Natural Science

Question 1

Salinity is a measure of dissolved solids in water. On average, 1,000 g of typical sea water contains 35 g of salt. The level of salinity is below average in areas where large amounts of fresh water enter the ocean and above average in hot, arid climates. The Mediterranean and the Red seas are adjacent to deserts. The water in these two seas would be expected to have

Answer 1

above-average salinity - The desert areas increase evaporation of the water that is present, causing a concentration of salts.

Question 2

Cold-blooded animals with bony skeletons, webbed feet, and separate sexes

Answer 2

Amphibia

Question 3

Cold-blooded animals with horny scales and a bony skeleton that lay eggs

Answer 3

Reptilia

Question 4

Cartilaginous fish

Answer 4

Chondrichthyes are fish with a cartilaginous endoskeleton, a two chambered heart, between five and seven gill pairs, no swim bladder or lung, and internal fertilization (sharks, rays, etc).

Question 5

Warm-blooded animals, mostly with wings, that lay eggs

Answer 5

Aves includes warm-blooded (endothermic) birds having a spindle shaped body (with head, neck, trunk, and tail), a long neck, paired limbs, wings for flying, a four-toed foot, feathers, leg scales, a bony skeleton, bones with air cavities, a beak, no teeth, and a well-developed nervous system. Aves also have a four-chambered heart, lungs with thin air sacs, separate sexes, and lay eggs with a hard calcified shell (birds—ducks, sparrows, etc.).

Question 6

Animals with a hairy body and highly developed brain that have live births (in most cases) and produce milk

Answer 6

Mammalia includes warm-blooded animals with hairy bodies, glands (sweat, scent, sebaceous, mammary), teeth, eyelids, four limbs (usually), external fleshy ears, a four-chambered heart, lungs, a larynx and a highly developed brain. They fertilize internally, give birth to live young (except monotremes), and produce milk (cows, humans, platypus, apes, etc.).

Question 7

Communication channel between the cytoplasm and nucleoplasm

Answer 7

Nuclear pores are holes in the nuclear membrane where the double nuclear membrane fuses together, forming a break or hole, allowing the selective intake and excretion of molecules to or from the nucleus. Thus, nuclear pores are the channel of communication between the cytoplasm and the nucleoplasm.

Question 8

Extensions that provide extra surface area for absorption

Answer 8

Microvilli are filaments that extend from the cell membrane, particularly in cells that are involved in absorption (such as in the intestine). These filaments increase the surface area of the cell membrane, thus increasing the area available to absorb nutrients.

Question 9

Packets that carry substances (hormones, fats, etc.) synthesized within the cell

Answer 9

Secretory vesicles are packets of material packaged by either the Golgi apparatus or the endoplasmic reticulum. The secretory vesicle carries the substance produced within the cell to the cell membrane. The vesicle membrane fuses with the cell membrane, allowing the substance to escape the cell.

Question 10

Network of membranes that deliver lipids and proteins throughout the cytoplasm

Answer 10

Smooth endoplasmic reticulum is a network of continuous membranous channels that connect the cell membrane with the nuclear membrane and is responsible for the delivery of lipids and proteins to certain areas within the cytoplasm. Smooth endoplasmic reticulum lacks attached ribosomes.

Question 11

Atoms are held together with network covalent attraction.

Answer 11

Silicon carbide (SiC) is held together with network covalent bonds, which creates a crystal entirely from covalent bonds and confers unusual strength (and a high melting point) upon the crystal.

Question 12

Atoms are held together with covalent attraction.

Answer 12

HC2H3O2

Acetic acid is a molecular compound that is held together with covalent bonds, in which electrons are shared between atoms, so that both atoms in the bond end up having a full octet of electrons.

Question 13

Atoms are held together with metallic attraction.

Answer 13

Cu

As a metal, copper is held together by metallic bonds, which involve delocalized d-orbital electrons.

Question 14

Bryophytes

Answer 14

Nonvascular plants are known as bryophytes (mosses). They lack tissue that will conduct water or food.

Question 15

Flowering plants

Answer 15

Angiosperms are those plants that produce flowers as reproductive organs.

Question 16

Shoots and roots

Answer 16

Angiosperms (flowering plants) have two main systems—the shoot system, which is mainly above ground, and the root system below ground.

Question 17

Produce seeds without flowers

Answer 17

Gymnosperms produce seeds without flowers.

Question 18

Conifers and cycads

Answer 18

Gymnosperms produce seeds without flowers, which include conifers (cone-bearers) and cycads.

Question 19

An athlete with a sore shoulder places a warm compress on it to transfer energy to soothe the muscle.

Answer 19

Conduction is the transfer of molecules by collisions, passing heat through one material into another.

Question 20

On a cold February morning, a blower system in a car warms up after several minutes and blows air through vents in the floor, dashboard, and windshield. Eventually, the driver is able to unbutton his coat and stay warm when the outside temperature is still 23ºF.

Answer 20

Convection is caused by the flow of heated liquid or gas through a volumetric medium.

Question 21

Getting ready for a fall cruise inspires a young lady to spend a couple of weeks going to a local spa and reclining under a tanning lamp. However, such practices might result in dangerous overexposure to ultraviolet rays that can lead to cancer or premature aging of the skin.

Answer 21

Radiation is waves traveling through space to transfer heat away from the energy source.

Question 22

This substance is a very strong oxidizing agent.

Answer 22

KMnO4

The manganese ion in potassium permanganate has a +5 oxidation state, and is therefore readily reduced. When it is reduced, it forces another species to be oxidized. Therefore, the permanganate ion is a very strong oxidizing agent.

Question 23

The metal in this substance has an oxidation number of +2.

Answer 23

MgO

The magnesium atom that is combined with oxygen has a +2 oxidation state. Oxygen carries a –2 oxidation state, and the sum of the oxidation states of oxygen and magnesium must total the charge on the compound, which is 0.

Question 24

The oxidation potential of this substance is zero.

Answer 24

H2

Hydrogen gas by definition, since it is a standard, has an oxidation potential of 0.

Question 25

Exponential population growth curve; population growth accelerates

Answer 25

One of the modes of population growth is represented by the exponential curve (or J-curve). The rate of growth accelerates over time since there are no limiters of growth.

Question 26

Birth rate minus death rate

Answer 26

Population rate of growth - The rate of increase within a population is represented by the birth rate minus the death rate.

Question 27

Death rate

Answer 27

Mortality is the death rate within a population.

Question 28

Birth rate

Answer 28

Natality is the birth rate within a population.

Question 29

Logistic population growth curve; population growth accelerates and then slows down because of limits

Answer 29

Another mode of population growth is represented by the logistic curve (or S-curve) for populations that encounter limiting factors in which acceleration occurs up to a point and then slows down.

Question 30

The evolution of plant species is considered to have begun with

Answer 30

The evolution of plant species is considered to have begun with aerobic prokaryotic cells.

Question 31

What type of a wave is a sound wave?

Answer 31

A sound wave is a compression or longitudinal wave, which means that it compresses and rarefies as it moves through a medium. Transverse waves oscillate up and down as they move through a medium. The other three terms are not commonly used to label sound waves.

Question 32

The discoveries of Galileo Galilei (1564–1642) and Isaac Newton (1642– 1727) precipitated the scientific revolution of the seventeenth century. Stressing the use of detailed measurements during experimentation enabled them to frame several universal laws of nature and to overthrow many of Aristotle’s (384–322 B.C.E.) erroneous ideas about motion, which were based on sheer reasoning alone. One of these universal laws is now known as the law of inertia or Newton’s first law of motion. According to this law, objects in motion tend to stay in motion and objects at rest tend to stay at rest unless acted upon by an external force. The more mass (inertia) an object has, the more resistance it offers to changes in its state of motion. According to the law of inertia, which of the following would offer the greatest resistance to a change in its motion?

Answer 32

A large watermelon

The property of an object that determines the object’s resistance to motion is its mass. A large watermelon has a far greater mass than the pellet of lead shot, the golf ball, the feather, or the sheet of notebook paper. The mass of an object never changes. Its mass is equal to the object’s weight divided by the acceleration due to gravity (g) at its current position in space.

Question 33

The site of transfer for nutrients, water, and waste between a mammalian mother and embryo is the

Answer 33

The placenta is the connection between the mother and embryo; it is the site of transfer for nutrients, water, and waste between them.

Question 34

The process of genetic inheritance was first investigated and explained by

Answer 34

Gregor Mendel studied the relationships between traits expressed in parents and offspring, and the genes that caused the traits to be expressed.

Question 35

The first cells to evolve on Earth were most likely NOT

Answer 35

Specialized

The first cells to evolve were most likely unspecialized. Since the Earth’s atmosphere was most likely lacking in oxygen, it is presumed that preplant cells were also anaerobic. Early cells were also small, aquatic, and prokaryotic.

Question 36

Which of the following best represents the sequence of human evolution?

Answer 36

Australopithecus afarensis, Homo erectus, Cro-Magnon, Modern man

Question 37

Which of the following demonstrates pi bonding?

Answer 37

C2H2

Acetylene shows a triple bond between the two carbons, which contains two pi bonds. In multiple bonds, the first bond is a sigma bond, in which electrons are shared along the internuclear axis. Any additional bonding is created by the sideways overlap of unhybridized p-orbitals above and below the internuclear axis. None of the other options for answers contain multiple covalent bonds between any two atoms.

Question 38

The Sun crosses the celestial equator going north on March 21. This is known as the

Answer 38

Spring Equinox

Equinoxes are described as the two points on the celestial sphere where the ecliptic crosses the celestial equator. Since the crossing occurs on March 21 in this question, it is the spring equinox. Solstices occur in the summer and winter, and correspond to the ecliptic being farthest from the celestial equator. In general, when this crossing occurs on March 21, the Moon is not necessarily aligned with the Earth and the Sun, so the odds of an eclipse occurring are very low. The autumnal equinox occurs at the other end of the celestial sphere on September 22.

Question 39

Cells of eukaryotes have all of the following EXCEPT

Answer 39

DNA floating free in the cytoplasm

The DNA of eukaryotes is organized into chromosomes within the nucleus.

Question 40

A small non-protein molecule such as iron that works with enzymes to promote catalysis is known as

Answer 40

An inorganic cofactor

Inorganic cofactors are small non-protein molecules that promote proper enzyme catalysis. These molecules may bind to the active site or to the substrate itself. The most common inorganic cofactors are metallic atoms such as iron, copper, and zinc.

Question 41

Which of the following will NOT inhibit enzymatic reactions?

Answer 41

Large amount of enzyme - Environmental conditions such as heat or acidity inhibit enzymatic reactions by changing the shape of the active site and rendering the enzyme ineffective. Certain chemicals inhibit enzymatic reactions by changing the shape of the enzyme’s active site. If there is a lack of substrate, the enzyme will have no substance to affect. Thus, a large amount of enzyme is the only factor that will not inhibit enzymatic reactions.

Question 42

Ketone

Answer 42

R-C-R
=
O

A ketone group has a double bond between oxygen and a carbon atom that is imbedded within a carbon chain.

Question 43

Alcohol

Answer 43

H
    -
R-C-OH
    -
   H

An alcohol group has a hydroxide group (OH) with the second bond from oxygen going to a carbon atom.

Question 44

Ester

Answer 44

H
            -
R-C-O-C-R
    =      -
    O     H

An ester group is an ether with an additional double bond to an oxygen from an adjacent carbon.

Question 45

Aldehyde

Answer 45

R-C-H
=
O

An aldehyde group has a double bond between an oxygen atom and a carbon that is one end of a carbon chain, or not otherwise bonded to any other carbons.

Question 46

The conversion of light energy into chemical energy is accomplished by

Answer 46

Photosynthesis

The process of photosynthesis is the crucial reaction that converts the light energy of the Sun into chemical energy that is usable by living things.

Question 47

Which of the following terms is defined as the increase in the statistical disorder of a physical system?

Answer 47

Entropy

Entropy is defined as the new state variable that describes the increase of disorder in a system. Stated positively, it describes the amount of increase in the statistical disorder of a physical system.

Question 48

Which of the following evolutionary developments is out of sequence?

Answer 48

The process of photosynthesis was developed within single cells.

The development of photosynthetic cells took place before the development of eukaryotes. The first photosynthetic cells were prokaryotic.

Question 49

Energy flows through the food chain from

Answer 49

from producers to consumers and on to decomposers

Energy flows through the entire ecosystem in one direction—from producers to consumers and on to decomposers through the food chain.

Question 50

If the Moon completely covers the sun as seen by an earthbound observer, there is a

Answer 50

Total solar eclipse

The eclipse must be a solar eclipse because the Moon is between the Earth and the Sun. The solar eclipse is total because the Moon’s disk covers the Sun from our view completely. Parallax has to do with the apparent displacement of a celestial object.

Question 51

The projection of the Earth’s axis on the sky is the

Answer 51

celestial poles

The celestial poles are extensions of Earth’s north and south geographic poles up into the sky. The celestial equator identifies the projection of Earth’s equator. The zenith is the point directly overhead above an observer. The ecliptic is the line that describes the Sun’s orbit across the celestial sphere. The zodiac is the name for the annual cycle of twelve stations along the ecliptic that the sun and planets travel along the celestial sphere.

Question 52

The process that releases energy for use by the cell is known as

Answer 52

Cellular respiration

Cellular respiration is the process that releases energy for use by the cell. There are several steps involved in cellular respiration, some require oxygen (aerobic) and some do not (anaerobic).

Question 53

Which of the following is NOT a step in the translation portion of protein synthesis?

Answer 53

tRNA anticodons line up with corresponding mRNA codons

When tRNA anticodons line up with corresponding mRNA codons, it is the last step in the transcription process before translation begins. Translation begins as a ribosome attaches to the mRNA strand at a particular codon known as the start codon. This codon is only recognized by a particular initiator tRNA. The ribosome continues to add tRNA whose anticodons complement the next codon on the mRNA string. A third type of RNA is utilized at this point, ribosomal RNA or rRNA. Ribosomal RNA exists in concert with enzymes as a ribosome. In order for the tRNA and mRNA to link up, enzymes connected to rRNA at the ribosome must be utilized. Ribosomal enzymes also are responsible for linking the sequential amino acids into a protein chain. As the protein chain is forming, the rRNA moves along the sequence, adding the amino acids that are designated by the codons on the mRNA. At the end of the translation process, a terminating codon stops the synthesis process, and the protein is released.

Question 54

Which of the following most closely represents the sequence leading to human evolution?

Answer 54

Coacervates, eukaryotes, plants, fish, amphibians, mammals, primates, man

The most likely sequence leading to human evolution begins with coacervates, then eukaryotes, plants, fish, amphibians, mammals, primates, and, finally, man.

Question 55

Water molecules are attracted to each other due to which of the following?

Answer 55

Polarity; partial positive charge near hydrogen atoms; partial negative charge near oxygen atoms

The hydrogen atoms in water molecules have a partial positive charge, while the oxygen atoms in water have a partial negative charge, causing polarity. This polarity allows the oxygen of one water molecule to attract the hydrogen of another. The partial charges attract other opposite partial charges of other water molecules allowing for weak (hydrogen) bonds between the molecules. Inert means non-reactive; it does not explain the attraction between H and O. There are no ionic bonds within water molecules, only covalent bonds. A crystal structure forms in ice because of the attraction of hydrogen bonds; the crystal structure does not cause the attraction. Brownian motion is the random movement of atoms or particles caused by collisions between them; it does not explain attraction between atoms or molecules.

Question 56

The voltage across the terminal of a circuit containing a resistor is 12 V, and it contains a resistor connected to the circuit which reads 8 ohms. What is the amperage of the service?

Answer 56

1.5 A

Using Ohm’s law, V = IR, we solve for I = V / R with V = 12 V and R = 8 ohms. I = 12.0 V / 8.0 ohms = 1.5 V / ohm = 1.5 A. The other answers are results of erroneous calculations or misapplications of Ohm’s law.

Question 57

The percentage of Earth’s surface that is water is

Answer 57

70 percent

Earth is approximately 70 percent water. Most of the water is in the oceans. Land makes up the remaining 30 percent.

Question 58

Traits that are produced by the expression of more than one set of genes are known as

Answer 58

polygenic traits

Traits, such as height and skin color, are produced from the expression of more than one set of genes and are known as polygenic traits.

Question 59

The major driving force of the evolution of species is known as

Answer 59

natural selection

Evolution is driven by the process of natural selection, a feature of population genetics first popularized by Charles Darwin in his book The Origin of Species (published in 1859).

Question 60

Which of the following items found on a bicycle is NOT a simple machine?

Answer 60

horn

The horn is not a simple machine. Simple machines are mechanical devices that alter the magnitude and direction of a force. They are represented by the following six objects: 1) lever, 2) wheel and axle, 3) pulley, 4) inclined plane, 5) pulley, and 6) screw. On a bike, the tire is a type of wheel. The pedal mechanism is a wheel and axle as well as a gear mechanism (two simple machines). The rear wheel gear mechanism is obviously one of the simple machines. The kickstand is a lever.

Question 61

Which of the following sets of quantum numbers (listed in order of n, l, ml, ms) describe the highest energy valence electron of nitrogen in its ground state?

Answer 61

2, 1, 1, +½

Since nitrogen is in the second row, its highest energy electron is at n = 2, which is the first number. The second number signifies that its outer electron is in a p-orbital. The third number indicates the third p-orbital to receive an electron, since nitrogen is the third element in the p-block in the periodic table. The last number is the magnetic spin quantum number and signifies that the highest energy electron is the only electron in the orbital.

Question 62

The change of state from liquid to solid or solid to liquid involves a phase where the temperature remains constant. This phase is known as the

Answer 62

Heat of fusion

Although there is a transition from one state of matter to another, there is no term “transition phase” to describe this process. The term fission is used in nuclear physics to describe the breaking apart of nuclear particles. It is not used to describe changes of state of matter. Specific heat is the amount of energy in calories required to raise one gram of a substance by 1°C. Equilibrium is the state of a system or body at rest or lacking acceleration which results when all the forces acting upon it are equal to zero and the sum of all of the torques equals zero. In chemistry, it is the state of a reaction when all the products and reactants are balanced.

Question 63

Which of the following solid crystals has, on average, one atom per cubic unit cell?

Answer 63

Simple cubic crystals only

A simple cubic crystal is the only unit cell mentioned that has, on average, one atom per unit cell. A simple cubic unit cell has one atom in each of the eight corners of the unit cell, but only one-eighth of each of those atoms is ascribed to that particular unit cell. A face-centered unit cell has four atoms per unit cell; while a body-centered unit cell has two atoms per unit cell.

Question 64

Which of the following is part of the alimentary canal?

Answer 64

Esophagus

The alimentary canal is also known as the gastrointestinal (GI) tract and includes the mouth, pharynx, esophagus, stomach, small intestine, and large intestine.

Question 65

Which of the following experimental evidence was NOT considered supportive of the Oparin Hypothesis?

Answer 65

In the laboratory, proteins are not useful as catalysts, indicating that early proteins were stable.

Proteins are catalysts in the laboratory, so the formation of proteins in the laboratory under conditions presumed to be representative of early earth history is key evidence of the evolution of life on earth. Stanley Miller provided support for Oparin’s hypotheses in experiments in which he succeeded in producing amino acids by exposing simple inorganic molecules to electrical charges similar to lightning. Sidney Fox conducted experiments that proved ultraviolet light may induce the formation of dipeptides from amino acids. He also showed that polyphosphoric acid could increase the yield of these polymers, a process that simulates the modern role of ATP in protein synthesis. Researcher Cyril Ponnamperuma demonstrated that small amounts of guanine formed from the thermal polymerization of amino acids.

Question 66

In snapdragons, a red flower crossed with a white flower produces a pink flower. In this illustration, R stands for red and W represents white. The Punnett square for a cross between a white snapdragon and a red snapdragon is shown here:

   R      R W| RW | RW W| RW | RW

The cross illustrated in this Punnett square is an example of

Answer 66

incomplete dominance

This is known as incomplete dominance. Neither white nor red is dominant over the other.

Question 67

In snapdragons, a red flower crossed with a white flower produces a pink flower. In this illustration, R stands for red and W represents white. The Punnett square for a cross between a white snapdragon and a red snapdragon is shown here:

   R      R W| RW | RW W| RW | RW

The symbol RW represents which of the following?

Answer 67

The genotype for pink

RW is a symbol for genotype. In this case, the RW genotype produces a pink phenotype. R and W represent the alleles for red and white, respectively.

Question 68

In snapdragons, a red flower crossed with a white flower produces a pink flower. In this illustration, R stands for red and W represents white. The Punnett square for a cross between a white snapdragon and a red snapdragon is shown here:

  R      R W| RW | RW W| RW | RW

In this cross, both parents have genotypes that are

Answer 68

Homozygous for color

Both parents have two alleles that are the same, thus they have homozygous genotypes for color.

Question 69

In snapdragons, a red flower crossed with a white flower produces a pink flower. In this illustration, R stands for red and W represents white. The Punnett square for a cross between a white snapdragon and a red snapdragon is shown here:

   R      R W| RW | RW W| RW | RW

Answer 69

Neither parent of the red snapdragon could be white.

While (A), (B), and (C) could have been true, a red snapdragon could have been produced by any of those choices. However, a white snapdragon cannot produce a red snapdragon as an offspring even if paired with a red snapdragon.

Question 70

In snapdragons, a red flower crossed with a white flower produces a pink flower. In this illustration, R stands for red and W represents white. The Punnett square for a cross between a white snapdragon and a red snapdragon is shown here:

   R      R W| RW | RW W| RW | RW

If two of the heterozygous offspring (RW) of this cross are bred, what will be the ratio of phenotypes of the offspring?

Answer 70

1 red: 2 pink: 1 white

If two of the heterozygous offspring of an incomplete dominant trait are bred, the Punnett square would be

  R      W R | RR | RW W| RW | WW

The phenotypic ratio of the offspring then is one-fourth red, one-half pink, and one-fourth white, a 1:2:1 ratio—1 red: 2 pink: 1 white.

Question 71

The physical place where a particular organism lives is called a

Answer 71

Habitat

A habitat refers to the physical place where an organism lives. A species’ habitat must include all the factors that will support its life and reproduction.

Question 72

What is the most likely explanation for the fact that a sample of solid nickel is attracted into a magnetic field, but a sample of solid zinc chloride is not?

Answer 72

There are unpaired outer electrons in nickel.

Nickel has an unpaired electron in its d-orbital, which induces a magnetic field and causes it to be attracted to another magnetic field. Zinc chloride does not have such an unpaired electron and is not attracted to a magnet.

Question 73

The specific heat of water is 4.2 J/g ºC. What mass of water will be heated by 10ºC by 840 J?

Answer 73

20g

The heat absorbed by the water equals the mass of the water multiplied by the specific heat of water times the increase in temperature change. The 840 J added to the water is enough heat to raise the temperature of 20 g of water by 10°C.

Question 74

A light year represents the

Answer 74

total distance that an object travels in space at the speed of light in one year

A light-year is a distance, not a speed or velocity. It is also not a time measurement. A light-year represents the measurement of the distance to one celestial body from another celestial body, measured as a multiple or fraction of the distance light travels in one year. It is equal to (3.0 × 108 m/s)(3.6 × 103 s/hr)(2.4 × 101 hr/day)(3.65 × 102 days/yr)(1 yr) = 95 × 1014 m = 9.5 × 1015 m = 9.5 × 1012 km = 9,500,000,000,000 km or 9.5 trillion kilometers.

Question 75

The half-life of C 14 is 5,730 years. A piece of cypress is measured to have ¾ of the carbon to be C 12 and ¼ C 14. How many years old is this piece of wood likely to be?

Answer 75

11,460

Since the half-life of C 14 is 5,730 years, that means it takes 5,730 years for half the C 14 to decay to C 12. Since the end sample has ¼ C 12, we see that two half-life periods would have occurred. The first would have decayed the sample to half of each type, and the second time period would degrade the half sample to a quarter sample. Two half-life periods is a total of 11,460 years.

Question 76

Igneous rock forms are commonly called

Answer 76

granite

An example of igneous rock is granite. Marble is a metamorphic rock, while limestone, cement, and sandstone are all sedimentary rocks.

Question 77

Which of the following statements is true?

Answer 77

The expansion of space makes galaxies appear to be moving apart, causing the color of their spectral lines to shift when observed.

Although it appears that galaxies are moving apart, Hubble’s law explains that this apparent motion is the expansion of the space between them, not the motion of the galaxies themselves. Hubble’s law states that the redshift in light coming from a distant galaxy is directly and linearly proportional to its distance from Earth.

Question 78

All of the following are major structural regions of roots EXCEPT the

Answer 78

Epistematic region

There is no epistematic region in plant roots. Roots have four major structural regions that run vertically from bottom to top. The root cap is composed of dead, thick-walled cells and covers the tip of the root, protecting it as the root pushes through soil. The meristematic region is just above the root cap. It consists of undifferentiated cells that undergo mitosis, providing the cells that grow to form the elongation region. In the elongation region, cells differentiate, large vacuoles are formed, and cells grow. As the cells differentiate into various root tissues, they become part of the maturation region.

Question 79

When a yellow pea plant is crossed with a green pea plant, all the offspring are yellow. The law that best explains this is the law of

Answer 79

Dominance

Gregor Mendel determined that one gene is sometimes dominant over another gene for the same trait (i.e., it expressed itself over the other). This is known as the law of dominance, Mendel’s second law of inheritance.

Question 80

Which of the following statements is true about electrons?

Answer 80

Electrons have less mass than protons and neutrons.

Electrons have very small mass, much less than either protons or neutrons. They are found orbiting in a cloud surrounding the nucleus. Electrons are negatively charged. An ion is an atom with a greater or fewer number of electrons than the standard atom for the element, causing a charge of positive or negative due to the unequal number of protons and electrons. An atom’s valence number is the number of electrons in its highest (not lowest) energy level.

Question 81

What is the energy-generating mechanism of the stars, including the Sun?

Answer 81

Fusion

Astrophysicists speculate that just 1/100 of a second after the big bang, the entire universe was filled with elementary particles (i.e., electrons, protons, positrons, nutrinos, photons, etc.). At 1 second, the temperature was 1010 K, which was still too hot for neutrons and protons to stay together in the nuclei by the strong nuclear force. After about 3 minutes, it had cooled to about 109 K. Electrons and positrons were annihilated, generating photons, neutrinos, anti-neutrinos, and a small number of neutrons and protons. The universe was now as hot and dense as the core of a star undergoing nuclear fusion. However, it wasn’t until 300,000 years later that the nuclei could hold on to the electrons, clearing the vast fog. The process then continued to cool, coalesce, and expand through fusion, forming stars and galaxies in the visible universe. Fission does not occur until much later in stellar evolution. Spontaneous generation, disproven by Pasteur, has nothing to do with the evolution of stars. Combustion is common in various exothermic processes in a general way. Stellar explosions indicative of the latter stages of stellar evolution generally occur toward the end of a star’s life, not at the origination.

Question 82

When measuring the flow of heat in a system, a natural process that starts at one equilibrium state and flows to another will go in what direction for an irreversible process which is impacted by the entropy of the system plus the environment?

Answer 82

Increase

The answer is that entropy increases as a natural process goes from one equilibrium state to another. This is the only direction that heat flow will go in an irreversible process.

Question 83

What is the resistance of an electric can opener if it takes a current of 10 A when plugged into a 120 V service?

Answer 83

12 ohms

Using Ohm’s law, V = IR, solve for R = V / I with V = 120 V and I = 10 A. R = 120 V / 10 A = 12 V / A or 12 ohms. All of the other answers are results of erroneous calculations or misapplications of Ohm’s law.