31.1
植物組織
植物は、特定の機能を実行するさまざまな種類の細胞で構成される組織系を備えた多細胞真核生物です。 さまざまな組織が連携して独自の機能を実行し、器官を形成します。 器官が連携して器官系を形成します。 維管束植物には、 苗条と根という 2 つの異なる器官があります。 苗条は、葉や茎などの植物の栄養 (非生…
植物は葉、茎、根で構成されています。葉の主な機能は光合成であり、茎は支えを貸し、根は植物を固定して水とミネラルの吸収を可能にします。
各植物器官は、分裂しない永久組織になるように特化しているメリストマティック組織または活発に分裂する組織で構成されています。分裂組織には大きく分けて3つのタイプがあります。
真皮組織は、蒸発による水分の損失を防ぐワックス状のキューティクルで植物を覆います。気孔と呼ばれるキューティクルの特殊な細孔は、ガスの交換を可能にします。
木部などの維管束組織は、根から水と溶解した栄養素を植物全体に運びます。対照的に、師部は光合成の部位から有機化合物を他の植物部分に分布させます。
粉砕された組織は、細胞の種類と場所に応じて異なる代謝機能を果たします。例えば、実質、コレンキマ、および強皮腫は、血管組織への支持マトリックスを提供し、水分と溶解した糖を貯蔵するのを助け、ステムに構造的なサポートを提供します。
View the full transcript and gain access to JoVE Core videos
Q1: What are the main functions of plant organs like leaves, stems, and roots?
Leaves perform photosynthesis to produce energy for the plant. Stems provide structural support and transport substances throughout the plant. Roots anchor the plant in soil and absorb water and minerals essential for growth and survival. Together, these organs form the shoot and root systems that enable plants to thrive.
Q2: How do meristematic tissues differ from permanent tissues in plants?
Meristematic tissues consist of actively dividing, undifferentiated cells that enable continuous plant growth. Permanent tissues are composed of differentiated cells that have stopped dividing and perform specialized functions. Meristematic tissues differentiate into three main types based on location: apical meristems at stem and root tips, lateral meristems for growth in thickness, and intercalary meristems in monocots for leaf elongation.
Q3: What role does dermal tissue play in protecting plants?
Dermal tissue covers the plant's outer surface and controls gas exchange. It includes a waxy cuticle that prevents water loss through evaporation. Specialized pores called stomata in the cuticle allow gases to enter and exit the plant, enabling photosynthesis while protecting against excessive water loss.
Q4: How do xylem and phloem work together in vascular tissue?
Xylem transports water and dissolved nutrients from roots throughout the plant using vessel elements and tracheids. Phloem distributes organic compounds produced during photosynthesis to other plant parts through living sieve cells. These two conducting tissues always lie adjacent to each other, forming vascular bundles in stems and the vascular stele in roots.
Q5: What are the different types of ground tissue and their functions?
Ground tissue includes parenchyma, collenchyma, and sclerenchyma cells that perform distinct metabolic functions. Parenchyma cells store water and dissolved sugars while providing a supporting matrix. Collenchyma offers flexible structural support to stems, and sclerenchyma provides rigid support. Together, ground tissues support vascular tissue and maintain plant structure.
Q6: How do complex tissues like xylem differ from simple tissues in composition?
Complex tissues consist of multiple specialized cell types working together, while simple tissues contain similar cell types. Xylem, a complex tissue, includes vessel elements, tracheids, and xylem parenchyma cells. Phloem similarly comprises sieve cells, companion cells, phloem parenchyma, and phloem fibers. This cellular diversity allows complex tissues to perform multiple functions efficiently.
Q7: Why is the plant cell wall important for tissue structure and function?
The plant cell wall provides structural support and rigidity to cells, enabling tissues to maintain their shape and function. It works with cell adhesion mechanisms to hold cells together in organized tissues. Understanding the plant cell wall composition and the role microtubules in cell wall deposition helps explain how plants build and maintain their tissue architecture.