Download Exam 3 Review Sheet KEY

Leader:
Course:
Exam 3 review
Supplemental Instruction
Iowa State University
1.
Instructor:
Date:
Tiffany
Biol 212 (1)
Powell-Coffman
03/27/2011
In cell-cell signaling, receptor-ligand binding is:
a. Covalent- bond where two electrons are shared between two atoms
b. Non-covalent
c. Hydrogen bonding- weak sharing of an electron pair between a hydrogen atom and another
atom.
d.
e.
2.
3.
4.
Van der Waals- weak interactions found in all molecules
Ionic - result of the attraction between groups with opposite electrical charges.
Signal transduction pathways result in cell-specific responses because
a. Ligands are unique for every cell type
b. Plasma membrane receptors are cell-type specific
c. Each cell type contains unique genetic material
d. Each cell type expresses a different set of target proteins
e. B & D
What is a typical steroid hormone receptor?
a. G protein-linked receptor
b. tyrosine kinase-linked receptor
c. ion channel-linked receptor
d. intracellular receptor
e. second messenger effector enzyme
steroids are small hydrophobic non-polar molecues that can diffuse through the cell membrane.
They typically will diffuse through the cell membrane and bind a receptor inside the cell.
Inositol triphosphate (IP3) stimulates Ca2+ entry into the cytoplasm from
a. Extra cellular fluid
b. Endoplasmic reticulum
c. Mitochondria
d. Nucleus
e. None of the above
5.
A signal sent from one cell to a cell in the same tissue would be a _______ signal
a. Juxtarine- signal between two neighboring cells
b. Autocrine- we did not learn about…
c. Paracrine
d. Endocrine- signal that travels through the circulatory system to a distant target cell
6.
Which of the following are qualities of a virus:
a. Consists of a nucleic acid genome surrounded by a protein coat (capsid)
b. Uses host machinery to replicate
c. Target of antibiotics
d. Cellular
e. A and B
f. A, B, and C
g. All of the above
7.
Which of the following mutations would have the least effect on a virus’ ability to infect and replicate in a host
cell
a. Nonsense- a point mutation in a sequence of DNA that results in a premature stop codon
b. missense- a point mutation in which a single nucleotide is changed, resulting in a codon that
codes for a different amino acid
c.
d.
frameshift- changes the reading frame
silent- a mutation that doesn’t result in a change to the amino acid sequence of a protein
Supplemental Instruction
1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu
Leader:
Course:
Exam 3 review
Supplemental Instruction
Iowa State University
8.
9.
Instructor:
Date:
Tiffany
Biol 212 (1)
Powell-Coffman
03/27/2011
Which of these cells is/are dead at maturity?
a. Sieve tube members
b. Vessel elements
c. Tracheids
d. B and C
e. All of the above
Vessel elements and tracheids are both types of xylem cells. Their developmental program is to
produce their cell wall and then undergo apoptosis, or cell death.
Germination without light will cause
a. Etoliation- what will happen to a potato in the dark, plant doesn’t invest energy in producing leaves
because there is no light for photosynthesis, which typically occurs in chloroplasts in leaves
b. De-etoliation- greening, occurs in the presence of light
c. Phototropism- growth toward light
d. Triple Response- we did not learn
e. Thigmotropism- we did not learn
10. ____________is to xylem as __________ is to phloem.
a. sclerenchyma cell; parenchyma cell
b. vessel element; sieve-tube member
c. apical meristem; vascular cambium
d. cortex; pith
e. tracheid; vessel element
other types of xylem cells: tracheids
other types of phloem cells: companion cells
11. Which does NOT contribute to positive pressure of phloem flow?
a. Cotransport of sugar into sieve tube members.
b. Osmosis into the sieve tube members at a sugar source.
c. Water vapor loss through stomata.
d. Cotransport of sugar from phloem sap into a sugar sink cell.
e. Osmosis into the xylem flow at a sugar sink.
c. is related to flow of water through xylem.
12. Which of the following pairs does not match (element: form plant uses)
a. N; NO3-, NH4+
b. C; CO2
c. O; CO2, H2O, O2
d. H; H2O
e. All of the above are correct
13. In the presence of Auxin, which of the following is incorrect:
a. Repressors will bind to ARF’s
b. Auxin will bind TIR1
c. Activated TIR1 will target repressors for proteasomal degradation
d. The function of the ARF is to recruit RNA polymerase and promote transcription of auxin response
genes
Repressors will bind to ARFs (transcription factors) when there is no Auxin in the cell. IN the presence of
Auxin in the cell, Auxin will bind TIR1, which will target repressors (bound to ARFs) for proteasomal
degradation. This will cause the ARF to function normally and to recruit RNA polymerase and promote
transcription of auxin response genes.
Supplemental Instruction
1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu
2.
Describe the difference between the lytic and lysogenic cycles of a T4 bacteriophage. A drawing may be
helpful in your explanation.
The lytic cycle results in death of the host cell. In the lytic cycle, a bacteriophage ( a virus that infects a
bacterium) will attach to a host cell (such as an Escherichia Coli bacterium) and then inject its DNA into
the host cell. Inside the host cell, host cell machinery will translate viral DNA that encodes for an enzyme
that degrades the host cell DNA. Then the phage DNA directs production of phage proteins and copies of
the phage genome by host enzymes, using components within the cell. After, three separate sets of proteins
self-assemble to form phage heads, tails, and tail fibers. The phage genome is packages inside the capsid as
the head forms. Finally, the phage encodes an enzyme that damages the bacterial cell wall and allows fluid
to enter the cell, lyse it, and release the phage copies.
The lysogenic cycle allows replication of the phage genome without destroying the host. After the viral
DNA has entered the host cell, it will be incorporated into the host cell DNA to make a “prophage.” Once
integrated into the host cell’s chromosome, the bacterium will continue to reproduce normally, copy the
prophage and transmit it to daughter cells with each cell division. Occasionally, a prophage will exit the
bacterial chromosome and will initiate the lytic cycle.
Plant cell
Animal cell
Mitochondria?
Yes
Yes
Chloroplasts?
Yes
No
Cell wall?
Yes
No
Central vacuole?
Yes
No
Nucleus?
Yes
Yes
Type of junctions?
plasmodesmata
Hormones (size, synthesis, effects)
Small organic molecules,
synthesized at multiple sites
throughout the plant, may have
multiple effects
Dermal (covers plant), Ground
(roles in photosynthesis, water and
food storage, and support),
Vascular (transport of fluids and
nutrients through xylem and
phloem)
Gap junctions; epithelial cells have
desmosomes and tight junctions
Proteins or small molecules,
produced by specialized glands or
cells, often will have specific
effects
Epithelial, Muscle, nervous,
connective
Types of tissues
Supplemental Instruction
1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu
3.
Explain the nitrogen cycle. In your explanation, include a drawing and demonstrate how a plant may obtain
bio-available nitrogen. Why is it important that a plant have nitrogen?
Nitrogen-fixing bacteria in the soil convert N2 (from the atmosphere) into NH3 (ammonia). NH 3 may combine with
H+ in the soil to form NH4+ (ammonium), which is a form of nitrogen that the plant is able to use. NH 4+ may be
converted by nitrifying bacteria into NO3- (nitrate), which is the other form of nitrogen that a plant may use.
It is important that a plant has nitrogen, because it is a macronutrient that is necessary to make macromolecules
(carbohydrates, proteins, nucleic acids) and lipids.
For the following diagram, explain the signal
transduction pathways that lead to de-etiolation.
1.
The signal (_light______) is
detected by the
__phytochrome_________
____receptor_________,
which then activates one of
two signal transduction
pathways.
2. a. One pathway results in
production of cGMP ( a
_second_______
___messenger__________),
which activates a specific
_____kinase______
b. In the other pathway ,
_____phtochrome________
activation opens __Ca++___
____channels_________ in the cell membrane, which increases Ca 2+ in the cytosol. Ca2+ then
activates a specific protein kinase
3. both pathways lead to expression of genes for proteins that function in the de-etoliation process,
such as genes that encode: _enzymes__ involved in supplying chemical precursors for chlorophyll and
plant __hormones___ that regulate growth
Supplemental Instruction
1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu
1.
Describe the processes of sugar transport and water transport in a plant.
Polar water molecules adhere to the walls of xylem tracheids and
vessels and to each other through hydrogen bonds. This will allow an
overall tension and form ‘columns’ of water in the plant
As the plant transpires, or opens its stomata and water evaporates, the
water molecules bound below it will be pulled up
1. Sugar is loaded from a companion cell (source cell) into a sieve tube by
active transport: A proton pump in the cell membrane of the sieve tube will use energy
(in the form of ATP) to pump protons out and generate a proton gradient across the
plasma membrane. Protons will then be co-transported with sucrose into the sieve cell.
2.
The presence of sucrose solutes in the sieve tube cell will cause water to
diffuse by osmosis into the sieve tube cell from the xylem.
3.
Sugar is unloaded by active transport into a sink cell
4.
Water is recycled back into the xylem.
Supplemental Instruction
1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu