Question 1

In cyanobacteria, where are the molecules that carry out photosynthesis found?

Accepted Answer

In cyanobacteria, the molecules that carry out photosynthesis are contained in the folds of the plasma membrane. This is where the photosynthetic pigments and electron transport chains are located.

Question 2

The relative impermeability of membranes to water soluble molecules is a result of

Accepted Answer

The presence of phospholipids in the lipid bilayer of membranes creates a selectively permeable barrier that is relatively impermeable to water soluble molecules. The hydrophobic fatty acid tails of the phospholipids form a barrier to polar hydrophilic molecules, while the hydrophilic head groups face the aqueous environments on either side of the membrane. This arrangement restricts the free passage of water soluble substances through the membrane.

Question 3

____ are involved in transfer of genetic information from one bacterial cell to another.

Accepted Answer

The answer of ____ are involved in transfer of genetic...

Question 4

Hydrophobic interactions of the tails of phospholipids produce

Accepted Answer

The hydrophobic interactions between the tails of phospholipids create a nonpolar region within the membrane, which results in the formation of a lipid bilayer.

Question 5

Which of the following statements is TRUE?

Accepted Answer

Lipids are classified as nonpolar substances and will not mix with water. The hydrophobic nature of lipids (nonpolar) does not allow them to mix with water (polar).

Question 6

A transport protein is analogous to a

Accepted Answer

A transport protein is analogous to a subway train as it moves molecules across a membrane in a specific direction, just like a subway train moves passengers along a track in a specific direction.

Question 7

The phospholipids of plasma membranes have

Accepted Answer

The phospholipids of plasma membranes have a hydrophilic head and two hydrophobic tails. This is because the head of the phospholipid is composed of a phosphate group and a glycerol molecule, which are both polar and hydrophilic. The tails, on the other hand, are made up of fatty acid chains that are nonpolar and hydrophobic. This creates a bilayer structure with the hydrophilic heads pointing outwards and the hydrophobic tails pointing inwards.

Question 8

Plasma membrane proteins might be involved in

Accepted Answer

Plasma membrane proteins are involved in all of these functions. They can act as receptors for signals, facilitate the transport of nutrients and participate in metabolic activities. Additionally, some plasma membrane proteins act as markers for cell-to-cell recognition.

Question 9

A hypothetical "microbullet" shot through a phospholipids bilayer will pass the component in which order?

Accepted Answer

The answer of A hypothetical "microbullet" shot through a phospholipids...

Question 10

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

Accepted Answer

The plasma membrane controls the contents of the cell by selectively allowing certain molecules to enter or exit the cell. B is incorrect as the main lipid of a cell membrane is phospholipid, not cholesterol. C is incorrect as carbohydrates play a role in cell-cell recognition and not most of the cell's dynamic functions. D is incorrect as there is no such thing as a cytoplastic reticulum enclosed by the plasma membrane.

Question 11

Most of the active functions of plasma membranes are carried out by

Accepted Answer

Proteins are responsible for most of the active functions of plasma membranes, such as transport, enzymatic activity, signal transduction, and cell adhesion. Cholesterol helps to stabilize the membrane and regulate its fluidity. Hydrophilic heads and hydrophobic tails make up the phospholipid bilayer, which forms the basic structure of the membrane. Carbohydrates are important for cell recognition and communication but do not carry out the active functions of the membrane.

Question 12

A prokaryote's cell shape is reinforced by

Accepted Answer

Protein filaments, such as actin and tubulin, provide structural support for prokaryotic cells and contribute to their shape.

Question 13

A water-soluble hormone (signaling molecule) would most likely bind to which of the following membrane proteins?

Accepted Answer

Water-soluble hormones, being hydrophilic, cannot pass through the hydrophobic plasma membrane on their own. Instead, they bind to specific receptor proteins that are embedded in the membrane, which triggers a signal transduction cascade inside the cell. Therefore, the most likely membrane protein for a water-soluble hormone to bind to is a receptor protein.

Question 14

An analysis of plasma or nuclear membrane would yield

Accepted Answer

The plasma and nuclear membranes are composed of phospholipids and proteins, with the phospholipids forming a bilayer that acts as a barrier between the inside and outside of the cell or nucleus. These membranes also contain other components, such as cholesterol and glycolipids, but phospholipids and proteins are the main constituents.

Question 15

If a plasma membrane were compared to a sandwich, ____ would be considered the filling.

Accepted Answer

The answer of If a plasma membrane were compared to...

Question 16

In the fluid mosaic model of a typical plasma membrane, what accounts for the fluidity?

Accepted Answer

The phospholipids in the plasma membrane are not bonded to each other and can move laterally within the bilayer, giving the membrane its fluidity. The proteins also contribute to the fluidity by allowing for movement and flexibility within the membrane. The other choices are not accurate explanations for membrane fluidity.

Question 17

How do the plasma membranes of Archaea differ from the plasma membranes of Eukarya?

Accepted Answer

The answer of How do the plasma membranes of Archaea...

Question 18

What is the function of ribosomes?

Accepted Answer

Ribosomes are responsible for the assembly of amino acids into polypeptides, which are the building blocks of proteins.

Question 19

In nature, a biofilm may include

Accepted Answer

A biofilm can include multiple types of microorganisms, including bacteria, microscopic algae, protists, and fungi. This allows for complex interactions and relationships within the biofilm community.

Question 20

No prokaryotic cells have

Accepted Answer

Prokaryotic cells do not have a true nucleus. Instead, their DNA is found in a region called the nucleoid.

Quiz 3: Cell Structure