O_5)_n \text{ (Cellulose)}

💡Examples

Problem 1:

A student observes a transverse section of a plant organ under a microscope. It shows radial vascular bundles with exarchexarch xylem. Identify the organ.

Solution:

The organ is a Root.

Explanation:

In roots, the vascular bundles are arranged in a radial manner (Xylem and Phloem on different radii). The term exarchexarch refers to the arrangement where protoxylem lies towards the periphery and metaxylem lies towards the center, which is a characteristic feature of roots.

Problem 2:

Why are vascular bundles in MonocotMonocot stems described as 'Closed'?

Solution:

Because they lack the vascular cambium.

Explanation:

Vascular cambium is the lateral meristematic tissue responsible for secondary growth. Since MonocotsMonocots do not undergo secondary growth in the stem, their vascular bundles lack cambium and are termed 'Closed'.

Problem 3:

Compare the chemical composition of the cell wall thickenings in Collenchyma vs. Sclerenchyma.

Solution:

Collenchyma: Cellulose+Hemicellulose+PectinCellulose + Hemicellulose + Pectin; Sclerenchyma: LigninLignin.

Explanation:

Collenchyma provides mechanical support to growing parts and is living; its corners are thickened with pectinpectin and cellulosecellulose. Sclerenchyma is usually dead and provides rigid structural support due to heavy ligninlignin deposition.

Anatomy and functions of different tissues Revision - Class 11 Biology CBSE