Plant Cell

Plant Cell

Plants are:EukaryoticAutotrophicMulticellularCell walls of cellulose

Vocabulary: - vascular – refers to an internal system of tubes or vessels to transport materials throughout the plant; basis or first major division of plants into bryophytes and tracheophytes; includes:

- xylem – transports water and minerals up from the roots to the shoots

- phloem – transports sugar (food) down from the leaves to the rest of the plant

Xylem brings water up from the roots to the shoots

Phloem carries sugar (food) down from leaves throughout the plant

Bryophytes – nonvascular plantsExamples include:

Moss Hornwort

Liverworts

20 mm

Bryophytes – nonvascular plants - economically importantEx) sphagnum moss – also called peat or peat mossGrows in boggy areas called peat bogs; extremely absorbant; used in agriculture/horticulture

VocabularySeed – adaptation to terrestrial life

composed of a plant embryo, stored food, and a protective coat

Seed dispersal by edible fruit, by wind, as well as other means. The picture to the right is of a samara from a maple tree.

Which is a monocot and which is a dicot? How do you know?

Tracheophytes – vascular plants•Seedless plants –whiskferns,

horsetails, and ferns

Whisk fern horsetail fern

Seedless vascular plants:Ferns - reproduce with spores - diagram shows spores growing in clusters called sori on the back of the frond of the fern

Seedless vascular plants dominated during the Carboniferous period.

VocabularyCone – reproductive structure of gymnosperms; contains pollen in males and ovules in femalesFlower – reproductive structure of angiosperms composed of 4 sets of modified leavesFruit – mature ovary of a flower that protects dormant seeds and aids in their dispersal

Ovulate cone from a pinetree (female)

Staminate cone from a pinetree (male)

Tracheophytes – vascular plants cont.•Seed plants

•Gymnosperms – have seeds in cones; include: ginkgos, cycads, gnetophytes, and

conifers

Ginkgo Cycad

Welwitschia Gnetum Ephedra

Gymnosperms called gnetophytes; only 3 extant species

Conifers: top row: Douglas fir, Sequoia, Cypress; bottom row: juniper, Australian pine tree; not shown: yew, spruce, other pines

Tracheophytes – vascular plants cont

* Seed plants•Angiosperms – flowering plants - have

flowers, fruits, and seeds

Grasses are flowering plants, too. So are trees.

Grass flowers

Flowerpistil (female)(male)

Ovaries with ovules become fruits with seeds after the ovule (egg) is fertilized by sperm from the pollen

Pollen grains contain sperm. They are produced in the anthers of the flowers in angiosperms.

Pollination - by many vectors, including:

WindWater

Animals

Fruit or VeggieHumans eat lots of different plant parts. A fruit is the ripened ovary and contains seeds. Therefore, tomatoes, peppers, squash, olives, and cucumbers are fruits, not vegetables.

Vegetables – the vegetative parts of the plants that we eat. Includes:•Roots – carrots, turnips,radishes•Stems – celery, bok choi, rhubarb, garlic, broccoli, onions, potatoes •Leaves – lettuce, cabbage, parsleyOther plant parts that we eat: Seeds – pinto beans, peas, sunflower seeds, corn, pepper corns, rice, pecans, coconut Flowers – anise flowers (licorice), basil; http://homecooking.about.com/library/weekly/blflowers.htm

Good rule of thumb: if you didn’t get it at the store, DON’T EAT IT!

We don’t just eat plants, we also wear them, build with them, and use them for

medicines!

Plant Structure & Function

Each plant part - root, stem, leaf - has a specific role in keeping the plant alive through photosynthesis

Monocots & Dicots

Cotyledons – nonphotosynthetic leaves of an immature plant; provide source of nutrients until plant can produce its own food

Leaves - site of photosynthesis - cross section

- epidermis – adaptation for terrestrial life - waxy cuticle - stomata - transpiration

Leaf

Leaf structure supports its function as the primary organ for photosynthesis

Leaves - composed of blade, veins, petiole - simple or compound (see identifying leaves ppt)

- pinnately or palmately compound - alternate or opposite if compound - pinnate or palmate venation

Overview of movement of photosynthesis reactants and products through a plant

StemsSupport and transportContains xylem and phloemModified:

Strawberry runners onionpotatoe

s

Define plant type: herbaceous, shrub, vine, tree

Stems

Herbaceous plant shrub vine

Stems – cross sections through a dicot and a monocot

RootsFunction – absorption, storage, anchorageRoot hairs – extensions of the epidermis that increase absorption by increasing surface area; see photo

Fibrous roots – see monocot information

Tap roots – see dicot information

Root Structure

Nitrogen fixation – occurs in the roots and in the soil around the roots of plants; performed by bacteria

Plants that live in nitrogen poor soils trap and break down insects with enzymes to obtain nitrogen

Venus fly trap Pitcher plant

VocabularyPrimary growth – increase in length; stems get longer, roots grow deeperMeristem – tissue that is growingApical meristem – tissue found at the tips of roots and stems that is actively dividing/growing

Plant Responses

Plant responses are called tropisms. Tropisms can be positive or negative. They include phototropism, gravitropism, and thigmotropism.Most plant responses involve the action of hormones, including gibberellins, auxins, and ethylene.

Plant Responses

Effect of gibberellens on Thompson’s seedless grapes and on growth in a dwarf plant

Auxins make plants bushier by making more branches at nodes when the apical meristem is cut off (the tips of the existing branches)

Positive Phototropism

Effect of ethylene on the ripening of an apple.

http://plantsinmotion.bio.indiana.edu/plantmotion/movements/tropism/gravitropism/gravi1/gravitrop.html

NEGATIVE Gravitropism in Stems

Vines Illustrate Positive Thigmotropism