Chapter 25

Question 1

The shoot

Answer 1

Stem and it’s leaves above ground, initiated during the development of embryo plumule

Plumule: epicotyl, young leaves, apical meristem

Provide support and conduction

Question 2

Shoot apex vs root apex

Answer 2

Includes apical meristem together with the subapical region bearing young leaf primordia. Produces leaves, axillary buds (Lateral shoots)

Root apex produces no lateral organs

Question 3

Apical meristem

Answer 3

The only part of the shoot lying distal or above the youngest leaf primordium.

Adds cells to the primary plant body, continuously produces leaf primordia and bud primordia this process is called phytomeres

Question 4

Leaf primordia vs bud primordia

Answer 4

Leaf primordia develops into leaves

Bud primordia develops into Lateral shoots

Question 5

Tunica-Corpus

Answer 5

Tunics- the outermost layer of cells that divide anticlinically (perpenducular to apical surface), surface growth without increasing cell layers on meristem

Corpus- body of cells that lie beneath tunica layers, add bulk to developing shoot, add cells by dividing periclinally (parallel to apical surface)

Question 6

Eudicot apices layers (3)

Answer 6

Two tunica layers and one initial layer of the corpus

L1 outermost, divides anticlinically or periclinally SOMETIMES
L2 Mid
L3 innermost

Question 7

Central Zone

Answer 7

The corpus and the portions of the tunica layers overlying the corpus, corresponds to the promeristem of the shoot apical meristem

Beneath is the pith meristem

Mitotically inactive

Question 8

Peripheral zone

Answer 8

Surrounds central zone, originates partly from Tunica layers L1, L2, and corpus

Mitotically active (cell division)

Question 9

Zones and Primary meristems

Answer 9

The protoderm always originates from the outer most layer (L1)

The procambium and part of the ground meristem derived from the peripheral meristem

The rest of the ground meristem is formed by the pith meristem

Question 10

Intercalary meristem

Answer 10

A localized meristematic region in the elongating internode

Question 11

Tissue maturation

Answer 11

Protoderm becomes epidermis, procambium becomes primary vascular tissues, and ground meristem becomes ground tissue

Question 12

Interfascicular regions

Answer 12

Parenchyma regions that interconnect the cortex and the pith

Question 13

Herbaceous

Answer 13

The stems of many eudicots undergo little or no secondary growth, nonwoody

Question 14

Closed/open vascular bundles

Answer 14

Closed vascular bundles are usually entirely surrounded by a sheath composed of Sclerenchyma cells

Vascular bundles that do give rise to a cambium are said to be open

Question 15

Leaf traces

Answer 15

The extension from the vascular system in the stem toward the leaves

A single leaf may have one or more leaf traces connecting its vascular system in the stem

Question 16

Leaf trace gaps

Answer 16

The gaps of ground tissue in vascular cylinder above the level where leaf traces diverge toward leaves

Question 17

Sympodium

Answer 17

A stem bundle and it’s associated leaf traces

Some or all of the sympodia are interconnected
OR
All the sympodia are independent units of the vascular system

Question 18

Phyllotaxis or phallotaxy

Answer 18

The arrangement of leaves on a stem

The most common type of phyllotaxis is spiral, or helical

Question 19

Types of phyllotaxis

Answer 19

Distichous: plants with a single leaf at each node

Opposite: plants with pairs of leaves at each node

Decussate: each successive pair of leaves at a right

Whorled: three or more leaves at each node

Question 20

Initiation of leaves hypothesis’s

Answer 20

First available space: when sufficient width and distance front the apex is attained

Inhibitory field: preexisting leaf primordia inhibit the formation of new ones in their immediate vicinity

Biophysical forces: a leaf primordium is initiated when a portion of the tunica surface bulges or buckles

Auxin: the plant hormone that initiates primordium, generates by L1 layer

Question 21

Sessile

Answer 21

Leaves without petiole, ex. Corn/Grass

Question 22

Plant water requirements

Answer 22

Mesophytes: plants that require am environment that is neither too wet nor too dry

Hydrophytes: plants that require a large supply of water or grow wholly or partly submerged in water

Xerophytes: plants that are adapted to arid habitats

Question 23

Stomata arrangement

Answer 23

Submerged hydrophytes lack stomata

Xerophytes contain a greater number of stomata than other

Most angiosperms the stomata scatter

Most monocots, the stomata are arranged in rows parallel with the long axis of the leaf

Question 24

Mesophyll

Answer 24

The ground tissue of the leaf, large number of intercellular spaces and chloroplasts, stomata

Question 25

Mesophyll parenchyma

Answer 25

Palisade parenchyma: columnar tissue, long and right angle to the epidermis, 2-4 times greater than spongy surface, upper side

Spongy parenchyma: irregular in shape, lower side

Question 26

Venation

Answer 26

Netted venation: reticulate venation, Veins arranged in a branching pattern, with success of the smaller veins branching from somewhat larger veins

Parallel venation: striate venation, almost equal in size or may vary in size with larger veins alternating with smaller ones

Xylem: upper side
Phloem: lower side

Minor veins: embedded in mesophyll tissue, collect photosynthases
Major veins: large veins within leaf rib, export photosynthases

Question 27

Bundle sheath extensions

Answer 27

They connect bundle sheaths to the upper or lower epidermis, by offering mechanical support to the leaf, some conduct water from the xylem to epidermis

Question 28

C3 vs C4 grasses

Answer 28

C4: The mesophyll cells and bundle sheath cells typically form to concentric layers around the vascular bundles (Kranz anatomy), there are very large parenchyma cells that contain large chloroplasts, export photosynthases rapidly, 2-4 mesophyll cells intervene between laterally adjacent bundle sheaths

C3: The mesophyll cells and bundle sheath cells are not concentrically arranged. They consist of small chloroplast and cells appear to be empty and clear, unless thick walled sheath called the mestome sheath, more than 4 mesophyll cells intervene

Question 29

Founder cells

Answer 29

The group of cells that span the 3 layers of meristem—L1, L2, L3

Found her cells divide forming a ball just called the leaf buttress, each buttress develops into a leaf primordium, next a band of cells form the blade called marginal meristems or marginal blastozones, Lastly the central region of the primordium differentiate into the midrib or rachis

Question 30

Light and leaf development

Answer 30

Sun leaves are smaller and thicker than shade leaves that develop under low light intensity’s

The thickness of sun leaves is due to greater development of Palisade parenchyma, There also more extensive vascularly and the walls of epidermal cells are thicker

Sun and shade leaves also occurred and shrubs and in herbaceous plants

Question 31

Abscission zone

Answer 31

Separation layer: relatively short cells with poorly developed for thickening that make it structurally weak, enzymes break down cell walls in the separation layer

Protective layer: heavily suberized cells is formed, further isolating the leaves from the main body of the plant before the leaf drops.

Leaf scar: After the leaf falls, the protective layer is left with is

Question 32

Transition Region

Answer 32

Where changes take place on the type of structure found in the route to that found in the shoot

Initiated during the appearance of the procambium system in the embryo and differentiates procambium tissues in the seedling

Question 33

Homeotic mutations

Answer 33

Wrong organ in the wrong place

Question 34

Homeotic genes

Answer 34

Genes affecting floral organ identity

MADS box genes: control species of development

Question 35

ABCDE model

Answer 35

B: loss of function results in the formation of Sepas instead of petals in the second world and of carpools instead of stamens in the third whorl

C: encoded by AG, loss results in the formation of petals instead of stamens in the third whorl and loss of carpels with additional sepals and petals

D: Arabidopsis, discovered and petunia this (STK) gene is involved in all of your development and is required for the disposal of seed in the true flowers

E: SEP genes mediate interactions between the organ identity proteins