Question 1

A type of transport protein found in the plasma membrane of cells lining the inside of the intestine allows sodium ions to diffuse down their concentration gradient.The ions move through the transport protein,and into the cell.These transport proteins will use the kinetic energy of the diffusing sodium ions to bring glucose into the cells as well.This transport protein would best be described as ________.

Accepted Answer

A symporter is a type of carrier protein that transports two different molecules across a membrane in the same direction. In this case, the transport protein allows both sodium ions and glucose to enter the cell, using the kinetic energy of the sodium ions moving down their concentration gradient. A pump, on the other hand, actively transports molecules against their concentration gradient, requiring energy input. A channel allows molecules to pass through the membrane passively, without any energy input from the cell.

Question 2

Cancerous cells can divide so rapidly that they will often produce a glycocalyx that is different than the other cells in the body.This may result in ________.

Accepted Answer

The glycocalyx, a glycoprotein and glycolipid covering that surrounds the cell membranes of some bacteria, epithelia, and other cells, plays a role in cell-cell recognition and communication. When cancer cells produce a different glycocalyx, it can lead to the immune system recognizing these cells as foreign, potentially leading to their destruction by immune cells. This is because the immune system is designed to identify and eliminate cells that are not recognized as part of the body, including cells that have undergone malignant transformation and exhibit abnormal surface markers.

Question 3

When tissues are injured or infected,chemical signals can be releases that affect the plasma membrane of cells that line the nearby blood vessels.These blood vessels cells (endothelial cells)respond to the chemical signals by displaying a type of glycoproteins on their surface.These proteins will attach to circulating white blood cells bringing them to the site of injury or infection.These glycoproteins would best be described as ________.

Accepted Answer

The glycoproteins that attach to circulating white blood cells and bring them to the site of injury or infection are known as Cell Adhesion Molecules (CAMs). Therefore, choice D is the correct answer. Desmosomes are cell junctions that provide mechanical stability for tissues, G-proteins are involved in intracellular signaling pathways, and transport proteins are involved in the movement of molecules across membranes.

Question 4

Bone is a connective tissue that provides support for the body with its strength and rigidity.Which of the following provides the best explanation for how this is so?

Accepted Answer

Bone cells secrete an extracellular matrix that when combined with minerals like calcium and phosphorus, becomes mineralized and hard, giving bone its strength and rigidity.

Question 5

If a cell is selectively reducing the concentration of a particular enzyme in the extracellular fluid it will likely utilize ________.

Accepted Answer

Receptor-mediated endocytosis involves the selective uptake of specific molecules or proteins through ligand-receptor interactions. Therefore, if a cell wants to reduce the concentration of a particular enzyme in the extracellular fluid, it may use receptor-mediated endocytosis to selectively internalize and degrade the enzyme. Phagocytosis and pinocytosis are non-selective processes that engulf extracellular material, whereas exocytosis involves the secretion of intracellular material into the extracellular space and would not lead to a reduction in extracellular enzyme concentration.

Question 6

Some hormones enter cells via ________.

Accepted Answer

Hormones typically bind to specific receptor proteins on the surface of target cells. Through receptor-mediated endocytosis, the hormone-receptor complex can then be internalized into the cell, where it can initiate cellular responses. Exocytosis, primary active transport, and pinocytosis are not typically used for hormone uptake.

Question 7

The lungs deliver a regular supply of oxygen to the blood,which is in turn circulated to most all the cells of the body.At the same time oxygen is consumed during aerobic cellular respiration within these cells.This implies that ________.

Accepted Answer

Oxygen will passively diffuse into the cells due to the concentration gradient created by the consumption of oxygen during cellular respiration. Active transport is not required for most cells to take up oxygen, and the rate of diffusion is dependent on the concentration gradient.

Question 8

A type of transport protein found in the plasma membrane of cells lining the inside of the intestine allows sodium ions to diffuse down their concentration gradient.The ions move through the transport protein,and into the cell.These transport proteins will use the kinetic energy of the diffusing sodium ions to bring glucose into the cells as well.Which of the following would stop transport of glucose through this transport protein?

Accepted Answer

The transport of sodium ions and glucose into the cell is dependent on the activity of the sodium-potassium pump. If the pump is stopped, the sodium ion concentration gradient necessary for the transport of glucose into the cell is disrupted, and glucose transport through this transport protein will stop. Increasing the number of digestive enzymes, increasing the concentration of glucose outside of the cell, or lowering the energy of activation would not directly affect the activity of the sodium-potassium pump or the transport of sodium ions and glucose through this transport protein.

Question 9

A cell engulfing a relatively large particle will likely utilize ________.

Accepted Answer

Phagocytosis is the process by which cells engulf large particles such as whole cells, bacteria, or debris. It involves the formation of pseudopodia (temporary projections of the cell membrane) which surround and engulf the particle, forming a phagosome. This process is utilized by cells such as macrophages and neutrophils in the immune system to engulf and destroy invading pathogens. Pinocytosis and receptor-mediated endocytosis are mechanisms by which cells take up smaller particles and molecules, while exocytosis is the process by which cells release substances outside of the cell.

Question 10

If a tRNA had an AGC anticodon,it could attach to a(n)________ mRNA codon.

Accepted Answer

The anticodon of a tRNA molecule is complementary to the codon on the mRNA molecule. In this case, an AGC anticodon would pair with a UCG mRNA codon through base pairing rules (A-U, G-C). The other options (B) TCG, (C) UGA, and (D) AUG are not complementary to AGC so they would not be the best choice.

Question 11

Myocardium (cardiac muscle tissue)must rhythmically contract for a lifetime.This requires a considerable amount of energy production by the cells.You would expect to see a relatively high amount of which organelle in these cells?

Accepted Answer

The high energy demands of myocardial cells require a large number of mitochondria for aerobic respiration to keep the cells functioning.

Question 12

If active transport establishes a concentration gradient with the use of ATP,then the concentration gradient can be looked at as ________.

Accepted Answer

The establishment of a concentration gradient through active transport creates potential energy that can be used for passive diffusion of molecules. This is because molecules will naturally move from an area of high concentration to an area of low concentration in order to reach equilibrium, allowing the gradient to power this process.

Question 13

Which of the following will NOT speed up the net rate of diffusion for glucose into a cell?

Accepted Answer

Decreasing the number of phospholipids in the plasma membrane will impair the function of the membrane, and may even cause cells to leak, which will slow down the net rate of diffusion. Increasing the concentration of glucose outside the cell, increasing the number of glucose transport proteins within the plasma membrane, and decreasing the concentration of glucose within the cell will all help to speed up the net rate of diffusion for glucose into the cell.

Question 14

The movement of water across the plasma membrane can be described by all of the following EXCEPT ________.

Accepted Answer

Water movement across the plasma membrane can occur through simple diffusion, passive membrane transport, and facilitated diffusion through aquaporins. Carrier-mediated facilitated diffusion typically involves the movement of substances other than water, using a carrier protein that undergoes a change in shape to transport substances across the membrane.

Question 15

If a cell is non-selectively engulfing samples of extracellular fluid,for example to absorb nutrients,it will likely utilize ________.

Accepted Answer

Non-selective engulfing of extracellular fluid to absorb nutrients is a characteristic of pinocytosis. Phagocytosis is the process of engulfing a large particle or microorganism, while receptor-mediated endocytosis is a selective process that requires specific receptors on the cell surface. Exocytosis is the process of releasing material from a cell.

Question 16

The myocardium (cardiac muscle tissue)undergoes a significant amount of physical stress due to its contractions.You would expect to see relatively large numbers of which of the following embedded within their plasma membrane?

Accepted Answer

Desmosomes are specialized protein structures that act like spot-welds to hold adjacent cardiac muscle cells together, resisting the mechanical stress of repeated contractions. Therefore, you would expect to see relatively large numbers of desmosomes embedded within their plasma membrane. Tight junctions are more commonly found in epithelial tissues where they provide a barrier to prevent substances from passing between cells. Glycolipids and transport proteins are not directly involved in cell-cell adhesion and do not have a significant role in resisting physical stress.

Question 17

Which of the following would NOT assist in establishing a resting membrane potential?

Accepted Answer

The answer of Which of the following would NOT assist...

Question 18

If a human cell were to increase the amount of cholesterol embedded within its plasma membrane which of the following would most likely happen?

Accepted Answer

Increasing the amount of cholesterol embedded within the plasma membrane will make the membrane more stable, less fluid, and less permeable. This is because cholesterol molecules fit snugly between the phospholipids and reduce their movement, thus decreasing the membrane's fluidity. Additionally, cholesterol molecules can also interact with the fatty acid tails of the phospholipids, making them more rigid and stable. Thus, option D is the best choice.

Question 19

Which of the following would not be restricted (limited)by low levels of ATP?

Accepted Answer

Osmosis is a passive process that does not require ATP, as it is driven by the concentration gradient of water molecules. Exocytosis, pinocytosis, and phagocytosis are all active processes that require ATP to power the movement of vesicles or engulfment of particles. Therefore, they would be restricted by low levels of ATP.

Question 20

Beta cells in the pancreas produce and secrete the protein hormone insulin.You would expect to see a relatively large amount of which organelles in these cells?

Accepted Answer

The Golgi apparatus is responsible for modifying and packaging proteins, including insulin, for secretion. The rough endoplasmic reticulum is also important for protein synthesis and secretion. Therefore, beta cells in the pancreas would have a relatively large amount of these organelles to facilitate insulin production and secretion. The other organelles listed are not directly involved in this process.

Quiz 3: Cells: the Living Units