Transcript Document

Included here are a series of questions used on previous Biology
EOCs. They have been “retired” for use as sample “practice” questions.
It is important to keep in mind this is NOT about memorizing
the answers to these questions (wouldn’t do you any good if
you did since they’re retired) but rather…
--get a “feel” for the format
--consider the topics (what biological concepts are
they addressing?)
--for the extended-response questions, it often isn’t
as much biological concept as it may be a
scientific approach to problem solving
Hope you find this useful…(feedback is welcome!!)
Hint…use the up/down arrow keys to navigate this power pt.
Question #1 is about (duh) feedback loops. Considered part of your knowledge
of “Systems”, this stand-alone question (not part of a scenario) is really asking,
“do you know the definition of positive (and negative) feedback loops?” Big
picture? Complex systems must have ways of reinforcing and/or balancing their
flows of matter and energy and you need to be able to express your competence
of such things. This is also the type of question that frankly, is a test of your
vocab as well. For example, you may have heard of positive feedback loops as
reinforcing loops while negative are often referred to as balancing feedback.
In other words, as you get more of A, you then get more of B too. Get it? The
loop is reinforced…called positive because you get more and more and more…
Whereas if getting more of A meant you would get less of B, the feedback brings
balance…the more being balanced by its opposite. Let’s use an example from
a lab you did recently.
As you may (or may not) recall, you dropped alka seltzer tablets into a couple
test tubes (CH 11, Carbon Lab #3) which generated CO2 gas. That gas
can easily turn right around and react with the water in the test tube
forming carbonic acid. Your results showed the acid-tube generated
more gas (finger height) than the water-tube (red arrow). That means
the now-acidic-tube will generate an even GREATER amount of gas…
ANSWER
which will, in turn, react with the solution making it even more acidic
which will, of course, generate even greater quantities of CO . Like a
Sweating is your body’s attempt to lower body temperature. 2
vicious circle…a
As the amt of sweat INCREASES, body temp DECREASES
snowball rolling
This is your body’s attempt to re-achieve BALANCE
downhill, gathering
A POSITIVE
ever-greater amounts
FEEDBACK
A balancing loop…NEGATIVE
FEEDBACK
of snow!
LOOP
An example of a negative?
Consider your iTunes library
and an iTunes gift card. As you
increase the # of songs in your
library, the amount on the
card is reduced. As your $$ goes
down and down, the size
of your library grows….& grows.
Here’s another example of a FEEDBACK LOOP-type question…
NEGATIVE (“balancing loop”) = as A increases B decreases
(or vice versa)
Choice C…adding insulin increases the amt of glucose…would be a reinforcing loop
or POSITIVE feedback…only choice…
…D… “balances” high levels of one by decreasing the other
Question #2 addresses your knowledge of the major chemical cycles on earth.
There’s the WATER cycle, the CARBON cycle, the OXYGEN cycle, and the NITROGEN
cycle (to name a few). Considering the fact that nearly 80% of earth’s atmosphere
is NITROGEN, yet exists in a form NOT USABLE by most life forms, and yet is a
fundamental element in ALL life forms (it’s the reason amino acids are literally
called AMINO!!), this is a question assessing whether or not you’ve learned of
the existence of (and dependence of life on) what are called “nitrogen-fixing”
bacteria (like those commonly found in root nodules of pea plants).
The next four Questions #3-6 are an example of scenario-based questions. While
You can obviously approach these by whatever means suits you best, many folks
that are uniquely-successful find the following technique most productive…
--skip over the scenario
--go straight to the questions
--read each question so you get an idea of the specific kinds of things they are
looking for (allows for a more “focused” read of the scenario)
--go back and read the scenario, keeping the questions in mind
Go ahead…give this method a try. I’ll wait (I’m not going anywhere ;-)
…use the up/down arrow keys to skip ahead/back
DON’T READ THIS UNTIL YOU’VE SKIPPED AHEAD AND BACK
…as you can see, questions 3 and 5 (the two multiple choice questions) really
have NOTHING to do with the scenario!! They are there to assess
your knowledge of experimental design (and if you are one of MY
students, you are THE BOSS when it comes to addressing RELIABILITY
and VALIDITY of experimental designs!!).
…questions #4 & #6 are extended response items which will take a little
explaining. Now, skip to the answers…
STOP. GO NO FURTHER UNTIL YOU’VE SKIPPED FORWARD/BACK LIKE IT SAYS ON
SLIDE #8. Good-to-go? Then let’s tackle 3 & 5 first…
RE
RE
Even if you totally forgot that
liability involves
peated trials*, look closer
at the options. Choices A, C, and D ALL involve CHANGES (“other acidities”, “increase
the volume”, and “use a different”)…only B keeps all conditions…
*the same.
Question 5 involves good ol…
As a veteran of LoomDog’s class you know full-well there are several ways to
increase the validity of an experimental design. In addition to a Peer Review,
running an experimental control group, and having LOTS of controlled variables,
only choice D is a step that will reduce the impact of human error/variance.
Choices B & C both involve RELIABILITY (multiple trials) and choice A…really?
Here’s another past-EOC question of similar style, but tied to a scenario about taking
a survey of salmonberry plants in/around a forest. The field study involves sampling
3 types of habitat using three 5-by-5m plots .
Like another Controlled Variable
No impact whatsoever
Smaller!? plots…nope
4 instead of 3? More reliable
An example of a 2-pt, extended response question is Question #4: Write a Conclusion
Best advice here…DOUBLE CHECK to make CERTAIN you answered EVERY BULLET!!!
Lucky for you, as a Tahoma sophomore, you are already quite familiar with the
first 2 bullets… “According to the data the hypothesis is…” AND BACK IT UP WITH
DATA!!!!
Let’s examine each bullet…
The prediction was supported by the data, as the pH
IMPORTANT: INcreased, the amt of foam also INcreased…to a point. The
Use AVERAGES AVERAGE amt of foam increased from 24ml to 35ml between
pH 6 and 7 then another 7ml between pH 7 & 8 BUT THEN it
if possible &
dropped an AVERAGE of 12ml between pH 8 and 9.
include both
Enzyme function is impacted by pH. In the case of
MAX & MIN
catalase, it appears to function best (judging by maximum foam
(range)
production) in a mild base (pH 8). It’s effectiveness drops
sharply in acidic solutions (below 7.0) and again in bases
stronger than 8.0 Acids impair the function of catalase
(destroy its chemical structure) as do strong bases. Potato
cells must have a slightly basic pH.
Question 6 is another 2-point extended response item: design a follow-up experiment
Again…PAY ATTENTION TO THE BULLETS!!!
In this example, rather than pH (MV) vs amt of foam (RV) you are tasked with a
Manipulated Variable (MV) of…
…and a responding variable (RV) of…
Let’s take a look at several possible responses…
…I don’t know where to start …the bullets?
0 controlled variables, 1 MV but only two “levels” (hot?
and unheated?), 1 RV (but how do you???), ignored
the last bullet, and this is not “logical” because no one
could repeat these steps with reliable results
SCORE = ZERO
Better…but still…
2 controlled variables (steps 1 & 3)
1 MV and three “levels” (34, rm temp, and 89)
1 RV (but again how do you measure “bubble data”?)
Again, the last bullet is ignored, no repeated trials
and this is not “logical enough”
SCORE = ONE PT
SCORE = ONE PT
Getting better…
Only 1 controlled variable (1 drop of peroxide) 
1 MV and three (weak) “levels” (fridge, rm, m-wave?)
1 RV …FINALLY!, something measurable, the last bullet
is included, AND repeated trials! But measurements
not recorded. However, steps ARE logical enough…
SCORE =
TWO PTs
2 controlled variables (steps 1, 2, & 3)
1 MV, 3 evenly-spaced “levels” (72, 82, and 92)
1 RV and last bullet (Step 4), enough detail to be
logical, reliable, and even a “validity measure” (using
SAME thermometer)
Here’s a few more “stand-alone” type questions…
Release? NO…consume? yep
Respiration yes but…not burning gasoline
Photosynthesis??
Respiration and fossil fuels…can you say “CH 11!!!?” ...hmmmm….respiration…
…glucose + oxygen  carbon dioxide + water…in order to generate energy (in
the form of ATP)
and burning fossil fuels…hmmmm….
…carbon compound (fossil fuels) + oxygen(burning)  carbon dioxide + water
Again…this isn’t about memorizing answers…it’s about getting a feel for both the style
as well as the “topics” (which you should feel good about)
or
ANY
species
As you can see, genetics figures prominently…these concepts were from “CH 7”…
Above…while mutation can increase genetic variation, the EPIC generator of diversity has
always been SEX (mixing of genes to get new/unique combinations)
And below…from that salmonberry scenario again (irrelevant)…this is remembering the
difference between MEIosis and MITosis. If it were asking for the former then you’d want
to respond that the GAMETES (pollen/ova) would have HALF (the diploid #) or 7 but since
it’s all about a non-reproductive structure (a leaf) and it’s MITOSIS (like cloning) you’d say…
Unsure why they specified “nonnative” plants…read it this way…
That’d be a neat trick
Huh? Glucose, not ash
You should IMMEDIATELY recognize (throw out) choice D… evolution-by-intent* is one
of those GROSS misunderstandings among people that “don’t get evolution.”
*something mutates to get what it wants/needs
From CH 14…a “niche”…a collection of factors that define the living space of a species
After a forest fire a lot of previously-claimed living space is suddenly “up for grabs”
(whether you’re a native species or not!)
Speaking of habitats…
As you’ve been learning in CH 16, “There are no such things as PERFECT solutions…there
are ALWAYS unintended consequences.”
In this question, “adding butterfly habitat” (structures providing biotic/abiotic needs for
butterflies) can mean many things, none of which (that I can see) would impact either
B or D of an entire ecosystem! Along those same lines would lie choice A…how would
adding say, a netting?, remove nutrients? (caterpillars need trees but adding trees won’t
REMOVE nutrients) But Choice C…
Whatever structure is added, no matter how small or seemingly insignificant, WILL
introduce something “new.”