Module Two: Plant Ecology

What traits do all land plants have?

Alternation of generations, embryos, cuticle

What species of land plants do not have stomata?

Liverworts

In what species is the sporophyte not the dominant generation?

Bryophytes (mosses), Liverworts

which species of plants have a vascular system?

Lycophytes, ferns, gymnosperms, angiosperms

Gametophyte

The haploid generation, produces gametes through mitosis

Sporophyte

Diploide generation, produces spores by meiosis

Spore

Produces via meiosis and typically dispersed (excepto in seed plants). Grow into gametophyte via mitosis

Gamete

Haploid reproductive cell; fuses during fertilization to form a zygote

Meiosis

Cell division that reduces the chromosome number by half (produces spores in plants)

Mitosis

Cell division that produces identical cells; used for growth

Bryophytes

Non-vascular plants (ex: Liverworts, Hornworts, Mosses). Gametophyte dominate

Liverworts

Type of bryophyte; have pores, but no stomata

Hornworts

A type of bryophyte; have longer-lived sporophyte than other bryophytes

vascular system

System of tissues (xylem and phloem) that transports water and nutrients; allow for larger, branched sporophytes

Xylem

Vascular tissue in plants responsible for transporting water and dissolved minerals from the roots to the rest of the plant, and also provides structural support.

Phloem

Vascular tissue in plants responsible for transporting sugars (food) during photosynthesis from the leaves to other parts of the plant like roots, fruits, and growing tissues

Seeds

Fertilized ovule

—> like human zygotes/embryo

Fruit

Structures derived from ovary

Gymnosperm

“Naked seed” plants (ex: pines, conifers); pollen delivered directly to the ovule

Angiosperms

Flowering plants; seeds enclosed within a carpel/ovary; make fruits

Flower

Reproductive structure of an angiosperm

Sporophyll

A modified leaf specialized for reproduction

Carpel (pistil)

Female reproductive organ; made of stigma, style and ovary

Ovary

Base of the carpel; contains the ovules; develops into fruit after fertilization

—> like human uterus

Ovule

Structure inside the ovary; contains the female gametophyte; develops into the seed after fertilization

—> like human egg

Stigma

Receptive tip of the pistil; the landing pad for pollen; held up by the style

—> like human vagina

Style

Stalk connecting the stigma to the ovary

Stamen

The male reproductive organ; made of the anther and filament

Anther

Part of the stamen; where pollen (male gametophytes) is produced

Filament

Stalk that holds up the anther

Pollen Grain

The male gametophyte in seed plants; typically three cells (tube cell and two sperm cells)

Pollination

The process of moving pollen from the anther to the stigma

Pollen tube

Tube that grows from the pollen grain down the style to deliver sperm to the ovule

Megastore Mother Cell

Diploid cell in the ovule that undergoes meiosis to create mega spores (female spores)

Microspore Mother Cell

Diploid cell in the anther that undergoes meiosis to create microspores (male spores)

Endosperm

The food supply for the embryo within an angiosperm seed

Double fertilization

Unique to angiosperms; Involves to fusion events: 1) Egg + Sperm = Zygote (diploid 2n), 2) Second sperm + Polar nuclei = endosperm (triploid, 3n)

Polar nuclei

The two nuclei in the large central cell of the female gametophyte; fuse with one sperm to form the endosperm

Germination

The process where a seed initiates growth

Radicle

The embryonic root; the first structure to emerge from the seed (grows downward to anchor and acquire water/nutrients)

Cotyledons

Embryonic leaves; provide early photosynthesis/nutrition until mature leaves develop

Hypocotyl

Embryonic stem; pulls cotyledons out of the soil

Eudicots (dicots)

Plant group whose embryos produce two cotyledons (ex: beans)

Monocots

Plant group whose embryos produce one cotyledons (ex: corn)

Meristem (Meristematic Tissue)

Undifferentiated tissue (similar to human stem cells) that allows for continuous growth. Found in buds and root/shoot tips.

Indeterminant Growth

The ability of a plant to grow continuously throughout its life from its meristems (unlike animals)

Bud

Cluster of meristem tissue that can grow and make new plant parts

Apical Bud

Bud located at the tip of a shoot or root; responsible for primary growth

Auxiliary Bud

Bud located in the axis (crook) where a leaf meets the stem

Primary Growth

Growth that results in the elongation of shoots and roots, and the production of leaves/flowers

Secondary Growth

Growth that results in making the plant wider/thicker (ex: forming the woody trunk of a tree)

Root cap

Protective layer of cells covering the apical meristem at the root tip

Zone of Cell Division

Location of the apical meristem; cells are undifferentiated and actively undergoing mitosis (cell division)

Zone of Elongation

Zone where cells move after division; cells grow much longer due to water uptake. This process also pushed the root tip further into the soil

Zone of Differentiation

Zone where cells finish elongating and become mature, specialized tissues. Their function is determined by their location.

Dermal Tissue

The outermost layer; includes the epidermis and cuticle

Epidermis

The protective outer layer of cells

Cuticle

Waxy layer on the epidermis of shoots/leaves; reduces water loss

Ground Tissue

All tissues other than vascular and dermal; functions include storage, support, and photosynthesis

Secondary Growth

Growth that results in the increase in girth of stems and roots. Occurs mainly in dicots

Cortex

Ground tissue outside vascular bundles; often used for sugar storage

Pith

Ground tissue inside the ring of vascular bundles (in dicot stem)

Endodermis

Ground tissue layer around the vascular bundles in roots; acts as a barrier

Vascular Bundle

Strand containing both xylem and phloem tissues

Mesophyll

Ground tissue in leaves; specialized for photosynthesis (palisade and spongy layers)

Guard Cells

Dermal cells surrounding a stoma; open and close to regulate gas exchange

Vascular Cambium

A type of lateral meristem that forms a ring in the stem; produces secondary xylem (to the inside) and secondary phloem (to the outside)

Cork Cambium

A type of lateral meristem that forms to the outside of the vascular cambium; produces bark/cork

Secondary Xylem

Wood; Tissue produced to the inside of the vascular cambium; makes up the majority of a woody plants girth; forms annual rings in temperature climates

Secondary Phloem

Part of the bark; tissue produced to the outside of the vascular cambium

Bark

All tissues external to the vascular cambium (includes secondary phloem and periderm/cork)

Tropism

A growth response that results in the curvature or turning of a plant organ in response to an environmental stimulus

Positive Tropism

Growth towards the stimulus

Negative Tropism

Growth away from the stimulus

Phototropism

Growth response to light

Compare number of cotyledons (embryonic leaves) between monocots and dicots

Monocots: one

Dicot: two

Compare the stem vascular bundles of monocots vs dicots

Monocots: vascular bundles are scattered randomly throughout the stem

Dicots: vascular bundles are arranged in a ring

Do monocots or dicots have a cortex and pith?

Dicots

Do monocots or dicots exhibit secondary growth?

Dicots

Compare root structures of a monocot and a dicot

Monocots: usually have fibrous roots, which are shallower and great for preventing soil erosion (like grass)

Dicots: usually have taproot (central, thick primary root), which is better for deep water access and anchoring large structures (ex: trees)

What does the Calvin Cycle do?

Takes CO2 out of the air and creates sugar

What process do all photosynthesizing plants take part in?

C3 photosynthesis 

What fixes CO2 in C3 photosynthesis?

RuBicCO

What fixes CO2 first in C4 photosynthesis?

PEP-C

What process does C4 photosynthesis eliminate?

Photorespiration 

Why do some plants not do C4 photosynthesis?

It is more costly to perform C4 photosynthesis

Why do plants need water?

• Photosynthesis and other hydrolysis reactions (<1%)

• Growth and expansion of cells (<5%)

• Transpiration- evaporation of water from leaves (~95%)

  • Provides transport og nutrients from roots to leaves

  • Cools leaves

  • Allows stomata to remain open for CO2 absorption

Is relative humidity generally (almost always) higher inside or outside of the leaf?

inside

As relative humidity increases, the transpiration rate…

decreases

As relative humidity decreases, the transpiration rate…

increases

Stomatal Conductance 

Function of stomatal density and stomal aperture 

What do guard cells do?

Govern aperture (they open and close stomata)

Adaptations that have contributed to the success of plants in terrestrial environments include seeds, long-lived sporophyte, stomata, and alternations of generations. List these adaptations in the order in which they appeared in the fossil record

alternations of generations, stomata, long-lived sporophyte, seeds

A trait of the common ancestor of charophytes and land plants that was exapted by land plants and allowed them to invade land was…

They were dispersed by spores

Which number could represent a multicellular embryo?

1

Which plant species exhibit this life cycle?

Bryophytes, gymnosperms, and angiosperms do, but charophytes do not

Stomata _______ in response to INCREASING light intensity

Open

Stomata ______ in response to DRY soil

Close