chapter 23.1 bio

lignin

-a complex molecule that resists water and gives wood much of its strength -cell walls from tracheids contain this

roots

-anchor plants in ground -hold soil in place -prevent erosion -bacteria and fungi help absorb water and dissolve nutrients in roots through mutualistic relationships -transport materials, store food, and hold plants upright against forces (wine, rain)

companion cells

-cells that surround sieve tube elements -support phloem cells and aid in the movement of substances IN AND OUT of phloem

parenchyma cells

-have a thin cell wall and a large central vacuole surrounded by a thin layer of cytoplasm -contain chloroplasts -site of most of a plant's photosynthesis -produce food (in leaves) and store food (in roots)

stems

-have support system for plant body -transport system to carry nutrients -contain tissues that lift water from roots to leaves -carry products of photosynthesis from leaves back down to roots -defensive system to protect plants against predators and disease -produce leaves and reproductive organs (flowers)

sieve tube elements

-main phloem cells -arranged end to end -have small holes in the walls to allow nutrients to move from cell to cell in watery stream -lose nuclei and organelles as they mature -remaining organelles are kept alive by companion cells -food goes through here

leaves

-main photosynthetic organs -broad, flat surface increase amount of sunlight absorb -adaptations that protect against water loss -pores of leaves help conserve water, let oxygen and co2 enter and exit leaf

vessel elements

-second form of xylem tissue -in angiosperms -wider than tracheids, stacked on top of each other - after they die, cell walls are left with little opening that let water move freely

collenchyma

-strong, flexible cell walls that support plant organs -thick cell walls

tracheids

-they are xylem cells that are in ALL seed plants - long + narrow, tough cell walls that support plant -after they die, they leave ONLY their cell wall -contain lignin

differentiation

1. new cells from meristems are unspecialized with thin cell walls 2. they develop into mature cells with specialized structure and functions 3. during this process they produce the tissue systems

epidermis

a single layer of cells in dermal tissue

phloem

a tissue that carries dissolved food up from roots -alive at maturity unlike xylem cells -sieve tube elements and companion cells

xylem

a water conducting tissue -tracheids and vessel elements -gets water from root to plant, one direction

pits

allow water to diffuse from tracheids into surrounding ground tissue -thin regions of cell walls

when pattern of gene expression changes what develops?

cone or flowers

dermal tissue

covers a plant almost like skin -in roots, dermal tissue has root hair cells that help absorb water

_______ _____ is the protective outer covering of a plant

dermal tissue

plants have three main tissue systems

dermal, vascular and ground

cells of a seed plant organized into:

different tissues, organs and systems

sclerenchyma

extremely thick, rigid cell walls (thickest) -make ground tissue tough and strong

vascular tissue

forms a system of pipelike cells help support the plant and serve as its bloodstream -transports water and nutrients -supports plant body

apical meristem

groups of unspecialized cells that divide to produce increased length of stems and roots -found in tips of stems and roots

unspecialized cells are produced by

mitosis

plants

move materials, grow, repair, respond to environment

trees produce

new leaves and new reproductive organs EVERY YEAR

ground tissue

produces and stores food like sugars and contributes to physical support of the plant -consists of parenchyma, collenchyma and sclerenchyma

meristems

regions of unspecialized cells in which mitosis produces new cells that are ready for differentiation (to have a function) -found in places where plants grow rapidly ex: the tips of stems and roots

3 principal organs of seed plants are

roots, stems and leaves

vascular tissue

supports the plant body and transports water and nutrients throughout the plant

cuticle

thick waxy layer that covers the outer surface of epidermal cells -protects against water loss

trichomes

tiny projections on epidermal cells -protect leaf and give it a fuzzy appearance

apex

tip of a stem or root

floral meristems produce

tissues of flowers

2 kinds of vascular tissue

xylem and phloem