b. disabled students.
c. children of congressional leaders.
d. female students.
Correct answer choice is :
The leader of the party that owns a majority of seats in either house of Congress or of a state legislature. Elected by their own party councils, majority leaders act as chief spokespersons and tacticians for their parties. The principal functions of a majority leader normally associate to floor duties. The majority leader is the lead speaker for the majority party during floor discussions, exhibits the calendar and supports the president or speaker with program advancement, policy formation, and policy decisions.
Answer:
I believe its C
Explanation:
Cell membrane (plasma membrane) acts as a selective barrier, regulating the traffic of materials into and out of the cell.
The cell membrane, also known as the plasma membrane, is a crucial component of all living cells. It serves as a selective barrier that controls the movement of substances into and out of the cell. This selective permeability is essential for maintaining the cell's internal environment and regulating the exchange of nutrients, gases, and waste products. The cell membrane consists of a lipid bilayer embedded with proteins, and its hydrophobic interior prevents the passage of most polar molecules.
To facilitate the transport of specific substances, the cell membrane contains various proteins, including transport proteins, receptor proteins, and enzymes. These proteins help regulate the flow of ions, nutrients, and signaling molecules across the membrane. Overall, the cell membrane is a vital structure that ensures the cell's survival and functionality by controlling its interactions with the external environment.
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The cell membrane acts as a selective barrier, regulating the traffic of materials into and out of the cell.
The structure that acts as a selective barrier, regulating the traffic of materials into and out of the cell is the cell membrane or plasma membrane.
The cell membrane is composed of a phospholipid bilayer with embedded proteins that control the movement of substances in and out of the cell. It selectively allows certain molecules to pass through while keeping others out, maintaining homeostasis within the cell.
For example, the cell membrane regulates the entry of nutrients and gases into the cell, as well as the removal of waste products and excess substances. It ensures that the cell maintains the appropriate balance of substances for proper functioning.
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Answer:
Stem cells are special human cells that are used to repair damaged tissues
Answer:
In multicellular organisms, stem cells are undifferentiated or partially differentiated cells that can differentiate into various types of cells and divide indefinitely to produce more of the same stem cell. Stem cells are undifferentiated cells that can turn into specific cells, as the body needs them. Scientists and doctors are interested in stem cells as they help to explain how some functions of the body work, and how they sometimes go wrong.
Answer:
Explanation:
A higher concentration of neurotransmitter above a certain threshold does not change the height of the action potential because the action potential is an all-or-nothing event. It's a rapid and brief electrical signal that travels down a neuron's axon, leading to the release of neurotransmitters at the synapse.
To understand why a higher neurotransmitter concentration doesn't affect the height of the action potential, let's delve into the molecular events that occur during an action potential:
Resting State: Neurons have a resting membrane potential, which is a difference in electrical charge between the inside and outside of the cell. This potential is maintained by ion channels in the cell membrane, primarily sodium (Na+) and potassium (K+) channels. At rest, there are more positively charged ions outside the cell than inside.
Depolarization: When a neuron receives a strong enough excitatory stimulus, it causes a brief change in the ion permeability of the cell membrane. Voltage-gated sodium channels open in response to this stimulus, allowing sodium ions to rush into the cell. This influx of positive ions depolarizes the membrane, meaning the inside of the cell becomes more positively charged compared to the outside.
Threshold: If the depolarization reaches a certain threshold, typically around -55 to -50 mV, it triggers an action potential. At this point, voltage-gated sodium channels open more widely, leading to a rapid influx of sodium ions. This is the "all-or-nothing" phenomenon – once the threshold is reached, the action potential is initiated, regardless of the strength of the initial stimulus.
Rapid Depolarization: The influx of sodium ions causes the membrane potential to become highly positive. This phase is known as rapid depolarization or the rising phase of the action potential.
Repolarization: After reaching its peak positive potential, voltage-gated potassium channels open. Potassium ions flow out of the cell, repolarizing the membrane and restoring the negative charge inside the cell.
Hyperpolarization: In some cases, the outflow of potassium ions overshoots the resting membrane potential, causing a brief hyperpolarization. This hyperpolarization is then corrected as potassium channels close and the sodium-potassium pump restores the resting ion concentrations.
Now, in terms of neurotransmitter concentration affecting the action potential height: once the action potential is triggered (step 3), the neuron goes through a cascade of events that are largely determined by the opening and closing of ion channels. The neurotransmitter concentration in the synapse influences whether the postsynaptic neuron will generate an action potential at all by contributing to the overall membrane depolarization, but it doesn't directly affect the height of the action potential once it's initiated. The action potential is a self-regenerating process, meaning that once it starts, it will proceed along the axon without losing strength, as long as the ion concentrations are maintained.
A higher concentration of neurotransmitter above the threshold does not change the height of the action potential. During an action potential, the movement of ions across the neuron's cell membrane is responsible for the changes in charge and the generation of the action potential.
During an action potential, the movement of ions across the neuron's cell membrane is crucial. At rest, the neuron maintains a negative charge inside compared to the outside, known as the resting potential. This is maintained by the selective permeability of the cell membrane and the presence of ion channels.
When a stimulus is received, the neuron undergoes depolarization. This occurs when the cell membrane becomes more permeable to sodium ions. Sodium channels open, allowing sodium ions to rush into the neuron. This influx of positive charge causes a rapid change in the neuron's charge, resulting in the generation of an action potential.
Once the action potential is generated, it propagates along the neuron. This is achieved through the opening and closing of ion channels along the neuron's membrane. As the action potential moves, sodium channels close and potassium channels open, allowing potassium ions to move out of the neuron. This repolarizes the cell membrane, restoring the negative charge inside the neuron.
The concentration of neurotransmitter above the threshold does not change the height of the action potential because the action potential is an all-or-nothing event. Once the threshold is reached, the action potential is generated with a consistent height. The concentration of neurotransmitter affects the likelihood of reaching the threshold, but once it is reached, the height of the action potential remains the same.
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B) carbon
C) magnesium
D) sodium
Answer:
D sodium
Explanation: