Exam 3

Question 1

Taproots: characteristics and places to find

Answer 1

Most dicots and gymnosperms
Large main root developed from radicle
Produces branch roots (lateral)
Penetrate deep or spread out far

Question 2

Fibrous Roots: characteristics and places to find

Answer 2

Seedless vascular plants
Radicle dies and roots grow from bottom of stem
Adventitious root, each develops lateral roots
Shallower, more spreading

Question 3

Root zones

Answer 3

Cell division: root apical meristem & 3 primary meristems
Elongation: derivatives stop dividing and elongate
Maturation: cells differentiate, epidermal cells -> root hairs

Question 4

Root cap

Answer 4

Produced by root apical meristem
Protects apical meristem
Produces mucigel

Question 5

Quiescent center

Answer 5

Center of apical meristem
Where initials are located and mitosis occurs

Question 6

Casparian strip

Answer 6

ring like cell wall modifications
Forces water and minerals through cell membrane
In root endodermis

Question 7

Nitrogen fixing bacteria

Answer 7

Convert nitrogen from air into ammonium (nitrogen fixation)
Plants take up fixed nitrogen
Bacteria infect roots -> roots for nodules for bacteria to live in -> nodules release nitrates into soil

Question 8

Mycorrhizae

Answer 8

Endomycorrhizae: fungi penetrate roots & produce arbuscules (branching structures)

Ectomycorrhizae: fungi network surrounds root, produces a mantle (sheath)

Question 9

Guard cells

Answer 9

Specialized pairs of epidermal cells surrounding stomata, contain chloroplasts

Question 10

Specialized stems

Answer 10

Bulb: large bud surrounded by fleshy leaves, small stem at lower end, store food (onion, lily, hyacinth, tulip)
Corm: resemble bulb, almost entirely stem tissue with papery leaves, store food (crocus and gladiolus)
Tuber: swollen, fleshy underground stem, stores food (potato)
Rhizome: horizontal stem, grows underground, long to short internodes (iris, some grass, fern)
Stolon: horizontal stem, grows above ground, long internodes

Question 11

Leaf epidermis

Answer 11

Single layer of non photosynthetic cells, derived from protoderm
Prevents water loss, abrasions, and disease entry
Regulates gas exchange via stomates
Transpiration: pulls water and minerals up & cools leaf

Question 12

Leaf veins

Answer 12

Vascular bundles in blade
Support leaf with bundle sheath cells
Netted or parallel venation

Question 13

Thorns and bracts

Answer 13

Thorn: (Spine like) Modified stem produced in axil of leaf
Bract: specialized leaf at base of flower or flower stalk

Question 14

Lateral meristems

Answer 14

Vascular cambium: secondary xylem and phloem increase plants capacity to carry water and nutrients up, sugars down, replaces primary xylem and phloem that stopped working, more secondary xylem, fusiform initials -> secondary xylem and phloem, xylem-> growth ring, ray initials->parenchyma for storage

Cork cambium: produces periderm (cork, phelloderm, Cork cambium cells), does not expand diameter, new forms within old

Question 15

Wood vs. Bark

Answer 15

Wood: secondary xylem, mostly dead cells, only new secondary xylem is active, thicker walls, lignin and cellulose in cell walls allow it to provide support

Bark: tissues outside vascular cambium, thinner than wood; inner bark-> secondary phloem and newest cork cambium/periderm; outer bark-> dead secondary phloem & old periderm; suberin -> protective, waterproof, prevents sap seepage, blocks gas passage; lenticels -> small openings for gas exchange

Question 16

Inflorescence

Answer 16

Groups of flowers that may open at the same time or follow an orderly progression to maturation

Question 17

Flower anatomy

Answer 17

Stamen: another, filament

Carpel (pistil): style, stigma, ovary (ovules inside)

Perianth: Petal, sepal

Receptacle

Peduncle

Question 18

Modified leaf, stem, root examples

Answer 18

Cones-> stems and leaves
Flowers-> leaves

Aerial roots-> adventitious, arise from stems, epiphytes- plants grow on plants for support but provide own nourishment, extra support or anchoring
Buttress roots -> flared roots extend from tree trunks, stability of tree
Contractile-> shorten and pull plant deeper into soil
Suckers-> asexual, arise from underground roots, form new shoots
Pneumatophores “air roots”-> provide oxygen for swamp area plants
Haustoria-> parasitic, penetrate other plant stems and roots to get water, minerals, organic materials

Question 19

Pericycle

Answer 19

Meristematic cells-> lateral roots

Surrounds stele

Question 20

Seed anatomy

Answer 20

Cotyledons- seed leaves, food storage
Endosperm- food storage, feeds embryo
Radicle- embryonic root
Plumule- embryonic shoot, generates epicotyl (embryonic stem above cotyledon)
Hypocotyl- embryonic stem under cotyledon above radicle

Question 21

Lignin

Answer 21

Strengthens cell walls

Question 22

Mucigel

Answer 22

Slimy, viscous substance

Protects root cap, lubricates root cap, creates symbiotic environment for nitrogen fixing bacteria and fungi

Question 23

Types of mesophyll

Answer 23

Ground tissue-> chlorenchyma cells where photosynthesis takes place

Palisade-> elongated thick layer under upper epidermis
Spongy-> loosely organized layer with space for carbon dioxide diffusion from stomata to other leaf parts

Question 24

Abscission zones

Answer 24

Area where leaf separates from plant

Form in response to shorter days and cooler weather near node where petiole attaches to stem

Environmental changes trigger abscisic acid production

Useful molecules moved out of leaf into stem

Protective layer forms between abscission and stem

Question 25

Types of stele

Answer 25

Stele- most monocots; vascular bundles scattered through ground tissue Protostele- seedless vascular plants; arrangements like in roots; earliest plants Siphonostele- most seedless vascular plants; continuous vascular cylinder surrounds pith core; phloem outside xylem or sandwiched around xylem; cylinder broken by leaf gaps where vascular tissue diverges to enter leaves Eustele- gymnosperms and dicots; vascular tissue forms vascular bundles; no leaf gaps; xylem toward center, phloem to the outside; vascular bundles in circle around pith -tight rings (some dicots and gymnos), loose rings (most dicots and gymnos)

Question 26

Adventitious roots

Answer 26

Develops from a stem or leaf

Question 27

Endodermis

Answer 27

Suberin laden cells in a single layer cylinder outside pericycle, found in roots

Question 28

Intercalary meristems

Answer 28

In grasses, add to stem length

Question 29

Periderm

Answer 29

Outer bark of woody plants, replaces epidermis, primarily cork cells

Question 30

Sapwood vs Heartwood

Answer 30

Sapwood: newer outer rings of conducting xylem Heartwood: older, non conducting rings of xylem in center of trunk

Question 31

Suberin

Answer 31

Fatty substance produced by cork cells while cytoplasm is still functioning that waterproofs bark

Question 32

Reaction wood vs tension wood

Answer 32

Reaction wood: response to gravity Softwood- compression wood Hardwood- tension wood

Question 33

Phyllotaxy

Answer 33

Basic pattern of leaf arrangements Alternate, opposite, whorled

Question 34

Meiosis vs mitosis

Answer 34

Meiosis I Prophase I: chromosomes coil-> shorter and thicker; 2 stranded chromosomes align in homologous pairs; nuclear envelope disassociates; chromosome exchange; chromosomes separate Metaphase I: chromosomes align at equator;see spindle Anaphase I: chromosomes migrate to opposite poles Telophase I: nucleoli reappear sans evelope either revert back to interphase or move to Div II Prophase II: chromosomes shorten and thicken Metaphase II: centromeres align along equator, spindle fibers arc to poles and attach to centromeres Anaphase II: centromeres and chromosomes separate and migrate to opposite poles Telophase II: nucleoli and nuclear envelopes reappear, new cell walls; half the original number of chromosomes

Question 35

Sporophytes vs gametophytes

Answer 35

Sporophyte- diploid, develops from zygote Gametophyte-haploid, changes to sporophyte via fertilization

Question 36

Primary meristems

Answer 36

Form from apical meristem Protoderm: gives rise to epidermis Ground meristem: parenchyma of cortex; also pith in stems minus dicots Procambium: primary xylem and phloem

Question 37

Secondary meristems

Answer 37

Lateral meristems Vascular and cork cambium