Exercise Solutions

Q1: Give examples.

1. Thallophyta: Spirogyra, Ulothrix, Ulva, Sargassum, Fucus, Chara.
2. Bryophyta: Funaria (Moss), Marchantia, Riccia.
3. Pteridophyta: Nephrolepis (Fern), Marsilea, Pteris, Adiantum, Equisetum.
4. Gymnosperms: Cycas, Pinus (Pine), Thuja (Christmas tree), Deodar.
5. Monocotyledonous plant: Maize, Wheat, Rice, Sugarcane, Onion.
6. Dicotyledonous plant: Pea, Bean, Mango, Banyan, Sunflower, Rose.

Q2: Write notes on:

1. Subkingdom Cryptogams
   Answer: Cryptogams are the non-flowering plants within Kingdom Plantae. The term 'cryptogams' literally means 'hidden reproduction', referring to their inconspicuous reproductive organs. They reproduce asexually by spores and do not produce flowers, fruits, or seeds. This subkingdom includes the most primitive plant groups: Thallophyta, Bryophyta, and Pteridophyta. They typically require water for reproduction, especially the bryophytes and pteridophytes, which limits their habitat to moist environments.
2. Division Pteridophyta
   Answer: Pteridophyta is a division of Cryptogams that represents the first group of plants to possess true roots, stems, and leaves. A significant evolutionary advancement in this group is the presence of well-developed vascular tissues (xylem and phloem), which allows for efficient transport of water and nutrients, enabling them to grow taller than bryophytes. Pteridophytes reproduce by spores, which are typically found in sori on the underside of their leaves. They do not produce flowers or seeds. Common examples include ferns like Nephrolepis, Marsilea, and Equisetum.
3. Class Dicotyledons
   Answer: Dicotyledons are a class within Angiosperms (flowering plants). Their defining characteristic is the presence of two cotyledons (seed leaves) in their seeds, which store food for the embryo. Dicotyledonous plants typically have a tap root system, where a single main root grows downwards with smaller lateral roots branching off. Their leaves usually exhibit reticulate (net-like) venation. The flowers of dicots are generally tetramerous (parts in multiples of four) or pentamerous (parts in multiples of five). Examples include pea, bean, mango, banyan, and sunflower.
4. Class Monocotyledons
   Answer: Monocotyledons are another class within Angiosperms. They are characterized by having only one cotyledon in their seeds. Monocot plants typically have a fibrous root system, which consists of a cluster of thin, thread-like roots. Their leaves are characterized by parallel venation, where veins run parallel to each other. The flowers of monocots are usually trimerous (parts in multiples of three). Common examples include maize, wheat, rice, sugarcane, and onion.

Q3: Differentiate between:

1. Monocotyledonous and Dicotyledonous plants

   Feature	Monocotyledonous Plants	Dicotyledonous Plants
   Cotyledons	One cotyledon in seed	Two cotyledons in seed
   Root System	Fibrous root system	Tap root system
   Leaf Venation	Parallel venation	Reticulate (net-like) venation
   Flower Parts	Trimerous (multiples of 3)	Tetramerous or Pentamerous (multiples of 4 or 5)
   Examples	Maize, Wheat, Rice	Pea, Bean, Mango

2. Cryptogams and Phanerogams

   Feature	Cryptogams	Phanerogams
   Reproductive Organs	Hidden/Inconspicuous	Visible (flowers)
   Reproduction	By spores	By seeds
   Flowers/Fruits	Absent	Present
   Seed Formation	Absent	Present
   Examples	Algae, Moss, Ferns	Cycas, Pine, Mango, Wheat

3. Thallophyta and Bryophyta

   Feature	Thallophyta	Bryophyta
   Plant Body	Undifferentiated thallus (no true roots, stems, leaves)	Differentiated into root-like rhizoids, stem-like, leaf-like parts (no true roots, stems, leaves)
   Habitat	Mostly aquatic	Terrestrial, but require water for reproduction (amphibious)
   Vascular Tissues	Absent	Absent
   Examples	Spirogyra, Ulva	Funaria, Marchantia

4. Bryophyta and Pteridophyta

   Feature	Bryophyta	Pteridophyta
   Plant Body	No true roots, stems, leaves; simple differentiation	True roots, stems, and leaves present
   Vascular Tissues	Absent	Present (xylem and phloem)
   Habitat	Moist, shady places; require water for reproduction	Moist, shady places; less dependent on water for vegetative growth due to vascular tissues
   Dominant Phase	Gametophyte	Sporophyte
   Examples	Funaria, Marchantia	Nephrolepis (Fern), Marsilea

Q4: Complete the table (Hierarchy of Plant Classification)

Here's the completed hierarchy based on the textbook diagram:

Kingdom Plantae
├── Subkingdom Cryptogams (Non-flowering plants)
│   ├── Division Thallophyta (e.g., Algae: Spirogyra, Ulothrix)
│   ├── Division Bryophyta (e.g., Mosses: Funaria, Marchantia)
│   └── Division Pteridophyta (e.g., Ferns: Nephrolepis, Adiantum)
└── Subkingdom Phanerogams (Flowering plants)
    ├── Division Gymnosperms (Naked seeds, e.g., Cycas, Pinus)
    └── Division Angiosperms (Seeds enclosed in fruit)
        ├── Class Dicotyledons (Two cotyledons, e.g., Pea, Mango)
        └── Class Monocotyledons (One cotyledon, e.g., Maize, Wheat)
                

Q5: Match the pairs:

Match the following plant groups with their characteristic examples:

• Thallophyta - Spirogyra
• Bryophyta - Funaria (Moss)
• Pteridophyta - Nephrolepis (Fern)
• Gymnosperms - Cycas
• Angiosperms (Dicot) - Mango
• Angiosperms (Monocot) - Maize

Q6: Explain the hierarchy of classification with examples.

Answer: The hierarchy of classification is a system used by biologists to group organisms into successive ranks, from broad to specific. This system helps in organizing and understanding the relationships among living things. The main ranks, from broadest to most specific, are Kingdom, Division (or Phylum), Class, Order, Family, Genus, and Species.

Example (for a Dicotyledonous plant like Mango):

• Kingdom: Plantae (All plants)
• Division: Angiospermae (Flowering plants)
• Class: Dicotyledoneae (Plants with two cotyledons)
• Order: Sapindales
• Family: Anacardiaceae
• Genus: Mangifera
• Species: indica (The scientific name is Mangifera indica)

Each level in the hierarchy groups organisms with increasing similarity, making it easier to study and identify them.

Q7: Explain the criteria for classification of plants.

Answer: The classification of plants is based on several key morphological and anatomical features that reflect their evolutionary development. These criteria include:

1. Differentiation of Plant Body: Whether the plant body is simple (thallus) or differentiated into true roots, stems, and leaves.
2. Presence of Vascular Tissues: The existence of specialized conducting tissues (xylem and phloem) for water and food transport. This is a major step in plant evolution, allowing for larger plant sizes.
3. Seed Formation: Whether the plant reproduces by forming seeds or by spores. Seed-bearing plants (Phanerogams) are more advanced than spore-bearing plants (Cryptogams).
4. Seed Enclosure: If seeds are present, whether they are naked (Gymnosperms) or enclosed within a fruit (Angiosperms). Fruit development provides protection and aids in seed dispersal.
5. Number of Cotyledons: For Angiosperms, the number of cotyledons (one or two) in the seed is a key distinguishing feature, leading to the classification into Monocotyledons and Dicotyledons, which also correlate with other characteristics like root system and leaf venation.

Q8: Sketch, label and describe:

1. Spirogyra (Thallophyta)
   Sketch: (Imagine a diagram showing a filamentous structure with spiral chloroplasts inside rectangular cells.)
   Description: Spirogyra is a common freshwater green alga belonging to Thallophyta. Its body is a simple, unbranched filamentous thallus, meaning it lacks true roots, stems, or leaves. Each cell is elongated and contains one or more spiral-shaped chloroplasts, which are responsible for photosynthesis. It reproduces asexually by fragmentation and sexually by conjugation.
2. Funaria (Bryophyta)
   Sketch: (Imagine a diagram showing a small, leafy green plant body (gametophyte) with root-like rhizoids at the base, and a stalked capsule (sporophyte) emerging from the top.)
   Description: Funaria, commonly known as moss, is a typical example of Bryophyta. It grows in dense patches in moist, shady areas. The main plant body is the gametophyte, which is green, leafy, and anchored by rhizoids (not true roots). From the gametophyte, a sporophyte develops, consisting of a foot, seta (stalk), and a capsule (spore-producing structure). Funaria requires water for the fertilization process.
3. Fern (Pteridophyta)
   Sketch: (Imagine a diagram showing a plant with an underground rhizome, true roots emerging from it, and large, compound leaves (fronds) unfurling from the rhizome. Show sori on the underside of a leaflet.)
   Description: Ferns are well-known examples of Pteridophyta. Unlike bryophytes, ferns have true roots, stems (often an underground rhizome), and large, well-differentiated leaves called fronds. They possess a well-developed vascular system. Ferns reproduce by spores, which are typically produced in clusters called sori, located on the underside of their fronds. They do not produce flowers or seeds.

Q9: Collect a monocot and dicot plant and observe them. Describe them in your own words.

Answer: This is an activity-based question. Here's what you would typically observe and describe:

Observation of a Monocot Plant (e.g., Maize/Corn plant):

• Seed: When you look at a maize seed, you'll see it's a single, undivided structure (one cotyledon).
• Roots: If you pull up a young maize plant, you'll notice a cluster of thin, fibrous roots spreading out from the base of the stem, without a prominent main root.
• Stem: The stem is usually unbranched and relatively uniform in thickness.
• Leaves: The leaves are long and narrow, with veins running parallel to each other from the base to the tip.
• Flowers: Maize flowers are small and arranged in multiples of three (though this might be harder to observe without close inspection).

Observation of a Dicot Plant (e.g., Bean plant):

• Seed: If you split a bean seed, it easily divides into two halves, each being a cotyledon.
• Roots: A bean plant will have a distinct main root (tap root) growing downwards, with smaller side branches coming off it.
• Stem: The stem is typically branched and can become woody.
• Leaves: The leaves are broader, and if you hold them up to the light, you can see a network of veins branching out from a central vein (reticulate venation).
• Flowers: Bean flowers have petals in multiples of five.