Download practice essays - Belle Vernon Area School District

Consider that quartz crystals have the ability to "grow" new crystal faces over time in the presence of
solutions, "reproducing" new crystals off the parent pattern. Quartz also "responds" to light by
generating a current. Since growth, reproduction and response are properties of life, why do we not
consider quartz to be "alive"?
When the unmanned Viking spacecraft was sent to land on the surface of Mars, the foremost question
was "Is there life on Mars?" Still photos and instrument readings had to be relayed back to earth as
transmissions–no real material could be returned. Now, the discovery of possible fossil bacteria in a
Mars meteorite has renewed our interest. What materials or properties would you search for with a
Mars spacecraft lander to detect and/or confirm current life on Mars? Consider the following: water,
carbon molecules, DNA, ATP, movement, and others.
Distinguish between an experimental variable, a dependent variable, and a control group.
A)You ask an auto mechanic to fix your car. It keeps stalling when you stop at stoplights. The mechanic
looks this symptom up in the car manual and it indicates that this is usually due to a dirty carburetor.
The carburetor is cleaned–but the car still stalls! Would you be happy to pay the bill at this point, and
would you consider this a "scientific method"? B)Unsuccessful at the first "cure," the mechanic thinks
through how the engine works and then decides to pull a spark plug. The gap appears to be fouled with
dirt, so all the spark plugs are replaced. The car now runs smoothly. Now would you be happy to pay,
and would you consider this a "scientific method"? Consider how the procedures followed by the
mechanic compare or contrast with the same general procedures followed by a surgeon in a medical
operation.
List and describe five properties of water that make it important in the presence of life on earth.
List those characteristics of carbon that make it the most important element in organic molecules.
Describe how DNA and RNA are both different from and similar to each other.
Describe several major differences between eukaryotic and prokaryotic cells.
Explain the endosymbiotic theory and the lines of evidence that support it.
Explain how the plasma membrane is selectively permeable, and tell how that is related to the
movement of materials across the membrane.
Describe active transport and give an example of its use in the cell.
Describe how cellular metabolism occurs within cells: what processes are involved and how do they
interact?
Explain how an enzyme works, and how a coenzyme or cofactor may be involved in an enzymatic
reaction.
Describe the effects of substrate concentration, pH, and temperature on the activity of an enzyme.