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bio 172 exam 4

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Which of the following lists cell types in order from those capable of differentiating into the greatest number of different specialized cells to those capable of differentiating into the least number of different specialized cells?
totipotent, pluripotent, multipotent
What is the underlying mechanisms of cellular differentiation?
Gene regulation causes cells to become progressively more specialized
Which of the following correctly lists the stages of human development?
fertilized egg, morula, blastocyst, gastrula
Which of the following cells or cell types has the greatest developmental potential?
fertilized egg
This germ layer will give rise to epithelial cells, pigment cells in the skin, and nerve cells in the brain.
ectoderm
The part of the blastocyst from which the body of the embryo develops is called:
inner cell mass
In almost all organisms that have been studied, the genes in Hox clusters:
are arranged on chromosomes in the same order as their products function along the anterior-posterior segments of the embryo.
Gehring tested the hypothesis that the <em>Pax6</em> gene acts as a master regulator of eye development by engineering <em>Drosophila Pax6</em> genes to be expressed in <em>Drosophila</em> antennae. What happened, and did it support or refute his hypothesis?
A fly eye developed on the antenna; this supports the hypothesis.
Abnormal development of the head and thorax in bicoid mutants indicates which of the following?
Bicoid is needed for the development of head and thorax
Define osmosis.
A net movement of water molecules from regions of high water concentration to regions of low water concentration.
What is the name of the channel that allows movement of water molecules through lipid bilayers?
aquaporin
Homeotic genes:
-are controlled by genes expressed earlier in development.
-are found in a wide variety of animals, from fruit flies to vertebrates.
-specify the identities of individual body parts or segments during development.
-encode transcription factors.
If the antennapedia gene is expressed in cells in the head of an adult fruit fly, you would expect
legs where the antennae belong
Which of the following is not a source of water for animals?
Bathing
What is an 'osmoconformer'?
Animals that match their internal osmotic pressure to that of their external environment.
If you were collecting fish and found that some had extra eyes, which of the genes listed below would you suspect to be the cause of abnormality?
Pax6
Which of the following is a protein that is found on the sperm of sea urchins which ensures species specific fertilization?
Bindin
The fact that homeotic complexes (HOX genes) in animals are homologous suggests
descent from a common ancestor
A mutation in which of these genes is most likely to generate a fruit fly embryo with two abdominal regions?
bicoid
What do we mean by cell membranes being semipermeable?
They allow the movement of some molecules across the membrane, but not others
What term is used to describe the regulation of water and solutes?
osmoregulation
The mammalian kidney has an outer layer called the ____________ and an inner layer called the ____________.
cortex; medulla
The first part of the renal tubule is called the ____________ and is specialized for ____________.
proximal convoluted tubule; reabsorption of electrolytes and other nutrients.
In the loop of Henle,
both water and salts can be reabsorbed.
Where on the neuron are the incoming signals summed to determine whether or not an action potential is fired?
axon hillock
The Na+/K+ ATPase is
important for establishing greater concentration of Na ions outside the cell, and greater concentration of K ions inside the cell
Which of the following are pushed through the slits and pores of the glomerolus in the renal corpuscle? (Select all correct choices.)
-wastes
-water
-glucose
-solutes from the blood
True or false: In the presence of ADH, urine becomes more concentrated.
true
The kangaroo rat lives in the desert and its only water source is the food it eats. What might be different in the Kangaroo rat's kidney compared to a human?
The kangaroo rat's loop of Henle would be very long.
Fluid enters the nephron of the kidney and follows a very specific path before transfer to the bladder. Which of the following lists the correct order of the path?
Glomerulus, proximal tuble, Loop of Henle, distal tubule, collecting duct.
An axon terminal communicates with a neighboring neuron through a junction called a
synapse
Which of the following statements are true about resting membrane potential? Select all correct choices.
-It results from K+ ions moving out of the cell through passive diffusion.
-It results from the sodium-potassium pump moving more Na+ ions out of the cell compared to the number of K+ ions moved into the cell.
Which of the following scenarios will most likely trigger an action potential? Select all correct choices.
-single EPSPs arriving simultaneously at two or more different synapses (spatial summation)
-multiple EPSPs arriving quickly at a single synapse (temporal summation)
Why are action potentials conducted in one direction?
The brief refractory period prevents re-opening of the voltage gated Na+ channels
Where would you expect to find ligand gated Na+ channels on a neuron?
On the dendrites of the postsynaptic cell
Which of the following classes of hormones are hydrophobic?
steroid hormones
Steroid hormones are derived from .....
cholesterol
You perform a parabiosis experiement with a healthy mouse and mouse that is very large because it carries a mutation in the gene that encodes the leptin receptor? What will be the predicted result?
The large amounts leptin produced by the obese mouse will cause problems in the healthy mouse. The obese mouse will stay large, while the normal mouse will starve.
The precursor in the synthesis pathway for a certain hormone is cholesterol. Where would you expect to find the receptor for this hormone?
Inside the cell
When under acute stress, all of the following are increased except
digestion
Which of the following is never found in a virus?
Ribosome
The enzyme reverse transcriptase synthesizes:
DNA from RNA.
Which of the following statements is true regarding steroid hormones? Select all correct choices.
They bind to cytoplasmic receptors.
They have structures similar to cholesterol
They are hydrophobic.v
Is insulin injection an effective way to treat patients with type II Diabetes mellitus? Why or why not?
It is not an effective way. Patients are able to produce insulin, but their organs do not respond properly to insulin
When cortisol levels increase, blood glucose levels will
increas
Viruses are considered to be
non living
Which of the following is not a hormone function?
Produce electrolytes
Phenotypically, what would you expect if a mouse were a homozygous mutant for both ob (leptin) and db (leptin receptor); ob/ob and db/db?
The mouse would be obese.
What effect does insulin have on blood glucose levels?
Insulin causes muscle and liver cells to take up glucose and convert it to glycogen for storage.
Viruses are not considered alive because
they require a host cell to complete their replication cycle
The nucleic acid genome of a virus is surrounded by a protein coat called ____________, and can also be surrounded by a lipid ___________________.
capsid, envelope
A cell in which viral reproduction occurs is called a:
host cell
The genome of viruses consists of:
-double-stranded RNA.
-single-stranded DNA.
-single-stranded RNA.
-double-stranded DNA.
Which of the following is not true with regards to viruses?
They use the host cell's reverse transcriptase for replication of the viral genome
Tobacco mosaic virus can infect different types of plants, but it does not infect animal cells. Which of the following is an explanation?
Viral proteins can bind cell surface proteins on some plant cells, but cannot interact with cell surface proteins on animal cells
Which of the following gets synthesized on ribosomes attached to the rough endoplasmic reticulum?
HIV glycoproteins 120 and 41
The order of concentric whorls of flower organs from outside to inside is
sepal, petal, stamen, carpel
Sepals are often _____, while petals are frequently __________.
green, brightly colored
What would you expect to happen if you added activity B to whorl 1?
you would get a flower with extra petals, but no sepals
In which of the following structures of a vascular plant would you expect to find totipotent cells? Select all correct choices.
-axillary buds
-shoot apical meristem
True or false: Plant cells usually divide and then increase in size.
true
What is the function of the endosperm?
Endosperm is a nutritive tissue that supports the growth of the embryo
Which vascular tissue in a plant transports sugar throughout the plant?
Phloem
The phloem consists of
sieve elements and companion cells.
Which of the following substances helps make cells of xylem rigid to avoid collapse?
lignin
Transpiration is best defined as:
the evaporative loss of water through the stomata.
Which of the following statements about nutrient transport in the phloem is false?
Signaling from Companion cells via the plasmodesmata control the rate of transport.
Which of the following is not a factor in water travelling up a plant?
Active transport of water molecules
The condition in which shoot apical meristems suppress the growth of axillary buds is called ____________.
apical dominance
Plant stems bend toward light. This means that they exhibit:
positive phototropism
Which of the following statements are not true of hormone actions in plants?
Plant hormones act independently and do not affect one another's actions.
Gravitropism is a result of:
auxin concentration and the movement of starch-filled organelles called statoliths.
Which of the following responses is NOT regulated by auxin?
stomata opening and closing
Organisms that contain recombinant DNA originating from a different species are referred to as:
transgenic organisms
Where in a growing plant would you expect to find the highest concentration of auxin?
in the apical meristem
During a phototropic response auxin moves ______, while during a gravitropic response auxin moves __________.
to the shade side, toward the bottom
What would happen to a growing bush if you applied inhibitors of PIN proteins to the tips of each main shoot?
Auxillary buds would start growing and forming branches
Which of the following is true of a plant with a loss-of-function mutation in the PHOT1 gene?
The plant would not bend toward the light
GMOs are
transgenic organisms
Making recombinant DNA molecules involves cutting a gene from its normal location, inserting it into a circular piece of DNA from a bacterial cell and transforming bacteria with the DNA. Which of the tools below is used to cut the gene from its normal location?
Restriction enzyme
It takes very few molecules of a peptide hormone to cause changes in a target cell. This may be explained by the fact that:
the mechanism of hormonal action may involve an enzyme cascade that amplifies the response to a hormone.
A virus achieves host specificity through ____________ on the surface of the capsid or envelope, which bind to the host cell.
proteins
What is one difference between viruses that carry a reverse transcriptase and viruses that carry an RNA-dependent RNA polymerase?
viruses with RNA-dependent RNA polymerase will not integrate their genome into the host cell's chromosome
You are bitten by a mosquito that carries Plasmodium.

True or false: There is no response because single-cell eukaryotes have no effect on humans.
false
Which of the following would NOT be required for HIV to complete its life cycle?
DNA polymerase
In the ABC model of floral development, flower development in <em>Arabidopsis</em> is regulated by ____________ activities controlled by ____________ genes.
4; 3
In seed plants, branches grow out from ____________, which are meristems that form at the base of each leaf.
axillary buds
Which of the following accurately describe development of the pollen grain?
meiosis is followed by two rounds of mitosis to give rise to two sperm nuclei and the pollen tube nucleus
Which aspect of development is unique to plants as compared to animals?
double fertilization
A farmer in Vermont is going to tap a tree in order to make maple syrup. Which of the following plant structures must the farmer break to release (and collect) the sugar-rich base for his syrup?
phloem
Sucrose movement into a companion cell requires
a proton/sucrose symport.
ATP is required for .....
stomata opening, but not for stomata closing
If you cover the tip of a young grass shoot, it no longer exhibits phototropism. Why?
Light is unable to trigger PHOT1 autophosphorylation
iPS cells are...
differentiated cells reprogrammed by the activation of a handful of genes
The virulence trait in Agrobacterium tumefaciens (Rhizobium radiobacter) is found on
tumor inducing plasmid DNA
A recombinant molecule in genetic engineering is produced by combining
two DNA segments
The muscle cells and nerve cells in a mouse look very different and serve very different functions in the mouse's body. These differences are because the muscle cells and nerve cells in the mouse ____________.
express different genes
Genes that determine where different body parts develop in the organism are called ______________ genes.
homeotic
Fertilization by more than one sperm is called
polyspermy
Which of the following is an example of a maternal effect gene?
bicoid
What component of the proximal tubule, if not functional, would have the most severe effect on kidney function?
The Na+/K+ ATPase.
Which statement is true about filtration in the glomerulus?
Small molecules pass through and enter the renal tubule.
Which of the following is not associated with saltatory propagation?
extremely low threshold potential
Ca++ ion channels are found:
only at the axon terminal membrane.
The release of neurotransmitter from the presynaptic cell is an example of:
exocytosis.
In the ABC model of floral development, A, B, and C stand for the activities of different ____________.
transcription factors
Plants grow throughout their entire lifetime because of the ______________that continues to divide.
meristematic tissue
Water transport in xylem depends on _________. (Select all correct answer options.)
solar energy
hydrogen bonding between H2O molecules
Why is a growing leaf is considered a sink and not a source?
It is using sucrose for its own growth.
Auxin moves between cells through a process called polar transport. Auxin molecules move from one cell to the next through PIN proteins. However, their movement is unidirectional. What accounts for this unidirectional movement?
PIN proteins are only found on the basal side of the cell.
The early cell divisions of human development differ from other mitotic cell divisions in that:
cells do not grow in size; they subdivide the cytoplasm of the fertilized egg.
Which of the following is false regarding bicoid?
It is a hox gene
What types of synaptic inputs can postsynaptic nerve cells receive?
inhibitory
excitatory
The body's response to adrenalin is very fast, while the response to cortisol is much slower. What contributes to this difference?
The cortisol receptor is a regulatory transcription factor and acts through transcription of target genes.
Which of the following HIV proteins is translated on host cell's rough ER?
gp120
A researcher discovers a mutant carnation plant that lacks any A-class homeotic genes. Which of the following structures would be malformed (or absent) in this mutant? Select all correct choices.
petals
sepals
Which of the following is triploid?
endosperm
The floral meristem consists of four whorls and the development of these whorls is dictated by genes A, B, and C. What will be the phenotype of a plant that lacks both the A gene and the B gene?
all four whorls will develop into carpels
Double fertilization is unique to flowering plants. Which of the following describes double fertilization?
One sperm nucleus combines with the egg nucleus to become the zygote and one sperm nucleus combines with two central cell nuclei to become the endosperm
Which of the following is not an important component of long-distance transport in plants?
Root hairs
The phloem transports
carbohydrates from leaves to the rest of the plant.
The xylem transports
water from the roots to the leaves.
What is the driving force for water transport?
Transpiration
Which of the following is not an example of a sink in plants?
Mature leaves
You are planting tulip bulbs, but accidentally you place them in the soil sideways. What will happen when the roots begin to grow?
The roots will grow downward, because the statoliths will redistribute due to gravity and this will change the direction of growth
During morula development the divisions are more rapid than in most normal adult cells and the individual cells get progressively smaller. Which stage(s) of the cell cycle are probably truncated (made shorter)?
G1 and G2
On a very hot day, what would you expect to happen to ADH levels?
Increase
The most common dental anesthetic used is lidocaine. Lidocaine blocks voltage-gated Na+ channels. Where along the facial nerve would you expect lidocaine to be active?
along the axon
In a neuron, what creates the electrochemical gradient favoring the outflow of K+ when the cell is at rest?
Na+/K+ ATPase
Steroid hormones are derived from .....
cholesterol
ADH is released from the pituitary gland and it affects the kidney, but not other organs. How is this specificity achieved?
Kidney cells have receptors for ADH, cells of unaffected tissues do not.
Which of the following statements is not true about phloem transport of sugars?
Removing sugars from phloem increases turgor pressure at the sink.
Which of the following statements about phloem transport is not true?
Sugar is actively transported into the phloem from the sinks
Transpiration in plants requires all of the following except
active transport through xylem cells
Which of the following best describes transport in the phloem?
solute moves from a high concentration in the "source" to a lower concentration in the "sink."
Which species of bacteria can produce the highly useful Ti plasmid, used by biologists interested in genetically engineering resistant crops?
Rhizobium radiobacter
Small extrachomosomal pieces of DNA found in bacteria that can be used as vectors in recombinant DNA technology are called
plasmids
Organisms that have been genetically engineered to carry foreign genes are called
transgenic organisms
The loops of Henle create a concentration gradient in the interstitial fluid surrounding the loop, with the concentration highest in the ____________ and lowest in the ____________ of the kidney.
inner medulla; cortex
True or false: All nervous system responses involve input from the brain.
false
It takes very few molecules of a steriod hormone to cause changes in a target cell. This may be explained by the fact that:
transcriptional activation produces many copies of mRNA, each of which is translated many times.
Which of the following is NOT a direct result of adrenalin action?
slow breakdown of lipids and proteins in the liver to restore energy balance
Which statement is correct about hormones that homeostatically regulate cellular functions?
Hormone release is often regulated via a negative feedback system.
Our bodies need to maintain a stable blood glucose concentration. In the negative feedback system for glucose regulation, what would be the stimulus?
High or low blood glucose levels
Which of the following accurately describes the path traveled by HIV protein gp120 in the host cell?
rough ER→ golgi→vesicle→host cell membrane→budding of new viral particle
The floral meristem consists of four whorls and the development of these whorls is dictated by genes A, B, and C. If gene C is not expressed...
gene A will be expressed in every whorl
If water molecules (H2O) suddenly stopped forming hydrogen bonds with one another, how would water transport in vascular plants change (if at all)?
It would stop, as water transport relies on H2O molecules being connected by hydrogen bonds.
Assuming there is sufficient light to drive photosynthesis, the rate of transpiration should _________ on a rainy day compared to a sunny day because _________.
decline; the H2O concentration gradient from the inside to the outside of the leaf would decrease
Water loss in leaves is due to...
transpiration and photosynthesis
ATP is required for .....
stomata opening, but not for stomata closing
Which of the following treatment would result in shoots which are unable to bend toward the light?
Inhibitors of H+-ATPase applied to whole shoot