Launchpad Quizzes
Which one of the amino acids is capable of forming a disulfide linkage with itself?
cysteine
An organism that carries out cellular respiration in its mitochondria:
could be a cell from a terrestrial (land) plant.
For the first three rows of the periodic table, elements in the same row have the same number and type of ________________.
electron orbitals
Which one is responsible for the addition of amino acids after translation initiation has begun?
elongation factors
Antennae work with reaction centers by providing:
energy transfer.
The controlled release of cellular material stored in membrane-bound vesicles to the outside of the cell is an example of:
exocytosis.
What correctly describes the role of cell junctions?
Adherens junctions are cell junctions that anchor cells to other cells.
Which of the elements would most likely have bonding properties similar to nitrogen (N)? Consult the periodic table provided if necessary. Sulfur Oxygen Silicon Carbon Phosporus
phosphorus (P)
Which protein level best matches the description "blocks on a string"?
primary
Which particles are pumped across the lysosomal membrane by a transport protein to create a special internal environment in the lysosome?
protons
Nicotine from cigarette smoke acts as a ligand and associates with specific proteins on the surface of cells in the brain, causing feelings of pleasure and well-being. In the following four questions, select the appropriate event in the cellular response to nicotine.
receptor activation.
During lactic acid fermentation, pyruvate is:
reduced
Complex macromolecular structures on which protein synthesis takes place are referred to as:
ribosomes
Translation is the process by which:
ribosomes synthesize protein from information in an RNA molecule.
You are given two true-breeding groups of rabbits. The first group has floppy ears and white fur. The second group has straight ears and black fur. When you perform a cross of these two groups to obtain an F1 generation you see that all of your rabbits have floppy ears and gray fur. Which of the possibilities appears to be supported by what you see in the F1 generation?
Floppy ears are dominant over straight ears; fur color is determined by incomplete dominance.
Which of the substances would be an example of a peripheral membrane protein associated with the plasma membrane of a cell?
Grb2, a protein that binds to the intracellular domain of the Epidermal Growth Factor Receptor when it is activated
During photosynthesis in plants and algae, ____ is oxidized and ____ is reduced.
H2O; CO2
A _____ square is a useful diagram to show the results of an F1 x F1 cross.
Punnett
The assembly of glucose molecules into polysaccharides is a(n) _____ process.
anabolic
In this interpretation of a photosystem, the item labeled 1 is a(n) _____ and its main function is to _____.
antenna chlorophyll; capture light energy from the sun
Which regulatory mechanisms are important in keeping glycolysis and the citric acid cycle in relative balance to each other? Select all that apply. - ATP inhibits phosphofructokinase-1 - ADP up-regulates phosphofructokinase-1 -AMP up-regulates phosphofructokinase-1 -Citrate inhibits phosphofructokinase-1
- ATP inhibits phosphofructokinase-1 - ADP up-regulates phosphofructokinase-1 -AMP up-regulates phosphofructokinase-1 -Citrate inhibits phosphofructokinase-1
Which of the outcomes represents the expected genotypes of an F1 generation consisting of 16 individuals from a cross of a true-breeding black (BB) rabbit and a true-breeding white (bb) rabbit?
0 BB, 0 bb, 16 Bb
A true-breeding black rabbit is crossed with a true-breeding white rabbit to produce an F1 generation with eight individuals. If blending inheritance were true, which of the outcomes would represent the expected phenotype of the F1 generation?
0 black rabbits, 0 white rabbits, 8 gray rabbits
Which number represents the pH of a solution with the highest concentration of hydrogen ions?
1.0
Consider a diploid organism with a haploid complement of 4 chromosomes in its gametes. At meiotic prophase I, how many total chromosomes copies will be present in a cell?
16; 4 pairs of homologous chromosomes and 2 sister chromatids per chromosome
How many chromosome pairs are there in a normal human genome?
23
Starting from glucose, lactic acid fermentation results in _____ molecules of lactic acid, each with _____ carbons, whereas ethanol fermentation results in _____ molecules of ethanol, each with _____ carbons.
2; 3; 2; 2
It is actually the component of a 30S ribosomal subunit that is responsible for recognition of a Shine-Dalgarno sequence on an mRNA. Which one of the sequences in the 16S rRNA would you predict is responsible for the interaction between a small subunit and mRNA?
3'-UCCUCCA-5'
How many residues separate amino acids that are stabilized by hydrogen bonds in α helices?
4
The FoxP2 gene is thought to be involved in language in humans. At prophase I, how many copies of the FoxP2 gene are present in a cell? Keep in mind that humans are diploid.
4 copies; 1 on each sister chromatid in a pair of homologous chromosomes
A template DNA strand contains the sequence 5'-ATGCTGAC-3'. The corresponding sequence in the RNA transcript is:
5'-GUCAGCAU-3'.
A template DNA strand contains the sequence 3'-ATGCTGAC-5'. The corresponding sequence in the RNA transcript is:
5'-UACGACUG-3'.
A true-breeding black rabbit is crossed with a true-breeding white rabbit. If the black color trait is dominant, which of the outcomes represents the expected phenotype of an F2 generation consisting of eight individuals?
6 black rabbits, 2 white rabbits, 0 gray rabbits
At the start of mitosis, how many sister chromatids are present in a human cell?
92
In order for a pathway to produce its products, it must have sufficient inputs. Which of the answer choices must be available in sufficient supply for glycolysis to proceed? Select all that apply.
ADP Glucose (or other sugar) ATP NAD+
What would happen if a pair of sister chromatids only connected to the mitotic spindle at one of their kinetochores? -One of the daughter cells would have an extra copy of that chromosome. -The sister chromatids would not separate. -All of these choices are correct. - Each chromatid is pulled to the opposite pole by a spindle fiber. If the spindle fiber was not attached to one of the chromatids, it would not separate from the other chromatid, and both would end up in the same daughter cell. -The chromosome would not line up properly at metaphase.
All of them
Ligand binding to a receptor kinase results in: -phosphorylation of the cytoplasmic domain of the receptor. -receptor dimerization. -binding of cytoplasmic signaling molecules.
All of these
Imagine that a researcher tries to reduce the size of an enzyme by removing all the amino acids from the protein except those flanking, and constituting, the active site. Why wouldn't this work? -The removal of the amino acids will likely affect the shape of the active site. -The removal of the amino acids may affect the ability of the enzyme to bind to substrates. -All of these choices are correct. -The balance of the amino acids of the full protein is critical in creating the 3-dimensional folding of the protein that put the amino acids of the active site into the proper spatial position, and amino acids can also contribute to the chemical environment of the active site. -Without the additional amino acids, the protein may not fold properly.
All of these are correct
Microtubules increase in length: -by lengthening outward from the centrosome. -in cycles, following rapid depolymerization. -more quickly at one end than the other. -by adding tubulin dimers to the ends. -All of these choices are correct.
All of these are correct
The prokaryotic protein FtsZ is evolutionarily related to eukaryotic tubulin. What does this mean? -The gene sequence for FtsZ is similar to tubulin. -The amino acid sequence for FtsZ is similar to tubulin. -The two proteins evolved from a common ancestral protein. -All of these choices are correct. -Evolutionarily related genes are similar because they both are derived from a common ancestor. They now differ because of the accumulation of mutations over time, but the prokaryotic and eukaryotic DNA sequences, amino acid sequences, and protein structures still share a resemblance. -The overall protein structure of FtsZ is similar to tubulin.
All of these are right
Imagine that a scientist is able to travel back in time to when the first proteins appeared. What would she observe?
All proteins would be relatively short.
In which of the statements is cell signaling prevented?
Allergy medicines, which are called antihistamines, bind to and block histamine receptors to keep fluids in capillaries that would normally be released and cause stuffy noses and watery eyes.
Nicotine from cigarette smoke acts as a ligand and associates with the acetylcholine receptor on specific cells in the nervous system. Nicotine eventually produces feelings of pleasure and well-being. The listed statements are descriptions of the events that happen in the cellular response to nicotine. Place the events in the correct order to describe the steps in the signaling pathway.A) The acetylcholine receptor is an ion channel, and when a ligand binds, the ion channel opens.B) An influx of ions carries the signal to the reward areas of the brain.C) Nicotine binds to the transmembrane protein that normally binds the neurotransmitter acetylcholine.D) The signal causes release of dopamine in the brain, which causes good feelings.E) Nicotine is quickly eliminated from the body (causing cravings for more cigarettes to produce good feelings).
C; A; B; D; E
During photosynthesis, _____ is reduced to _____.
CO2; triose phosphate
A researcher has devised a technique that allows her to label all the integral membrane proteins with a fluorescent tag. She uses a laser to bleach the fluorescence in a specific area of the cell membrane. After 24 hours, she notices that fluorescence has returned to the bleached area. What can she deduce from this experiment?
Integral membrane proteins are able to move laterally within the cell membrane.
When oxygen is depleted, the citric acid cycle stops. Which of the answer choices would you need to add to the system to restore activity? Select all that apply.
NAD+ FAD
You have learned that mutations can occur in DNA sequences. Are all mutations deadly?
No, some mutations can have no effect or can be beneficial.
Which of the following statements about amino acids is correct? -A turn or kink in a protein is more likely to be induced by a glycine than by a proline. Every amino acid is asymmetric. -The bridge between cysteines, which connects parts of a protein, is a stable covalent interaction. -At typical cellular pH, the R groups of basic amino acids are negatively charged. -The more asparagines that are found in a polypeptide's primary sequence, the more flexible the backbone of that polypeptide.
The bridge between cysteines, which connects parts of a protein, is a stable covalent interaction.
During the signal transduction process, the signal often triggers a signal transduction cascade. For example, a single activated receptor can activate hundreds of protein A molecules. Each activated protein A molecule activates hundreds of protein B molecules, and so on, until a cellular response occurs. What purpose does this cascade serve?
The cascade serves to amplify the signal so one activated receptor can have a significant response.
Predict what would happen if an embryonic epidermal cell switched from expressing E-cadherin to N-cadherin.
The cell would leave the epidermis and adhere to neural cells.
A biologist working in a lab adds a compound to a solution that contains an enzyme and substrate. This particular compound binds reversibly to the enzyme at the active site. Once the compound is bound to the enzyme, the catalysis of substrate to product stops. Which of the statements is true of the compound?
The effect of the compound can be overcome by adding more substrate.
Imagine that several atoms bond to form a carbohydrate, creating a more orderly system. Which of the statements is true regarding the universe after this carbohydrate forms?
The entropy of the universe increases.
A patient in a physician's office has a deep cut, and as it is being stitched up, a sample of tissue is taken for testing. Analysis of the tissue reveals it has few cells, surrounded by a large amount of extracellular matrix proteins with some blood vessels, sweat glands, and nerve cells. What kind of tissue is this?
The tissue is most likely dermis, and should also have some fibroblasts, but few keratinocytes and melanocytes.
What outcomes could happen if a defect in S phase occurred during cell division? Select all that apply.
There could be too few chromosomes. There could be too many chromosomes.
A beaker contains two solutions of salt dissolved in water. The two solutions have different concentrations of salt (measured by molarity, M) and are separated by a membrane that is permeable to both salt and water. The salt and water will move through the membrane by diffusion. Which statement is true about the diffusion of these solutions?
There will be a net movement of salt from side B to side A and net movement of water from side A to side B.
In the citric acid cycle, after the acetyl-group (2C) from acetyl-CoA is transferred to oxaloacetate (4C) to produce citrate (6C), subsequent reactions eventually result in 4C intermediates that are rearranged to regenerate oxaloacetate. What happens to the other two carbons?
They are released as CO2 byproducts.
One of your friends is arguing that viruses are alive. What information would you provide to convince him that viruses can't be considered alive?
Viruses cannot carry out metabolic reactions on their own.
Which of the choices is an example of anabolism?
Which of the choices is an example of anabolism?
Which of the DNA molecules would be more stable under conditions of increasing temperature?
a DNA molecule that has more guanine and cytosine nucleotides
Cadherin is an example of:
a cell adhesion molecule.
A decrease in cell-cell adhesion was caused by the introduction of an experimental substance that compromised the structural integrity of the tissue. Which type of cell junction would most likely be affected by this treatment given that the treatment caused a decrease in the strength of cell-cell adhesion?
adherens junctions
The microtubules that form the mitotic spindle extend out from the centrosome. Where would you expect to find the plus (fast-assembling) end of a spindle microtubule?
away from the centrosome and toward the kinetochore
Why does meiosis result in more genetic variation than can be explained by mutation alone? Select all that apply.
because of the random alignment of maternal and paternal homologs during metaphase of meiosis I AND because of crossing over between homologs during prophase I
Which cytoskeletal elements is/are associated with supporting the movement of materials inside the cell?
both microtubules and microfilaments
How might an enzyme inhibitor slow down the action of an enzyme without binding to the active site?
by binding to another site on the enzyme and changing its shape
Helicase is an enzyme that separates the double helix of the DNA into two separate strands. How do you think helicase does this?
by breaking hydrogen bonds
Carbon dioxide dissolves in water to form:
carbonic acid.
Which of the answer choices correctly lists the three phases of the Calvin cycle?
carboxylation, reduction, and regeneration
What is a pigment associated with chloroplasts that plays a role in energy harvesting?
chlorophyll
pH is a measure of the acidity of a solution and equals the negative logarithm of the proton concentration. When the light is on and the proton pump is activated, the pH:
decreases inside the vesicle and increases outside of the vesicle.
At the end of mitosis, the daughter cells are _____, whereas at the end of meiosis the daughter cells are _____.
diploid; haploid
In meiosis, recombination occurs:
during only prophase I and involves exchange between chromatids of homologous chromosomes.
The bond between the last two phosphate groups in ATP is relatively _____ to break because of the _____ between _____.
easy; repulsion; negative charges
Where would you expect to find the receptor for a nonpolar ligand?
either in the nucleus of the cell or in the cytosol
Most ligands form covalent bonds with their associated receptors, these complexes are more or less permanent and can only be broken through the hydrolysis of ATP.
false
Over time a population of black and white rabbits will progressively become all gray because white fur in rabbits is caused by a single gene mutation.
false
Purified phospholipids mixed in water will only form membranes if the appropriate enzyme is present.
false
Which component of a phospholipid is found in the interior of a lipid bilayer?
fatty acids
Which summary sequence correctly tracks electrons through the overall process of aerobic cellular respiration?
glucose -> electron carriers -> electron transport chain -> water
Based on what you know of ATP's chemistry, which of the substances is most likely to have similar functions in energy-management processes?
guanosine nucleotide triphosphate
A human cell with a total of 23 chromosomes is:
haploid
The poly(A) sequence that is added to RNA during processing:
helps prevent rapid breakdown of the messenger RNA.
A testcross involves crossing with a(n) _____ individual and is used to determine the _____ of the tested parent.
homozygous recessive; genotype
A polymerization reaction is made irreversible by:
hydrolysis of a pyrophosphate group.
When a charged tRNA is about to bind to the vacant A site of a ribosome, where is the growing polypeptide?
in the P site
Where must the SRP receptor be located in a cell?
in the membrane of the rough endoplasmic reticulum
Enzymes present in the lumen of the Golgi apparatus are responsible for modifying proteins and lipids. Where must these proteins have been before they entered the Golgi apparatus?
in the rough endoplasmic reticulum
In skin, the cells of the epidermis connect to the basal lamina through cellular junctions known as hemidesmosomes. Select the cytoskeletal element that helps maintain the integrity of this connection.
intermediate filaments
Which type of receptor is involved in rapid responses of muscle cells and neurons?
ligand-gated ion channel
ATP production in photosynthesis requires:
light, electrons, and protons.
The class of organic molecules defined by a physical property rather than a structure are the:
lipids
Homologous pairs of chromosomes separate during:
meiosis I only.
Which of the choices enable(s) the movement of cells?
microtubules and microfilaments
Select the answer option that arranges the components in order from smallest to largest. -nucleotide, nucleoside, gene, genome -nucleoside, nucleotide, gene, genome -nucleoside, nucleotide, genome, gene -gene, nucleotide, genome, nucleoside - genome, gene, nucleotide, nucleoside
nucleoside, nucleotide, gene, genome
A reproductive cell, or gamete, has:
one allele of each gene.
During the citric acid cycle, the production of CO2 is the result of the _____ of intermediate compounds of the citric acid cycle coupled to the production of _____.
oxidation; NADH
Which type of fatty acid would be likely to have the lowest melting temperature?
short tails and low saturation
During meiosis I:
sister chromatids are not separated.
Photosynthesis is the pathway used to synthesize carbohydrates from:
sunlight, CO2, and H2O.
Insulin signaling through its receptor kinase enables virtually every cell in our body to transport glucose across the plasma membrane into the cytosol. In the next set of questions, select the appropriate event in the cellular response to insulin.
termination
In which of the ribosomal sites does the anticodon of a tRNA pair completely with the mRNA codon?
the A site and the P site
What is an example of a hydrogen bond?
the bond that forms between a hydrogen atom in one water molecule and an oxygen atom in another water molecule
The stroma of the land-plant chloroplast is evolutionarily derived from:
the cytoplasm of cyanobacteria.
Where does the energy come from to add a uracil to the 3' end of a transcript?
the hydrolysis of two phosphate groups from the incoming UTP molecule
Chloroplast ATP synthases are powered by the flow of protons from the:
thylakoid lumen to the stroma.
What is the function of histone proteins?
to package DNA in eukaryotic chromosomes
Why was it important for Mendel to remove the anthers from pea plants in his experiments when crossing two different true-breeding pea plants?
to prevent self-fertilization
A template strand of DNA and a newly transcribed RNA molecule are antiparallel.
true
Observations are used by scientists to draw tentative explanations called hypotheses.
true
There are two stages to the cell cycle: M phase and interphase.
true
Whichever DNA strand is transcribed, the RNA polymerase reads the template strand from 3' to 5'.
true
At night time, Zebrafish embryos change the color of the melanophore cells in their skin to a darker shade by:
using kinesin motor proteins to move pigment granules outward from the center of the cell.
When Mendel crossed true-breeding dominant yellow-seed plants with true-breeding recessive green-seed plants, the offspring were phenotypically:
yellow-seed plants.