Brooks Biodiversity Unit 3 Exam

Plants Architecture

Plants Architecture

Plant needs

i. collection & conversion of solar energy -> leaves

ii. positioning & support of leaves -> stems

iii. anchorage & absorption -> roots

iv. transport -> vascular system

Leaf Structure

Epidermis, Mesophyll, and Vein (Vascular Bundle)

Epidermis contains what?

- Cuticle

- Guard cells with Stomata

Epidermis

outermost cell layer of a plant body

cutin: (wax) excreted by epidermis

Cuticle

Waxy waterproof covering of a plant.

Produced by the epidermis and has wax to resist desiccation.

Guard Cells

Responsible for opening and closing stomata.

Works together with stomata to regulate gas exchange.

Prevents movement of water ACROSS surface

Stomata

Small openings on the underside of a leaf through which oxygen and carbon dioxide can move.

Mostly on lower surfaces, sometimes on upper surfaces. Found on both surfaces.

Allows for gas exchange.

2 aspects of Photosynthesis

light dependent reactions

light independent reactions

Mesophyll contains what?

- Parenchyma

- Dicots have Palisade & Spongy Layers

Mesophyll

Middle leaf structures photosynthetic layer.

Parenchyma

Ground tissue that forms the bulk of the mesophyll

Can be modified into collenchyma and sclerenchyma

Thin and flexible cells

Most common and versatile ground tissue

Used for metabolic functions and storage of organic products

Palisade & Spongy layers

Palisade layer: where light dependent reactions occur, near the surface. Top part of the mesophyll in dicot plants.

Spongy mesophyll or spongy parenchyma: soft lower layer. Has access to CO2 through stomata. Kelvin Cycle: where carbon fixation occurs, converting nonorganic CO2 into sugars.

Vein (Vascular bundle)

Transports materials throughout the leaf and contains the xylem and phloem.

Separating the VB = damage.

Stem Structure

Epidermis, Cortex, Collenchyma, Sclerenchyma, Vascular Tissues

Xylem

(Xylem Up)

Distributes water from roots throughout

Aimed towards stem

Red

Tells age of tree

Contains: tracheids & vessel members

Tracheids

Thin, hollow, narrow tube, dead cells with perforated, tapered ends.

Vestigial structure

First kind of tube made

Present in early vascular plants and present in angiosperms and gymnosperms (slow flow)

Vessel Members

Thick, hollow, wide tube, dead cells with large holes on end.

Clearly visible

Phloem

(Phloem Down)

Distributes the products of photosynthesis (sugary water) to plants tissues.

Blue

Contains: Sieve tube members (element) & Companion cells

Sieve Tube Members

hollow, living cells with perforated cells

Companion Cells

living cells that help keep sieve tube member cells alive.

Production of sugars in Kelvin Cycle require transportation done by companion cells into phloem

Which 4 cell types is most active metabolically when fully functional?

companion cells

Epidermis in Trees

is replaced by bark or cork. Produced by the cork cambium (tissues that produce other tissues).

Cork (dead) = phloem (alive)

Cork cambium produces cork.

Trees grow wider cause xylem will get clogged

The cork is produced when?

Secondary phloem

Composition of Bark

is produced from phloem, cork cambium, or cork.

Lenticels

cracks in the bark to facilitate gas exchange

Secondary Growth

How a plant increases in girth (diameter)

1. Vascular Cambium

2. Cork Cambium

3. Wood

4. Bark

5. Lenticels

6. "Girdling Plants"

Wood

produced by xylem.

annual rings

Heartwood: clogged xylem, little water transport. Located deeper into trunk, harder wood

Sapwood: newer xylem, free flowing water transport. Phloem makes sap.

Girdling Plants

Weed-Whakers

Cutting a HORIZONTAL band around the circumference of the plant, can be deadly because the vascular cambium, in which nutrients and water travel vertically, can be damaged.

What happens to initial phloem?

it gets crushed

What happens to the xylem?

it gets clogged

Cortex

Yellow layer inside epidermis

Separated by a ring of vascular bundles.

Ground Tissue System

Includes various cells specialized for functions such as storage, photosynthesis, and support

Types of Ground Tissue

Parenchyma, Collenchyma, Sclerenchyma

Collenchyma

celery fibers for support

Sclerenchyma

hard fibers & nodules responsible for support

(ex) rope

Sclerids

nodules glued together to form shells of nuts.

Fibers

secretions that reinforce the stem

Pith

Middle of stem, large because it contains nutrients.

Separated by a ring of vascular bundles.

Replaced by xylem

Procambium

Becomes Vascular Cambium

Makes xylem inward and phloem outward

Grows in rings

Gives rise to vascular tissues

Forms advanced tissues

Monocots

have no cortex

Germ layers

= stem cells

Root Structure

i. Epidermis (permeable) with root hairs

ii. Cortex

iii. Endodermis with Casparian strips

iv. Stele

v. Apoplastic vs Symplastic pathways

Stele

Central cylinder with vascular tissues inside.

Caspian strips

wax, prevents water from growing in between cells

Used to aid a plant and tell weather in the past

Annual rings

Apoplastic vs. Symplastic pathway

Water enters through root epidermis and passes in the spaces "between" cortex cells apoplastically until reaching the endodermis. Casparian strips prevent water from passing between endodermal cells. Thus, water is forced through the cell membranes symplastically where it is filtered before reaching the vascular tissues within the stele = osmosis

Root nodules & Symbiotic bacteria

Bacteria fix nitrogen and are housed in root nodules to supply "fertilizer," thus allowing the plant to thrive, even in soils that are nutrient poor.

Nitrogenace- enzyme that breaks down the triple bond in nitrogen

Microbes contain this enzyme and they're anaerobic.

Mycorrhizae: most plants have an association between their roots and fungi in the soil. This association is critical in aiding water/mineral uptake by the plant.

Abiotic Fixation

Doesn't involve organisms

Lightning converts nitrogen into other sources because N2 isn't a usable form

Less important because lightning doesn't occur enough to be useful for plants

Biotic Fixation

Process by which free nitrogen (N2) is extracted from the atmosphere and converted (fixed) into nitrogen compounds which are plant nutrients (fertilizer). In nature, this process is carried out by certain bacteria such as cyanobacteria

Usable forms of nitrogen for plants

Nitrate NO3

Nitrite NO2

Ammonia NH3

Vegetative Asexual Reproductive modes of flowering plants

Runner (stolon), strawberry

Rhizome- underground stem (bermuda grass)

Corm- modified stem

Tuber- modified underground stem. Gives rise to new growth onion; Potato (however some potatoes are roots)

Bulb- modified stem

Parthenogenesis

development of egg without fertilization

Propagation

vegetative reproductive. Cut off a piece of plant off and it grows.

Plant Development

'... After germination"

Upward growth

-Epicotyl or Coleoptile

-Phototropism

Downward growth

Radicle or Hypocotyl

Gravitropism

Positively Phototropic

Growth in response to light

Structures responsible for downward growth

Radicle and Hypocotyl

Contain statoliths (little rocks) that can sense movement in bottom of cell, triggering the plant to grow towards the center of the earth (down)

Positive Gravitropism

grows in the direction of gravity via statolith sensors

Meristematic Tissues

Plants version of germ cells

Apical Meristems

responsible for increase in plant HEIGHT

Lateral Meristem

responsible for increase in plant DIAMETER (girth)

Meristems vs. Germ Cells

A meristem is the tissue in most plants containing undifferentiated cells (meristematic cells), found in zones of the plant where growth can take place. Meristematic cells give rise to various organs of the plant and keep the plant growing.

A germ cell is any biological cell that gives rise to the gametes of an organism that reproduces sexually.

Meristems are in plants and germ cells are in humans but in essence are essentially preforming the same function

Three Primary Meristems

1. Protoderm = Epidermis

2. Ground Meristem = Parenchyma, Collenchyma, Sclerenchyma = undifferentiated or modified to store pith

3. Procambium = VB w/ xylem and phloem

Exchange & Transport

i. Plants obtain gases, nutrients, minerals, & water via internal fluids

ii. Gas exchange begins with the stomata; roots, lenticils

iii. Internal transport = xylem & phloem

Fluid movement in xylem

Adhesion: Attraction of 2 of different things; water molecules bind to cell wall

This makes sure that the water doesn't go back down (capillary action)

Cohesion: Attraction of two of the same things sticking together; water molecules bind to one another via hydrogen bonding which pulls water molecules upward through xylem, like beads on a string

Evaporation: as water evaporates, it pulls on other water molecules that haven't been evaporated yet

Osmosis: Occurs in roots (root pressure)

Low solute concentration to high solute concentration

Capillary Action: allows water to go up, just a little bit

Transpiration Pull aka Cohesion/Adhesion Tension

The main motive force for transporting water up to the top of a plant (sometimes several hundred feet)

As water evaporates from the leaf's surface the cohesive-adhesive properties of water pull water molecules from below establishing a water tension and pressure

Drawbacks w/ Transpiration Pull

It requires significant water loss from the plant.

In dry conditions or arid environments, this water loss for vertical transport can be critical in plants

Therefore, a replenishing water supply is vital for the roots

Water loss in the tropics doesn't matter cause its always raining there.

Water evaporation = shade

Fluid movement in Phloem

Mass Flow: An active transport mechanism

Source vs. Sink:

Source: Sugars produced by the leaves

Sink: Sugars produced by the rest of the plant. Gravity can assist in this downward movement, however getting the sugars into the cells of the Phloem requires energy

Kingdom Animalia

1. Multicellular

2. Heterotrophs

3. Lack Cell Walls

Two Major Groups of Kingdom Animalia

1. Invertebrates (no backbone) about 15-30 million

2. Vertebrates (chordates with backbones and spinal columns) about 50,000. 30,000 of the 50,000 are fishes

There are animal species that haven't been described yet. 3 million have been described.

Phylum Cortada

vertebrates, fish, amphibians, mammals, birds, reptiles

Metazoa

transition from an animal-like protists to multicellular (choanoflagellate)

Advantages:

1. Large Size

2. Increased Mobility

3. Stable Internal Environment (Homeostasis)

4. Relative independence from environment

Radial Symmetry

Diploblastic

Can be cut in half anywhere along a central axis

No head

Little movement

Bilateral Symmetry

Triploblastic

Can be divided down a central line but cannot be cut anywhere

Cephalization: concentration of sensory structures in the head

(ex) orchids, humans

Asymmetry

No symmetry

Sponges

Ontogeny

= development

"Ontogeny recapitulates phylogeny"

Significant similarities among true appearance of vertebrate embryos due to evolution.

Most abundant skeleton

exoskeleton which tells the shape of the animal

Problem: gets in the way of growth

Largest animal that ever existed on this plant

blue whale

weight (mass) that makes them big

Largest organism on the planet

Humungous fungus

Largest land animal

elephant

Largest invertebrate

squid

First organism to conquer land

Reptiles, by producing a self-enclosed egg (aka shell egg). (ex) birds

# 1 species diversity

tropical rain forests

# 2 species diversity macroscopically

coral reefs

#1 species abundance and diversity

arthropods

#2 species abundance and diversity

mollusks

# 3 species abundancy

Roundworms

1st organism to be cephalized and have excretory system

flatworms

1st organism to have a closed circulatory system and complete digestive tract

ribbon worms

Secondary Compounds

how plants defend themselves from insects, creating medicine.

Almost all animals are

arthropods -> insects -> beetles

Most abundant and diverse

Embryology

i. Cleavage patterns: early cell divisions

ii. Cell fate

Radial Cleavage

new cells placed directly beside or on top of previous cells; deuterosome feature

Spiral Cleavage

new cells placed at juncture between previous cells; protostome feature

Determinate Cell Fate

fate of cells determined early; separated early cells incapable of developing into entire organism; protostome feature

determined @ 4 cell stage

Indeterminate Cell Fate

fate of cells determined relatively late; separated early cells can develop into entire organism; allows for 'twinning' or genetically identical individuals; deuterosome feature

(ex) humans

Developmental Stages

1. Morula

2. Blastula

3. Gastrulation

4. Gastrula

5. Germ Layers

Morula

Solid ball of cells

First stage of development in animals

Blastula

Hollow ball of cells

Blastocoel is in the center

Second stage of development in animals

Blastocoel

Chamber (body cavity) of hollow area within a blastula

Blastocoel is replaced by

mesoderm and coelm