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practice questions

The basic structural units of matter and life are _______.

atoms

Which scientist(s) is/are credited with developing the theory of evolution in the mid-1800s?

both Charles Darwin and Alfred Russel Wallace

All elements are _____.

a unique form of matter

Natural selection would be best illustrated by which of the following?

a bacterial cell in the human body with a genetic variation that allows it to survive when the person takes antibiotics. This cell has a change that allows it to survive in the enviornment with the antibiotics..

When an atom ionizes, what happens?

It gives up or takes up one or more electrons, atoms become charged or ionized by giving up or gaining electrons.

"organic" is a term that can have different meanings. What does this term mean to a chemist?

Organic compounds are compounds of carbon and hydrogen

Mutations are accidental changes in genes

It is a prevalent misconception that mutations are directed by the environment, but they are not There is no way for the environment to "speak" to genes and "tell" them how they should mutate to make more useful genes. Mutations are random processes, most of the time they are either neutral or harmful, but on occasion they produce genes that make the carrier better adapted to the enviroment and are passed on to the next generation.

Which of the following functional groups would you expect to help make an organic molecule soluble in water?

a carbon backbone with many hydroxyl groups, OH. Hydroxyl groups are polar and would thus contribute hydrophilic properties to organic molecules for which they act as a functional group.

Which type of organic molecules contain a phosphate functional group?

both nucleic acids and phospholipids. The structure of nucleic acids and phospholipids contains the phosphate functional group.

The complexity of living systems __________.

is also highly organized. Living systems exhibit a combination of complexity and organization that is unique

A scientist is testing whether a new cancer drug will work on prostate cancer in humans. To properly interpret results of an experiment, control experiments are needed. Which of the following treatments would serve as a control in these experiments, so that the researchers can conclude that the changes they see in the patients are due to the drug?

Some patients receive a "mock" injection that contains the same solution base and the same volume as the drug but does not actually contain the drug itself.

Which of the following groups of organisms contain prokaryotic cells?

Bacteria and Archaea. They represent the two domains of life that are prokaryotic. The 3rd domain Eukarya contains only eukaryotic organisms.

Covalent bonds ________.

share electrons with another atom. The sharing of electrons is how you define a covalent bond.

To provent the artifacts from decaying you want to fill the capsule with a gas that would be reactive. Which of these gases would you choose: oxygen gas (O2), carbon dioxide (CO2), argon gas (Ar), or hydrogen gas (H2)? The atomic numbers of the atoms in these molecules are as follows: oxygen =8, carbon=6, argon =18 and hydrogen =2.

argon gas. Argon atoms do not react at all because their outermost electron shell is filled, argon atoms do not form chemical bonds, either with each other or with other atoms.

The diversity of life is mainly due to _______.

genetic variation. Most of the traits that cause living organisms to differ from one another are controlled by genes/DNA.

An autotrophic organism _______.

would be one that derives its energy from a renewable external energy source such as sunlight (i.e. photosynthetic organisms)

Identify a characteristic that is representative of some, but not all, life-forms.

movement over great distances. Not all living things are capable of movement.

In Francesco Redi's experiment with the meat in the jars, which is the control?

the meat in the jar w the lid

Complex carbohydrates have numerous roles in plant cells, including ______.

long-term energy storage and giving of structure to plant cell walls. Starch and cellulose are both complex carbohydrates and can be used for long-term energy storage and structural support, respectively.

Proteins are polymers of _____

amino acids. Amino acids are the building blocks of proteins.

The correct order of size, going from smallest to largest is:

electron, proton, atomic nucleus, electron shell, atom, molecule. Molecules are made of atoms, which have an outer electron shell and an inner nucleus. Electrons are smaller than both neutrons and protons.

The R group is

responsible for the wide diversity of function attributed to proteins. There are 20 amino acids that are commonly found in organisms. Each amino acid has a different molecule or atom (or R group) attached. Each unique R group is responsible for the unique properties of its amino acid. The interaction of the amino acids in the 3-dimensional organization of a protein, therefore, dictates the biological function of the protein.

Fat accumulates in our bodies when we overeat. This is because ______.

lipids are a form of long-term energy storage. Lipids are the main form of long-term storage.

A nucleotide is composed of _____.

a sugar, a phosphate group, and a nitrogen-containing base. This is the composition of a nucleotide.

The 3 natural processes that form the basis for evolution are _______.

genetic variation, inheritance and natural selection.

Which of the following molecules would rearranging the order of the subunits have an effect on molecular function?

both protein and DNA

The high specific heat of water means that living systems are ____.

more resistant to changes in temperature. The high specific heat means that much energy must be put into a water-based system to change its temperature.

Rapid breathing increases the pH of your blood, making it more basic.

When you breath out, you are decreasing the amount of H+ in the blood. This in H+pH makes the blood more basic. The conditon is known as (alkaline is synonym for basic).

Lipids contain fatty acids, which are made mostly of nonpolar bonds. Will these molecules be soluble or insoluble in water?

They would be insoluble in water due to their nonpolar bonds. These molecules have many nonpolar bonds, which make them insoluble in water.

Why does water so greatly resist increases in temperature?

It takes great energy to break the huge number of hydrogen bonds that hold water molecules together. Before water molecules begin to increase their speed of motion, the hydrogen bonds between molecules of water must first be broken.

Protein functions in cells include__________.

defense, catalysis of biochemical reactions, structure and movement, and transport.

The protein composition of a cell determines its ______.

shape, behavior, and function of the cell.

How many covalent bonds can the nitrogen (atomic number 7) atom form?

Three. The innermost orbital can hold two electrons. That leaves five in the outermost orbital, which has room for three more to give a total capacity of eight.

What is the role of DNA and RNA in cells?

Preserving and expressing genetic information. DNA stores info and RNA is involved in its expression.

Proteins are polymers of _____.

Amino acids; they are the building blocks of proteins.

An atom other than hydrogen has a single electron in its outermost shell. What is the most likely outcome for this atom in terms of chemical bonding?

The atom will lose its outermost electron, becoming an ion with a charge of +1.

What would happen if there is no genetic variability in a population?

then there is nothing for nature to select from; everyone either reproduces and the population doesn't change, or no one reproduces and the population becomes extinct.

what would happen without inheritance?

the winning combination of genes doesn't get passed on to the next population, so again no evolution.

What happens if there is no natural selection?

The passing of genes to the next generation is random and the population and the population doesn't change in ways that make the population better suited to the environment.

A group of researchers developed a hypothesis and tested it by designing an experiment. The results of the experiment did not support the original hypothesis. What should the researchers do next?

They should reject the original hypothesis and develop a new hypothesis. If your results negate your hypothesis, then you must either modify the original hypothesis accordingly, or completely through out the hypothesis and develop a new one according to the findings of the experiments.

Why are hydrophobic molecules such as fats and oils unable to dissolve in watery solutions?

Water molecules form hydrogen bonds with each other, excluding the hydrophobic molecules. Water molecules are charged and thus act like weak magnets that prefer to be next to other charged molecules and thus push neutral molecules such as fats and oils out of the way.

Saturated fats _____.

contain the maximum number of hydrogen atoms possible. Due to the single covalent bonds, the molecule must be saturated with hydrogen atoms.

The following are NOT correct statements:

Eukaryotic cells are simpler that prokaryotic cells.

Genes are proteins that produce DNA.

A scientific theory is similar to an educated guess.

Heterotroph means "self-feeder."

Why is studying biology a worthwhile endeavor?

It allows for a greater appreciatin of the natural world. It allows us to make more informed decisions on how humans should manage themselves. It allows us to make sense of the biological activity that occurs around us daily. It allows us to make more informed decisions on health and natural resource management issues.

Atoms are the basic building blocks of elements. Atoms, and therefore the elements themselves, are made up of subatomic bits of matter that are electrically negative (electrons), electrically positive (protons), and electrically neutral or uncharged (neutrons). Which subatomic component defines (characterizes) the fundamental nature of each element?

protons.The unique chemical properties of each element depend on the atomic number.

Oxygen atoms have an atomic number of 8. Neon atoms have 10 electrons. Predict whether or not these atoms are generally reactive with other atoms (i.e. can form chemical bonds with other atoms).

Oxygen is reactive because its outermost electron shell contains six electrons (is not filled); neon is not reactive because its outermost electron shell contains 8 electrons (is filled).

Science assumes that natural laws (such as the law of gravity) ________.

apply uniformly through space and through time. If the scientific laws couldn't generalize across space and time, they would be meaningless.

The basic structural units of matter and life are ____.

atoms; they differ by their composition of electrons, protons, and neutrons.

Living systems need energy to ______.

replace worn-out parts and build new parts, help maintain a constant internal enviornment, and grow larger. Almost everything about being alive takes energy, which is why acquiring and using energy are characteristics of life.

Carbohydrates _________.

can function as a source of energy or can function as an extremely durable structural material, depending on the specific nature of the chemical bonds between subunits (monomers). Carbohydrates are a primary source of energy for many organisms and can form durable structures as well.

A characteristic of the carbon atom that contributes to its ability to form an immense diversity of organic molecules is its ________.

ability to covalently bond with up to four other atoms. The carbon atom has four electrons in its outer shell, allowing it to covalently bond with up to four other atoms.

Energy bar claiming to contain only carbon, oxygen and hydrogen atoms contains what kind of biological molecules?

Carbohydrates and lipids which are composed nearly exclusively of C, H and O. In addition, lipids such as fats and oils also contain only C, H, and O.

The atomic number of carbon is 6. A carbon atom has ___ protons and ___ electrons.

6,6. The atomic number gives the number of protons, which equals the number of electrons.

A scientist examines an organism and finds that it is eukaryotic, heterotrophic, multicellular, and it absorbs nutrients. She concludes that the organism is most likely a member of the Kingdom ____.

Fungi. All fungi are eukaryotic, heterotrophs that absorb nutrients and most, but not all, are multicellular.

All elements are _____.

a unique form of matter. Each element is a basic and unique form of matter.

The general class of biological molecules containing large, nonpolar regions, which make these molecules insoluble in water, is called ____.

lipids, which are the general class of molecules, and include triglycerides, waxes, steroids, and phospholipids.

A scientist is studying the metabolism of proteins in yeast and wants to follow the formation of proteins from the earliest possible point. In her experiment, she will feed the yeast radioactive nutrients and follow the fate of the radioactivity in the cells. Which of the following atoms will allow her to exclusively follow proteins in the cell?

radioactive sulfur. The only macromolecules in cells that contain sulfur are proteins (sulfur is present in the amino acids methionine and cysteine), so only protein molecules would be radioactively labeled if yeast were fed radioactive sulfur.

The process of homeostasis is _______.

how organisms maintain a constant internal environment, even in changing external environments.

Why is a control needed in an experiment?

to provide a comparison with the experimental results obtained when changing the variable. With out a control it would be impossible to determine if the variable being tested was responsible for the results observed.

Isotopes are ____.

atoms with the same number of protons but different numbers of neutrons.

correctly paired organic compounds with one of its building blocks

polysaccharide-monosaccharide

protein-amino acid

fat-fatty acid

Glycerol is a compound often found in ____.

lipids, but not in nucleic acids.

In ancient times the Egyptian bodies would dehydrate the dead bodies quickly leaving a mummy like corpus. The trunk region of the body dehydrates much slowly than peripheral areas such as hands of feet. By using your knowledge of the process of hydrolysis, which regions of a mummy's body would give the most intact pieces of DNA?

fingers, they would have one of the fastest dehydration rates, leaving behind the least amount of water to be used in hydrolysis reactions, so more segments of DNA would be intact.

A nucleotide is composed of ______.

a sugar, a phosphate group, and a nitrogen-containing base.

Which of the following functional groups would you expect to help make an organic molecule soluble in water?

a carbon backbone with many hydroxyl groups, OH. Hydroxyl groups are polar and would thus contribute hydrophilic properties to organic molecules for which they act as a functional group.

How are large organic molecules (macromolecules) synthesized?

by a dehydration reaction utilizing monomers. A "dehydration reaction" is a synthetic, or building, reaction. Macromolecules (polymers) are built from monomers (e.g., the macromolecule glycogen from the monomer glucose).

Complex carbohydrates have numerous roles in plant cells, including __________.

long-term energy storage and giving of structure to plant cell walls

Simple sugars typically function as

short-term energy stores.

How are you able to use the energy in the starch of a potato but not in the cellulose of celery?

Our bodies can't break the bonds in cellulose but can break those in starch. The spatial orientation of the bonds is different.

What is the difference between a simple sugar and a complex carbohydrate?

Complex carbohydrates are polymers of simple sugars.
Starch is a polymer of the simple sugar glucose.

Phospholipids contain a "head group" that is _____ and two fatty acid "tails" that are _____.

hydrophilic, hydrophobic. The phosphate head of a fatty acid is charged and thus water-loving or hydrophilic, whereas the fatty acid tails are not charged and thus are hydrophobic or water-hating.

If a lipid is completely saturated, would you predict it to be liquid or solid at room temperature?

It would be a solid at room temperature. With no double bonds to inhibit packing, this lipid would likely be solid at room temperature.

Lipids contain fatty acids, which are made mostly of nonpolar bonds. Will these molecules be soluble or insoluble in water? Explain.

They would be insoluble in water due to their nonpolar bonds. These molecules have many nonpolar bonds, which make them insoluble in water.

Saturated fats __________.

contain the maximum number of hydrogen atoms possible. Saturated fats have only single covalent bonds in their carbon chain.

Proteins are polymers of _____.

Amino acids which are the building blocks of proteins.

The quaternary level of protein structure __________.

refers to a functional (biologically active) complex of two or more three-dimensional proteins (e.g., hemoglobin)

primary level of organization

refers to the serial sequence, or arrangement, of amino acids that make up a protein

Proteins are macromolecules that can perform many different functions within an organism. This diversity of function is due to the unique nature of one of the protein macromolecule's four functional groups, which is bound to a central carbon atom. Which functional group is responsible for the wide diversity of function attributed to proteins?

the R group. There are 20 amino acids that are commonly found in organisms. Each amino acid has a different molecule or atom (or R group) attached. Each unique R group is responsible for the unique properties of its amino acid. The interaction of the amino acids in the three-dimensional organization of a protein, therefore, dictates the biological function of the protein.

You have identified a protein that is unable to form disulfide bridges. This would affect which of the following?

tertiary structure of the protein. Disulfide bridges are involved in the tertiary structure of proteins that form them.

In which of the following molecules would rearranging the order of the subunits have an effect on molecular function?

both protein and DNA

Excess nitrogen wastes in our food are converted to urea. Which of the following types of foods would you expect to increase the levels of urea in your blood?

meats that contain a lot of protein and legumes that contain a lot of nucleic acid. Both proteins and nucleic acids contain nitrogen.

What allows one atom to physically interact with a second atom?

properties of the electrons

The chemical bonding properties of an atom are determined directly by __________.

the outer shell of electrons, atoms are stable when their outermost shell of electrons is filled.

Nonpolar covalent bonds are different from polar covalent bonds because __________.

electrons are shared equally in nonpolar covalent bonds and are shared unequally in polar covalent bonds

One solution has a pH of 2 and another has a pH of 3. What would be the relative difference in H+ ion concentration?

a tenfold difference in concentration

The molecule H2SO4 is ionized to H+ ions and SO4-ions in water. Would you predict this to result in a solution that is acidic or basic?

The solution would be acidic, as there would be more H+ than OH- ions. This is sulfuric acid.

Experiments are carfully designed in an attempt to ____.

test a single experimental variable which allows you to minimize errors in the interpretation of results.

Organisms that can make their own food are called ____; organisms that must obtain energy from molecules made by other organisms are called _____.

autotrophs, heterotrophs. If organisms do not rely on other living organisms to produce molecules for them to acquire energy then they are considered self-sufficient and referred to as autotraphs, whereas organisms that do rely on other living things to produce molecules for them are called heterotrophs.

A fundamental characteristic of life on Earth is that ____.

living things grow and reproduce, nonliving things do not share this characteristic.

a sample of an organism that is very simple, single cells with no nucleus is what type of organism?

Bacterium-- both bacteria and archaea are prokaryotes (cells without a nuclei) but you are more likely to find a bacterium in your fridge.

prokaryotes

cells without a nuclei

The process of evolution involves ______.

natural selection of organisms that produce more offspring under certain environmental conditions. Natural selection is the primary mechanism for populations to evolve.

The organic complexity and organization of living organisms depends on the periodic capture of raw materials and energy. Ultimately, the source of this energy is ____.

the sun. Energy from the sun converted by photosynthetic organisms (plants, algae, and certain bacteria) is passed along the food chain through the vast majority of organisms. Deep-sea organisms are an exception, depending on geothermal energy that vents through rifts in the seafloor, as sun energy cannot reach their location.

NASA scientist discovered an organism in outerspace that contains its genetic material in the cytoplasm rather than in a nucleus. Given this characteristic, how might you classify this organism?

prokaryote, they do not contain a nucleus so their DNA is present in the cytoplasm.

The diversity of life is mainly due to ________.

genetic variation, most traits that cause living organisms to differ from one another are controlled by genes/DNA.

If the 7 characteristics for living organisms could be condensed into two general descriptive properties exclusive to all living organisms, what would they be?

macromolecular complexity and multiple levels of organization. Living organisms are composed of organic macromolecules arranged along hierarchical levels of organization.

Simple experiments generally isolate and test one ____ at a time.

variable- which is the condition that is being tested in the experiment.

An autotrophic organism ____.

would be one that derives its energy from a renewable external energy source such as sunlight (i.e. photosynthetic organisms)

Your baby starts to cry, you assume she's hungry, your statement is a ______.

hypothesis, an educated guess based on past experiences.

Functional groups are __________.

groups of atoms in organic molecules that can participate in certain types of chemical reactions

In chemical reactions, the molecules that take part in the reaction are called reactants. Conversely, molecules produced by a chemical reaction are called products. During the process of polymerization (synthesis of biological polymers), water is a __________, and the reaction is consequently called a __________ reaction.

by-product, dehydration

Carbohydrates are a class of biological molecules that include __________.

sugars and polymers of sugars

ring-shaped molecules that are soluble in water

monosaccharides, disaccharides, and polysaccharides

components of DNA and RNA

The general class of biological molecules that contains large, nonpolar regions that make these molecules insoluble in water is called __________.

lipids

Saturated fats _______.

have no double covalent bonds

are solid at room temperature

contain the maximum number of hydrogen atoms possible

Phospholipids contain a "head group" that is _________ and two fatty acid "tails" that are __________.

hydrophilic, hydrophobic

Proteins are polymers of __________.

amino acids

Protein functions in cells include __________.

catalysis of biochemical reactions

structure and movement

storage and defense

transport and defense

A nucleotide is composed of __________.

a sugar, a phosphate group, and a nitrogen-containing base

Imagine that you see a diagram of molecular structures in which the atoms are shown as dots and covalent bonds are shown as lines between the dots. The molecules in the diagram have a variety of complex shapes, including long chains, branched chains, rings, and combinations of chains and rings. What type of molecules are these and what is the key atom in them?

The complex structures of these molecules indicate that they are organic molecules and, therefore, contain carbon.

How are large organic molecules (macromolecules) synthesized?

by a dehydration reaction utilizing monomers

Carbohydrates __________.

can exist as monomers (monosaccharides), dimers (disaccharides), and polymers (polysaccharides)

can function as a source of energy or can function as an extremely durable structural material, depending upon the specific nature of their chemical bonds between subunits (monomers)

have the general chemical formula of (CH2O)n

A cell membrane is primarily composed of __________.

phospholipids

Proteins are macromolecules that can perform many different functions within an organism. This diversity of function for this macromolecule is due to the unique nature of one of its four functional groups that is bound to a central carbon atom. Which functional group is responsible for the wide diversity of function attributed to proteins?

the R group

The quaternary level of protein structure __________.

refers to a functional (biologically active) complex of two or more three-dimensional proteins (e.g., hemoglobin)

Nucleotides __________.

are found in nucleic acids, intracellular messenger molecules, and high-energy molecules

All of the following are polysaccharides

glycogen

starch

cellulose

glucose is a

monosaccharide

You have identified a protein that is unable to form disulfide bridges. This would affect which of the following?

tertiary structure of the protein

All of the following are proteins

enzymes and antibodies

What types of biological molecules transport fat molecules through the human bloodstream?

lipoproteins

Which of the following is not found in DNA?

uracil-- this is only found in RNA.

the following are present in DNA

adenine, guanine, cytosine, anad thymine

Individual subunits of large organic molecules are called _______.

monomers polymers. A train made of many individual cars is an example of these.

A carbohydrate consisting of just one sugar molecule is called a ________.

monosaccharide - it means "single sugar"

When two or more single sugars are linked together, they form a _____.

polysaccharide, which means "many sugars"

Oils, fats, and waxes are similar in that they all contain one or more ______.

fatty acids, which are long chains of carbon and hydrogen.

Proteins are polymers of ____.

amino acids which consist of amino group and a carboxyl group.

The primary structure is the sequence of amino acids in a protein, while the _______ is the three-dimensional appearance of a protein.

tertiary structure. These are the first and third levels of protein structure.

the following are functions of polysaccharides in organisms:

formation of cell walls

structural support

formation of exoskeletons

energy storage

Characteristics of carbon that contribute to its ability to form an immense diversity of organic molecules include its:

tendency to form covalent bonds

ability to bond with up to four other atoms

capacity to form single and double bonds

ability to bond together to form extensive, branched or unbranched carbon skeletons

Foods that are high in fiber are most likely to be derived from

plants

Proteins differ from one another because

the sequence of amino acids in the polypeptide chain differs from protein to protein

Which of the following statements about lipids is false?

The body doesn't need any cholesterol.

True statements about lipids :

Beef fat is highly saturated.

Both male and female sex hormones are steroids.

Unsaturated fats are liquid at room temperature.

A wax is a lipid.

Energy, like gasoline for your car, is required for organisms to survive, and even thrive, in the face of diverse environments. An autotrophic organism __________.

would be one who derived its energy from a renewable external energy source such as sunlight (i.e., photosynthetic organisms)

would include cucumbers growing in your garden

Another way to describe the "scientific method" would be that it is __________.

dependent upon observations leading to a hypothesis and careful experimental design and scrutiny of experimental results (data), leading to a conclusion that refutes or supports the hypothesis

a conceptual and ethical framework that guides scientific inquiry

dependent upon "getting the word out" to other scientists via peer-reviewed publications, including electronic journals

Natural selection is best measured by __________.

reproductive success

Which of the following terms includes all of the others?

molecule. An atom is the building block of a molecule.

The units of heredity that provide information needed to control life are the _____.

genes.

The most important force in evolution is ______.

natural selection

Structures, physiological processes, or behaviors that aid survival and reproduction in a particular environment are _____.

adaptations

A ______ is a supposition of prediction, based on previous observations, that is given as a possible explanation for an observed phenomenon

hypothesis

the following are paired correctly:

cytoplasm—watery substance within cells that contains organelles

cell—the smallest unit of life

plasma membrane -surrounds each cell

genes—units of heredity

Choose the answer that best describes the scientific method

observation, hypothesis, experiment, conclusion

the following are characteristics of living things

They reproduce.

They respond to stimuli.

They are complex and organized.

They acquire energy

The three natural processes that form the basis for evolution are

genetic variation, inheritance, and natural selection

The basic structural units of chemistry and life are __________.

atoms

Ions are atoms that have __________.

gained or lost an electron

Chemical bonds __________.

are interactions between the outermost electron shells of atoms

are the forces that hold atoms together in molecules

result when atoms gain or lose one or more electrons

result when atoms share one or more electrons

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