Kingdom PLANTAE

Multi-celled / eukaryotic

Autotrophic / chloroplast

Cell wall - cellulose

Kingdom PLANTAE Plant Evolution

Plants: Alternation of Generation Gametophyte (n): Haploid, produces eggs and sperms which then unite to form sporophyte

Sporophyte (2n): Diploid which goes through meiosis to produce spores which grow into gametophytes

Plants: Alternation of Generation

Plants: Alternation of Generation - MOSSES

Plants: Alternation of Generation - FERNS

Plants: Flowers Alternation of Generation

Plants: Flowers Most plants are angiosperms, flowering plants

Angiosperm seeds protected and dispersed in fruits, which develop from ovaries

Plants: Flowering Plants Angiosperms, or flowering plants, are most familiar and diverse plants

Two main types of angiosperms Monocots: orchids, bamboos, palms, lilies, grains, and other grasses

Dicots: shrubs, ornamental plants, most trees, and many food crops

Comparison between dicot and monocot seeds

Figure 31.11B

Seed coat

Embryonicleaves

Embryonicroot

Embryonicshoot

Cotyledons

Fruit tissue

Seed coat

Endosperm

Embryonicshoot

Embryonicroot

Cotyledon

Embryonicleaf

Sheath

COMMON BEAN (DICOT)

CORN (MONOCOT)

Plants: Monocots vs Dicots

The angiosperm flower is a reproductive shoot consisting of sepals petals stamen carpels

Plants: Flowering Plant Reproduction

Figure 31.9A

Stigma

Ovary

Carpel

Anther

Petal

Ovule Sepal

Stamen

Plants: Stamens - male reproductive organs of plants Pollen grains develop in anthers, at the tips of stamens

Carpels - female reproductive organs of plants Ovary at the base of the carpel has ovule

Life cycle of angiosperm involves several stages

Figure 31.9B

Ovary, containingovule

Fruit,containing seed

Seed

Embryo

Germinating seed

SeedlingMature plant withflowers, wherefertilization occurs

Figure 31.10

Plants: The ovule develops into a seed After fertilization, ovule becomes seed Fertilized egg inside seed - embryo

Other fertilized cell - endosperm, stores food for the embryo

Resistant seed coat protects the embryo and endosperm

Figure 31.11A

Triploid cell

OVULE

Zygote

Two cells

Embryo

Root SEED

Shoot

Endosperm

Cotyledons

Seed coat

Seed dormancy is an important evolutionary adaptation in which growth and development are suspended temporarily It allows time for a plant to disperse its seeds

It increases the chance that a new generation of plants will begin growing only when environmental conditions favor survival

Plant: Asexual Reproduction Asexual reproduction:

Bulbs: parts of root split and form new bulb (ex. tulip)

Tubers: modified underground stem have buds (ex. potato)

Runners: plant stem run above ground (ex. Strawberry)

Rhizomes: woody underground stem (ex. Iris)

Modified stems include runners, asexual reproduction

rhizomes, plant growth and food storage

tubers, food storage as starch

Figure 31.4B

STRAWBERRYPLANT

POTATOPLANT

IRISPLANT

Runner

TuberTaproot

Rhizome

Rhizome

Root

Asexual runners

Figure 31.14D

Vegetative propagation: cuttings or bits of tissue increase agricultural productivity But it can also reduce genetic diversity

Cutting: cut stem form roots Layering: bent stem touching ground form roots

Grafting: stock of one grafted on stem (scion) of another

Plant: Asexual Reproduction

Plants: Shoot and Root System

Root system Provides anchorage Absorbs and transports minerals and water

Stores food Shoot system

Consists of stems, leaves, and flowers in angiosperms

Stems: located above ground and support leaves and flowers

Leaves: main sites of photosynthesis in most plants

Plant: Cell Structure

Plants: 3 Tissue Systems Instead of organs, plants have roots, stems, and leaves are made of three tissue systems The epidermis The vascular tissue system

The ground tissue system

PLANTS: Epidermis and Vascular Tissue

The epidermis covers and protects the plant The cuticle is a waxy coating secreted by epidermal cells that helps the plant retain water

The vascular tissue contains xylem and phloem It provides support and transports water and nutrients

Xy: high (water) Phlo: lo (nutrients) Rise of water: transpiration pull, capillary action, root pressure

Phloem transports food molecules made by photosynthesis

Figure 32.5B

Figure 32.3

Plants: Vascular & Ground Tissue Vascular tissue:

Xylem: inside, bring water up; usually dead cells act as tube

Phloem: outside bundle, brings nutrients down

Pith: storage and structure Cambium: growth tissue – divide into xylem and phloem (2nd growth)

The ground tissue system functions mainly in storage and photosynthesis

Figure 31.6B

Xylem

Phloem

Epidermis

VASCULARTISSUESYSTEM

GROUNDTISSUESYSTEM

Cortex

Endodermis

These microscopic cross sections of a dicot and a monocot indicate several differences in their tissue systems

Figure 31.6C

Three tissue systems in dicot leaves Epidermis: stomata (singular, stoma) surrounded by guard cells – regulate opening/closing of stomata

Figure 31.6D

Ground tissue system of a leaf – mesophyll, site of photosynthesis

Figure 31.6D

Vascular tissue: xylem and phloem

Figure 31.6D

Guard cells: control transpiration Opening and closing of stomata - adaptation to help plants regulate water content / adjust to changing environmental conditions

Plants: Guard cells control transpiration

Figure 32.4

Guard cellsH2O H2O

K+

H2O

H2OH2O

Vacuole

Stoma opening Stoma closing

H2O

H2O

H2OH2O

H2O

Most plants continue to grow as long as they live (as opposed to animals that stop growing)

Two types of growth:- primary growth (length)- secondary growth (width)

Plant Growth: Primary vs Secondary

Plants: Primary Growth Growth from tissue meristems

Meristems: unspecialized, dividing cells (like our stem cells)

Apical meristems: tips of roots and stems and terminal buds ; length growth

Primary growth (length growth) - new cell productions

Figure 31.7A

Terminal bud

Axillary buds

Arrows =directionof growth

Roottips

Figure 31.7B

Vascularcylinder

Cortex

Epidermis

Root hair

Cellulosefibers

Apical meristemregion

Rootcap

DIF

FE

RE

NT

IAT

ION

EL

ON

GA

TIO

NC

EL

LD

IVIS

ION

Plants: Secondary growth Secondary growth: Increase in a plant's width

Lateral meristem (also called cambium): Vascular cambium (located between xylem and phloem)

Cork cambium (not in grasses or herbs, but found in woody dicots, ex. oaks)

Vascular cambium thickens stem by adding layers of secondary xylem, or wood, next to its inner surface Also produces secondary phloem- tissue of bark

Cork cambium produces protective cork cells located in bark

Figure 31.8A

Plants: Secondary Growth Everything outside vascular cambium – bark Secondary phloem Cork cambium Protective cork cells

Woody log result of several years of secondary growth (inside “dead”; outside “growing”)

Figure 31.8B

Sapwood

Heartwood

Rings

Woodrays

Heartwood

Sapwood

Vascular cambium

Bark

Secondary phloem

Cork cambium

Cork

Plant behavior: Phototropism Gravitropism Geotropism thigmotropism

Plant: Behavior = Tropism

Figure 33.1A

Phototropism is the bending toward light It may result from auxin moving from the illuminated side to the shaded side of a stem

Figure 33.1A

Gravitropism is a response to gravity

Figure 33.9A

Thigmotropism - response to touch Responsible for coiling of tendrils and vines around objects

Enables plants to use other objects for support while growing toward sunlight

Figure 33.9B

Phototropism

Figure 33.1B

Shadedside ofshoot

Light

Illuminatedside ofshoot

Hormone controls phototropism

Figure 33.1C

Light

Control Tipremoved

DARWIN AND DARWIN (1880) BOYSEN-JENSEN (1913)

Tip coveredby opaque cap

Tip coveredby trans-parent cap

Basecoveredby opaqueshield

Tipseparatedby gelatinblock

Tipseparatedby mica

Figure 33.1D

Shoot tip placed on agar block.Chemical (later called auxin)diffuses from shoot tip into agar.

Agar

Control

NO LIGHT

Block withchemicalstimulatesgrowth.

Offset blocks withchemical stimulatecurved growth.

Other controls:Blocks with nochemical haveno effect.

Hormones affect: cell elongation cell differentiation

Plants: Hormones

Table 33.2

Auxin: stimulates cell division – phototropism and geotropism

Positive and negative geotropism (b/c unequal distribution of hormone, unequal growth & root grows faster)

Cytokinins: promote cell division Produced in actively growing roots, embryos, and fruits

Opposite auxin, so plant coordinates growth of root and shoot systems

Plants: Hormones

Cytokinins – develop side growth Ex grow branch

Auxin – stimulate length growth w/o auxin, plant becomes thicker b/c cytokinins Terminal bud

No terminal bud

Figure 33.4

Gibberellins: stimulate cell elongation and cell division in stems and leaves

Gibberellins: can stimulate seed growth

Plants: Hormones

Figure 33.5A

Gibberellins with auxin - influence fruit development

Grapes at right treated with gibberellin, left not

Figure 33.5B

Abscisic acid (ABA) inhibits germination of seeds

Ratio of ABA & gibberellins determines whether seed remain dormant or germinate

Also “stress hormone” – close stomata when too dry

Plants: Hormones

Seeds of many plants remain dormant until ABA inactivated or washed away Ex. flowers grow from seeds after rainstorm in Mojave Desert

Figure 33.6

Ethylene: triggers fruit ripening Given off as cells age

Plants: Hormones

Figure 33.7A

Fruit growers use ethylene to control ripening Apple farmers slow down ripening action of natural ethylene

Tomato farmers pick unripe fruit and then pipe ethylene into storage bins to promote ripening

Circadian rhythms: internal biological clock controls daily cycles Even in the absence of environmental cues, they persist with periods of about 24 hours

But such cues are needed to keep them synchronized with day and night

Plants: Circardian Rhythms

Figure 33.10