Exercise 5

Exercise 5Plant Cell Types and Tissues

Tissue – group of cells that perform a specific function

2 kinds of tissues (state of development):1. Meristematic tissues/ meristerms

- responsible for the production of new cells2. Permanent tissues

- perform specific functions

Kinds of meristems based on their position or location:1. Apical meristem – responsible for the increase in

length of stems or roots- at tips or apices of stems and roots- with very small or no vacuole at all- very thin-walled and isodiametric

Includes:a. Protodermb. Ground meristemc. Procambium

2. Lateral meristem3. Intercalary meristem – at bases of young

leaves and internodes

- for further lengthening of stems and leaves far away from the tips of stems

Kinds of Permanent Tissues:

1. Simple permanent tissues- consist only of one kind of cella. Epidermis – outermost tissue of leaves, stems and roots of all monocots and herbaceous dicot- has a layer of cuticle made up of waxy substance called cutin to prevent excessive evaporation of water- uniseriate when young, multiseriate when old

b. Parenchyma – uniformly thin-walled

- Function: for food storage

- Examples: cassava pith, tomato fruit pulp, Spanish flag petiole

c. Collenchyma – with unevenly thickened walls

- function: for strengthening & support and sometimes for storage

- examples: lotus petiole, celery petiole, coleus petiole

d. Sclerenchyma – with heavily thickened walls because of the presence of lignin

- function: for strengthening & support

- Examples: mungbean seed coat, peanut pericarp, pineapple leaf

e. Cork – outermost tissue of leaves and roots of woody dicot plants

- function: for protection

2. Complex Permanent Tissue

Sieve tubes Companion cellsArranged end to end Shorter, narrower, vertically

elongatedDenucleated when matured Nucleated even when matured

1. Phloem – conducts dissolved organic food materials

2. Xylem – conducts water

a. Tracheids – without perforations

b. Vessel elements – with perforations

Accessory cells – participate in osmotic changes involved in movements of the guard cells

Closed Stomata Open Stomata

Exercise 6 Absorption

1. Tap Root2. Fibrous Root

Specialized RootsSpecimen Modification & functionCamote Enlarged fleshy root for food

storage

Radish Enlarged fleshy root for food storage

Carrot Enlarged fleshy root for food storage

Rhizophora Brace roots for supportPandan Prop roots for support

*brace roots – aerial roots arising from the main stem which penetrates the ground

*prop roots – aerial roots arising from the branches which penetrate the ground

Exercise 7 Transport & Nutrition Origin of the stem: from the epicotyl and

partly from the hypocotyl of the embryo

Shoot – a stem with leaves

Shoot system – all the stems and leaves of a plant

General Features of the Stem:

1. Node – where leaves, branches & buds arise2. Internode – portion between 2 consecutive nodes3. Leaf sheath

- in some monocotyledons (Poaceae/ Gramineae/ grass family), a distinct petiole is lacking. Instead, the blade is supported by a flattened structure called the leaf sheath, which clasps the stem.

4. Petiole – or leaf stalk- holds the blade upright

5. Leaf scar – mark left on the stem by a fallen leaf

6. Bundle scar – cut end of vascular bundles seen within each leaf scar

7. Leaf axil – angle formed by the leaf stalk and the stem

8. Axillary bud – located at the leaf axil9. Terminal bud – located at the tip of the stem10. Bud scale – protective scale that covers

the bud11. Lenticels – tiny raised pores on dicot stems

for gaseous exchange

Modified Stems:Plant Specimen Modification

Fern plant, Ginger Rhizome for food storage

Gabi Corm

Potato (Solanum tuberosum)

with “eyes” = budsTuber for reproduction

Bermuda Grass Runner/StolonBougainvillea Thorn for protectionDilang-baka Cladophyll

Vine TendrilCycas Spines for protection

Exer 7 Leaf

Important Terms:1. Phyllotaxy – system of leaf arrangement on the

stem:a. Alternate or spiral – only 1 leaf develops at each

nodeb. Opposite – 2 leaves develop opposite each other

at a nodec. Whorled – 3 or more leaves develop equidistantly

around the node

2. Blade or lamina – thin, flattened, green structure

3. Leaf stalk or petiole – holds the blade upright; to provide maximum exposure

*sessile – leaf without petiole4. Stipules – a pair of outgrowths at base of

some dicotyledonous leaves*exstipulate – without stipules

Petiolule – stalk of each leaflet Stipels – outgrowths in pairs found at the

base of petiolule Rachis – continuation of the petiole

5. Nature of leaf blade

a. Simple leaf – blade consists of only 1 pieceb. Compound leaf – blade is divided into

separate segments called leaflets or pinna

6. Venation – arrangement of vein of a leaf blade

a. Netted or reticulate venation – veins branch profusely and form a network over the blade; commonly found in dicot leaves

b. Parallel venation – veins do not form a network; commonly found in monocot leaves