REVIEW: PHOTOSYNTHESIS = LIGHT + H20 + CHLOROPLAST = O2 +H+ AND ENERGY (ATP), THEN: ENERGY IS USED TO 'FIX' CARBON [CO2] INTO HYDROCARBONS, MOSTLY POLYSACCHARIDES STARCH AND CELLULOSE. (WHAT DO THESE TWO HAVE IN COMMON? [GLUCOSE] - AND HOW DO THAT DIFFER? (LINEAR VS. LINKED - BONDING - SEE FIG. 11-11, P. 362]. Also, (added 10 Sep 97) with regard to the question on Cellulose digestion in humans, it appears that we lack the required enzymes (cellulases).  These are only produced by 'hardcore' decomposing elements of the biosphere (fungi, bacteria, etc.) and mammals must evolve 'cooperative' systems (ruminants) to deal with cellulose digestion.  Rabbits have a large, pouch-like structure (cecum) that carries cellulase-producing bacteria and our G.I. tracts have a reduced cecum (with vermiform appendix), suggesting a similar set up in our phylogenetic past (vestigial), BUT herbivorious primates (Gorilla) are also (like Homo) not equipped to digest cellulose.  Since cellulose digestion is an active topic from an environmental point of view (re-cycling), there is a lot of info on this topic available on the web.  Use a web search engine, like Alta-Vista, to explore by inserting a series of words in the query box, in this case "cellulose digestion animal" will produce 49, 460 references with those most relevant to the 'set' of terms on the 1st page.  CAUTION:  web-based info comes in varying qualities - consider the source.

 
LAST TIME, TALKED ABOUT SHUNT OF 'PHOTOSYNTHATE' INTO VEGETATIVE PARTS OF THE PLANT [SHOOT, LEAVES AND ROOT]. MAN INTERVENES TO HARVEST BULBS, TAP/TUBEROUS ROOTS, TUBERS BEFORE THEY CAN BE USED BY THE PLANT.

NOW TIME TO LOOK AT THE DIRECT SHUNTING OF PHOTOSYNTHATE TO THE NEXT GENERATION TO FORM THE ANGIOSPERM EMBRYO AND ITS NUTRIENT SUPPLY - THE ENDOSPERM. UNIQUE TO FLOWERING PLANTS.
 

• What is endosperm? (triploid nutritive tissue)

• Where is endosperm found? (seed)

• Where are seeds found? (fruit)

• Where are fruits found? (flower)

• What is a flower?

 
FLOWER AS A MODIFED SHOOT - 4 FLORAL WHORLES - PHYLETIC ORIGIN OF THE STAMEN AND PISTIL (BASIC 201 APPROACH-FOCUS ON GYNOECIUM)

 
Lowermost two whorles are asexual:

 
1. CALYX - BRIEF

2. COROLLA - POLYPETALOUS/SYMPETALOUS, REGULAR/IRREGULAR (FLOWERING PLANT TRENDS). DO WE EAT PETALS? (CUCURBITA)
 
DIVERT=====to explanation:

Next two whorles are sexual - too understand these, must look at angiosperm evolution:

 
ALTERNATION OF GENERATIONS - MOSSES VS. ANGIOSPERMS - REDUCTION OF THE GAMETOPHYTE

START OF ANGIOSPERM SEX:

SPOROPHYTE (DIPLOID - MEIOSIS - MICROSPORES/MEGASPORES - MICROSPORANGIA/MEGASPORANGIA)

GAMETOPHYTE (MICRO AND MEGA)

ENDOSPORIC GAMETOPHYTE DEVELOPMENT (within spore wall)

DOUBLE FERTILIZATION/ENDOSPERM

BACK TO STRUCTURE: Fertile fern frond - sporangia producing identical spores which germinate to produce identical, photosynthetic bisexual gametophytes (homosporus) - for angiosperm, imagine:
 

• simple leaf with all sporangia combined (synangium

• reduction of the photosynthetic tissue

• all spores (produced from microspore mother cell [2n] with sporangium) will produce only a sperm-producing gametophyte reduced to 3 nuclei (1 'generative' and two sperm) and this develops within the spore wall (= pollen grain)

• each megasporangium is enclosed within two thin layers of tissue (=integuments - at maturity = seed coat or testa) which is known as the 'ovule' or - at maturity - the seed.

• The leaf that carries these 'packages' (ovules) FOLDS to join at the margins (conduplicate carpel theory) and thereby enclose the ovules (not so enclosed in the other seed-plant lineage - gymnosperms) in a 'vessel' (angiosperm = 'vessel seed', gymnosperm = 'naked seed'). This folded megasporophyll known as a carpel which matures to form an ovary (when mature = fruit). It is unique to flowering plants and the most important natural produce for our species. Angiosperm evolution has proceeded in such a way that fruits are often composed of more than one carpel fused together.

4. GYNOECIUM - WE EAT GYNOECIA - MEGASPOROPHYLL [GYMNOSPERM VS. ANGIOSPERM] TO CARPEL - SPECIALIZATION OF THE CARPEL [STIGMA (SAFFRON), STYLE, OVARY], SYNCARPY, SIMPLE PISTIL VS. COMPOUND