plant cells

Topics: Plant anatomy, Phloem, Plant physiology Pages: 5 (916 words) Published: October 23, 2013
CHAPTER 36
PLANT CELLS
The first barrier to form between daughter cells is the middle lamella.

Daughter cells expand to their final size and make polysaccharides for a primary wall.

After expansion stops waterproofing materials are added for a secondary wall.

Water and dissolved materials move from cell to cell by way of pit pairs. A pit is a thin spot in the primary wall where the secondary wall is absent or separated from the primary wall by a space.

Strands of cytoplasm called plasmodesmata pass through pit pairs and the middle lamella to allow substances to move from cell to cell

Parenchyma cells- they store substances in their cytoplasm. Starch is stored in leucoplasts, lipids in oil droplets, and photopigments in chloroplasts.

Sclerenchyma cells- they are for support. There are two types of sclerenchyma cells: 1. Fibers- they are in bundles and give rigid support to wood and bark 2. Sclereids- they form shells for nuts and coats for seeds by being packed tighly.

Collenchyma cells- they lack a secondary wall and give support to petioles, nonwoody shoots and growing organs of the plant.

Tracheary elements- cells found in the xylem of tracheophytes that die before they transport water and dissolved minerals.

Tracheids- the tracheary elements of gymnosperms.

Vessel elements- the tracheary elements of angiosperms.

Sieve tube member- living cells of the phloem in flowering plants that transport foods from their sources to the tissues.

PLANT TISSUES
Tissue- an organized group of cells working together as a functional unit

Simple tissue- tissue made of one type of cell (parenchyma cells, parenchyma tissue)

Complex tissue- tissue made of more than one type of cell (parenchyma cells and sclerenchyma cells in the same tissue) Plant tissues are organized into three tissue systems that extend throughout the plant: 1. vascular tissue system- conducts materials from one part of the body to another 2. dermal tissue system- protects the body surface, the outer covering of the plant 3. ground tissue system- produces and stores food materials PLANT ORGANS

Most tracheophytes have 3 major organs:
1. Leaves (organs of photosynthesis)
2. Stem (holds leaves to the sun and has transport connections to the roots) 3. Roots (anchors plant and absorbs water and mineral nutrients from the soil)
Leaves, stem, and flowers are called a shoot.

Leaves attach to the stem at the nodes.

Stem regions between nodes are internodes.

Shoot system- all stems and all leaves

Root system- primary and branched roots

There are two types of root systems:
1. taproot system- a single, large, deep-growing root with secondary roots (for food storage, carrots, radishes) 2. fibrous root system- numerous thin roots roughly equal in diameter

PLANT GROWTH
Primary growth- growth in length that occurs from the apical meristems.

There are two apical meristems:
1. At the tip of each root there is a tissue composed of rapidly dividing cells called the root apical meristem- produces all the cells for growth in root length 2. At the tip of each stem or branch is a shoot apical meristem- it produces all the cells for growth in stem length

Secondary growth- growth in the diameter of stems and roots.

ROOT ANATOMY
Root hairs- epidermal cells of the root that increase the surface area of the root.

Cortex- below the epidermis, ground tissue that stores food.

Stele- below the cortex and consists of:
1. pericycle
2. xylem
3. phloem

STEM ANATOMY
Vascular bundles- the vascular tissue which is scattered in monocots and forms a cylinder in dicots.

Vascular cambium- cells that divide to produce new xylem and phloem.

Cork cambium- produces waxy-walled cork cells which forms bark to cover the tree.

Pith rays- the ground tissue system that lies in between the vascular bundles.

LEAF ANATOMY
Dicot leaves have two zones of photosynthesizing tissues refered to as mesophyll (middle of...
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