Module 1; The Chemistry of Life

An atom has 6 electrons in its outer shell. How many unpaired electrons does it have? 0 2 4 6 2 or 4

2

Which of these is an example of inductive reasoning? Hundreds of individuals of a species have been observed and all are photosynthetic; therefore, the species is photosynthetic. These organisms live in sunny parts of this area so they are able to photosynthesize. If horses are always found grazing on grass, they can be only herbivores and not omnivores. If protists are all single-celled, then they are incapable of aggregating. If two species are members of the same genus, they are more alike than each of them could be to a different genus.

Hundreds of individuals of a species have been observed and all are photosynthetic; therefore, the species is photosynthetic.

Which of the following statements best distinguishes hypotheses from theories in science? Theories are hypotheses that have been proved. Hypotheses are guesses; theories are correct answers. Hypotheses usually are relatively narrow in scope; theories have broad explanatory power. Hypotheses and theories are essentially the same thing. Theories are proved true; hypotheses are often falsified.

Hypotheses usually are relatively narrow in scope; theories have broad explanatory power

The following is a list of biology themes discussed in Chapter 1. Use them to answer the following questions. I. New properties emerge at each level in the biological hierarchy. II. Organisms interact with other organisms and the physical environment. III. Life requires energy transfer and transformation. IV. Structure and function are correlated at all levels of biological organization. V. Cells are an organism's basic units of structure and function. VI. The continuity of life is based on heritable information in the form of DNA. VII. Feedback mechanisms regulate biological systems. VIII. Evolution accounts for the unity and diversity of life. Which theme(s) is/are best illustrated by a group of investigators who are trying to classify and explain the ecology of an area known as the Big Thicket? I only II only VIII only IV and VI I and II

I and II (New properties emerge at each level in the biological hierarchy; Organisms interact with other organisms and the physical environment)

Use the following information to answer the questions below. Golden algae are a group of protists whose color is due to carotenoid pigments: yellow and brown. Most have two flagella and all are photosynthetic. A group of students was given a significant sample of one of these (Dinobryon) that is colonial. Their instructions for the project were to design two or more experiments that could be done with these organisms. The students decide that for one of their experiments, they want to see whether the organisms can photosynthesize. Which of the following is the best hypothesis? If the Dinobryon can live > 5 days without added food, they must be able to photosynthesize. If the Dinobryon can live without exposure to light for > 5 days, they must be able to photosynthesize. If the Dinobryon photosynthesize, they must need no other minerals or nutrients and will be able to live in distilled water and light alone. If the Dinobryon are kept in the dark, one-half will be expected to die in 5 days. If the Dinobryon are able to photosynthesize, the students should be able to extract photosynthetic pigments.

If the Dinobryon are able to photosynthesize, the students should be able to extract photosynthetic pigments.

If a salamander relied on hydrogen bonds to cling to surfaces, what type of surface would cause the most problems for this animal? a surface coated with a thin film of water a surface made with carbon and hydrogen atoms covalently bonded together a surface made with carbon, hydrogen, and oxygen atoms covalently bonded together a surface made with carbon, hydrogen, nitrogen, and oxygen atoms covalently bonded together a surface made with silicon and oxygen atoms covalently bonded together

a surface made with carbon and hydrogen atoms covalently bonded together

Which of these systems is least likely to be at chemical equilibrium? a test tube of living cells a test tube of organic molecules, kept in the freezer a test tube of dry organic molecules, kept at room temperature a test tube of organic molecules dissolved in water, kept at room temperature a test tube of dead cells in water, kept at room temperature

a test tube of living cells

In the methane molecule shown in the figure above, bonds have formed that include both the s orbital valence electrons of the hydrogen atoms and the p orbital valence electrons of the carbon. The electron orbitals in these bonds are said to be double orbitals. tetrahedral orbitals. complex orbitals. hybrid orbitals. polar orbitals.

hybrid orbitals.

Prokaryotic and eukaryotic cells generally have which of the following features in common? a membrane-bounded nucleus a cell wall made of cellulose ribosomes flagella or cilia that contain microtubules linear chromosomes made of DNA and protein

ribosomes

Systems biology is mainly an attempt to analyze genomes from different species. simplify complex problems by reducing the system into smaller, less complex units. understand the behavior of entire biological systems. build high-throughput machines for the rapid acquisition of biological data. speed up the technological application of scientific knowledge.

understand the behavior of entire biological systems.

How many electron pairs are shared between carbon atoms in a molecule that has the formula C2H4? 0 1 2 3 4

2

What coefficients must be placed in the following blanks so that all atoms are accounted for in the products? C6H12O6→ ___ C2H6O + ___ CO2 1; 2 3; 1 1; 3 1; 1 2; 2

2; 2

What is the maximum number of hydrogen atoms that can be covalently bonded in a molecule containing two carbon atoms? 2 3 4 6 8

6

We can represent atoms by listing the number of protons, neutrons, and electronsfor example, 2p+; 2n0; 2e- for helium. Which of the following represents the 18O isotope of oxygen? 6p+, 8n0, 6e- 8p+, 10n0, 8e- 9p+, 9n0, 9e- 7p+, 2n0, 9e- 10p+, 8n0, 9e

8p+, 10n0, 8e-

A water sample from a hot thermal vent contained a single-celled organism that had a cell wall but lacked a nucleus. What is its most likely classification? Eukarya Archaea Animalia Protista Fung

Archaea

Given the cooperativity of science, which of the following is most likely to result in an investigator being intellectually looked down upon by other scientists? Making money as the result of studies in which a new medication is discovered. Doing meticulous experiments that show data that contradict what has been previously reported by the scientific community. Spending most of a lifetime investigating a small and seemingly unimportant organism. Getting negative results from the same set of experiments. Being found to have falsified or created data to better fit a hypothesis.

Being found to have falsified or created data to better fit a hypothesis.

In comparing covalent bonds and ionic bonds, which of the following would you expect? An atom can form covalent bonds with multiple partner atoms, but only a single ionic bond with a single partner atom. Covalent bonds and ionic bonds occupy opposite ends of a continuous spectrum, from nearly equal to completely unequal sharing of electrons. Both involve electrical attraction between the electrons of one atom and the nucleus of the other atom. Ionic interactions remain when covalent bonds are broken in water. Ionic bonds are much stronger than covalent bonds.

Covalent bonds and ionic bonds occupy opposite ends of a continuous spectrum, from nearly equal to completely unequal sharing of electrons.

What is the difference between covalent bonds and ionic bonds? Covalent bonds are formed between atoms to form molecules; ionic bonds are formed between atoms to form compounds. Covalent bonds involve the sharing of pairs of electrons between atoms; ionic bonds involve the sharing of single electrons between atoms. Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the electrical attraction between atoms. Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the sharing of protons between atoms. Covalent bonds involve the transfer of electrons between atoms; ionic bonds involve the sharing of electrons between atoms.

Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the electrical attraction between atoms.

Which drawing in the figure above depicts the electron configuration of an element with chemical properties most similar to Helium (2He)? A B C D E

E

Which of the following molecules contains the most polar covalent bond? H2 O2 CO2 H2O CH4

H2O

The atomic number of sulfur is 16. Sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound: HS HS2 H2S H3S2 H4S

H2S

In a high school laboratory, which of the following constitutes an experiment? I. learning to use a microscope by examining fixed specimens on slides II. being able to examine swimming protists under a microscope III. extracting pigments from plant leaves and separating the types of pigments for identification IV. preparing root tips for examination by staining them I only II only III only II and III only II, III, and IV

III only (extracting pigments from plant leaves and separating the types of pigments for identification)

When a hypothesis cannot be written in an "Ifthen" format, what does this mean? It does not represent deductive reasoning. It cannot be a scientific hypothesis. The subject cannot be explored scientifically. The hypothesizer does not have sufficient information. It cannot be testable.

It does not represent deductive reasoning.

Which of the following best describes a model organism? It is often pictured in textbooks and easy for students to imagine. It lends itself to many studies that are useful to beginning students. It is well studied, easy to grow, and results are widely applicable. It is small, inexpensive to raise, and lives a long time. It has been chosen for study by the earliest biologists.

It is well studied, easy to grow, and results are widely applicable.

The atomic number of chlorine is 17. The atomic number of magnesium is 12. What is the formula for magnesium chloride? MgCl MgCl2 Mg2Cl Mg2Cl2 MgCl3

MgCl2

The organic molecules in living organisms have a measurably lower ratio of carbon-13/carbon-12, two stable isotopes of carbon that comprise approximately 1.1% and 98.9% of atmospheric carbon, respectively. What is a reasonable explanation for this phenomenon? Photosynthesis preferentially uses carbon dioxide molecules with carbon-12, and the lower carbon-13/carbon-12 ratio propagates through the food chain. Carbon dioxide molecules with carbon-13 stay in the upper atmosphere and are less available to terrestrial plants and algae. Carbon-13 has a different valence electron configuration and is therefore less chemically reactive than carbon-12. Oxygen atoms preferentially react with carbon-13, thereby enriching the atmosphere with carbon dioxide molecules containing carbon-13 atoms. Carbon dioxide molecules containing carbon-13 are heavier and sink into the ocean depths, making them less available to living organisms.

Photosynthesis preferentially uses carbon dioxide molecules with carbon-12, and the lower carbon-13/carbon-12 ratio propagates through the food chain.

What are archaea? Prokaryotes characterized as extremophiles that share some bacterial and some eukaryotic traits. Organisms that are adapted to high temperature environments, such as in volcanic springs. Single-celled organisms that are killed by the application of antibiotics at certain concentrations. Bacteria-like organisms that can live only in extreme salt environments. Primitive protist-like creatures possessing fewer than two chromosomes per cell.

Prokaryotes characterized as extremophiles that share some bacterial and some eukaryotic traits.

Why is a scientific topic best discussed by people of varying points of view, a variety of subdisciplines, and diverse cultures? They can rectify each other's approach to make it truly scientific. Robust and critical discussion between diverse groups improves scientific thinking. Scientists can explain to others that they need to work in isolation to utilize the scientific method more productively. This is another way of making science more reproducible. Scientists need to exchange their ideas with other disciplines and cultures so that all groups are in consensus with the course of future research.

Robust and critical discussion between diverse groups improves scientific thinking.

Which statement is true of all atoms that are anions? The atom has more electrons than protons. The atom has more protons than electrons. The atom has fewer protons than does a neutral atom of the same element. The atom has more neutrons than protons. The net charge is 1-.

The atom has more electrons than protons.

Which of the following is an example of qualitative data? The temperature decreased from 20°C to 15°C. The plant's height is 25 centimeters (cm). The fish swam in a zigzag motion. The six pairs of robins hatched an average of three chicks. The contents of the stomach are mixed every 20 seconds.

The fish swam in a zigzag motion.

Which of the following statements correctly describes any chemical reaction that has reached equilibrium? The concentrations of products and reactants are equal. The reaction is now irreversible. Both forward and reverse reactions have halted. The rates of the forward and reverse reactions are equal. No reactants remain.

The rates of the forward and reverse reactions are equal.

Which of the following best describes the relationship between the atoms described below? 1 H 1 3 H 1 They are isomers. They are polymers. They are isotopes. They contain 1 and 3 protons, respectively. They each contain 1 neutron.

They are isotopes.

All the organisms on your campus make up an ecosystem. a community. a population. an experimental group. a taxonomic domain

a community.

What do these two plants have in common? adaptations to extreme heat adaptations to conserve water identical stem structures identical flower structures lack of photosynthesis

adaptations to conserve water

QUESTION 18 Darwin's finches, collected from the Galápagos Islands, illustrate which of the following? mutation frequency ancestors from different regions adaptive radiation vestigial anatomic structures the accuracy of the fossil record

adaptive radiation

Electrons exist only at fixed levels of potential energy. However, if an atom absorbs sufficient energy, a possible result is that an electron may move to an electron shell farther away from the nucleus. an electron may move to an electron shell closer to the nucleus. the atom may become a radioactive isotope. the atom would become a positively charged ion, or cation, and become a radioactive isotope. the atom would become a negatively charged ion, or anion.

an electron may move to an electron shell farther away from the nucleus.

Oxygen has an atomic number of 8 and a mass number of 16. Thus, what is the atomic mass of an oxygen atom? exactly 8 grams exactly 8 daltons approximately 16 grams approximately 16 daltons 24 amu (atomic mass units)

approximately 16 daltons

Atoms whose outer electron shells contain 8 electrons tend to form ions in aqueous solutions. form hydrogen bonds in aqueous solutions. be stable and chemically nonreactive, or inert. be gaseous at room temperature. be both chemically inert and gaseous at room temperature

be both chemically inert and gaseous at room temperature

About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements make up approximately 96% of living matter? carbon, sodium, hydrogen, nitrogen carbon, oxygen, phosphorus, hydrogen oxygen, hydrogen, calcium, nitrogen carbon, hydrogen, nitrogen, oxygen carbon, oxygen, nitrogen, calcium

carbon, hydrogen, nitrogen, oxygen

In a hypothetical world, every 50 years people over 6 feet tall are eliminated from the population before they reproduce. Based on your knowledge of natural selection, you would predict that the average height of the human population will remain unchanged. gradually decline. rapidly decline. gradually increase. rapidly increase.

gradually decline.

Which of the following explains most specifically the attraction of water molecules to one another? nonpolar covalent bond polar covalent bond ionic bond hydrogen bond hydrophobic interaction

hydrogen bond

Charles Darwin proposed a mechanism for descent with modification that stated that organisms of a particular species are adapted to their environment when they possess non-inheritable traits that enhance their survival in the local environment. non-inheritable traits that enhance their reproductive success in the local environment. non-inheritable traits that enhance their survival and reproductive success in the local environment. inheritable traits that enhance their survival and reproductive success in the local environment. inheritable traits that decrease their survival and reproductive success in the local environment.

inheritable traits that enhance their survival and reproductive success in the local environment.

Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates, but not by other organisms such as bacteria or plants? nitrogen calcium iodine sodium phosphorus

iodine

Through time, the lineage that led to modern whales shows a change from four-limbed land animals to aquatic animals with two limbs that function as flippers. This change is best explained by natural philosophy. creationism. the hierarchy of the biological organization of life. natural selection. feedback inhibition.

natural selection.

When two atoms are equally electronegative, they will interact to form hydrogen bonds. van der Waals interactions. polar covalent bonds. nonpolar covalent bonds. ionic bonds.

nonpolar covalent bonds.

A covalent bond is likely to be polar when one of the atoms sharing electrons is much more electronegative than the other atom. the two atoms sharing electrons are equally electronegative. oxygen is one of the two atoms sharing electrons. one of the atoms has absorbed more energy than the other atom. the two atoms sharing electrons are different elements.

one of the atoms sharing electrons is much more electronegative than the other atom.

A covalent chemical bond is one in which electrons are removed from one atom and transferred to another atom so that the two atoms become oppositely charged. protons and neutrons are shared by two atoms so as to satisfy the requirements of both atoms. outer-shell electrons of two atoms are shared so as to satisfactorily fill the outer electron shells of both atoms. outer-shell electrons of one atom are transferred to fill the inner electron shell of another atom. an electron occupies a hybrid orbital located between the nuclei of two atoms.

outer-shell electrons of two atoms are shared so as to satisfactorily fill the outer electron shells of both atoms.

A localized group of organisms that belong to the same species is called a biosystem. community. population. ecosystem. family.

population.

Once labor begins in childbirth, contractions increase in intensity and frequency until delivery. The increasing labor contractions of childbirth are an example of which type of regulation? a bioinformatic system positive feedback negative feedback feedback inhibition enzymatic catalysis

positive feedback

Protists and bacteria are grouped into different domains because protists eat bacteria. bacteria are not made of cells. protists have a membrane-bounded nucleus, which bacterial cells lack. bacteria decompose protists. protists are photosynthetic.

protists have a membrane-bounded nucleus, which bacterial cells lack.

Which of the following categories of organisms is least likely to be revised? kingdom class order phylum species

species

Based on electron configuration, which of these elements in the figure above would exhibit a chemical behavior most like that of oxygen? carbon hydrogen nitrogen sulfur phosphorus

sulfur

Which branch of biology is concerned with the naming and classifying of organisms? informatics schematic biology taxonomy genomics evolution

taxonomy

The application of scientific knowledge for some specific purpose is known as technology. deductive science. inductive science. anthropologic science. pure science.

technology.

A controlled experiment is one that proceeds slowly enough that a scientist can make careful records of the results. tests experimental and control groups in parallel. is repeated many times to make sure the results are accurate. keeps all variables constant. is supervised by an experienced scientist.

tests experimental and control groups in parallel.

Knowing just the atomic mass of an element allows inferences about which of the following? the chemical properties of the element the number of protons in the element the number of neutrons in the element the number of protons plus neutrons in the element both the number of protons and the chemical properties of the elemen

the number of protons plus neutrons in the element

Organisms interact with their environments, exchanging matter and energy. For example, plant chloroplasts convert the energy of sunlight into the energy of motion. carbon dioxide and water. the potential energy of chemical bonds. oxygen. kinetic energy.

the potential energy of chemical bonds.

A controlled experiment is one in which the experiment is repeated many times to ensure that the results are accurate. the experiment proceeds at a slow pace to guarantee that the scientist can carefully observe all reactions and process all experimental data. there are at least two groups, one of which does not receive the experimental treatment. there are at least two groups, one differing from the other by two or more variables. there is one group for which the scientist controls all variables.

there are at least two groups, one of which does not receive the experimental treatment.