AP BIOLOGY FIRST SEMESTER FINAL
EXAM REVIEW QUESTIONS AND
ANSWERS
What are membrane receptors that attach phosphates to specific amino acids in
proteins called? - Answer-receptor tyrosine kinases
What type of signal molecule can bind to an intracellular receptor and thereby cause a
gene to be turned on or off? - Answer-steroids
During signal transduction, the phosphorylation of proteins does what to those proteins?
- Answer-As enzymes, they catalyze biochemical reactions. Proteins also act as
receptors that bind with other substances and control cell activity. As part of a hormone,
proteins can initiate or suppress major cellular activities, such as secretion. A cell uses
phosphorylation as a switch to turn protein activity on or off
Why are phosphorylation cascades involving a series of protein kinases useful for
cellular signal transduction? - Answer-they amplify the original signal manyfold
What is the explanation for why certain cells only respond to certain hormones? -
Answer-A target cell responds to a hormone because it bears receptors for the
hormone. In other words, a particular cell is a target cell for a hormone if it contains
functional receptors for that hormone, and cells which do not have such a receptor
cannot be influenced directly by that hormone.
How does the hypothalamus control the anterior pituitary? - Answer-Hypothalamus
controls the anterior pituitary by releasing hormones causing it to synthesize and
secrete other hormones. The hormones produced by the hypothalamus is either a
releasing hormone or an inhibiting hormone
What is the physiological action of each of these hormones: oxytocin, thyroxine, insulin,
ACTH? - Answer-The two main actions of oxytocin in the body are contraction of the
womb (uterus) during childbirth and lactation. Oxytocin stimulates the uterine muscles to
contract and also increases production of prostaglandins, which increase the
contractions further.
Thyroxine is the main hormone secreted into the bloodstream by the thyroid gland. It is
the inactive form and most of it is converted to an active form called triiodothyronine by
organs such as the liver and kidneys.
Insulin helps control blood glucose levels by signaling the liver and muscle and fat cells
to take in glucose from the blood. Insulin therefore helps cells to take in glucose to be
, used for energy. If the body has sufficient energy, insulin signals the liver to take up
glucose and store it as glycogen.
ACTH- It stimulates secretion of glucocorticoids such as cortisol, and has little control
over secretion of aldosterone, the other major steroid hormone from the adrenal cortex.
ACTH is secreted from the anterior pituitary in response to corticotropin-releasing
hormone from the hypothalamus.
What happens during positive feedback? - Answer-In a positive feedback, the stimulus
is amplified, leading to a greater response.
Ex. Milk is released in response to the suckling which leads to more stimulation. During
the birth process, the contraction is driven by positive feedback regulation leading to
more contractions until the birth process is complete.
What are the components of innate immunity in humans? - Answer-Innate Immunity
Recognition of traits shared by broad ranges of pathogens, using a small set of
receptors
Rapid Response
Barrier defenses: skin, mucous membranes, secretions, saliva, tears, stomach acid
Internal defenses: phagocytic cells, toll-like receptors, neutrophils, macrophages,
dendritic cells, natural killer cells, antimicrobial proteins, interferons, complement
system, inflammatory response, histamine, mast cells
What are antigens? - Answer-foreign molecules that trigger the generation of antibodies
What is the structure and function of antibodies? - Answer-Antibodies (immunoglobulin)
Structure: have a Y-shaped structure, but are secreted rather than membrane bound.
Different antibodies recognize different epitopes. Many noncovalent bonds between
epitope and binding site offer a stable and specific interaction.
Function: do not actually kill the pathogen, but they interfere with the pathogen activity
or mark pathogens in ways for inactivation or destruction. They also prevent infection of
a host cell, thus neutralizing the virus; Prevent toxins from entering the body cells.
Promotes the phagocytosis by macrophages or neutrophils. Activates a complement
system in which the membrane attack the foreign cell's membrane, allowing water and
ions to rush in, eventually causing the cell to swell and lyse (rupture of the cell wall)
In what situations will helper T-cells be activated? - Answer-Situations when the Helper
T cell is activated:
Inside the host cell, when the antigen fragment binds to the MHC molecule and is
displayed on the surface of the cell.
A foreign molecule must be present that can bind specifically to the antigen receptor of
a T cell
What is the difference in the way B-cells and cytotoxic T-cells respond to invaders? -
Answer-B-cells can connect to intact antigens right on the surface of the invading virus
or bacteria. This is different from cytotoxic T-cells, which kill antigen carrying cells
EXAM REVIEW QUESTIONS AND
ANSWERS
What are membrane receptors that attach phosphates to specific amino acids in
proteins called? - Answer-receptor tyrosine kinases
What type of signal molecule can bind to an intracellular receptor and thereby cause a
gene to be turned on or off? - Answer-steroids
During signal transduction, the phosphorylation of proteins does what to those proteins?
- Answer-As enzymes, they catalyze biochemical reactions. Proteins also act as
receptors that bind with other substances and control cell activity. As part of a hormone,
proteins can initiate or suppress major cellular activities, such as secretion. A cell uses
phosphorylation as a switch to turn protein activity on or off
Why are phosphorylation cascades involving a series of protein kinases useful for
cellular signal transduction? - Answer-they amplify the original signal manyfold
What is the explanation for why certain cells only respond to certain hormones? -
Answer-A target cell responds to a hormone because it bears receptors for the
hormone. In other words, a particular cell is a target cell for a hormone if it contains
functional receptors for that hormone, and cells which do not have such a receptor
cannot be influenced directly by that hormone.
How does the hypothalamus control the anterior pituitary? - Answer-Hypothalamus
controls the anterior pituitary by releasing hormones causing it to synthesize and
secrete other hormones. The hormones produced by the hypothalamus is either a
releasing hormone or an inhibiting hormone
What is the physiological action of each of these hormones: oxytocin, thyroxine, insulin,
ACTH? - Answer-The two main actions of oxytocin in the body are contraction of the
womb (uterus) during childbirth and lactation. Oxytocin stimulates the uterine muscles to
contract and also increases production of prostaglandins, which increase the
contractions further.
Thyroxine is the main hormone secreted into the bloodstream by the thyroid gland. It is
the inactive form and most of it is converted to an active form called triiodothyronine by
organs such as the liver and kidneys.
Insulin helps control blood glucose levels by signaling the liver and muscle and fat cells
to take in glucose from the blood. Insulin therefore helps cells to take in glucose to be
, used for energy. If the body has sufficient energy, insulin signals the liver to take up
glucose and store it as glycogen.
ACTH- It stimulates secretion of glucocorticoids such as cortisol, and has little control
over secretion of aldosterone, the other major steroid hormone from the adrenal cortex.
ACTH is secreted from the anterior pituitary in response to corticotropin-releasing
hormone from the hypothalamus.
What happens during positive feedback? - Answer-In a positive feedback, the stimulus
is amplified, leading to a greater response.
Ex. Milk is released in response to the suckling which leads to more stimulation. During
the birth process, the contraction is driven by positive feedback regulation leading to
more contractions until the birth process is complete.
What are the components of innate immunity in humans? - Answer-Innate Immunity
Recognition of traits shared by broad ranges of pathogens, using a small set of
receptors
Rapid Response
Barrier defenses: skin, mucous membranes, secretions, saliva, tears, stomach acid
Internal defenses: phagocytic cells, toll-like receptors, neutrophils, macrophages,
dendritic cells, natural killer cells, antimicrobial proteins, interferons, complement
system, inflammatory response, histamine, mast cells
What are antigens? - Answer-foreign molecules that trigger the generation of antibodies
What is the structure and function of antibodies? - Answer-Antibodies (immunoglobulin)
Structure: have a Y-shaped structure, but are secreted rather than membrane bound.
Different antibodies recognize different epitopes. Many noncovalent bonds between
epitope and binding site offer a stable and specific interaction.
Function: do not actually kill the pathogen, but they interfere with the pathogen activity
or mark pathogens in ways for inactivation or destruction. They also prevent infection of
a host cell, thus neutralizing the virus; Prevent toxins from entering the body cells.
Promotes the phagocytosis by macrophages or neutrophils. Activates a complement
system in which the membrane attack the foreign cell's membrane, allowing water and
ions to rush in, eventually causing the cell to swell and lyse (rupture of the cell wall)
In what situations will helper T-cells be activated? - Answer-Situations when the Helper
T cell is activated:
Inside the host cell, when the antigen fragment binds to the MHC molecule and is
displayed on the surface of the cell.
A foreign molecule must be present that can bind specifically to the antigen receptor of
a T cell
What is the difference in the way B-cells and cytotoxic T-cells respond to invaders? -
Answer-B-cells can connect to intact antigens right on the surface of the invading virus
or bacteria. This is different from cytotoxic T-cells, which kill antigen carrying cells
