Which of the following is true about scientific knowledge?
scientific knowledge is not absolute, because the possibility is always held open that the new experimental evidence may one day demonstrate new information that changes understanding
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Scientific theories do not represent speculations or guesses about the natural world. Rather they are explanations for natural phenomena that have been:
a. so strongly and persuasively supported by empirical evidence that the scientific community views them as unlikely to be altered by new evidence
The ocean is becoming increasingly acidic, one of the many effects of climate change.
A researcher wants to understand the role that acidic conditions play in oyster growth so she sets up an experiment. She predicts that lower aquatic pH conditions will be harmful to oyster growth. She grows oysters in two tanks of saltwater: one tank has a neutral pH and another is acidic.
She finds that oysters grow poorly in acidic conditions. What is the (1) null hypothesis; (2) the alternative hypothesis; and (3) which was supported in this experiment?
a. that growth would be the same in both tanks; that oyster growth would be negatively impacted by more acidic conditions; the alternative hypothesis was supported.
In question 3- what is the independent variable?
e. the pH of the water in the tanks
Your friend believes astrology should be considered a scientific discipline and you want to explain to her why it is not. Which of the following arguments is the MOST sound reason why astrology is not considered a true scientific discipline?
d. astrology cannot be tested and supported by controlled experiments
The liver releases glucose into the bloodstream if you don’t eat for a long time. This represents an example of a characteristic possessed by all living things.
Which is it?
a. maintaining a relatively constant internal environment
What is meant by the statement “life is thermodynamically unstable”?
e. living things import order and export entropy which keeps them from being at equilibrium with their environment
When Pasteur tested the hypothesis of spontaneous generation, he compared the ability of a sterilized growth medium (meat broth) to produce a population of bacteria in two different types of flasks. One had a simple neck open to the outside, and the other had a “goose neck” bend that also was open to the environment. Pasteur expected that bacteria would appear in the flask with the standard neck.
In this experiment, the standard neck flask served as a/an:
The discrediting of a scientist who published work that claimed to establish a link between the measles, mumps, and rubella vaccination and the rise in autism revealed one of the ways science is designed to seem correct, because ultimately the results were not:
Why is carbon such a critical element to life?
a. it forms 4 stable bonds so it can form complex molecules and t is electroneutral, meaning it shared the electrons equally
Chemistry is driven by:
e. both A and C
What is it about carbon-12, carbon-13, and carbon-14 that makes them all carbon?
d. they all have the number of protons that is characteristic of carbon
What is the difference between an ionic and covalent bond?
a. in an iconic bond, one atom accepts electrons from the other; in a covalent bond, a pair of atoms share electrons
In some vintage science fiction movies, space travelers find themselves on a planet orbiting a distant star in which there are curious forms of life based on silicon instead of carbon.
Although the story clearly is sci-fi, there is an aura of plausibility that the choice of silicon, an atom with 14 protons, in place of carbon as this alien life- form’s central atom. The reason is that silicon:
c. has four electrons in its outermost shell
Chlorine has an atomic number of 17, and argon has an atomic number of 18. From this information alone, you can predict that:
chlorine is more chemically reactive than argon
A polar covalent bond results when:
b. one of the atoms sharing electrons is more electronegative than the other atom
What do polysaccharides, nucleic acids and proteins have in common?
b. they are all built of chemically linked monomers
In a nucleic acid there are ______ components of a nucleotide which are:
a. 3; sugar, phosphate group, nitrogenous base
Molecules of water “stick” to each other because:
d. hydrogen bonds form between the hydrogen atom of one molecule and the oxygen atom of another molecule
This is a molecule of cholesterol. What type of biological molecule is it?
e. both A and D
Which of the following describes an accurate difference between prokaryotic and eukaryotic cells?
eukaryotes have a nucleus, prokaryotes do not
Cystic fibrosis is a genetic disorder which is the result of mucus buildup from cells leading to breathing problems ultimately caused by:
a. an abnormal chloride channel transport protein in the cell membrane
Many antibiotics work by blocking the function of ribosomes. Therefore, these antibiotics will:
a. block protein synthesis
Butter, which is made from milk fat, tends to be harder at room temperature than most margarines. If you wanted to make a butter that is softer at room temperature, you should consider:
d. creating more double bonds in the fatty acid chains
The _______ of a phospholipid molecule will seek water, whereas the ________ of the molecules will avoid water, thereby forming the cell membrane.
hydrophillic head; hydrophobic tail
Which of the following is true of cellulose?
a. plants cell walls are made up of cellulose
Glycogen is a polysaccharide used for energy storage by:
Which choice below correctly matches organelle with function?
smooth endoplasmic reticulum- lipid production
Membrane proteins perform all of the following functions except:
e. maintenance of membrane flexibility
What maintains cell shape, anchors organelles in place, and moves materials within a cell?
In simple diffusion molecules move ______ until they are ______
e. down their concentration gradients; evenly distributed
Short chains of sugars attached to proteins or phospholipids in the cell membrane make up the:
Which of the following lipids is the primary component in the cell membrane?
Facilitated diffusion is similar to simple diffusion because:
in both, materials move down their concentration gradient
Insulin and many other hormones are protein molecules. Based on your knowledge of transport processes, you can say that cells that secret these types of hormones do so through:
One difference between passive and active transport through a cell membrane is that:
b. active transport requires ATP
Proteins that are composed of more than one polypeptide chain are said to have ______ structure.
It seems that bacteria and molds should grow well in jam. It’s extremely high in sugar, a substance many cells can use for energy, and contains enough other nutrients to support cell growth.
Yet jam can be left unrefrigerated for a very long time without contamination by microorganisms. How can this be?
d. the high sugar concentration causes bacterial and mold cells to shrink and die due to hypertonic conditions
You shake up a bottle of vinegar and oil dressing to mix it each time you use it. The reason you need to do this is that:
c. oil is hydrophobic and won’t dissolve in vinegar, so the oil and vinegar separate upon standing
The monomers of polysaccharides are:
Unsaturated fatty acids like those found in plants:
a. have one or more double bonds between the carbons
Every protein has a unique shape and function because:
each protein has a unique sequence of amino acids
Nucleotides are the building blocks for:
e. DNA, and RNA
You isolate a cell with the following characteristics: (1) no nucleus, (2) only a single type of organelle, and (3) 2 um in size (really small). This cell could be a/an:
A secretory protein that exists from the endoplasmic reticulum within a vesicle will head directly to the:
c. golgi complex
Which of the following is a function of the nucleolus?
c. to synthesize ribosomal RNA
Cells can increase the number or size of some organelles in response to new demands. The amount of one organelle often is increased dramatically in the livers of alcoholics or other substances abuser. Based on what you know of organelle function, this organelle is the:
smooth endoplasmic reticulum
Tay-Sachs disease results from the accumulation of fatty deposits within neurons, when normally they should be broken down within these cells. The organelle that would be defective in Tay-Sachs would therefore likely be the:
Which organelles are believed to have originated from free-standing bacteria ingested by ancient eukaryotic cells?
d. mitochondria and chloroplasts
The ultimate source of energy for the most life on Earth is:
b. the sun
You owe your life to chloroplasts. The reason for this is that:
chloroplasts produce the oxygen we breathe and ultimately are the source of most nutrients we consume
What is the relationship between genes and chromosomes?
b. a chromosome is a DNA molecule with many genes
The eukaryotic cell cycle consists of four phases. Which of the following is the correct sequence or order (a cycle can ‘start’ at any point):
a. Gap 2, mitosis, Gap 1, and DNA synthesis
Normal, non-dividing cell operations occur in the “gap” period of interphase called:
What is the initial step in DNA replication?
c. unwinding of the DNA double helix using the enzyme DNA helicase
What is meant by saying one strand of DNA is the template for the synthesis of another strand?
c. the template specifies the order of bases of the new strand being made
What is one way that incorrect nucleotides are removed from a newly synthesized molecule of DNA?
a. DNA polymerases remove incorrect nucleotides and replace them with correct ones
During DNA replication, which of the following statements is TRUE?
b. the leading strand is synthesized in a continuous manner and the other anti-parallel lagging strand is synthesized in fragments and then bonded together by DNA ligase
What is the complementary RNA sequence for a segment of DNA with the sequence ACGACT?
The DNA of cell is analyzed and found to contain 28 percent thymine. What percent of the DNA would be cytosine?
e. 22 percent
There are between 20,000 and 25,000 genes in the human genome, yet our cells are capable of producing more than 90,000 different proteins.
How is this possible?
c. primary transcripts can be edited in different ways by alternative splicing to produce different mRNAs.
Which of the following statements is correct?
a. the more complex the organism, the higher the percentage of the non-coding (codes for protein) DNA it has
What is a codon?
a. a three-base sequence of mRNA that codes for a specific amino acid
What are the products of transcription and translation?
c. mRNA and protein
Cancer is a disease caused by mutations. Yet in most instances if one of your parents tragically died from cancer, this does not put you at greater risk than a person whose parents do not develop cancer. How can cancer be caused by mutations and yet not be heritable?
most cancers arise from mutations in somatic cells
Mitosis results in:
a. daughter cells with the same number and composition of chromosomes
Chromosome I from your mother and chromosome I from your father are said to be homologous. This is because the chromosomes:
have the same genes in the same locations on them
When in meiosis does a cell become haploid?
c. at the end of meiosis I
A cell is said to have reached the metaphase stage of mitosis when:
c. the centromeres have arrived at the equatorial plate
Which of the following are features that distinguish cancer cells from normal cells?
e. both B and D are correct
What is being separated during anaphase of mitosis?
b. sister chromatids
What stage of mitosis does this cell microscope image represent?
What stage of mitosis does this cell microscope image represent?
What stage of mitosis does this cell microscope image represent?
What event occurs in both anaphase of mitosis and anaphase II of meiosis II?
sister chromatids separate
Crossing over in meiosis means the same as:
b. the process by which pieces of homologous chromosomes are exchanged
In anaphase I of meiosis, ______ are separated such that at the end of meiosis I the cells are each ______, and in anaphase II _______ are separated.
d. homologous chromosomes; haploid; pairs of sister chromatids
A diploid cell undergoes meiosis. What are the products of this division?
d. four haploid cells
Kinetic energy is _______ and potential energy is _________.
d. energy that is being used; stored energy
The second law of thermodynamics states that:
d. in energy-yielding reactions, matter goes from a more-ordered to a less-ordered state.
Living things are highly ordered. So why does life not violate the second law of thermodynamics?
b. life takes in energy to maintain order and, in doing so, decreases order elsewhere.
When we metabolize our food, we produce heat that helps to keep us warm. Which of the following best describes why?
b. when we break down our food, the reactions are not 100 percent efficient; therefore, energy is lost as heat.
In a _________, multiple enzymes are working together in a multistep process.
c. metabolic pathway
Enzymes work to speed up a chemical reaction by:
lowering the activation energy of the reaction
Methyl alcohol (wood alcohol) is a common solvent and paint remover. It is poisonous if swallowed. The enzyme alcohol dehydrogenase in the liver converts methyl alcohol into formaldehyde, which then gets converted into a toxic product. Grain alcohol, ethyl alcohol, is also acted upon by alcohol dehydrogenase. One antidote for methyl alcohol poisoning is to make a person drink a lot of ethyl alcohol. This blocks the active site of the enzyme so that it can’t bind to and break down the methyl alcohol.
In this capacity, the ethyl alcohol is acting as a/an:
c. competitive inhibtor
When you digest the starch in plants into glucose, some energy is lost as heat. This increases the __________ of the universe.
Why do biologists believe glycolysis evolved before the Krebs cycle and the electron transport chain?
c. all organisms use glycolysis; not all use the Krebs cycle and the electron transport chain
The Calvin cycle takes place in the:
The majority of ATP in cellular aerobic respiration is produced by:
the electron transport chain
When glucose is the fuel source, what is the correct sequence of stages in cellular respiration?
b. glycolysis, Krebs cycle, electron transport
Chloroplasts transform _________ energy into the _______ energy of ATP.
b. light; chemical
What is the energy source used to drive the enzyme ATP synthase to produce ATP in photosynthesis and cellular respiration?
a. an H+ ion gradient built up across a membrane via a flow of electrons through an electron transport chain
The sugar that first bonds with carbon dioxide in the Calvin cycle is ________ and is captured by the enzyme _________.
c. RuBP; rubisco
Which of the following equations properly summarizes photosynthesis?
c. 6CO2+6H20+photons/sunlight —> C6H1206 +602
A pigment that captures photons, such as chlorophyll a, is found in which part of the plant cell?
a. thylakoid membrane of a chloroplast
During cellular respiration, what molecule collects the majority of the electrons from the food that we eat?
Eukaryotic cells require oxygen to:
c. serve as an electron acceptor in the electron transport chain
Chlorophyll a and the accessory pigments of a photosystem act as an antenna by:
c. absorbing energy from sunlight and passing it on
The products of the light reactions that are then used by the Calvin cycle are:
Both photosynthesis and cellular respiration rely on electron carrier molecules to provide electrons to ultimately help produce ATP. In photosynthesis, the source of electrons is ________ and in cellular respiration the source of electrons is ________.
a. water; glucose
The three main products of glycolysis are:
a. ATP, NADH, and pyruvic acid
The splitting of water in photosynthesis provides:
c. 02 and electrons
In respiration, the end products that come out of the Krebs cycle include all of the following except:
The electron carrier _________ in photosynthesis transports electrons from light reactions to the Calvin Cycle and donates electrons to CO2 so that it can be fixed into sugars is:
What function does sunlight perform in photosynthesis?
e. sunlight excites electrons in chlorophyll to a higher energy level
Cells capture the energy from food and store it in the form of:
How is the information that specifies a gene stored in DNA?
d. in the sequence of bases
Mendel crossed true-breeding pea plants and found the dominant trait always appeared in the F1 generation, but it appeared in a _______ ration of dominant recessive in the F2 generation.
Cystic fibrosis (CF) is caused by a recessive allele. A child has CF, even though neither of his parents has CF.
This couple also has a child who does not have CF. What is the probability the unaffected child is heterozygous?
Dimpled cheeks are dominant to undimpled cheeks. If there exists a 50 percent chance that a child will have dimpled cheeks, the parental genotypes must be:
b. Dd and dd
The Law of Segregation states that:
differing characters in organisms result from two alleles that separate in gamete formation, such that each gamete gets only one of the two alleles.
In humans, the autosomal trait of “unattached” earlobes are dominant over “attached” earlobes. Widow’s-peak hairline is dominant over non-widow’s-peak hairline. Use E and e for the earlobe phenotype alleles and W and w for the hairline phenotype alleles. A woman with unattached earlobes and a widow’s peak and a man with attached earlobes and a widow’s peak have a child.
The child has attached earlobes and a non-widow’s-peak hairline. What are the genotypes of the parents?
c. EeWw and eeWw
The Law of Independent Assortment states that:
a. in gamete formation, gene pairs are transmitted independently of each other.
Let S= smooth pea and s= wrinkled pea; Y= yellow pea and y= green pea. What are the different possible genotypes of the gametes produced by a plant that is heterozygous for both characters?
e. SY, Sy, sY, and sy
In humans, freckles are dominant to no freckles, and unattached earlobes are dominant to attached earlobes.
Two individuals who both have freckles and unattached earlobes have a child with no freckles and attached earlobes. What are the genotypes of the parents? (F= freckles; E= unattached earlobes)
a. FfEe x FfEe
Snapdragons are an example of incomplete dominance. Crossing a true-breeding red-flowered snapdragon with a true-breeding white-flowered snapdragon produces all pink snapdragons in the F1 generation.
If F1 individuals are crossed, what will be the ratio of phenotypes in the F2 generation?
d. 1 red: 2 pink: 1 white
A woman who is a carrier for the hemophilia gene has a child with a man who does not have hemophilia. Which prediction is correct?
d. half of the sons and none of the daughters will have hemophilia
Nondisjunction in meiosis gives rise to gametes with abnormal chromosome numbers. Which event is likely to produce a higher percentage of abnormal gametes?
failure of homologous chromosomes to separate at meiosis 1
A, B, and O blood type in humans is controlled by a single gene with three alleles: A, B, and O. Type O is the recessive trait. The O allele is recessive to both A and B. Which of the following could be possible genotypes of the parents of a person with type O blood?
e. both A and D answer choices
A woman who does not carry the color-blindness allele has children with a man who is color blind. What proportion of their children will be color blind?
An autosomal recessive disorder:
will appear only in children of parents who both carry the gene
Why do X-linked conditions appear more frequently in males than in females?
a. a male with a nonfunctioning allele on the X chromosome does not have another allele of that gene on the Y chromosome that could cover up the nonfunctioning one
A person who is heterozygous for the Huntington disease (HD) allele has offspring with someone who does not have HD. What proportion of their children will have HD?
Nondisjunction in somatic cells can result in aneuploid cells.
This may give rise to:
Which statement is a characteristic of plasmids?
a. they can be used to create recombinant DNA
Scientists have developed tobacco plants have had a gene from fireflies inserted into them which makes them glow.
These tobacco plants would be considered:
b. transgenic organisms
What is the function of restriction enzymes in bacteria?
d. they cut foreign DNA, for example, the DNA of invading viruses
In reproductive cloning, a sperm is not used, but an egg is still required.
d. egg proteins are required for embryonic development.
Biotechnology can be defined as the:
a. use of technology to control biological processes as a means of meeting societal needs
Why is PCR useful?
b. it allows for making many copies of DNA when the starting sample is small
What distinguishes an embryonic stem cell from a somatic cell of an adult organism?
c. embryonic stems cells can produce more of themselves as well as produce specialized cells, but somatic cells are already specialized
In forensic science, DNA fingerprinting is performed using _______ that ________ in order to identify individual suspects with a probability of 1 out of >6 billion people.
d. tandem base repeats; are non-coding regions of DNA
Embryonic stem cells are taken from:
Which choice is an example of “recombinant DNA”?
b. a bacterial plasmid combined with a human gene
What is a “cloning vector”?
b. a DNA vehicle that carries recombinant DNA into cells
Much of the food crops in the United States are transgenic.
This primarily has been done to give the crops what properties?
b. the ability to resist insects and herbicides
The combination of a somatic cell with an enucleated egg cell is:
b. somatic cell nuclear transfer
“By cotton” refers to cotton that:
c. is resistant to insect pests
It is beneficial for children in underdeveloped countries to eat genetically modified “golden rice,” rather than regular rice, because golden rice:
d. produces a vitamin A precursor, which helps prevent blindness in children
Which of the following is a correct sequence of events in the history of life on Earth?
b. prokaryotes, photosynthesis, eukaryotes, land organisms
In order for natural selection to influence a population, what must be true of a trait?
b. the trait must be variable in the population, heritable and there must be differential reproductive success based on the trait
Disruptive selection operates whenever:
the extremes in a distribution of phenotypes are more fit than the intermediate phenotypes
Habitats set aside for endangered species are often sectioned into areas by roads, producing separate small populations. This causes problems in conservation because it:
a. reduces gene flow between populations
In the absence of geographic barriers, _______ speciation may occur when reproductive isolating mechanisms develop between two populations.
Which of these gases was absent in the early Earth atmosphere at the time life first appeared?
To be a successful cell evolutionary, the earliest cells had to:
Which of the following statements best describes the history of life on Earth?
e. both A and D are correct
Modern whales have bones that are remnants of a pelvis and legs that serve no function. This would be an example of a/an:
b. vestigial character
Comparison of gene sequences among species has revealed:
a. the greater the similarities in gene sequences, the more recently two species shared a common ancestor
The limbs of animals such as whales, cats, bats, and humans contain the same set of bones organized in similar ways yet have dissimilar functions. These structures are said to be:
At its most basic level, evolution is a:
c. change in the frequency of alleles in a population
The formation of new species over many generations is an example of:
Imagine a population of monkeys in South America whose habitat has been reduced to the point where only 25 monkeys survive out of an original population of 2000.
This is an example of:
a. population bottleneck
Shrews have been documented to travel across frozen lakes and establish populations on previously uninhabited islands. If this migration leads to a gene pool with allele frequencies that are very different from the allele frequencies found in the original source population, then this would be an example of:
Evolution by genetic drift is most obvious in ________ making it a concern in the conservation of species:
b. small populations
The term “natural selection” is not interchangeable with the term “evolution” because:
c. a population may evolve through mechanisms other than natural selection
Male guppies are known for their bright colors. Having bright colors attracts mates, but it also attracts predators. So in an environment with a lot of predators, male guppies have more dull colors. In an experiment, guppies were removed from an area with predators to an area without predators. Over a period of 12 months the population became much more colorful.
This is an example of a response to:
c. directional selection
Charles Darwin was influenced by three scientists of his time who studied geology, fossils, and biology: Charles Lyell, Georges Cuvier and Jean-Baptiste de Lamarck. What common theme from their work inspired Darwin’s theory of evolution through natural selection?
a. the world is not static; it is constantly changing
The major weakness of Charles Darwin’s theory during his lifetime was the:
b. lack of a mechanism to explain how traits were passed to offspring intact when most believed inheritance worked through blending
Both Charles Darwin’s and Alfred Russel Wallace’s work on the Theory of Evolution were influenced by the writings of the economist Thomas Malthus’s on the topic of:
b. exponential population growth
A population with an S-shaped growth curve is said to exhibit ______ growth, limited by ________.
e. logistic; carrying capacity