Question 1

The structural combination of DNA and protein forms ________.

Accepted Answer

Chromatin is the structural combination of DNA and protein, which forms the chromosome in eukaryotic cells. Nucleoli are structures within nuclei that produce ribosomes. RNA is a type of nucleic acid that is transcribed from DNA and may serve various functions within cells. Ribosomes are organelles that synthesize proteins.

Question 2

When mixed with water,phospholipids spontaneously form membranes because they ________.

Accepted Answer

Phospholipids have hydrophilic phosphate groups that are attracted to water and hydrophobic fatty acid tails that avoid water. When mixed with water, the hydrophilic heads face outward towards the water while the hydrophobic tails face inward, resulting in the spontaneous formation of a membrane.

Question 3

Plants are susceptible to bacterial infections,which can damage their structure or even kill them.Which of the following would be the best antibiotic to treat a plant that is infected with bacteria?

Accepted Answer

D

Question 4

You find a cell of a type you have never seen before.The cell has both a nucleus and a cell wall.Therefore,you conclude that it is likely to be a(n)________ cell.

Accepted Answer

Only cells of the plant kingdom have both a nucleus and a cell wall. Animal cells have a nucleus but no cell wall, bacterial cells have a cell wall but no true nucleus, and prokaryotic cells lack both a true nucleus and a cell wall.

Question 5

The extracellular matrix of animal cells ________.

Accepted Answer

The extracellular matrix of animal cells serves to protect and support cells, providing a framework for their structure and influencing their behavior. It is composed of a variety of molecules, including proteins, polysaccharides, and glycoproteins, and is involved in cell signaling, adhesion, and communication. It does not provide avenues for the exchange of DNA, nor is it primarily a site of dead matter and waste materials. Though it can store certain substances, such as calcium ions, it is not a warehouse for the storage of extra lipids and carbohydrates.

Question 6

Most human cells contain ________ chromosomes.

Accepted Answer

The average human cell contains 46 chromosomes (23 pairs).

Question 7

Which of the following is a function of the plasma membrane?

Accepted Answer

The plasma membrane is responsible for regulating the traffic of chemicals in and out of the cell. It acts as a selectively permeable barrier, allowing certain substances to pass through while keeping others out. This is essential for maintaining the internal environment of the cell and for communication with other cells and the environment. The other choices are not functions of the plasma membrane.

Question 8

The nuclear envelope is composed of ________.

Accepted Answer

The nuclear envelope is composed of a double membrane, often called the nuclear membrane. This membrane separates the contents of the nucleus from the cytoplasm of the cell.

Question 9

Information is transferred from the nucleus to ribosomes via ________.

Accepted Answer

mRNA (messenger RNA) is the molecule that carries genetic information from the nucleus to ribosomes, where it is translated into protein. The rough endoplasmic reticulum and smooth endoplasmic reticulum are involved in protein synthesis and lipid metabolism respectively, but they do not directly transfer information from the nucleus to ribosomes. DNA remains in the nucleus and does not directly interact with ribosomes.

Question 10

Which theory states that all living things are composed of cells?

Accepted Answer

The cell theory states that all living things are composed of cells.

Question 11

________ store the information necessary to produce proteins.

Accepted Answer

Genes store the information necessary to produce proteins.

Question 12

Where does protein synthesis take place?

Accepted Answer

Protein synthesis takes place on ribosomes, which are either free in the cytoplasm or attached to the rough endoplasmic reticulum. The nucleolus is responsible for ribosome synthesis but not protein synthesis, and smooth endoplasmic reticulum is not involved in protein synthesis. The nucleus contains DNA and is not directly involved in protein synthesis.

Question 13

One difference between eukaryotic and prokaryotic cells is that eukaryotic cells ________ prokaryotic cells.

Accepted Answer

Eukaryotic cells have membrane-enclosed organelles such as the nucleus, mitochondria, and endoplasmic reticulum, while prokaryotic cells lack these membrane-bound structures. Both types of cells have DNA and a plasma membrane, and while prokaryotic cells have a nucleoid region, eukaryotic cells have a true nucleus.

Question 14

The concept of a membrane as a fluid mosaic reflects the ability of ________.

Accepted Answer

The fluid mosaic model of the membrane suggests that both phospholipids and proteins are able to move laterally within the plane of the membrane, creating a fluid and dynamic structure. While carbohydrates may be present on the exterior of the membrane, they do not contribute to the fluidity of the structure. Therefore, choice A is the best option as it accurately reflects the concept of a membrane as a fluid mosaic.

Question 15

When using a microscope to view cells you obtained from scraping under your fingernails,you notice that the cells lack nuclei; therefore,you conclude that the cells must be a type of ________ cell.

Accepted Answer

Prokaryotic cells are characterized by not having a nucleus, while eukaryotic cells, found in plants and fungi, do have a nucleus. Therefore, the lack of a nucleus in the cells obtained from scraping under your fingernails indicates that they are likely prokaryotic cells.

Question 16

In eukaryotic cells,what name is given to the region between the nucleus and the plasma membrane?

Accepted Answer

The cytoplasm is the region between the nucleus and the plasma membrane in eukaryotic cells. It contains various organelles and cytoskeletal elements that support cell structure and function. The phospholipid bilayer is a component of the plasma membrane, which surrounds the cytoplasm. The nucleoid is a region in prokaryotic cells where DNA is located, whereas the nucleus is the membrane-bound organelle that contains DNA in eukaryotic cells. Chloroplasts are organelles found in plant cells that carry out photosynthesis.

Question 17

Which of the following structures manufactures the components of ribosomes?

Accepted Answer

The nucleolus is a substructure within the nucleus that is responsible for manufacturing the two components of ribosomes: ribosomal RNA (rRNA) and proteins. Therefore, the nucleolus is the best choice for the structure that manufactures the components of ribosomes.

Question 18

Some ribosomes are suspended in the cytosol of a cell,whereas other ribosomes ________.

Accepted Answer

Ribosomes are attached to the rough endoplasmic reticulum and the outer membrane of the nuclear envelope, not the smooth ER or plasma membrane.

Question 19

________ are the major lipids of plasma membranes.

Accepted Answer

Phospholipids are a major component of plasma membranes, forming a lipid bilayer that serves as a barrier between the cell and its environment. Steroids and fatty acids can also be found in membranes, but in smaller amounts and with less structural importance. Starches are not found in plasma membranes.

Question 20

Which of the following is a feature of prokaryotic cells but NOT eukaryotic cells?

Accepted Answer

Pili are hair-like structures found on the surface of many prokaryotic cells, such as bacteria, and are not a feature of eukaryotic cells.

Quiz 4: A Tour of the Cell