Biology 35 Ib Notes

Topics: Plant physiology, Xylem, Plant anatomy Pages: 4 (749 words) Published: January 21, 2013
BIO 35 IB Plant Science: Book 1/3

Angiospermophytes- flowering plants

One seed leaf (cotyledon)Two seed leaves
Leaf venation is parallelLeaf venation is net-like
Floral parts in multiples of 3In multiples of 4 or 5
Fibrous rootsTap root system
Vascular bundle randomly arrangedVascular bundle arranged in rings Corn, wheat, irisWater lily, violet, rose

External part of Dicotyledons:
Terminal bud - located at the tip of the shoot
-main growing point
Axillary buds – located in upper angles of leaves
-usually dormant, have potential to develop into leaf-bearers Leaf Tissue:
-Upper and Lower Epidermal ells tightly interlocked
-Waxy Cuticle acts as water barrier, conserving water
-Guard Cells (lower epidermis) controls opening and closing of stomata; allow for gas exchange -Palisade Membrane contains cholorplast; specialized for light absorption and PHOTOSYNTHESIS -Spongy Mesophyll (irregularily-shaped cells); also carries out PHOTOSYNTHESIS. Surrounded by air spaces; O2 and CO2 circulate. -Vein: xylem (water, minerals) & phloem (sugars, organic)

Meristems- sites of cell division. Cells differentiate into other plant tissues or produces bark. Apical meristems- found in buds and growing tips of roots. Begin growth of new cells in young seedlings. Lateral meristems- found in between the xylem and phloem of vascular bundles, increases thickness of roots and stems.

Apical Dominance- where one meristem prevents the growth of another meristem. As a result the plant will have one clearly defined trunk.

Mechanism of apical dominance based on the plant hormone auxin. Produced in the apical meristem, and transported by active transport towards the roots in the cambium. Regulates amount, type, and direction of plant growth. Auxin moves to shaded side to balance growth; causes cells on the shaded side of the stem to grow larger than lighted side, and plant bends toward light.

Phototropism- the...
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