Biology Questions

A black guinea pig crossed with a guinea pig with albinism produced 12 black offspring When the albino was crossed with a second black animal six blacks and six albinos were obtained What is the best explanation for this genetic situation Albinism is a dominant trait black is incompletely dominant Albinism is a recessive trait black is codominant Albinism and black are codominant Albinism is a recessive trait black is a dominant trait

Most repressor proteins are allosteric Which of the following molecules binds with the repressor to alter its conformation and therefore affect its function O promoter CAMP transcription factor

Starting with a fertilized egg zygote a series of six cell divisions would produce an early embryo with how many cells 32 12 16 64

Albinism is a recessive trait A man and woman both show normal pigmentation but both have one parent who has albinism without melanin pigmentation What is the probability that their first child will have albinism 01 1 2 1 4

When taken up by a cell which of the following molecules binds to a repressor so that the repressor no longer binds to the operator Opromoter Orepressor Ocorepressor

What is meant by the description antiparallel regarding the two strands that make up the DNA double helix The double helix structure of DNA creates nonparallel strands Base pairings create unequal spacing between the two DNA strands One strand contains only purines and the other contains only pyrimidines The 5 to 3 direction of one strand runs counter to the 5 to 3 direction of the other strand

In yeast signal transduction a yeast cell releases a mating factor which diffuses through the membranes of distant cells causing them to produce factors that initiate long distance migrations binds to receptors on the membranes of other types of yeast cells acts back on the same cell that secreted the mating factor changing its development passes through the membranes of neighboring cells binds to DNA and initiates transcription

Not all intercellular signals require transduction Which one of the following signals would be processed without transduction a signal that is weakly bound to a nucleotide a lipid soluble signal a signal that binds to a receptor in the cell membrane a signal that binds to the extracellular matrix

At which phase of the cell cycle do centrioles begin to move apart in animal cells Otelophase anaphase metaphase prophase

A triploid cell contains three sets of homologous chromosomes If a cell of a diploid species that normally has 42 chromosomes per cell is triploid this cell would be expected to have which of the following sets of chromosomes 63 chromosomes in 21 sets of 3 63 chromosomes each with 3 sister chromatids 21 chromosome pairs and 21 unique chromosomes 63 chromosomes in 31 1 2 pairs

What is a primary function of transcription factors They regulate the release of calcium from the endoplasmic reticulum They convert ATP into CAMP They control gene expression They regulate the synthesis of DNA in response to a signal

Mendel s law of independent assortment has its basis in which of the following events of meiosis I alignment of pairs of homologous chromosomes along the middle of the cell the division of cells at telophase synapsis of homologous chromosomes crossing over of homologous pairs of chromosomes

Certain cell types normally have several nuclei per cell How could such multinucleated cells be explained The cell had multiple S phases before it entered mitosis The cell underwent repeated mitosis with simultaneous cytokinesis The cell underwent repeated cytokinesis but no mitosis The cell underwent repeated mitosis but cytokinesis did not occur

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication It synthesizes RNA nucleotides to make a primer It stabilizes the unwound parental DNA O It unwinds the parental double helix It joins Okazaki fragments together

When a neuron responds to a particular neurotransmitter by opening gated ion channels the neurotransmitter is serving as which part of the signal pathway transducer Oresponse molecule relay molecule signal molecule

In which of the following ways do plant hormones differ from hormones in animals Plant hormones commonly travel through the soil from one plant to another Animal hormones typically travel from the hormone producing cell to an adjacent responding cell through gap junctions Animal hormones are only local regulators Plant hormones frequently travel through the air as a gas

Which of the following statements is true of a species that has a chromosome number of 2n 16 The species has 16 sets of chromosomes per cell A gamete from this species has four chromosomes Each diploid cell has eight homologous pairs of chromosomes The species is diploid with 32 chromosomes per cell

Within a double stranded DNA molecule adenine forms hydrogen bonds with thymine and cytosine forms hydrogen bonds with guanine What is the significance of the structural arrangement It determines the tertiary structure of a DNA molecule It allows variable width of the double helix It permits complementary base pairing It determines the type of protein produced

How does extracellular glucose inhibit transcription of the lac operon by strengthening the binding of the repressor to the operator O by inhibiting RNA polymerase from opening the strands of DNA to initiate transcription by weakening the binding of the repressor to the operator by reducing the levels of intracellular CAMP

The genetic code is essentially the same for all organisms From this one can logically assume which of the following statements to be true A gene from an organism can theoretically be expressed by any other organism The same codons in different organisms translate into different amino acids DNA was the first genetic material Different organisms have different types of amino acids

In pea plants the tall phenotype is dominant to the dwarf phenotype If a heterozygous pea plant is crossed with a homozygous tall pea plant what is the probability that the offspring will be dwarf in size 01 1 4 01 2 0

For each of the following indicate whether the condition will cause the membrane potential to become more positive more negative or largely unchanged when compared to the normal physiological resting membrane potential Drag the appropriate items to their respective bins View Available Hint s More Positive Double the size of the cell without adding channels Double the concentration of K outside the cell Double the number of closed channels for K Double the number of K leak channels More Negative Triple the number of Na leak channels Decrease the concentration of Nat outside the cell by half Largely Unchanged Reset Help

The individual with genotype AaBbCCDdEE can make many kinds of gametes Which of the following correctly describes why this situation is possible different possible assortment of chromosomes into gametes occurs there is a tendency for dominant alleles to segregate together recurrent mutations form new alleles crossing over during prophase I leads to genetic variety

Listen In E coli there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin of replication Which of the following events would you expect to occur as a result of this mutation No replication fork will be formed Replication will occur via RNA polymerase alone Replication will require a DNA template from another source Additional proofreading will occur

Which of the following statements describes the chromosomal makeup of each daughter cell after telophase of meiosis l The cells are haploid and the chromosomes are each composed of two chromatids The cells are diploid and the chromosomes are each composed of a single chromatid The cells are haploid and the chromosomes are each composed of a single chromatid The cells are diploid and the chromosomes are each composed of two chromatids

FtsZ is a bacterial cytoskeletal protein that forms a contractile ring involved in binary fission Its function is analogous to the cell plate of eukaryotic plant cells O the mitotic spindle of eukaryotic cells the microtubule organizing center of eukaryotic cells the cleavage furrow of eukaryotic animal cells

In a diploid cell with 5 chromosome pairs 2n 10 how many centromeres will be found in a nucleus at G2 of the cell division cycle 40 20 5 10

Which of the following statements supports the one gene one enzyme hypothesis A mutation in a single gene can result in a defective protein Multiple antibody genes can code for different related proteins depending on the splicing that takes place post transcriptionally Sickle cell anemia results in normal hemoglobin O Alkaptonuria results when individuals lack multiple enzymes involved in the catalysis of homogentisic acid

Which of the following events happens at the conclusion of meiosis l Four daughter cells are formed Homologous chromosomes of a pair are separated from each other Sister chromatids are separated The chromosome number per cell remains the same

In what way do kinetochore microtubules facilitate the process of splitting the centromeres They use motor proteins to hydrolyze the centromere at specific arginine residues They slide past each other like actin microfilaments They phosphorylate the centromere thereby changing its conformation They create tension by pulling toward opposite poles

Which of the following processes might produce a human zygote with 45 chromosomes failure of the egg nucleus to be fertilized by the sperm failure of an egg to complete meiosis Il an error in meiotic anaphase occurring in either an egg or sperm incomplete cytokinesis during spermatogenesis after meiosis I

How do cells at the completion of meiosis compare with cells that are in prophase of meiosis l The cells have half the amount of cytoplasm and twice the amount of DNA The cells have half the number of chromosomes and one fourth the amount of DNA The cells have half the number of chromosomes and half the amount of DNA The cells have the same number of chromosomes and half the amount of DNA

During which of the following processes do sister chromatids separate from each other during meiosis I only during both mitosis and meiosis I during meiosis II only during both mitosis and meiosis II

Which of the following processes occurs in meiosis but not in mitosis synapsis of chromosomes chromosome replication alignment of chromosomes at the equator condensation of chromosomes

What is the function of the enzyme topoisomerase in DNA replication elongating new DNA at a replication fork by adding nucleotides to the existing chain building RNA primers using the parental DNA strand as a template reattaching the hydrogen bonds between the base pairs in the double helix relieving strain in the DNA ahead of the replication fork caused by the untwisting of the double helix

Which of the following statements correctly describes the primary difference between enhancers and proximal control elements Enhancers improve transcription proximal control elements inhibit transcription Enhancers are DNA sequences proximal control elements are proteins Enhancers are transcription factors proximal control elements are DNA sequences Enhancers are located considerable distances from the promoter proximal control elements are close to the promoter

Metaphase is characterized by O separation of the centromeres alignment of chromosomes on the equator of the cell of sister chromatids Oseparation cytokinesis

Why does testosterone a lipid soluble signaling molecule that crosses the membranes of all cells affect only target cells Intracellular receptors for testosterone are present only in target cells Only target cells possess the cytosolic enzymes that transduce the signal from testosterone to adenylyl cyclase O Only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor Only target cells retain the appropriate genes regulated by testosterone

Yeast cells of mating type a are genetically engineered to produce only mating factor a instead of the normal mating factor a The gene for the mating factor receptor was unaltered How will these engineered cells behave in terms of mating They will mate with each other or with normal mating type a cells but not with normal mating type a cells They will only mate with normal mating type a cells They will only mate each other and not with normal mating type a or a cells They will only mate with normal mating type cells

What role do phosphatases play in signal transduction pathways They inactivate protein kinases to turn off signal transduction They amplify the second messenger CAMP O They transfer a phosphate group from one protein in the pathway to the next molecule in the series They activate protein kinases by phosphorylation

Which of the following processes would result from a mutation that deactivates a regulatory gene of a repressible operon in an E coli cell complete inhibition of transcription of the structural gene controlled by that regulator continuous translation of the mRNA because of alteration of its structure irreversible binding of the repressor to the operator continuous transcription of the structural gene controlled by that regulator

Which of the following statements describes the process of transformation in bacteria A strand of DNA is created from an RNA molecule External DNA is taken into a cell becoming part of the cell s genome Bacterial cells are infected by a phage DNA molecule A strand of RNA is created from a DNA molecule

What is the function of the release factor during translation in eukaryotes It releases the ribosome from the ER to allow polypeptides into the cytosol It releases the amino acid from its tRNA to allow the amino acid to form a peptide bond It binds to the stop codon in the A site in place of a tRNA It supplies a source of energy for termination of translation

A signal transmitted via phosphorylation of a series of proteins is generally associated with which of the following events O production of ATP in the process of signal transduction activation of a ligand gated ion channel O binding of a hormone to an intracellular receptor conformational changes to each protein in the series

During which phase of mitosis do the chromatids become chromosomes Ometaphase prophase anaphase telophase

What is the name of the microtubule organizing center found in animal cells as an identifiable structure present during all phases of the cell cycle centromere O centriole kinetochore centrosome

Eukaryotic chromosomes are composed of which of the following macromolecules ODNA and RNA ODNA and proteins DNA and phospholipids ODNA only

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE 64 16

Which of the following statements correctly explains the fact that all seven of the pea plant traits studied by Mendel obeyed the principle of independent assortment All of the genes controlling the traits were located or he same chromosome All of the genes controlling the traits behaved as if they were on different chromosomes The diploid number of chromosomes in the pea plants was seven None of the traits above

Listen Why did all of the F offspring of Mendel s classic pea cross always look like one of the two parental varieties The traits blended together during fertilization Each allele affected phenotypic expression One allele was dominant No genes interacted to produce the parental