Question 1

The surface area-to-volume ratio of a cell

Accepted Answer

The surface area-to-volume ratio determines how efficiently substances can enter and exit a cell. As the volume of a cell increases, so does its surface area-to-volume ratio, which reduces its efficiency in exchanging substances with the external environment. This sets a limit on the size of cells, explaining why most cells are small.

Answer: E 
 The surface area-to-volume ratio affects how molecules are distributed across the cell, as it influences the rate and efficiency of diffusion of molecules in and out of the cell. A smaller surface area-to-volume ratio allows for faster and more efficient diffusion, ensuring that essential molecules reach all parts of the cell in a timely manner.

Question 2

Refer to the figure below.  Which letter is paired with the correct label?

Accepted Answer

D

Question 3

Though science fiction has produced stories like The Blob, we do not see many large, single-celled organisms.Which is a reason for the limitation to cell size?

Accepted Answer

The primary limitation to cell size is the difficulty of moving molecules rapidly within a large cell. As cells increase in size, the volume increases much faster than the surface area, making it difficult to transport nutrients, waste, and other molecules quickly enough to support the cell's needs.

Question 4

Which is a difference between a prokaryotic and a eukaryotic cell?

Accepted Answer

The DNA in a prokaryotic cell is not enclosed in a membrane-bound nucleus, whereas in a eukaryotic cell, the DNA is enclosed in a membrane-bound nucleus. This is the primary difference between prokaryotic and eukaryotic cells.

Question 5

Which cell carries out the most chemical activity within a minute (all else being equal)?

Accepted Answer

The larger the cell, the smaller its surface area-to-volume ratio. A smaller surface area-to-volume ratio means there are fewer openings for material exchange, which reduces the amount of chemical activity that can occur. Therefore, cell 4 with a diameter of 10 micrometers has the least surface area-to-volume ratio and would carry out the most chemical activity within a minute.

Question 6

Five statements comparing prokaryotes and eukaryotes are given.Which statement provides evidence that supports the claim that all cells share a common ancestor?

Accepted Answer

The fact that prokaryotes and eukaryotes use the same genetic code suggests that they share a common ancestor. If the genetic code was different between the two groups, then it would suggest that they evolved independently and did not share a common ancestor. However, the fact that they share the same genetic code suggests that the genetic code was present in the last universal common ancestor (LUCA) of all cells.

Question 7

Which cell exchanges the most substances and waste products with its environment relative to its internal chemical activity?

Accepted Answer

A smaller cell has a higher surface area-to-volume ratio, allowing for more efficient exchange of substances and waste products relative to its internal chemical activity.

Question 8

Which statement is one of the tenets of cell theory?

Accepted Answer

The tenet of cell theory stating that all cells come from preexisting cells is a fundamental principle of biology and is widely accepted by scientists today. This principle was first proposed by Rudolf Virchow in 1855, and it helps to explain how living organisms can maintain continuity from generation to generation. The other statements are either only partially true or not directly related to cell theory.

Question 9

A student suggests that prokaryotic and eukaryotic cells must be about the same size since both types of cells can be observed using a light microscope.Which statement provides the best response to this suggestion?

Accepted Answer

The suggestion that prokaryotic and eukaryotic cells must be about the same size since both can be observed using a light microscope is not reasonable because light microscopes can allow a wide range of cell sizes to be seen. While it is true that human eyes can only see objects down to a certain size limit, this is not the reason why the suggestion is not reasonable. Additionally, while both prokaryotic and eukaryotic cells have an upper limit on size due to the limitations of molecular movement in and out of the cell, this is not the best response to the suggestion. The fact that eukaryotic cells are found in both unicellular and multicellular organisms, whereas all prokaryotes are unicellular, is not relevant to the suggestion about cell size. Finally, while prokaryotic and eukaryotic cells do share a basic internal structure, this does not necessarily mean that they are about the same size.

Question 10

A general function of all cellular membranes is to

Accepted Answer

Cellular membranes act as a selective barrier, allowing certain molecules to enter or exit the cell while preventing others from doing so. This regulation is crucial for maintaining proper cellular function and homeostasis.

Question 11

A student claims that the study of cell biology can be considered the same as studying life.Which statement makes the best response to this student's claim?

Accepted Answer

Cell biology can be considered the same as studying life because cells are the basic unit of life and express all the principles of life found in all living organisms.

Question 12

Prokaryotic cells

Accepted Answer

The answer of Prokaryotic cells
...

Question 13

The technique of _______ microscopy can be used to visualize the embedded components of a cell membrane.

Accepted Answer

Freeze-fracture microscopy involves freezing a sample and then breaking it apart to reveal the internal structures, allowing for visualization of the embedded components of a cell membrane. Light, scanning electron, and phase-contrast microscopy do not provide this level of detail, and confocal microscopy is typically used for visualizing fluorescently-labeled samples.

Question 14

Which technique would be best suited to a study of normal cell migration during embryonic development?

Accepted Answer

The answer of Which technique would be best suited to...

Question 15

Many pieces of evidence support the claim that all modern cells share the same ancestor in their evolutionary histories.If a living organism is discovered on another planet or moon, what data would biologists collect to determine whether this organism also shares the common ancestor that all cells on Earth share?

Accepted Answer

The chemical composition of an organism's hereditary molecules, such as DNA or RNA, would provide insight into its evolutionary history. If these molecules resemble those found in all modern cells on Earth, it would be evidence that the organism shares a common ancestor with Earth's cells. However, if the hereditary molecules are significantly different, it would suggest a different evolutionary history. The other options listed may provide information about the organism's ability to survive or function, but they would not be as relevant to determining its evolutionary relationship to Earth's cells.

Question 16

How does the surface area-to-volume ratio of a sphere 1 mm in diameter compare with the surface area-to-volume ratio of a sphere 3 mm in diameter?

Accepted Answer

The surface area-to-volume ratio decreases as the size of the sphere increases, meaning smaller spheres have a higher ratio compared to larger ones.

Question 17

A student claims that the image below demonstrates that life is continuous.  Which statement best evaluates the student's claim?

Accepted Answer

The answer of A student claims that the image below...

Question 18

Researchers must use _______ to distinguish the structure of a ribosome from that of a Golgi apparatus.

Accepted Answer

A ribosome and Golgi apparatus are both subcellular structures that cannot be distinguished with the naked eye, a handheld magnifying glass, or a bright-field microscope. A phase-contrast microscope may provide some contrast between different structures within a cell, but an electron microscope is typically necessary to distinguish the intricate details of subcellular structures such as ribosomes and Golgi apparatus. Therefore, the best choice for distinguishing between a ribosome and a Golgi apparatus is an electron microscope.

Question 19

The cytosol and _______ are two components of the cytoplasm in a prokaryotic cell.

Accepted Answer

Prokaryotic cells, unlike eukaryotic cells, do not have membrane-bound organelles such as mitochondria, chloroplasts, or the Golgi apparatus. The cytoplasm of a prokaryotic cell is made up of two components: the cytosol, which is the liquid portion of the cytoplasm, and ribosomes, which are the protein-producing machines of the cell. The smooth ER is also a membrane-bound organelle found in eukaryotic cells, and is not present in prokaryotes.

Question 20

Most plant and animal cells are

Accepted Answer

Most plant and animal cells are large enough to be seen with a light microscope, typically ranging from 10 to 100 micrometers in size, which allows them to be observed with this equipment.

Quiz 5: Cells: the Working Units of Life