Chapter 35 Notes

Plant Structure and Growth

Concept 35.1

Plants are made up of two main systems: the root system and shoot system

Plants have three basic organs- roots- stems- leaves

Concept 35.1

Root system- anchor plants in the soil- absorb minerals and water- store food

Monocots have fibrous roots: mat of thin roots that spread out below the soil surface

Concept 35.1

Dicots have a taproot: one large vertical root that produces lateral branch roots

Root hairs: increase surface area and help absorption of water/minerals

Adventitious roots: roots that are above ground; extend from stem

Concept 35.1

Shoot systemStem

- an alternating system of nodes (place where leaves are attached) and internodes (the stem between the nodes)- auxiliary bud: structure that forms a branch

Concept 35.1

- terminal bud: place of growth of a young shoot- apical dominance: growth focuses on the terminal bud; inhibits the axillary bud

Concept 35.1

Concept 35.1

Leaves- main photosynthetic organ of plants- consist of a flattened blade and a petiole (stalk that join to the node of the stem)- monocots have parallel veins in leaves- dicot leaves have a multibranched network of veins

Concept 35.1

Concept 35.1

Plant organs are composed of three tissue systems: dermal, vascular, and ground

Dermal tissue- single layer of tightly packed cells that covers and protects all young parts of the plants- for the cuticle

Concept 35.1

Vascular tissue- involved in the transport of materials between the root and the shoot- xylem: moves water and dissolved minerals upward from roots

- tracheids and vessel elements are elongated cells that are dead at functional maturity

Concept 35.1

Concept 35.1

- phloem: moves food made by leaves to the roots

- sieve-tube members transport sucrose and other organic materials

- sieve plates help move fluid from cell to cell

- companion cell: assist the STM

Concept 35.1

Concept 35.1

Ground tissue- tissue that is neither dermal nor vascular- in dicots, divided into the pith (internal to the vascular tissue) and the cortex (external to vascular tissue)- photosynthesis, storage, and support

Concept 35.1

Concept 35.1

Plant tissues are composed of three basic cell types: parenchyma, collenchyma, and sclerenchyma

Parenchyma cells- have 1o cell walls, but lack 2o

- typical plant cell; least specialized- perform most metabolic functions of the plant

Concept 35.1

Collenchyma cells- thicker 1o cell walls - support young parts of the plant shoot- provide support without restraining growth

Concept 35.1

Sclerenchyma cells- support; form thick 2o cells that are strengthened by lignin- occur in areas of plants that have stopped growing- dead at functional maturity- ex. xylem cells

Concept 35.1

Concept 35.2

Most plants grow as long as the plant lives (indeterminate growth)

Annuals: complete their life cycle in one year

Biennial: life of the plant spans two years

Perennials: live many years

Concept 35.2

A plant is capable of indeterminate growth because it always has embryonic tissue called meristems- cells that divide to produce additional cells

Plant growth depends on the location of the meristems

Concept 35.2

Apical meristems: located at the tips of roots and in the buds of shoots

Primary growth: enables roots to grow through soil and shoots to increase their exposure to sunlight

Secondary growth: thickening of the roots and shoots- formed by lateral meristems

Concept 35.2

Concept 35.3

Primary growth of rootsThe root tip is covered by a root

capThe zone of cell division include

the apical meristem and the 3 primary meristems (protoderm, procambrium, and ground meristem)- produce the three 1o tissue systems

Concept 35.3

Concept 35.3

Primary growth of shootsThe apical meristem of the shoot tip

gives rise to the 3 primary meristems that turn into the different tissue systems

Vascular tissue runs through the stem in strands called vascular bundles- surrounded by ground tissue

Concept 35.3

Concept 35.3

In dicots, the vascular bundles are arranged in a ring, with the pith inside the ring, the cortex is outside

In monocots, the vascular bundles are scattered throughout the ground tissue

Concept 35.3

Concept 35.3

Concept 35.3

Tissue organization of leavesThe epidermis is composed of tightly

interlocked cells- stomata: tiny pores that allow for gas exchange w/ the help of guard cells

The ground tissue is sandwiched between the upper and lower epidermis in the mesophyll

Concept 35.3

- the mesophyll consists of parenchyma cells w/ chloroplasts

The vascular tissue also flows through the leaf from the stem- contains the xylem and phloem

Concept 35.3