Free PDF download of Important Questions for CBSE Class 12 Biology Chapter 13 - Organisms and Populations prepared by expert Biology teachers from the latest edition of CBSE (NCERT) books. 5. ★ The roots are extensively branched. 36. Mosses have few or no stems. A xerophyte is a species of plant that has adaptations to survive in an environment with little liquid water, such as a desert or an ice- or snow-covered region in the Alps or the Arctic. Consequently, they can survive in habitats that dry very quickly because of high temperatures and wind that favor a high rate of transpiration. Learn about and revise hot deserts, their characteristics and the opportunities and challenges that they face with GCSE Bitesize Geography (AQA). Sunken stomatal pits function. blade to reduce the transpiration area. Plants show three types of phyllotaxy- alternate, opposite and whorled types of phyllotaxy. Plant defense against herbivory or host-plant resistance (HPR) describes a range of adaptations evolved by plants which improve their survival and reproduction by reducing the impact of herbivores. Physiological Adaptations Xerophytes. 37. Mesophyll is well differentiated and vascular tissues and mechanical tissues are well developed. Dead tracheids, parenchyma, intercellular spaces, mucilaginous substances are generally present for absorption and retention of sufficient amount of water. 2. List out the anatomical adaptations of hydrophytes. e.g. Such a habitat is termed as xeric. There are species that tolerate cold, heat, drought and floods. Sclerenchymatous cap over the vascular bundles. The root system is very well developed with root hairs and root caps. Xerophytic adaptations are morphological and physiological characteristics that enable an organism to survive under conditions of water deficit. Modification of the stem into the phylloclade for storing water and food and at the same time performing functions of leaves is characteristic of many desert plants (viz. Leaves show well developed cuticle, succulent leaves in. Differentiate primary and secondary successions. Many hydrophytes show heterophylly, i.e., production of different forms of leaves in the same plant. This layer forms an insulating envelope and checks increasing temperature. Give in detail the anatomical adaptations shown by xerophytes. Opuntia and other cacti). While they have developed in air they show marked differentiation of mesophyll, presence of stomata and fibro-vascular bundles. The morphological, physiological, and behavioral adaptations that desert plants have formed over time enable them to survive the harsh conditions common in arid environments . These adaptations include a decrease in leaf surfaces, small cells, a large number of small stomata, a dense network of veins, pubescent leaves, a waxy coat, and submerged stomata. Answer: Presence of multilayered epidermis with heavy cuticle to prevent water loss due to transpiration. In certain plant leaves leaves are very thick and leathery to reduce transpiration. Perhaps the most amazing fire adaptation is that some species actually require fire for their seeds to sprout. Sometimes in life, things change. The vertical lines, called branches, represent a lineage, and nodes are where they diverge, representing a speciation event from a common ancestor. Cauducuous (Fagacious): Falling off … 9. In Euphorbia and Zizyphus jujuba stipules become modified into spines. Aquatic plants (hydrophytes) also have their own set of anatomical and morphological leaf adaptations. In desert communities, xerophytes have adaptations to hold water, which is in very short supply. Show in the same way the position of each of the following :—aorta, hepatic portalfiveip, pulmonary artery, right atrium, renal vein. In many plants the leaves are reduced to scaly or spiny e.g.ruscus, asparagus etc. Leaves are arranged in a position to maximise absorption of sunlight. Depending on the shape of the leaves and their structure, xerophytes are classified into following four classes: The leaves of xerophytes are generally caducous; e.g., Euphorbia. #64 Adaptations of the leaf, stem and root to different environments. Ø Phyllode: leaf petiole or rachis modified (flattened) into leaf like organ Example: Acacia. Both upper as well as lower epidermis are multiseriate or multiple. Leaves are small, reduced and may even be absent. i) Xerophytes ii) Mesophytes iii)Halophytes iv) Hydrophytes. Adaptations. 6. In addition there are other morphological adaptations to reduce the rate of transpiration. Question 12. Structural Adaptations • Adaptations to get food –Leaves and stems absorb energy from the sun. In biology, an adaptation is a Sometimes they may be reduced to spines, as for example, in Ulex, Opuntia, Euphorbia splendens (Fig. Without the bulk flow of liquid water, minerals cannot be transported from roots to shoots and fixed carbon from shoots to roots. 5) Leaves are very much reduced to small, scale like and sometimes modified into spines to reduce the rate of transpiration. There are two major classification of plants are non-vascular & vascular. Presence of thick cutical on leaf and stem epidermis. e.g. Ø Heterophylly (morphologically different leaves in a single plant) is present in some plants. As per the rule, the root does not bear leaves and tree buds. A. 4. Some plants have shining leaf surface to. In Opuntiaphylloclade is covered with spines. Ø The leaves of free floating hydrophytes are with smooth waxy surface. Organisms, from microbes to plants and animals, inhabit environments that can change to become drier, hotter, colder, more acidic, darker and sunnier -- with an almost infinite number of variables. In grasses, the leaves roll when the condition becomes dry and hot. Depending on their ability to withstand drought condition of the soil, following are the different classes of xerophytes: Xerophytes exhibit some special features for their adaptation to xeric habitat. The root system is very well developed with root hairs and root caps. Stems are stunted, woody, dry, hard, ridged, and covered with thick bark, may be underground, e.g. This reduces the rate of transpiration. 2. The plants usually have a long and stout tap root which branches profusely. Some enzymes, such as catalases, perioxidases are more active in xerophytes than in mesophytes. Root: The roots show the following xerophytic features: Shoot: Following are the xerophytic features of shoot. The root bears unicellular root hairs. The Xerophytes have very high osmotic pressure, which increases the turgidity of the cell sap. - Leaves are modified into thorns to reduce the surface area for transpiration. Stems of non-succulent xerophytes show a very thick cuticle, well developed epidermis with thickened cell wall, several layered and sclerenchymatous hypodermis e.g. Numerous crystals of calcium oxalate are present in the palisade cells. The roots are fasciculated as in Asparagus. Stem may also be fleshy and growth remains stunted. The roots go deep into the soil in search of water. If the leaves have developed under water, they show characteristics of submerged leaves. This process is experimental and the keywords may be updated as the learning algorithm improves. E.g.nerium odorum. These plants are termed as succulents. China rose. Briefly discuss the different kinds of hydrophytes with examples. Morphological Adaptations of Xerophytes . Minimises water loss, as it's waterproof. Most desert plant species are called xerophytes because they have in some way changed their physical structure to tolerate extremely hot and dry conditions . In xerophytes, the chemical compounds of cell sap are converted into wall forming compounds (eg) Cellulose, Suberin etc. Calotropis. Lamina may be narrow or needle like as in Pinus or divided into many leaflets as in Acacia or succulents as in Aloe. 1. ADVERTISEMENTS: In this article, we will discuss about the xerophytes. Plants which live in extreme environments have adaptations to control their transpiration rate. Give in detail the anatomical adaptations shown by xerophytes. Organisms : Environmental factors - Climatic, Edaphic, Biotic, Relationships among Organisms : Positive and Negative Interactions, Hydrophytes And Classification of Hydrophytes, Morphological and Anatomical adaptations of Hydrophytes, Xerophytes and Classification of Xerophytes, natural resources and Types of natural resources, Social Forestry and Conservation of Forests, Conservation of Water and Types of Harvesting Rainwater. Enumerate the morphological adaptations of xerophytes Ask for details ; Follow Report by Salmankhan9999 03.02.2020 Log in to add a comment It is extensive and more elaborate than shoot system. The leaves of amphibious plants show great variations in form and structure. Common adaptations to reduce the rate of transpiration include: Thick waxy cuticle: The cuticle cuts down water loss in two ways: it acts as a barrier to evaporation and also the shiny surface reflects heat and so lowers temperature. 2. Prevention of loss of water by transpiration 4. Epidermal cells are radially elongated to absorb necessary amount of light. The three categories of xerophytes are: (1) Ephemeral Annuals (2) Succulent Perennials and (3) Non-Succulent Perennials. They have reduced the rate of water transpiration to a bare minimum. After reading this article you will learn about: 1. Depending on the shape of the leaves and their structure, xerophytes are classified into following four classes: Sclerophyllous: Leaves are stiff and hard; e.g., Banksia etc. Root hairs and root caps are well developed in Opuntia. Depending on ability pupils can either research the adaptations listed to discover the purpose of these for themselves or match each adaptation to the descriptions given – an answer sheet has been provided for your convenience. Plants can sense being touched, and they can use several strategies to defend against damage caused by herbivores. Xerophytes (pronounced "zero-phytes") are plants that are normally found in hot, dry areas such as deserts. One of the most interesting of all botanical adaptations … Define plant succession. In the same way Mosses are soft cushiony plants that live in damp places. 4. Name the structures leaves which control gas exchange with the environment. The stomata of these plants open during night hours and remain closed during the day. Many xerophytes have extensive root systems in order to trap available water. The plant of this group are adapted to live partly in water and partly above substratum and free from water (a) Xerophytes (b) Mesophytes (c) Hydrophytes (d) Halophytes Answer: (b) Mesophytes. Observations Record your observation in the given tables: Xerophytes Adaptations 1. Stem is covered with thick coating of wax and silica in Equisetum or dense hairs as in Calotropis. They require none of the morphological adaptations that other strategists require. These cells are sensitive to changes in turgor and thus, contract when conditions are dry. They adapt themselves to dry and sandy or rocky soils having poor water content and extreme atmospheric conditions. (BS) Developed by Therithal info, Chennai. Plants such as Limnophylla heterophylla, Sagittaria, Ranunculus, Salvinia, Azolla etc show heterophylly, with submerged dissected leaves offering little resistance against the water currents, and absorbing dissolved carbon-di-oxide from water. We'll focus here on broad adaptations shared by several different species. The diagram represents the circulatory system in mammal. Annuals’ “goal” is to grow fast (large leaves, maximal photosynthesis, heavy transpiration), flower, set seed, disperse seed, and persist through the dry period as a seed. Reproduction: Most of the xerophytes multiply by their perennial organs such as stem. Terminology of phylogenetic trees. Discuss the adaptations of the following plants to their various habitats. This means there is as little overlap between leaves as possible so that as many photons of light as possible hit a leaf. Calotropis. 7. Calotropis. CO ... Morphological (external) adaptations; (2) Anatomical (internal) adaptations; (3) Physiological adaptations. Behavioral Adaptations • Adaptations to get food –Plants lean or grow towards the sun. 6) Certain xerophytes shed their leaves during the dry period. Some plant… Enumerate the morphological and anatomical adaptations of xerophytes. The other types of leaves include acicular, linear, lanceolate, orbicular, elliptical, oblique, centric cordate, etc. Many plants have very small and narrow leaf blade to reduce the transpiration area. The aerial leaves show … ADVERTISEMENTS: Let us make an in-depth study of the categories of xerophytes and its physiological adaptation. Drought-evading plants. This is another adaptation to xeric conditions. Xeromorphism is frequently associated with the loss of leaves and their replacement with … These adaptations limit the loss of water and allow the plant to survive in dry environments. Ø In heterophyllous forms, the submerged leaves are linear or ribbon like or highly dissected, whereas the floating leaves or aerial leaves are usual or circular shaped. 35. Sunken shaped stomata are present only in the lower epidermis with hairs in the sunken pits. Xerophytic characters: The transverse section shows the following xerophytic characters : Transverse section of the leaf shows the following important anatomical characters: CBSE Class 10 Science Questions and Answers. They grow close to the ground. Stem is covered with thick coating of wax and silica in, Leaves are very much reduced, small scale-like, appearing only for a brief period (Caducous) sometimes modified into spines or scales as in, Lamina may be narrow or needle like as in, Root hairs and root caps are well developed in, 2. 1. Characteristics of Xerophytes. If the temperature increases or drops below this range, the organism dies. Ask for details ; Follow Report by Arnav9675 08.10.2018 Log in to add a comment Roots may become fleshy to store water as in, In succulent xerophytes, stems possess a water storage region (thin walled parenchyma cells). Some areas become dryer, wetter, or maybe taken over by a certain type of organism. The leaves, stems, roots, and reproductive parts of plants can be very different depending on where the plant lives. e.g. 9. The trunk at the base of the tree, is actually called the root.The root node represents the most recent common ancestor of all of the taxa represented on the tree. Desert plant (xerophytes) and plants that grow on other plants (epiphytes) have limited access to water. Usually, a root cap protects the root tip. Although the focus is on plant adaptations, papers in this Special Issue also show that further improvements in knowledge of halophytes and their mechanisms might be applied to develop more salt-tolerant crops – either conventional crops or halophytic species – and to enhance re-vegetation of degraded lands. Mesophyll is well differentiated and vascular tissues and mechanical tissues are well developed. Vascular tissues are present in large amount. The root system is very well developed with root hairs and root caps. Conifers possess many adaptations that enable them to conserve water. Both of these adaptations help prevent water loss by trapping water vapour just above the surface of the leaf and above the stomata, creating a warm and saturated microclimate in the area, which means that there is less of a concentration gradient and so less evaporation and diffusion of the water out of the stomata pore. 8.8, 8.9 A, and 8.10. 8. Presence of waxy layer on the epidermis for reflection of light. Storage of Water 3. Adaptations of xerophytes-thick, waxy, cuticle-sunken stomatal pits-fewer stomata-reduced leaf area-hairy leaves-curled leaves-succulents-leaf loss-root adaptations-avoiding issues. When only a single leaf develops at each node alternatively, it is an alternate type of phyllotaxy.E.g. Types of Plants: Botanists classify plants into several groups that have similar & distinguishing characteristics. Ø If leaves are present, usually they are caducous (fall off easily). Some plants, such as the lodgepole pine, Eucalyptus, and Banksia, have serotinous cones or fruits that are completely sealed with resin.These cones/fruits can only open to release their seeds after the heat of a fire has physically melted the resin. 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