ap bio final exam
if 2n=46 which of the preceding is true at the end of meiosis i
23 pairs of chromosomes
If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be
2x
If fa cell has 46 chromosomes at the beginning of meiosis, then at anaphase I there would be a total of
46 chromosomes In metaphase I, homologous chromosomes pair at the metaphase plate. If cell started with 46 chromosomes, 23 chromosomes move to each side during anaphase II so total is still 46 chromosomes Meiosis I -- chromosomes don't separate into chromatids
if a cell has 46 chromosomes at the beginning of mitosis then at the end of anaphase there would be a total of
92 chromosomes
The diagram above illustrates feedback control as exerted by the hormone thyroxine. Following surgical removal of the thyroid gland, the level of TSH in the blood will increase. Which of the following best explains this increase?
A decrease in thyroxine levels means a loss of inhibition to the hypothalamus and anterior pituitary, leading to increased TSH secretion.
The mechanism of action of many common medications involves interfering with the normal pathways that cells use to respond to hormone signals. Which of the following best describes a drug interaction that directly interferes with a signal transduction pathway?
A medication enters the target cell and inhibits an enzyme that normally synthesizes a second messenger.
Five dialysis bags, constructed from a semipermeable membrane that is impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed) and the percent change in mass of each bag was graphed. 5. Which line in the graph represents the bag that contained a solution isotonic to the 0.6 M solution at the beginning of the experiment?
Bag B
A biologist ground up some plant leaf cells and then centrifuges the mixture to fractionated the organelles. Organelles in one of the heavier fractions could produce ATP in the light, while organelles in the lighter fraction could produce ATP in the dark. The heavier and lighter fractions are most likely to contain respectively..
Chloroplasts and mitochondria
High cholesterol levels are considered a major risk factor for heart disease. If it is so bad for humans, why does the body make cholesterol in the first place?
Cholesterol is the thing for many important molecules such as sex hormones.
Epinephrine is a protein hormone found in many animals. Epinephrine stimulates a signaling pathway that results in the breakdown of glycogen to glucose in the liver cells. Which of the following describes the initial steps in the process whereby epinephrine stimulates glycogen breakdown?
Epinephrine binds to a cell-surface receptor, the activated receptor stimulates production of the second messenger, cAMP
Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose rich food into their glucose-poor cytoplasm. Using this information, which transport mechanism is most probably functioning in the intestinal cells.
Facilitated diffusion
Epinephrine binds as a ligand molecule to receptors on the outside of liver cells, causing a cascade of chemical reactions to occur on the inside of the cell. Which pathway correctly describes what occurs after the ligand has bonded with the extracellular receptor protein?
G protein changes shape and transmits signal to cytoplasm protein kinases amplify signal through phosphorylation signal activates receptor's protein kinase
Which of the following happens at the conclusion of meiosis I?
Homologous chromosomes are separated
Based on the experimental results, which of the following describes the most likely defect in the muscle cells of patients with type 2 diabetes?
IRS-1 activation is reduced at high insulin concentrations
Which of the following statements is true regarding the movement of substances across cell membranes?
Ions are unable to move through the phospholipid bilateral because the no polar tail regions of the phospholipids hydrophobic
If a cell has completed the first meiotic division and is just beginning meiosis II, which of the following is an appropriate description of its contents?
It has half the amount of DNA as the cell that began meiosis.
A cell with a predominance of free ribosomes is most likely
producing primarily cytoplasmic proteins.
Which of the following statements is true about the neurotransmitter used to transmit the impulse at the synapse? [http://i.imgur.com/8UIReMc.png]
It is released by fiber X when an impulse travels the length of fiber X.
Membrane-bound organelles have been an important component in the evolution of complex, multicellular organisms. Which of the following best summarizes an advantage of eukaryotic cells having internal membranes?
Organelles isolate specific reactions, increasing metabolic efficiency.
If ATP breakdown (hydrolysis) is inhibited, which of the following types of movement across cell membranes is also inhibited?
Passage of a solute against its concentration gradient
A new mutation that arose in one copy of gene x in a somatic cell resulted in a tumor. Which of the following pieces of evidence best describes how the new mutation directly caused the tumor?
Protein x normally stimulates cell division and the mutation created an overactive version of protein x.
Which of the following depicts the most probable pathway of processing and packaging a secretory protein within a eukaryotic cell?
Rough endoplasmic reticulum → Golgi body → secretory vesicles → cell membrane
When a stimulus is applied to a receptor in the skin, an action potential is propagated along a neuron to the brain, where another signal is sent back to then muscle for response. Which of the following best describes what occurs when the action potential reaches a chemical synapse at the end of an axon
The action potential cause a release of neurotransmitter that travel across the synapse
At which phase are centrioles beginning to move apart in animal cells?
prophase
The diagram above represents a typical rod shaped bacterium. Which of the following best describes a feature shown in the diagram that is unique to archaea and bacteria?
The organism does not have a nuclear membrane surrounding its genetic material.
A patient has had a serious accident and lost a lot of blood. In an attempt to replenish body fluids, distilled water, equal to the volume of blood lost, is transferred directly into one of his veins. What will be the most probable result of this transfusion?
The patient's red blood cells will swell because the blood fluid is hypotonic compared to the cells.
The diagram above depicts the response to a pinprick (stimulus) on the tip of a human finger. The arrows show the direction of impulse transmission along the labeled axons. If axon II was damaged before the pinprick, which of the following is most likely?
The person's finger will not withdraw reflexively.
Which of the following is a valid interpretation of the experimental results that explains how individuals with type 2 diabetes differ from individuals without diabetes?
The relatively low levels of glucose uptake in individuals with type 2 diabetes indicate that mobilization of GLUT4 to the cell surface is reduced in muscle cells of those individuals
.A group of students was viewing a sample of onion cells under the microscope. One of the students accidentally made the wet mount using a saline solution instead of a tap water solution, which resulted in the photographs of the cells shown above. Which of the following describes why the cells appear as they do?
The salt water was hypertonic to the onion cells and caused water to move out of the onion cells.
Mammalian blood contain the equivalent of 0.15M NaCl. Seawater contains the equivalent of 0.45 M NaCl. What will happen if red blood cells are transferred to seawater?
Water will leave the cells, causing them to shrivel and collapse
A common laboratory investigation involves putting a solution of starch and glucose into a dialysis bag and suspending the bag in a beaker of water, as shown in the figure below. The investigation is aimed at understanding how molecular size affects movement through a membrane. Which of the following best represents the amount of starch, water, and glucose in the dialysis bag over the course of the investigation?
a
different body cells can respond differently to the same peptide hormones because
a target cell's response is determined by the components of its signal transduction pathway
Which of the macromolecules below could be structural parts of the cell, enzymes, or involved in cell movement or communication?
proteins
In order for a protein to be an integral membrane protein it would have to be which of the following?
amphipathic
Observation of the direction of the nerve impulse supports the conclusion that fiber X is [http://i.imgur.com/8UIReMc.png]
an axon
in typical cell division by mitosis and meiosis, all of the following contribute to genetic variation except:
anaphase of mitosis
Cruise ship passengers find themselves fighting flu like symptoms for the first 4 or 5 days of their trip, but eventually they recover and enjoy their trip. What is the last defensive component involved in their recovery?
antibodies
Which of the following is one of the ways that the membranes of winter wheat are able to remain fluid when it is extremely cold?
by increasing the percentage of unsaturated phospholipids in the membrane
Within a forest ecosystem, there is a large amount of diversity among members of warbler species. Of the following stages of meiosis illustrated for a typical cell, which contributes most to diversity among the warblers?
c) (look at cell where chromosomes are crossing over)
Consider this pathway: epinephrine -> G protein-coupled receptor -> G protein -> adenylyl cyclase -> cAMP. Identify the second messenger.
cAMP
Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to
disruption of mitotic spindle formation.
If the cell whose nuclear material is shown in Figure 12.2 continues toward completion of mitosis, which of the following events would occur next?
formation of telophase nuclei
A toxin that binds specifically to voltage-gated sodium channels in axons would be expected to
prevent depolarization phase of the action potential
The solutions in the two arms of this U-tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half filled with a solution of 2 M sucrose and 1 M glucose. Side B is half filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels on both sides are equal. See figure 7.2
isotonic
The function of antibodies is to
mark pathogenic cells for destruction.
When an individual is first exposed to the smallpox virus, several days pass before significant numbers of specific antibody molecules and T cells are produced. However, a second exposure to the virus causes a large and rapid production of antibodies and T cells. This later response is an example of
memory b cells
The chemical reactions involved in respiration are virtually identical between prokaryotic and eukaryotic cells. In eukaryotic cells, ATP is synthesized primarily on the inner membrane of the mitochondria. In light of the endosymbiont theory for the evolutionary origin of mitochondria, where is most ATP synthesis likely to occur in prokaryotic cells?
on the plasma membrane
Yearly vaccination of humans for influenza viruses is necessary because
rapid mutation in flu viruses alters the surface proteins in infected host cells.
One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, and then activating relay proteins. Which type does this?
receptor tyrosine kinases
The transmission of information from sensory neurons to interneurons typically involves the
release of chemical messengers into the space between the axon of the sensory neuron and the plasma membrane of the interneuron
Glandular organs such as the pancreas and salivary gland produce a large quantity of enzymes used by the body on a daily basis. Cells of these organs would be expected to contain a large quantity of which organelle?
ribosome
What kinds of molecules pass through a cell membrane most easily?
small and hydrophobic
Liver cells are specialized cells that carry out a multitude of tasks, including the synthesis of cholesterol and the breakdown of protein metabolites. These cells would be expected to contain a large proportion of which organelle relative to all others?
smooth ER
According to the endosymbiont theory, this structure is thought to have been prokaryotic in nature. It contains thousands of inner folds that increase the surface area available for the chemical reactions of the Krebs cycle and electron transport chain.
structure D
Which of the following signal molecules pass through the plasma membrane and bind to intracellular receptors that move into the nucleus and function as transcription factors to regulate gene expression?
testosterone, a steroid hormone
When a plant cell, such as one from a peony stem, is submerged in a very hypotonic solution, what is likely to occur?
the cell will become turgid
Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large and complex lipids. Which cellular organelle must be involved in this condition?
the lysosome
After the depolarization phase of an action potential, the resting potential is restored by
the opening of voltage-gated potassium channels and the closing of sodium activation gates.
Positive feedback differs from negative feedback in that
the positive feedback's effector responses are in the same direction as the initiating stimulus rather than opposite to it
A key part of the humoral immune response is
the production of antibodies by plasma cells
Independent assortment of chromosomes is a result of
the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I.
The primary function of polysaccharides attached to the glycoproteins and glycolipids of animal cell membranes is
to mediate cell-to-cell recognition.
The primary function of humoral immunity is
to protect the body against extracellular pathogens.