110 possible, 107 maximum, 86 average

Biology 332
Spring 2000

Exam 1

Name_________________________

This test has two design criteria:

1. to test your knowledge of basic biology concepts (from prerequisites for this course) and
2. to check how well you are learning concepts in the first few weeks of this course.

What is science? Give a brief definition. 2 pt.

a methodical approach to the
acquisition of knowledge

Use all seven steps of the scientific method in sequence to determine whether the cells of a moss gametophyte "leaf" produce starch as a product of photosynthesis. Name the steps and what you would do/see in each one! 21 pt.
Name of StepWhat you Do
Observation Look critically and measure with the metric system. In this case, check out the cell structure of moss "leaf" cells, notice chloroplasts
Question Be curious and ask questions. In this case"Do moss 'leaf' cells produce starch as a product of photosynthesis?"
Hypothesis Make an educated guess. Since reading indicates true plants store photosynthate in the form of starch, H="Moss 'leaf' cells produce starch as a product of photosynthesis!"
Prediction If our hypothesis is true, then we should observe some change in a dependent variable when we manipulate the independent variable. In this case, we should observe more black specks in the chloroplasts after photosynthesis when we treat with iodine.
Experiment Our manipulation would be a light treatment (for photosynthesis) so our control will be darkness (for lack of photosynthesis). For several hours put the manipulated moss in reasonably bright light...keep the control moss in darkness. After incubation, wet-mount 10 leaves of each moss in iodine stain and wait 3 minutes. Microscopically observe and score 10 randomly-selected chloroplasts in different cells by counting black specks in each chloroplast.
Analysis Calculate average speck counts and perform a student's t-test. Allow 5% for error due to chance alone.
Decision If p<0.05 then differences are significant. If we find significantly more black specks in light-treated 'leaves' than untreated 'leaves' we cannot reject our hypothesis (but we can reject the null hypothesis).

What is Biology? Give a brief definition. 2 pt

The Study of Life (see below)

What are some fundamentally-different properties of life? 6 pt
Cell StructureGrowthMovement
metabolismReproductionResponsiveness

Evolution often Missed as shown Above!

Make a list of "typical" (parenchyma) plant cell structures and their primary function: 24 pt

StructureIts Primary Function
Middle Lamella Glues cells together
Cell Wall Allows turgor development for support
Cell Membrane Involved in import/export
Cytosol Glycolysis, etc.
Nucleus Transcription, Replication
Endoplasmic Reticulum Internal Transport for Cell
Ribosome Translation (Protein Synthesis)
Golgi Apparatus Sorting and Packaging for Export
Mitochondrion Kreb's Cycle and Oxidative Phosphorylation
Chloroplast Photosynthesis
Vacuole Toxic waste processing
Vesicle Import/Export Package

Other possibilitites: peroxysomes, glyoxysomes, plasmodesmata, microtubules, microfilaments, etc.

Below tell how the structures of a meristematic cell would be different from the structures in the parenchyma cell. 4 pt

1. The cell wall would be thinner
2. There would be no mature plastids
3. The vacuole would be very small, if present at all
4. The cell would be much smaller in total volume
5. A spindle apparatus might be visible as eventually would be stages of mitosis (PMAT)

Write around the clock!
Describe the various phases/stages of the cell cycle...in sequence! 24 pt

Phase/StageWhat happens
G1 Interphaseall normal biochemical functions except replication
S Interphasetranscription is halted as nucleus accomplishes genome replication; all other normal biochemical functions continue; translation continues using pre-formed mRNA
G2 Interphaseall normal biochemical functions except replication.
Note: in meristematic cells that cycle, this includes preparations for mitosis...but many "mature" cells do NOT do this as they are "frozen" in G1 or G2.
Prophase of mitosischromosomes condense out of chromatin, nuclear envelope disappears, nucleolus disappears
Metaphase of mitosisspindle apparatus forms, spindle fibers attach to centromeres and push chromosomes to equatorial plane
Anaphase of mitosiscell elongates, spindle fibers shorten, centromeres break down, sister chromatids are pulled to opposite poles
Telophase of mitosisnuclear envelope reforms, chromosomes decondense into chromatin, nucleolus reappears, spindle apparatus disappears
Cytokinesiscytoplasm is divided into two cells by formation of a phragmoplast at the equatorial plane, the developing wall is sometimes called a cell plate, remaining perforations are called plasmodesmata; sometimes cytokinesis is not at equatorial plane; process is fundamentally different in animals and fungi

What is a seed? Name its three fundamental parts. 3 pt

seed coatdormant embryostorage tissue

Compare and contrast the three parts of a corn (Zea mays) and a bean (Phaseolus vulgaris) seed. 12 pt

CornBean
Seed Coat: is inside a fruit, so no hilum or micropyle visible; instead scar for style attachment visible Seed Coat: is true seed, so hilum and micropyle are both visible
Embryo: is a monocot so has only one seed leaf, radicle with coleorhiza sheath, epicotyl with coleoptile sheath Embryo: is a dicot so has two seed leaves, radicle and epicotyl lack any kind of sheath
Storage: starch mostly in endosperm tissue Storage: starch mostly in cotyledon tissue

How can you... 12 pt

detect the presence of mitochondrial activity in a seed? Treatment: stain with methylene blue
Look for: tiny blue organelles in cytosol
detect the presence of starch in a seed? Treatment: stain with iodine solution
Look for: blue/black grains in cytosol
detect the presence of lignin in a cell? Treatment: stain with toluidine blue
Look for: cyan stain in the secondary wall
or
Treatment: stain with phloroglucinol/HCl
Look for: red stain in the secondary wall
detect the presence of oil in a seed? Treatment: stain with sudan IV
Look for: oil droplets picking up intense red color
decrease the turgor pressure in a cell? Treatment: mount in hypertonic salt solution
Look for: plasmolysis (cell membrane pulling away from cell wall)
determine where growth occurs in a portion of a young plant? Treatment: mark tissue at intervals with indelible marker (Sharpie)
Look for: changes in spacing of marks



This page © Ross E. Koning 1994.

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Koning, Ross E. "Exam 1 2000". Plant Physiology Website. 1994. http://koning.ecsu.ctstateu.edu/plant_biology/ex1.00.html (your visit date).

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