Biology 332
Spring 1996
Exam IName________________________

There were 130 possible points on the test. The maximum obtained by anyone was 104. I used 100 as the divisor to obtain your score (an additional bonus of 4 points). The average score was 70.2%. I would have liked it higher, but sometimes the first exam is an adjustment for both of us. I need to shorten the next exam, I need to lecture on photosynthesis more effectively, and some of you need to study a bit better. This exam file includes the key answers rendered in a larger green font along with point values and selected comments. Please don't be offended by the comments, the "you" in the comments is plural (y'all)...meaning anyone who had trouble with the question.

Why Study Plants?
Wake up, start your day, and tell how your life is impacted by plants...directly or indirectly. Go through your day trying to think of as many different ways plants are involved in your life. You only need to mention a fundamental "connection" once. A list might be the best way to approach this question.

One point each item above...13+ total
Glaring omissions: oxygen, ozone, latex


Cell Structure
Here is a place to strut your stuff on the structure and function of cell components. Draw a photosynthetic parenchyma cell, label each part with both name and function(s). You should not spend a lot of time drawing copies of organelles...one of each would be enough (even though more than one would be more realistic)! Most organelles (eg. chloroplast) should have two functions each (hint: internal structure might assist you in this). For functions, "protection" or "support" would be insufficient as they are way too vague...protection from what? support of what type? storage of what material? etc. Art is only a very small part of this question.

Please excuse the lack of diagram here (only a small grading component)...no time to make one. You did fairly well on this question. Only two most-expected functions are shown here...there are others possible.

Cell Wallstructural support
turgor pressure
Cell Membraneimport
export
Golgisorting
packaging
Nucleusreplication
transcription
Cytosolglycolysis
sucrose synthesis
Endoplasmic Reticulumtranslation
internal transport
MitochondrionKreb's Cycle
Electron Transport
ChloroplastCalvin Cycle
Light Reactions
VacuoleToxic Processing
Malate Storage (CAM), pigments
One point for each organelle name,
one point for each of two possible functions...27 total


Respiration
What is the basic pathway (three major components) of respiration? What are the inputs and outputs? Where do they take place?
Name of ComponentInputsOutputsLocation
GlycolysisSugar, etc.Pyruvate
ATP
NADH+ H+
Cytosol
Kreb's CyclePyruvate
Acetyl CoA
CO2
ATP
NADH + H+
Mitochondrial
Matrix
Electron Transport
Ox. Phos.
NADH + H+
O2
ATP !!
H2O
Mitochondrial
Cristae
(inner memb)

Note: not all inputs and outputs are shown, only the most critical ones!

One point each item in each cell above...others did not count...18 total
Most glaring omissions: oxygen ---> water in ETS/Ox Phos!!
Why do you breathe? Kind of important, huh!

How is this pathway controlled?

Phosphofructokinase, an enzyme in mid-Glycolysis, is allosterically up-regulated by ADP, down-regulated by ATP, and down-regulated by Citrate.

Four points total. I guess I didn't make this point well.

Make a graph showing the relationship between respiration, photosynthesis and light intensity. Write a paragraph describing its features and what they mean for culture of plants.

One point for each word-item below and one point for each line shape, 11 total
You did fairly well on this one.


Photosynthesis
Give the overall reaction for photosynthesis:

CO2 + H2O + light + chlorophyll --------> CH2O + O2

Six points total

In your reaction above, circle the components involved in the light reactions.

You should have circled:
H2O + light + chlorophyll --------> O2

Four points total

Why do you think the reaction center pigments absorb red wavelengths rather than other colors of light? Why would evolution come up with this particular arrangement?

Three points total

There is no single control step for photosynthesis (unlike that one in respiration). Why not?

Three points total...fortunately

Briefly describe the photorespiration problem.

RUBP + O2 --RUBISCO--> CO2 + NO ATP
"wastes" Calvin cycle precursor

Six points total...needs additional study

Summarize the C-4 modifications that help solve that problem.

PEP + CO2 --PEPCO--> malate ---> 3-C + CO2 to Calvin Cycle RUBISCO

This C-4 "pump" swamps out RUBISCO with CO2 so photorespiration is turned OFF.

Eight points total...some got it, most got some of it


CAM Photosynthesis
Why are CAM plants such slow growers? Why do you think evolution might have arrived at this particular adaptation? How could it possibly be competitive?

Five points total...quite good really...I was pleased!

Cell Types
Contrast the four cell types in plants:
Cell Type Namemeristematicparenchymacollenchymasclerenchyma
Distinguishing
Structure(s):
very thin wall
no vacuole
immature organelles
even thin wall
vacuole
mature organelles
uneven 1° wall
mature mitchondria
lignified 2° wall
no cytoplasm
Distinguishing
Function:
mitosisactive biochemistryplastic supportbrittle support

1 point each name, one function, each of two structures: 16 total
We'll see more of this, thank goodness!

Tissue Types
Compare and Contrast Xylem and Phloem. Why do you think evolution arrived at the particular structural design for each tissue to carry out its function? Of course you will have to tell the structure and function of each tissue as part of your answer.

This was incredibly disappointing for me.
I thought it would be a "freebie" for you.
We will see this again!

Xylem Structure: Conducting Cells are sclerenchyma (hollow tubes)
Xylem Function: Carry water and minerals from soil up plant

Phloem Structure: Conducting Cells are parenchyma (with cytoplasm)
Phloem Function: Carry water and sugar/amino acids from leaf

up to flower, fruit, apical bud
down to stem and root
Water and minerals from soil are too dilute to be cytoplasm, so must use empty "pipe" for xylem.

Need to defend sugar and amio acid transport pathway with live cells (having a defense)

Six points total


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