Ms. Van Sciver’s Grade 7

Chapter 8 - Plants

Autotrophs – make their own foodMulticellularEukaryotes – have a nucleusCells surrounded by cell walls.

Plants

Plant Origins

Obtaining Water•Non vascular – must contact water•Vascular – tubes for water transport

Retaining Water•CuticleTransporting Materials•Non-vascular – diffusion/osmosis•Vascular – tubelike tissue

Land AdaptationsSupport• Rigid cell walls• Vascular tissueReproduction•Gametophyte –•Reproductive cells

• Sporophyte –• Spores

•Zygote – fertilized egg

Plant Life Cycle

Low GrowingMaterials transport from cell to cellLive in damp shady placesThin cell walls

Seedless PlantsNon-Vascular - Bryophytes

Bryophyte Life Cycle

Non-Vascular - MossesMore than 10,000 speciesGametophyte – green- fuzzy appearing tiny leave like parts Root like structures –

rhizoid

Sporophytestalkcapsule contains

spores

Non-Vascular - LiverwortsMore than 8,000 speciesFound – moist rocks along streams Gametophyte – “liver” shapedSporophytes – too small to see in umbrella shaped stalk

Fewer than 100 speciesFound in moist soilSporophytes – slender, horn shaped

Non-Vascular - Hornworts

• Ferns• Horsetails• Club Mosses• True Vascular

Tissue• Release Spores• Need water for

reproduction

Seedless Plants – Vascular

• More than 12,000 species

• True Roots, stems, leaves

• Sporophyte• Leaves – Fronds• Spore cases• Gametophytes• Tiny• Grow low to

ground

Ferns

Fern Life Cycle

• Few Species alive now

• Needle Like Branches

• grow in circle around joints

• Small leaves • grow flat against

stem• Stem contains Silica

Horsetails

• Only a few hundred species

• Resembles branch of a pine tree• Ground pine• Grows in spiral around

stem

Club Mosses

• Have Vascular Tissue• Xylem – carries water and minerals• Phloem – carries food (sugars)• Use Pollen and Seeds to reproduce• Pollen – male reproductive cell• Seeds – embryo, food supply, seed coat

Gymnosperms• Seeds not protected by fruit

Angiosperms• Produce Flowers• Seeds protected by fruit

Seed Plants

Seed StructureMonocot – one cotyledon (seed leaf)Dicot – 2 cotyledons

• Seeds must be dispersed to prevent competition

• Water• Sunlight• Minerals• Dispersed by• Wind• Water• Animals

Seed Dispersal

Needs- correct moisture, correct temperature, correct time – some seeds are dormant first

Germination

• Tip Covered by a root cap• Protects root during growth• New cells develop behind

root cap• Root hairs• Tiny• Absorb water, minerals• Anchor plant in soil

Roots

• Xylem• Phloem• Fibrous Roots -

spreading• Taproot - deep

Xylem – carries mineral, waterPhloem – carries foodSupporting Cells

Stems

HerbaceousSoftNo wood

Woody StemsOuter bark – CorkLiving PhloemCambiumLiving XylemSapwoodHardwoodAnnual Rings

Conduct Photosynthesis

Lose water from stomates during transpiration

Guard cells control amount of water lost

Leaves

Gymnosperms Ginkgo

ConiferLargest groupCone bearing

Cycadtropical

GnetophyteDeserts, tropical rain forestsCan live 1,000 yrs.

Seed Not Protected by a fruitNeedle like or scale like leavesDeep roots system

Gymnosperm Reproduction

Pollination pollen - male parts

Fertilization sperm reaches ovule

Seed development

Seed Dispersal

Produce FlowersSeeds are protected by fruits

Angiosperms

Live almost everywhere

Flower Parts

Angiosperm Life Cycle

Dicots vs. Monocots

A plant grows toward a stimulus – positiveA plant grows away from a stimulus – negativeTouch – ThigmotropismLight – PhototropismGravity – Gravitropism or Geotropism

Hormones – Auxin – causes cells to lengthen on side away from light. Plant bends toward light.

Tropisms

• Photoperiodism – response to length of day vs. night.• Critical Night Length • Short Day Plants – Bloom when daylight is shorter

autumn

Seasonal Changes

• Long Day plants – Bloom when daylight is longer – spring and summer

• Day Neutral – No effect

Perennials• Flower every year• Most have woody steam• some have herbaceous stems• leaves and stems die each winter, but

new are produced in spring.

Life Spans of Angiosperms• Annuals

Complete cycle in one growing season

herbaceous stems• Biennials

Year one – stems, leaves

Year Two – flowers, fruits, seeds