CELLULAR AND MOLECULAR BIOLOGY MIDTERM EXAM NEWEST 2024 ACTUAL EXAM 100 QUESTIONS AND CORRECT DETAILED ANSWERS WITH RATIONALES (VERIFIED ANSWERS) |ALREADY GRADED A+

CELLULAR AND MOLECULAR BIOLOGY
MIDTERM EXAM NEWEST 2024 ACTUAL EXAM
100 QUESTIONS AND CORRECT DETAILED
ANSWERS WITH RATIONALES (VERIFIED
ANSWERS) |ALREADY GRADED A+
Which of the following is not found in all cells?
nucleus
plasma membrane
RNA
Ribosome - ANSWER-nucleus
mitochondria - ANSWER-energy production center in the cell
The following organelles are made of two layers of membranes EXCEPT:
nucleus
mitochondrion
chloroplast
endoplasmic reticulum - ANSWER-Endoplasmic reticulum
Which organelle contains no DNA?
nucleus
central vacuole
chloroplast
mitochondrion - ANSWER-central vacuole
A confocal microscope is a type of microscope that can obtain 3D images with a very
little background. Which of the following is FALSE about confocal microscopes?
A. it uses a laser as a light source
B. it captures images from a very thing place of specimen at a time
C. it dissolves the cytoplasm leaving the cell membrane for imaging
D. it collects a series of 2D images to reconstruct a 3D image - ANSWER-C
The highest resolution of a transmission electron microscope - ANSWER-.002
micrometers
The Basic design of a fluorescence microscope is sown on the right. Which of the
following is true?
A. it uses electron breams as the light source
B. The filter 1 Allows a particular wavelength of light to stimulate the fluorescence
emission
C. the device 2 is called a condenser which can condense the fluorescent lights to make
the signal brighter
D. you need to stain the specimen with hematoxylin and eosin in order to observe the
structure with fluorescence scope - ANSWER-B
Which of the following is false about IgG antibody?
A. it is a complex formed by 4 subunits
B. IgG is a synthetic molecule created by organic chemistry methods
C. IgG can activate white blood cells to remove pathogens
D. The antigen-binding site has strong affinity to specific antigen - ANSWER-B
Which of the following cannot diffuse across the cell membrane?
A. H+ ion
B. H2O
C. Ethanol
D. CO2 gas - ANSWER-A
Which of the following is true about active transport?
A. it transports solute from low to high concentration
B. it can be done by the carrier and ion channel
C. it usually requires a signal molecule to initiate the transport
D. it happens to those molecules that can freely diffuse across the membrane -
ANSWER-A
Which of the following is false about ion channels?
A. they form aqueous pores on the membrane
B. They transport ions across membrane against concentration gradient
C. they are also called gated ion channels because they need signals to trigger the
opening
D. they are highly selective for the ions to pass through - ANSWER-B
When the sodium ion channel is in the inactivated conformation,
A. the ion channel won't respond to any stimulus
B. the membrane potential is at a resting state
C. sodium will flux out of the cell
D. the membrane potential is at -40 mv - ANSWER-A
At the synapse, the electrical signal of an action potential is converted to a chemical
signal, which then travels through the synaptic cleft reaching the receptors on the
postsynaptic membrane. Which of the following is FALSE?
A. the chemical signal is often referred to as the neurotransmitter
B. the calcium in the presynaptic nerve terminal triggers the release of the chemical
signal
C. the chemical signal is usually stable and stays in the synaptic cleft for a long time
D. the receptor for the chemical signal is usually an ion channel - ANSWER-C
Which of the following is TRUE about the slow response triggered by a signal molecule?
A. the signal is transduced to cytoplasm only
B. the signal activates transcription of target genes
C. the signal alters cytoskeletal systems
D. the signal molecule is taken into the cell - ANSWER-B
Which of the following is TRUE about the G-protein coupled receptors?
A. they become active when they are bound with GTP
B. they are able to bind DNA and activate the transcription of target genes
C. they phosphorylate the Ga subunit of G proteins
D. after binding with a signal molecule, they cause separation of Ga from GBy -
ANSWER-D
Enzyme coupled receptors typically ___________________ after signal molecules bind
to them.
A. dimerize and phosphorylate each other
B. Dissociate from cell membrane and travel to nucleus
C. Bind and activate other enzyme, such as PKA
D. split into several functional units which are called adaptors - ANSWER-A
The structure in C. elegans that functions like a human brain is called - ANSWER-nerve
ring
what are the energy sources for active transport? - ANSWER-electrochemical gradient
ATP driven pump
Light-driven pump
PKA - ANSWER-activated by cAMP
PKC - ANSWER-Activated by Ca+2 and DAG
receptor tyrosine kinases - ANSWER-activated by phosphorylation
phospholipase C - ANSWER-cleaves inositol phospholipid
MAPKKK - ANSWER-activated by Ras
Two mechanisms that regulate the activity of intracellular signaling molecules -
ANSWER-phosphorylation
GTP-GDP switch
Phosphorylation is activated by - ANSWER-kinase
phosphorylation is deactivated by - ANSWER-GTP phosphatase
Intracellular signaling protein off of GTP GDP switch - ANSWER-hydrolysis
normal function of Ras - ANSWER-promote cell growth
what type of cell surface receptor activated the signal cascade of Ras - ANSWERenzyme receptor
Ras is inactive when bound with - ANSWER-GDP
Ras is active when bound with - ANSWER-GTP
Ras signal cascade - ANSWER-Ras --> MapKKK-->MapKK->MapK--> other proteins
leading to different cell responses
In Ras mutation, what causes it to stay constantly active? - ANSWER-Can't hydrolyze
GTP leaving it constantly on
The central dogma of molecular biology refers to transcription and translation.
Transcription is the process using DNAs to make ________ whereas translation is using
________ to make proteins. - ANSWER-RNAs; RNAs
A transmission electron microscope (TEM) picture of a yeast cell is shown on the right.
Which of the following is FALSE about the cell?
A. the cell is a eukaryotic cell because you can see its organelles
B. the cell has to cell membrane because it is a yeast cell, not an animal cell
C. the organelle indicated by the white arrow is the nucleus
D. The structure on the right (black arrow) is a vesicle - ANSWER-A
Cell membrane is formed by two layers of phospholipids. Therefore the thickness of the
cell membrane is within the size range