1. Explain the different types of tissues found in flowering plants and their functions.
Answer: In flowering plants, there are three main types of tissues – meristematic, permanent, and secretory. Meristematic tissues are responsible for the growth and development of the plant. Permanent tissues can be further classified into simple and complex tissues. Simple tissues include parenchyma, collenchyma, and sclerenchyma, which have various functions such as storage, support, and protection. Complex tissues include xylem and phloem, which are responsible for the transportation of water, minerals, and organic substances throughout the plant. Secretory tissues are involved in the production and storage of various substances like resins, gums, oils, etc.
2. Discuss the anatomical features of stems in flowering plants and their significance.
Answer: The stem is an essential part of a flowering plant, as it provides support, conducts water and nutrients, and stores food. Anatomically, the stem is composed of different tissues such as epidermis, cortex, vascular bundles, and pith. The epidermis forms the protective outer layer, while the cortex provides mechanical support and stores food. The vascular bundles, consisting of xylem and phloem, are responsible for the transportation of water, minerals, and organic substances. The pith, located at the center of the stem, stores food and provides mechanical support.
3. Elaborate on the various types of root systems found in flowering plants and their adaptations.
Answer: Flowering plants exhibit different types of root systems, namely taproot and fibrous root systems. In taproot systems, a single dominant root, known as the primary root, grows vertically downwards, giving rise to lateral roots. This type of root system is commonly found in dicotyledonous plants and provides stability and efficient absorption of water and nutrients. On the other hand, fibrous root systems consist of numerous thin, branching roots that arise from the base of the stem. This type of root system is typically found in monocotyledonous plants and helps in anchoring the plant firmly in the soil and absorbing water and nutrients from a larger area.
4. Describe the anatomical features of leaves in flowering plants and their functions.
Answer: Leaves are the primary sites of photosynthesis in flowering plants and play a crucial role in the exchange of gases and transpiration. Anatomically, leaves consist of different tissues such as epidermis, mesophyll, and vascular tissues. The upper epidermis is usually thin and transparent, allowing light to pass through. The lower epidermis contains stomata, which regulate the exchange of gases and water vapor. The mesophyll is the main site of photosynthesis and consists of two layers – the upper palisade mesophyll and the lower spongy mesophyll. Vascular tissues, including xylem and phloem, are responsible for the transportation of water, minerals, and organic substances to and from the leaves.
5. Discuss the adaptations of xerophytic plants in relation to their leaf anatomy.
Answer: Xerophytic plants are adapted to survive in arid or desert-like conditions, where water availability is limited. These plants have specific leaf adaptations to reduce water loss through transpiration. One such adaptation is the presence of a thick cuticle on the leaf surface, which acts as a barrier to prevent water loss. The presence of sunken stomata and a dense layer of hairs on the leaf surface also helps in reducing transpiration. Additionally, some xerophytic plants have modified leaves called spines or scales, which further minimize water loss by reducing the surface area exposed to the environment.
6. Explain the significance of secondary growth in woody stems of flowering plants.
Answer: Secondary growth is the increase in girth or thickness of stems and roots in woody plants. It occurs due to the activity of lateral meristems, namely the vascular cambium and cork cambium. The vascular cambium is responsible for the formation of secondary xylem (wood) towards the inside and secondary phloem towards the outside, thus increasing the diameter of the stem. The cork cambium produces cork cells towards the outside, forming a protective layer called the bark. Secondary growth is crucial for the structural support of the plant, as well as the transportation of water, nutrients, and sugars.
7. Discuss the anatomical adaptations of hydrophytic plants in relation to their stem and root anatomy.
Answer: Hydrophytic plants are adapted to live in aquatic or waterlogged environments. They have specific anatomical adaptations to facilitate their survival in such conditions. In hydrophytic stems, the presence of air spaces or aerenchyma allows the plant to float and provides buoyancy. The stem may also have reduced mechanical tissues, as the water provides support. Hydrophytic roots often have poorly developed or absent root caps, as they do not require protection from soil particles. They may possess numerous small lateral roots or root hairs to maximize water absorption from the surrounding water.
8. Elaborate on the anatomical features of the periderm in woody stems and roots of flowering plants.
Answer: The periderm is a protective tissue that replaces the epidermis in woody stems and roots of flowering plants during secondary growth. It is composed of three main layers – cork cambium, cork cells, and phelloderm. The cork cambium is a lateral meristem that produces cork cells towards the outside and phelloderm cells towards the inside. Cork cells are dead at maturity and have suberin in their walls, which makes them impermeable to water and gases. Phelloderm cells are living parenchyma cells that provide mechanical support. The periderm acts as a protective barrier against physical damage, pathogens, and water loss.
9. Discuss the adaptations of parasitic plants in relation to their stem anatomy.
Answer: Parasitic plants are adapted to obtain nutrients and water from other plants, known as hosts. They have specific stem adaptations to facilitate this parasitic lifestyle. One common adaptation is the presence of haustoria, specialized structures that penetrate the host plant’s tissues and establish connections with its vascular system. Haustoria allow the parasitic plant to extract water, minerals, and organic substances from the host. Additionally, the stem of parasitic plants may lack or have reduced chlorophyll, as they rely on the host for photosynthesis. This adaptation helps them conserve energy and focus on nutrient acquisition.
10. Explain the anatomical features of tendrils in climbing plants and their role in climbing.
Answer: Tendrils are specialized structures found in climbing plants that aid in their attachment and climbing. Anatomically, tendrils are modified leaves, leaflets, or stipules. They possess sensitive cells known as pulvini, which respond to touch or contact with objects. When a tendril comes into contact with a support, the pulvini cells on that side of the tendril elongate, causing the tendril to coil around the support. This coiling action allows the climbing plant to anchor itself and climb upwards towards sunlight. The anatomical features of tendrils, including their sensitivity and coiling ability, enable climbing plants to find support and optimize their exposure to light.