CBSE Class 11 Biology Exemplar: Anatomy of Flowering Plants NCERT Solutions

Solution: The process of double staining is used in histology to differentiate various plant tissues. Safranin is a basic dye that stains lignified cell walls, such as those found in xylem, red. Fast green is an acidic dye that stains cytoplasm and cellulose-rich cell walls green. Therefore, when a stem section is double-stained with safranin and fast green, the xylem typically appears red due to its lignified walls, and the phloem, which has less lignification and more cellular components, appears green. Other color combinations like orange, yellow, or purple are not characteristic results of this specific staining procedure.

Answer: (a) Red and green

Solution: Let's match the tissues with their correct descriptions:

1. Meristem (A): These are tissues composed of actively dividing cells responsible for plant growth. So, A matches with 3.
2. Parenchyma (B): This is a fundamental tissue involved in various functions, including photosynthesis (in chlorophyll-containing cells) and storage of food materials. So, B matches with 1.
3. Collenchyma (C): This tissue provides mechanical support to growing plant parts, especially stems and petioles, and is characterized by uneven thickening at the corners of its cells. So, C matches with 4.
4. Sclerenchyma (D): This tissue consists of dead cells at maturity, providing rigid mechanical support. It includes fibers and sclereids (like those found in nutshells or grit of pears). So, D matches with 5.
5. Epidermal tissue (E): This tissue forms the outermost protective layer and includes structures like stomata, which regulate gas exchange. So, E matches with 2.

Based on these matches, the correct code is A-3, B-1, C-4, D-5, E-2. This corresponds to option (b).

Answer: (b) 3 1 4 5 2

Solution: Let's match the items from Column I to Column II:

1. Cuticle (A): This is a protective, waxy layer secreted by the epidermis, primarily on aerial parts of plants, to prevent water loss. So, A matches with 3 (Waxy layer).
2. Bulliform cells (B): These are large, empty, thin-walled cells found in the epidermis of grass leaves. They absorb water and become turgid, causing the leaf to unfold, and lose water, causing it to fold, thus regulating water loss. So, B matches with 2 (Empty colourless cell).
3. Stomata (C): These are pores, typically on the leaf surface, surrounded by specialized cells called guard cells, which regulate their opening and closing for gas exchange. So, C matches with 4 (Guard cells).
4. Epidermis (D): This is the outermost protective layer of cells, usually consisting of a single layer of cells. So, D matches with 1 (Single layer).

Therefore, the correct matching is A-3, B-2, C-4, D-1. This corresponds to option (a).

Answer: (a) 3 2 4 1

Solution: Plant bodies are organized into three tissue systems: the dermal tissue system, the ground tissue system, and the vascular tissue system.

• The epidermal tissue system forms the outermost protective covering of the plant body and includes the epidermis, cuticle, and stomata.
• The ground tissue system consists of parenchyma, collenchyma, and sclerenchyma tissues, which form the bulk of the plant body and are involved in photosynthesis, storage, and support.
• The vascular tissue system comprises xylem and phloem, responsible for transport within the plant.

Among the given options, Parenchyma, Xylem, and Phloem are types of tissues. Epidermis, however, is a component of the epidermal tissue system, and the question asks to identify a tissue system. While epidermis itself is a tissue, it is often referred to in the context of the epidermal tissue system. Considering the options, 'Epidermis' is the most appropriate choice representing a tissue system's primary component.

Answer: (c) Epidermis

Solution: The description provided points to a specific type of plant tissue:

• Living cells: This eliminates sclerenchyma and mature xylem vessels, which are typically dead at maturity.
• Angular wall thickening: This is a characteristic feature of collenchyma tissue, where the primary cell walls are unevenly thickened, especially at the corners.
• Provide mechanical support: Both collenchyma and sclerenchyma provide mechanical support, but collenchyma offers flexible support to growing parts, while sclerenchyma provides rigid support.

Considering all these features, collenchyma is the tissue that fits the description perfectly. Xylem is primarily for water transport, and epidermis is for protection.

Answer: (b) collenchyma