1.
Which way do polar heads tend to orient?
Correct Answer
A. Toward the water
Explanation
Polar heads tend to orient toward the water because they are hydrophilic, meaning they have an affinity for water. This is due to the polar nature of the molecule, with one end being positively charged and the other end being negatively charged. The positive end is attracted to the negative oxygen atoms in water molecules, while the negative end is attracted to the positive hydrogen atoms in water molecules. This orientation allows for the formation of hydrogen bonds between the polar heads and water molecules, promoting solubility and interaction with water.
2.
Why is the bi-layer stable?
Correct Answer
A. Water's afinity for hydrogen bonding never stops.
Explanation
Water's affinity for hydrogen bonding never stops because water molecules are polar, with a partially positive hydrogen atom and a partially negative oxygen atom. This polarity allows water molecules to form hydrogen bonds with each other, creating a stable network. These hydrogen bonds are constantly forming and breaking, but they never completely cease. This constant formation and breaking of hydrogen bonds contribute to the stability of the water molecule and the stability of the bi-layer.
3.
What is the plasma membrane composed of?
Correct Answer
D. Lipids and globular proteins.
Explanation
The plasma membrane is composed of lipids and globular proteins. Lipids, such as phospholipids, form a bilayer structure that makes up the majority of the membrane. These lipids provide a barrier that separates the inside of the cell from the external environment. The globular proteins are embedded within the lipid bilayer and have various functions, including transport of molecules across the membrane, cell signaling, and structural support. Together, the lipids and globular proteins make up the plasma membrane, which is essential for maintaining the integrity and functionality of the cell.
4.
Which of the following is a component of the cell membrane?
Correct Answer
A. pHosopHolipid bilayer
Explanation
The cell membrane is composed of a phospholipid bilayer, which is a double layer of phospholipids. These phospholipids have a hydrophilic (water-loving) head and a hydrophobic (water-fearing) tail. The hydrophilic heads face outward towards the watery environment both inside and outside the cell, while the hydrophobic tails face inward, creating a barrier that separates the cell's internal environment from the external environment. This phospholipid bilayer is a crucial component of the cell membrane, providing structural integrity and regulating the movement of molecules in and out of the cell. Transmembrane proteins are also present in the cell membrane, but they are not the primary component.
5.
Which of the following are membrane transport proteins?
Correct Answer
E. All of the above.
Explanation
All of the options mentioned in the question are membrane transport proteins. Transporters are proteins that facilitate the movement of molecules across the cell membrane. Attachments to cytoskeleton help in maintaining the structural integrity of the cell membrane and are involved in intracellular transport processes. Enzymes located in the cell membrane are involved in various metabolic reactions. Cell surface identity markers are proteins that help in cell recognition and communication. Cell adhesion proteins are responsible for binding cells together. Hence, all of these options are examples of membrane transport proteins.
6.
The membrane protein structure is: multiple-pass anchors, single pass chanels and carries, and pores.
Correct Answer
B. False
Explanation
The statement is false because the correct structure of a membrane protein includes multiple-pass anchors, single-pass channels and carriers, and pores.
7.
Diffusion is:
Correct Answer
C. The net movement of substances to go from regions of high concentration to low concentration.
Explanation
Diffusion is the process by which substances move from an area of high concentration to an area of low concentration. This movement occurs due to the random motion of particles, and it continues until equilibrium is reached. Therefore, the correct answer is "The net movement of substances to go from regions of high concentration to low concentration."
8.
Cell transport channels are selectively permeable. How so?
Correct Answer
D. Only certain molecules can enter.
Explanation
Cell transport channels are selectively permeable, meaning they allow only certain molecules to enter. This is important for maintaining the balance and homeostasis within the cell. By controlling what molecules can enter, the cell can regulate its internal environment and prevent harmful substances from entering. This selective permeability ensures that only necessary molecules, such as nutrients and ions, can enter the cell while keeping out unwanted substances.
9.
Ions can move between the cytoplasm of a cell and the extracellular fluid without the assistance of membrane transport proteins.
Correct Answer
B. False
Explanation
The statement is false because ions cannot move between the cytoplasm of a cell and the extracellular fluid without the assistance of membrane transport proteins. Membrane transport proteins, such as ion channels and ion pumps, are necessary for the movement of ions across the cell membrane. These proteins facilitate the transport of ions by creating specific pathways or using energy to move ions against their concentration gradient. Without these proteins, ions would not be able to cross the cell membrane and move between the cytoplasm and extracellular fluid.
10.
What transports ions and other solutes across the plasma membrane?
Correct Answer
A. Carriers
Explanation
Carriers are proteins that transport ions and other solutes across the plasma membrane. These proteins bind to specific molecules and undergo a conformational change to transport them across the membrane. This process is essential for maintaining the balance of ions and molecules inside and outside the cell, allowing for proper cellular function and communication.
11.
How do carriers facilitate movement?
Correct Answer
A. pHysically binding molecules on one side of the membrane, and releasing them on the other.
Explanation
Carriers facilitate movement by physically binding molecules on one side of the membrane and releasing them on the other. This process allows for the transportation of molecules across the membrane, enabling movement from one side to the other.
12.
What is the tendencies of a molecule to go from a region of lower concentration to a higher one?
Correct Answer
A. Osmosis
Explanation
Osmosis is the process in which molecules move from a region of lower concentration to a higher concentration. This occurs through a semipermeable membrane, allowing only certain molecules to pass through. The tendency for molecules to move in this way is driven by the goal of achieving equilibrium, where the concentration is equal on both sides of the membrane. Therefore, the correct answer is osmosis.
13.
What is Isomatic?
Correct Answer
C. Solutons are equal.
Explanation
The correct answer is "Solutons are equal." This means that Isomatic refers to solutions that have the same solute concentration. In other words, the concentration of solutes in both solutions is the same, indicating that they have an equal amount of dissolved substances.
14.
To which of the following are hyposmotic solutions?
Correct Answer(s)
A. Extrusion
B. Turgor
C. Isomotic solutions
Explanation
Hyposmotic solutions refer to solutions with a lower solute concentration compared to another solution. Extrusion, turgor, and isomotic solutions can all be considered hyposmotic because they have a lower solute concentration. Extrusion refers to the process of pushing something out, turgor refers to the pressure exerted by fluid inside a cell, and isomotic solutions have the same solute concentration as another solution. Therefore, all three options are correct answers for the question.
15.
What is endocytosis?
Correct Answer
D. Enveloping food
Explanation
Endocytosis is a cellular process in which the cell engulfs external materials by forming a vesicle around them. This allows the cell to take in various substances, including nutrients and molecules, from the extracellular environment. In the case of enveloping food, endocytosis refers to the process by which the cell engulfs solid particles of food, allowing them to be transported into the cell for digestion and nutrient absorption.
16.
What is phagacytosis?
Correct Answer
B. Material taken in is in particulate form.
Explanation
Phagocytosis is a process in which cells engulf and ingest solid particles, such as bacteria or cellular debris. It is a form of endocytosis, where the cell membrane surrounds the particle and forms a vesicle called a phagosome. This phagosome then fuses with lysosomes, which contain digestive enzymes, to break down the ingested material. Therefore, the correct answer is "Material taken in is in particulate form."
17.
What is pinocytosis?
Correct Answer
B. Material taken in is in liquid form.
Explanation
Pinocytosis is a type of endocytosis where the cell takes in extracellular fluid and solutes by engulfing them in small vesicles. It is a non-selective process that occurs in response to the cell's need for nutrients or to regulate the composition of the extracellular fluid. Unlike phagocytosis which involves the engulfment of larger solid particles, pinocytosis specifically refers to the uptake of liquid material by the cell. Therefore, the correct answer is "Material taken in is in liquid form."
18.
What is exocytosis?
Correct Answer
D. Discharge of materials from vesicles at the cell surface.
Explanation
Exocytosis is the process by which materials are released from vesicles at the cell surface. This means that the materials stored inside vesicles, such as hormones or neurotransmitters, are transported to the cell membrane and then released outside the cell. This process is important for various cellular functions, including cell signaling and communication.
19.
What is receptor-mediated?
Correct Answer
C. Transport of speficic molecules.
Explanation
Receptor-mediated refers to a process in which specific molecules are transported into a cell. This process involves the binding of molecules to specific receptors on the cell surface, which then triggers internalization and transport of the molecules into the cell. This mechanism allows cells to selectively take up certain molecules and is important for various physiological processes such as nutrient uptake, hormone signaling, and immune responses.
20.
What is active transport and what does it involve??
Correct Answer
A. Involves the expenditure of energy to move substances against their concentration gradient
Explanation
Active transport is a process that requires the use of energy to transport substances across a cell membrane against their concentration gradient. This means that the substances are moved from an area of lower concentration to an area of higher concentration. Unlike passive transport, which does not require energy, active transport involves the use of specialized proteins called pumps to move molecules or ions across the membrane. This process is crucial for maintaining the balance of ions and molecules inside the cell and is essential for various cellular functions.