A&p Self Quiz Chapter 3

The Na+/K+ ATPase pump is indeed an important and abundant active mechanism that helps maintain cellular tonicity. This pump actively transports sodium ions out of the cell and potassium ions into the cell, using ATP as an energy source. By doing so, it helps regulate the concentration of these ions inside and outside the cell, which is crucial for maintaining the cell's osmotic balance and overall tonicity. Therefore, the statement "An important and abundant active mechanism that helps maintain cellular tonicity is the Na+/K+ ATPase pump" is true.

If the concentration of solutes in the extracellular fluid (ECF) and intracellular fluids (ICFs) are equal, the cell is in an isotonic solution. In an isotonic solution, the concentration of solutes inside and outside the cell is balanced, resulting in no net movement of water across the cell membrane. This allows the cell to maintain its shape and normal functions without gaining or losing water.

The incorrect match is "carrier: allows cells to recognize each other and foreign cells." Carriers are membrane proteins that facilitate the transport of molecules across the cell membrane, but they do not play a direct role in recognizing cells or foreign cells. This function is typically carried out by receptor proteins.

A small membrane surface area will not increase the rate of diffusion across the cell membrane. In fact, a larger membrane surface area would be more beneficial for diffusion because it provides more space for molecules to pass through. A smaller surface area would limit the number of molecules that can diffuse at a given time, thus reducing the rate of diffusion. Therefore, the statement is false.

During meiosis, a type of cell division, the original cell undergoes two rounds of division resulting in the formation of four genetically different cells. This is because during meiosis, homologous chromosomes pair up and exchange genetic material through a process called crossing over. This genetic recombination leads to the creation of new combinations of genes in the resulting cells, making them genetically distinct from the original cell. Therefore, the statement "The cells created during meiosis are genetically different from the original cell" is true.

The correct answer is 1, 2, and 5. This is because nucleoli within the nucleus are indeed the sites of ribosome synthesis. The nucleus contains the cell's hereditary units, which are the DNA molecules. In nondividing cells, DNA is found in the nucleus in the form of chromatin, which is a complex of DNA and proteins. Therefore, statements 1, 2, and 5 are true regarding the nucleus.

The mRNA base sequence that is complementary to the DNA base sequence ATC would be UAG. In DNA, the base pairs are A-T and C-G. In mRNA, the base pairs are A-U and C-G. So, the complementary base sequence of ATC in mRNA would be UAG.

Apoptosis is the process of programmed cell death that occurs as a normal part of an organism's development or as a response to cellular stress. It is a highly regulated process that involves the controlled dismantling of the cell and its components. On the other hand, necrosis is a form of cell death that is caused by external factors such as tissue injury, infection, or lack of blood supply. Unlike apoptosis, necrosis is characterized by cell swelling, inflammation, and the release of cellular contents, which can trigger an immune response.

Lysosomes and peroxisomes are organelles that function primarily in decomposition reactions. Lysosomes contain enzymes that break down waste materials and cellular debris, while peroxisomes are involved in the breakdown of fatty acids and the detoxification of harmful substances. Proteasomes, on the other hand, are responsible for the breakdown of proteins, not decomposition reactions. Therefore, the correct answer is 2, 3, and 5.

The three major parts of the cell are the plasma membrane, cytoplasm, and nucleus. The plasma membrane is the outer boundary of the cell that controls what enters and exits the cell. The cytoplasm is the gel-like substance inside the cell where most of the cellular activities occur. The nucleus is the control center of the cell that contains the genetic material and regulates cell functions.

Telomeres are special DNA sequences located at the ends of chromosomes. They act as protective caps, preventing the erosion and degradation of the genetic material during cell division. Telomeres play a crucial role in maintaining the stability and integrity of chromosomes. However, with each cell division, telomeres gradually shorten, and when they become critically short, cells can no longer divide and enter a state of senescence or cell death. This erosion of telomeres contributes to cellular aging and ultimately leads to the death of the cell.