Biology 332
Fall 2003

Exam 2

1. Compare the products of the two cambium layers in a dicot stem. 12-
Name of cambium? vascularcork
Cambium forms between which 2 layers? xylem/phloemepidermis/cortex
Sclerenchyma matures on which side? insideoutside
Sclerenchyma derivative is botanically called? 2° xylemcork
Sclerenchyma derivative layer commonly called? woodcork/bark
Parenchyma maturing on other side is called? 2° phloemphelloderm
2. What is produced when a fusiform initial puts a new wall in the: 3-
2° xylem/phloem transverse
ray initial radial
fusiform initial
3. The annual growth ring in a tree trunk is visualized because: 4-
large spring cells just outside
small fall cells of previous year.
4. Label the flower completely: 13-
5. Under the name for each of the four whorls above, write the collective name for the leaves of that whorl. 4-

under stamen: androecium
under petal: corolla
under carpel: gynoecium
under sepal: calyx

6. Photosynthesis: give the one-step generic reaction diagram... 6-
CO2 + H2O -------------------------> O2 + CH2O
7. Light Reactions of Photosynthesis 19-

The sunlight for the light reactions covers the entire visible spectrum from 400 to 700 nm. There are a range of antenna pigments that transfer light energy to the two reaction-center pigments: P680 and P700 . The numbers in these names indicate maximal light absorption of the color: red . This is why wavelengths longer than 700 nm cannot drive photosynthesis at all. The reaction center pigment P680 loses electrons to an electron transport chain and this provides the energy required to split H2O and produce the molecule: O2 (thanks plants!). The electrons flow through an electron transport system that has carriers with the metallic cofactors: Fe and Cu . Some of these carriers transport the H ion from the stroma into the thylakoid lumen . As these ions leak back across the membrane, they pass through an ATPsynthase which produces the high-energy molecule ATP . As the energy of this molecule is held in a phosphate-phosphate bond, the process coupled to electron transport is called photophosphorylation . Ultimately the electrons and protons end up being trapped onto the B-vitamin: NADP .

8. Calvin Cycle 20-

The Calvin Cycle is traditionally named the dark reactions, but this is quite misleading. The Calvin Cycle requires both ATP and NADPH from the light reactions; so the Calvin Cycle can only operate in the light. The Calvin Cycle uses the enzyme: Rubisco to pull CO2 from the atmosphere. In a series of steps, ultimately a 3 -carbon molecule can be used to make a range of biomolecule products. When two of these are fused, the traditionally-described product: glucose is synthesized. Two of these hexoses can be joined to make the disaccharide: sucrose which is transported through the phloem/sieve cells to the rest of the plant. One of the problems with the Calvin Cycle is the fact that its first enzyme must take its substrate from the atmosphere. The atmosphere has the structurally-similar molecule: O2 in great abundance. As the enzyme cannot distinguish these two molecules, there is a competing pathway called: photorespiration which releases carbon dioxide but makes no ATP. This greatly reduces the efficiency of the Calvin Cycle. The C4 plants have evolved the enzyme: PEPcarboxylase which uses the dissolved substrate: HCO3- rather than an atmospheric one. As oxygen is insoluble in water, the enzyme is far more efficient. In typical plants of this type, the efficient enzyme is found in mesophyll cells while the Calvin Cycle operates in bundle sheath cells. In another group of plants called CAM plants, the efficient enzyme operates during the night while the Calvin Cycle operates during the day .

9. Produce a cladogram from the following dataset for plants found growing in a jungle: 23-
taxon 123456789
zilcho 000000000
marko 100000000
aleppo 110000000
hippo 111000000
sinko 111111100
drinko 111111001
mucho 111111010

The taxon, zilcho, is properly called a(n) outgroup for the rest of the taxa.
The characters 7, 8, and 9, are properly called autapomorphies .
The characters 4, 5, and 6 are properly called synapomorphies for the taxa: sinko, drinko, and mucho.
The character state of 0 is called plesiomorphic while 1 is called apomorphic .
Now that you are done with the cladogram, add the following fossils to your cladogram that a geologist colleague found in some deep strata. Be sure to put them in the right place! You might need to organize your cladogram a bit to fit it all in a consistent way.

taxon 123456789
fosso 111010000
rocko 111011000


10. Tell me just a little bit more about each of these cyanobacterial structures. 14-
Cell Wallpeptidoglycan-murein
Cell Membraneglycolipid and sulpholipid too
MesosomesETS and light reactions
Phycobilisomesaccessory pigments-phycoerythrin-phycocyanin
Nucleoidnaked, circular DNA
Starchcyanophycean, stored energy
Polyhedral BodiesRubisco crystals
Cyanophycinstorage protein-N storage
PolyphosphatePO4 storage
Lipid Dropletfat energy storage
Gas Vacuolebuoyancy in water column
HeterocystN2 Fixation
11. In the space below diagram a typical sporic life cycle. 12-