Chapter 1 Flashcards
- Which of the following statements is not true of scientific experiments?
a. They yield useful results regardless of whether the hypothesis is supported or rejected.
b. They must occur under carefully controlled conditions found in a laboratory.
c. They must be well documented.
b. They must occur under carefully controlled conditions found in a laboratory.
In an experiment, investigators try to control all of the variables except one—the one that tests the hypothesis. Which of the following reasons is the primary rationale for controlling variables in an experiment?
a. To enable investigators to repeat the test
b. To create a control group
c. To eliminate alternative explanations for the results of an experiment
c. To eliminate alternative explanations for the results of an experiment
Which of the following statements could not be supported or rejected by a scientific experiment?
a. College students think football is more fun to watch than baseball.
b. The first living cell on Earth came from outer space
c. Grass is green because it contains chlorophyll
b. The first living cell on Earth came from outer space
Which of the following statements is true of a hypothesis?
a. A hypothesis can be supported or rejected through experimentation.
b. A hypothesis can be proved.
a. A hypothesis can be supported or rejected through experimentation.
All the organisms on your campus make up
a. an ecosystem
b. a taxonomic domain
c. a community
d. a population
c. a community
- Which of these best demonstrates unity among organisms?
a. natural selection
b. descent with modification
c. emergent properties
d. the structure and function of DNA
d. the structure and function of DNA
- A controlled experiment is one that
a. proceeds slowly so a scientist can make careful records
b. is repeated many times to make sure the results are accurate.
c. keeps all variables constant.
d. tests experimental and control groups in parallel
d. tests experimental and control groups in parallel
- Which of the following statements best distinguishes ¬hypotheses from theories in science?
a. Hypotheses usually are relatively narrow in scope; theories have broad explanatory power.
b. Theories are proved true; hypotheses are often contradicted by experimental results.
c. Hypotheses are guesses; theories are correct answers.
d. Theories are hypotheses that have been proved
a. Hypotheses usually are relatively narrow in scope; theories have broad explanatory power.
- The universal genetic language of DNA is common to virtually all organisms on Earth, however diverse. What is the best explanation for this fact?
a. All living things share a common genetic language of DNA because they share a common ancestry
b. The universal nature of the genetic language of DNA is due to coincidence.
c. The universal genetic language is explained by the chemistry of DNA and proteins.
a. All living things share a common genetic language of DNA because they share a common ancestry
- Electrons are held in an atom by attraction to what particle or location?
a. Attraction to the positively charged protons in the nucleus
b. Attraction to the magnetic neutrons in the nucleus
c. Attraction to the lowest electron shell
d. Attraction to the other electrons in the atom
a. Attraction to the positively charged protons in the nucleus
- What can happen to an electron when sunlight hits it?
a. It can drop down to a lower electron shell
b. It can stay in its original shell
c. It can collide with the nucleus
d. It can move out to a higher electron shell
b. It can stay in its original shell
d. It can move out to a higher electron shell
The mass number of an atom is 15, and its atomic number is 7. The atom probably has…
a. 7 electrons in the nucleus.
b. at least 15 electrons.
c. 7 units of negative charge in the nucleus.
d. about as much mass in electrons as in protons.
e. 8 neutrons in the nucleus.
e. 8 neutrons in the nucleus.
Which statement is true of atoms?
a. Protons attract other protons.
b. Electrons determine the atom’s size.
c. Most of an atom’s volume is filled with matter.
d. Protons repel electrons.
e. All of the above.
b. Electrons determine the atom’s size.
Which statement is true of the energy levels of electrons in shells?
a. Electrons must lose energy to move from the first to the second shell.
b. All the electrons in an atom have similar amounts of energy.
c. The valence shell has higher energy than other occupied shells.
d. All of the above.
e. None of the above.
c. The valence shell has higher energy than other occupied shells.
Two atoms always represent the same element if they have …
a. the same number of protons.
b. the same mass number.
c. the same number of electrons.
d. the same number of shells.
e. the same number of particles in the nucleus.
a. the same number of protons
Chemists assign atoms to chemical elements by counting their ________.
a. isotopes
b. electrons
c. neutrons
d. protons
d. protons
What name is given to the bond between water molecules?
a. hydrophobic
b. ionic
c. hydrogen
d. polar covalent
e. single (nonpolar) covalent
c. hydrogen
Atoms with the same number of protons but with different electrical charges _____.
a. have different atomic numbers
b. are different isotopes
c. have different numbers of neutrons
d. have different atomic masses
e. are different ions
e. are different ions
An ionic bond involves _____.
a. no atoms other than sodium and chlorine
b. an attraction between ions of opposite charge
c. the sharing of a single pair of electrons
d. water avoidance
e. the unequal sharing of an electron pair
b. an attraction between ions of opposite charge
A phrase that applies to covalent bonding and not other kinds of bonds is …
a. electron-sharing.
b. paired electrons.
c. great strength.
d. charge attraction.
e. All of the above.
a. electron-sharing.
The reactivity of an atom arises from
a. the sum of the potential energies of all the electron shells.
b. the potential energy of the valence shell.
c. the average distance of the outermost electron shell from the nucleus.
d. the existence of unpaired electrons in the valence shell.
d. the existence of unpaired electrons in the valence shell.
The unequal sharing of electrons within a water molecule makes the water molecule _____.
a. polar b. ionic c. have a low surface tension d. hydrophobic e. change easily from a liquid to gaseous form
a. polar
What process exerts the pull on water molecules that is relayed from leaf to root via cohesion?
a. gravity
b. evaporation
c. antigravity
d. precipitation
b. evaporation
The tendency of an atom to pull electrons toward itself is referred to as its _____.
a. tonicity
b. covalency
c. electronegativity
d. polarity
e. ionic potential
c. electronegativity
