Question

What tissues/cell types contribute to a plant's ability to grow taller? Choose several tissue/ cell types and for each type you choose, explain how it contributes to a plant's ability to grow taller. (Challenge: on a separate piece of paper (to have more room) try taking every cell type and, in clear and logical steps, explain how a plant could not grow taller without this cell type).

Answer 1

Plant body organization | Roots, Stems, leaves maan: Nascular tissue I Ground tessue Dermal tissue. Tissues : cells: Ground tissue Vascular cells: tissue cells: Parenchyma, collenchymal Tracheids Scherenchyma houd vessel elements; Sieve tubes and companion Dermal tissue cells Epidermal cells, Stomata, Trichomes. cells.

Most plants continue to grow throughout their lives, Like other multi cellulare organisms, plants grow through a combination of cell growth and cell division. Cell growth increases cell size, while cell division (mitosis) increases the number of cells. As plant cells grow, they also become specialised into different cell types through cellular differentiation. Once cells differen- tiate, they can no longer divide. The key to continued growth and repair of plant cells. is Meristem. It is a type of plant tissue consisting of undifferentiated cells that can continue to divide and differentiate. Apical meristems are found at the apex, or tip of roots. and buds, allowing roots and stems to grow in length and leaves and flowers to differentiate. Roots and stems grow in length because the meristem adds tissue "behind" it, constantly propelling itself further into the ground (for roots) or air ( for stems). Often, the apical meristem of a single branch will become dominant, suppressing the growth of meristems on other branches and leading to the development of a single trunk. In grasses (monocot), meristems at the base of the leaf blades. Apical meristens differentiate into three basic types of meristen tissues Protoderm - produces new epidermis • Ground meristem - produces ground tissue • Procambium- new seylem and phloem. arimary meristem allowing growth of in length and height PRIMARY GROWTH

Tissues that do not help to grow taller • Secondary meristems - allow growth in diameter Caecondary growth) in woody plants. Herbaceous plants do not have secondary growth. The two types of secondary meristem. o cambium ef Vasculare - toward centre of root or stem I cork – between epidermis and the phloem. Vascular cambium adds growth to the diameter of the plant. - produces wood, builds the sturdy trunks of toees. Cork cambium - replaces the epidermis of roots and stem with bark, which consists of one layer that is cork. This causes lateral growth by cell division in lateral meristem. Cork cambium also produces a layer of cells known as Phelloderm, which grows in ward from the cambium. The cork cambium, cork cells and phelloderm are collectively termed the periderm. Differentiated tissues - Ground tissue cells. Parenchyma : photosynthesis in the leaves and storage in roots. • Collenchyma: shoot support in areas of active growth support in areas • Scherenchyma: shoot where growth has ceased. Vascular tissues : • Xylem - conducts water • Phloem - conducts sugars and other organic - compounds. Xylem - vessel elements & tracheids - both of them are dead at functional maturity and also have a secondary cell wall made of lignin, neither conditions allow them to grow.

Phloema sieve & companion - They are alive at - cells cells functional maturity, but lack a nucleus, ribosoma or other cellulare structures - Sieve plates Companion cells lie adjacent to sieve plants and provide metabolic support and regulation. Dermal tissue cells- Epidermal cells provide protection and have other specialized adaptations in different plant organy. Babes Endodermis - found only in roots, serve as checkpoint for material entering root's vascular system Casparian strip forces water and solutes to cross the plasma membranes of endodermal cells instead of slipping between the cells - Wasy region in the endodermis Stomata - is for gaseous exchange, having quared trichomes - hair - line structures on the epidermal surface that help reduce transpiration * ( O