life science & physical science final quiz

ANATOMY OF MUSCLES

Muscles are made of bundles of cells wrapped in connective tissue called fascicles. Each bundle contains many cylindrical muscle cells or muscle fibers. Like other cells, muscle fibers have mitochondria that provide energy, a plasma membrane that separates the inside and outside of the cell, and endoplasmic reticulum, where proteins are made. However, muscle cells are different from other cells in several ways. First, muscle cells have more than one nucleus. Second, the muscle cell’s plasma membrane surrounds bundles of cylindrical myofibrils that contain protein filaments and regularly folds into the deep parts of the fiber to form a transverse tubule or T-tubule. Third, the muscle cell’s endoplasmic reticulum is called sarcoplasmic reticulum; it is regularly structured, envelops the myofibrils, and ends near the T-tubule in sacs called terminal cisternae.

According to the passage, what is the shape of a muscle cell?

• a. sphere

• b. cylinder

• c. disc

• d. cube

Which is a difference between a muscle cell and another type of cell?

• a. Only muscle cells have mitochondria.

• b. The plasma membrane separates the inside from the outside of the cell.

• c. Muscle cells have more than one nucleus.

• d. Muscle cells do not have endoplasmic reticulum.

Oxygen is a very corrosive substance and will combine with many other substances or oxidize other substances. A common example is that of a piece of iron left out in the air. Over time, the iron rusts. The rust is a chemical change and can be described by a chemical reaction. Four atoms of solid iron (Fe) combine with three molecules of gaseous oxygen (O2) from the air to form two molecules of solid iron oxide (Fe2O3). The chemical reaction can be written by this chemical equation: 4Fe(s) + 3O2(g) q 2Fe2O3(s) This class of chemical reaction is called a combination reaction.

Using the information presented in the passage, write each substance’s symbol.

Fe₂O₃

Fe

O₂

_{iron. oxygen, iron oxide}

Notice that the concentrations of hydrogen ions correspond to values of pH. If a chemist measures a solution with a pH value of 9, what is the hydrogen ion concentration? 1 c. mole per liter 9 d. 9.0 moles per liter

• 10⁻⁹ moles per liter

• 10⁹ moles per liter

• mole per liter 1/9

• 9.0 moles per liter

From the arrow on the left, notice that acidic substances have pH values less than 7, while basic substances have pH values greater than 7. If a chemist measures that a solution has a pH value of 5.5, this indicates the solution is

• acidic

• alkaline

• neutral

• none

In this diagram, what is the name of the process that moves water directly from bodies of water into the atmosphere? __________

Which way does water move during infiltration?

• from air into the ground

• from ground up to the surface

• from surface down into the ground

• from surface into the air

Suppose that you are a chemical engineer and must make a facility that will produce large amounts of ammonia using the Haber process. The best conditions to produce the greatest percent yield of ammonia would be: __________ atm at _________°C.

• 400 atm at 350°C

• 100 atm at 550°C

• 400°C at 350 atm

• 550 atm at 100°C

Katy always buys bread with preservatives so that it will last longer. She wants to know if the preservatives really do make a difference in slowing the growth of mold on bread. She conducts the following experiment:

1. Obtains one slice of bread containing preservatives and one slice of bread without any preservatives.

2. Dampens two paper towels.

3. Places each paper towel inside a separate zip-top plastic bag.

4. Places one slice of bread in each bag, seals the bags, and labels the bags.

5. Puts the bags in a dark, temperature controlled environment for one week.

6. Records the mold growth once a day for one week.

What is the most likely hypothesis for Katy’s experiment?

• If bread is damp, then it will grow mold faster than dry bread.

• If bread is placed in a cool, dark environment, then it will stay preserved longer.

• If bread with preservatives is placed in plastic, then it will resist mold for more than one week

• If bread has preservatives, it will grow mold more slowly than bread without preservatives.

Katy always buys bread with preservatives so that it will last longer. She wants to know if the preservatives really do make a difference in slowing the growth of mold on bread. She conducts the following experiment:

1. Obtains one slice of bread containing preservatives and one slice of bread without any preservatives.

2. Dampens two paper towels.

3. Places each paper towel inside a separate zip-top plastic bag.

4. Places one slice of bread in each bag, seals the bags, and labels the bags.

5. Puts the bags in a dark, temperature controlled environment for one week.

6. Records the mold growth once a day for one week.

Which is the dependent variable in Katy’s experiment?

• time

• moisture

• mold growth

• bread with preservatives