Chapters 22, 23, & 25

Are eukaryotic, are multicellular, and have cell

walls.

Plants

Adaptations of plants

Meristem– where new cells are found; tip of stem.

• Plants grow in response to environmental factors:

– Light

– Moisture

– Gravity

– Temperature

Adaptations of plants

Some plants respond to chemicals or hormones.

Auxin – is a hormone that makes stems grow toward light ad away from the pull of gravity. They make roots grow away from sunlight and toward the pull of gravity.

Cytokinins – hormones that stimulate cell division and make dormant seed sprouts. Opposite of auxins.

Adaptations of plants

Tropisms – response to gravity, light, and touch.

• Gravitropism – response of a plant to gravity. Ex. Roots grow into soil.

• Phototropism – response of a plant to light. Ex. Change in color; leaves fall off; grow in direction of light.

• Thigmotropism – plant’s response to touch. Ex. Venus flytrap.

Adaptations of plantsAdaptations

• Aquatic plants – live in mud with little oxygen so have air-filled sacs that oxygen diffuses out of.

• Salt water plants – cells pump slat out of leaves.

• Desert plants – (xerophytes) tolerate heat, sand, winds and little rain. Seeds are often dormant.

• Carnivorous & Parasitic plants – soil has little nutrients so must trap & digest insects or live on a host plant to get nutrients.

• Epiphytes – not rooted in soil so grow directly on other plants. (not parasites)

• Many plants produce chemicals that are poisonous if eaten. Tobacco – Nicotine.

Classification of Classification of PlantsPlants

Plant Kingdom

Flowering Plants

Non-flowering Plants

Plant Life Cycle

• 2 phases

– Sporophyte – diploid (2N)

– Gametophyte – haploid (N)

Alternating from diploid to haploid is called alternation of generations.

• Use energy from sunlight to carry out Photosynthesis.

A plant can be divided into 3 partsA plant can be divided into 3 parts

3 groups

FernsFernsMossesMosses GymnospermsGymnosperms

Non - flowering Plants

Do NOT produce flowers

Examples of Examples of MossesMosses

spores

Spore-producing capsule

No true roots, No vascular tissues (no transport)

Characteristics of Characteristics of Mosses (Bryophytes)Mosses (Bryophytes)

Simple stems & leaves

Have rhizoids for anchorage; no roots

Spores from capsules (wind-dispersal)

Damp terrestrial land

Simplest plants

underground stem

root

A leaf (finely divided into small parts)

True roots, feathery leaves & underground stems

Characteristics of Ferns

have vascular tissuesvascular tissues (transport & support)

DampDamp & shadyshady places

Spore-producing organSpore-producing organ on the underside of leaves called a sporangia (reproduction)

needle-shaped leaves

Male cones (in clusters)

Female cones (scattered)

roots, woody stems

Characteristics of Characteristics of GymnospermsGymnosperms

needle-shaped leaves

tall evergreen trees

cones with reproductive structures

dry places

vascular tissues (transport)

naked seeds in female cones

Angiosperms – Flowering Plants

• Have reproductive organs called flowers.

• Flowers attract animals which carry pollen (pollination).

• Seeds are protected and develops into a fruit.

• 2 groups – monocot (1 seed leaf)& dicot (2 seed leaves).

• Annuals (1 season), Biennials (2 seasons), Perennials (many years)

2 2 groupsgroups

MonocotyledonsMonocotyledons DicotyledonsDicotyledons

Flowering Plants

roots, stems, leaves

vascular tissues (transport)

flowers, fruits (contain seeds)

MonocotyledonsMonocotyledons

Parallel veins

one seed-leaf

Characteristics of Characteristics of MonocotyledonsMonocotyledons

leaves have parallel veins

herbaceous plants

e.g. grass, maize

DicotyledonDicotyledonss

Veins in network

two seed-leaves

Characteristics of Characteristics of DicotyledonsDicotyledons

leaves have veins in network

e.g. trees, sunflower, rose

Roots, Stems, & Leaves

• Made up of: – Dermal tissue -“skin”; prevents water

loss.– Vascular tissue -moves water &

nutrients.– Ground Tissue – cells that lie b/w

dermal & vascular.– Meristematic – responsible for new

plant cells and growth.

Roots, Stems, & Leaves

Roots:• Seedlings grow into primary roots,

then to secondary roots.• Has a vascular cylinder (xylem &

phloem).• Function is to anchor plant to ground

& absorb water and dissolved nutrients from the soil.

• Root pressure forces water upward.

Roots, Stems, & Leaves

Stems:• Function is to produce leaves, branches &

flowers; hold leaves upright to sun; transport water & nutrients b/w roots and leaves.

• Monocot stems-vascular bundles are scattered throughout stem.

• Dicot stems-vascular bundles are in a ring & contain xylem and phloem tissue.

Roots, Stems, & Leaves

Leaves:

• Plants main organs.

• Make food (photosynthesis).

• Have chloroplasts.

• Xylem and Phloem tissue are in bundles called veins which connect to the stem.

• Stomata allow air/gases in & out.

Transport in Plants• Xylem – moves water.• Phloem – moves sugars.• Root pressure forces water up.• Water is pulled up by a force called

cohesion (molecules pulled together).• Water molecules are also attracted

to other molecules by adhesion.• Capillary action is cohesion and

adhesion together causing water to move upward. Water will move higher in a narrow tube than in a wider tube.

Plant ClassificationPlant Classification

Non-flowering

Plants

Flowering

Spore-bearing

Naked seeds

No roots

with roots

Mosses Ferns

Gymnosperms

1 seed-leaf

2 seed-leaves

Monocots Dicots