Question 1

Where would you expect to find tight junctions?
A) in the epithelium of an animal's stomach
B) between the smooth endoplasmic reticulum and the rough endoplasmic reticulum
C) between plant cells in a woody plant
D) in the plasma membrane of prokaryotes

Accepted Answer

Tight junctions are a type of cell junction found in the epithelial tissue of animals, particularly in organs that require a barrier function such as the stomach, bladder, and intestines. Tight junctions serve to prevent leakage of substances between cells and maintain the integrity of the epithelial barrier.

Question 2

Which of the following statements is FALSE?
A) When plant cells are growing, they release expansins, which are enzymes that can expand the primary cell wall.
B) The secondary cell wall often contains structural components, like lignin, that form a relatively rigid and complex network within the cell wall.
C) A plant cell continues growing after the secondary cell wall forms but stops growing with the formation of the tertiary cell wall.
D) Pectin is a component of the cell wall that attracts and holds water.

Accepted Answer

Plant cells do not form a tertiary cell wall. After the formation of the secondary cell wall, the cell stops growing. Therefore, option C is false.

Question 3

What do the cell walls of plants and the extracellular matrix of animal cells have in common?
A) They are largely composed of phospholipids and glycoproteins.
B) Their proteins are made by free cytoplasmic ribosomes.
C) They form rigid structures that provide structural support for cells but limit their expansion.
D) They limit the passage of small molecules.
E) They have functional connections with the cytoskeleton inside the cell.

Accepted Answer

Both the cell walls of plants and the extracellular matrix of animal cells have functional connections with the cytoskeleton inside the cell. Plant cell walls are connected to the cytoskeleton via plasma membrane-bound proteins, while animal cell extracellular matrix is connected to the cytoskeleton via transmembrane proteins called integrins. These connections play important roles in cell signaling, communication, and movement.

Question 4

One characteristic of life and living systems is that they are able to adapt. In general, cells interact with other cells and their environment through the action of their ________.
A) plasma membrane and extracellular matrix
B) microtubular tracks
C) hormones
D) intracellular electrical currents

Accepted Answer

The plasma membrane acts as a barrier and allows cells to selectively interact with their environment. The extracellular matrix provides support to cells and also plays a role in cell signaling and communication. Together, these structures allow cells to respond and adapt to changes in their environment. The other options listed do not play as significant of a role in cell interaction and adaptation.

Question 5

For the following question(s), match the labeled component of the cell membrane in the figure with its description. 
-Which component is a protein fiber of the extracellular matrix?
A) A
B) B
C) C
D) D
E) E

Accepted Answer

The answer of For the following question(s), match the labeled...

Question 6

Plasmodesmata in plant cells are most similar in function to which of the following structures in animal cells?
A) peroxisomes
B) desmosomes
C) gap junctions
D) extracellular matrix
E) tight junctions

Accepted Answer

Gap junctions are the closest analog to plasmodesmata in animal cells, as they allow for intercellular communication and transport of small molecules between adjacent cells. Desmosomes, extracellular matrix, and tight junctions are involved in cell adhesion and maintaining tissue structure, while peroxisomes are organelles involved in various metabolic processes.

Question 7

The cell walls of bacteria, fungi, and plant cells and the extracellular matrix of animal cells are all external to the plasma membrane. Which of the following is a characteristic common to all of these extracellular structures?
A) They must block water and small molecules to regulate the exchange of matter and energy with their environment.
B) They must permit information transfer between the cell's cytoplasm and the nucleus.
C) They must provide a rigid structure that maintains an appropriate ratio of cell surface area to volume.
D) They are constructed of polymers that are synthesized in the cytoplasm and then transported out of the cell.
E) They are composed of a mixture of lipids and nucleotides.

Accepted Answer

These extracellular structures are indeed made of polymers that are synthesized within the cytoplasm before being transported outside the cell.

Question 8

Signals from the extracellular matrix to the cytoskeleton may be transmitted by ________.
A) fibronectin
B) proteoglycans
C) integrins
D) collagen
E) middle lamella

Accepted Answer

Integrins are transmembrane proteins that link the extracellular matrix to the cytoskeleton. They bind to components of the extracellular matrix, such as fibronectin or collagen, on one end and to cytoskeletal proteins, such as actin, on the other end, allowing for communication between the outside environment and the cell's internal machinery. Proteoglycans and the middle lamella are important components of the extracellular matrix, but they do not directly transmit signals to the cytoskeleton.

Question 9

A mutation that disrupts the ability of an animal cell to add polysaccharide modifications to proteins would most likely cause defects in its ________.
A) nuclear lamina and nuclear matrix
B) nuclear matrix and extracellular matrix
C) mitochondria and Golgi apparatus
D) Golgi apparatus and extracellular matrix
E) nuclear pores and secretory vesicles

Accepted Answer

Polysaccharides are added to proteins in the Golgi apparatus, which is responsible for modifying and sorting proteins before they are secreted outside of the cell. Therefore, a mutation that disrupts this process would most likely cause defects in the extracellular matrix, which is composed of secreted proteins and carbohydrates. The other organelles listed are not directly involved in polysaccharide modifications to proteins.

Question 10

Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through ________.
A) plasmodesmata
B) intermediate filaments
C) tight junctions
D) desmosomes
E) gap junctions

Accepted Answer

Gap junctions allow ions to travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell. Plasmodesmata are channels between plant cells, while intermediate filaments, tight junctions, and desmosomes do not allow for direct ion transfer between cells.

Question 11

All of the following proteins may be found in the extracellular matrix of animal cells EXCEPT ________.
A) collagen
B) fibronectin
C) actin
D) All of the listed proteins are found in the extracellular matrix of animal cells.

Accepted Answer

Actin is not typically found in the extracellular matrix of animal cells, as it is a cytoskeletal protein that is primarily found within the cell. Collagen and fibronectin, on the other hand, are commonly found in the extracellular matrix, where they provide structural support and help to organize cell adhesion and signaling.

Question 12

Osteocytes are bone cells. Collagen fibers and calcium salts are found in abundance between and among the osteocytes. The collagen and calcium salts are ________.
A) components of the plasma membrane of osteocytes
B) part of the extracellular matrix
C) extensions of the endoplasmic reticulum
D) deposited by the circulatory system but not associated with the osteocytes

Accepted Answer

Collagen fibers and calcium salts are part of the extracellular matrix of bone tissue, which is secreted by bone cells and provides structural support and strength to the bone. They are not components of the plasma membrane or extensions of the endoplasmic reticulum, and they are intimately associated with the osteocytes.

Question 13

Which of the following would you NOT find in a plant cell?
A) pectin
B) polysaccharides
C) collagen
D) lignin

Accepted Answer

Collagen is a protein found in animal connective tissues and is not present in plant cells. Pectin, polysaccharides, and lignin are all components found in plant cells.

Question 14

In plant cells, the middle lamella ________.
A) allows adjacent cells to adhere to one another
B) prevents dehydration of adjacent cells
C) maintains the plant's circulatory system
D) allows for gas and nutrient exchange among adjacent cells

Accepted Answer

The middle lamella is a layer of pectin that cements neighboring plant cells together, allowing for adhesion between cells. It does not play a role in preventing dehydration, maintaining the circulatory system or allowing for gas and nutrient exchange among adjacent cells.

Question 15

Scientists have found that extracellular matrix components may induce specific gene expression in embryonic tissues such as the liver and testes. For this to happen there must be direct communication between the extracellular matrix and the developing cells. Which kind of transmembrane protein would most likely be involved in this kind of induction?
A) integrins
B) collagens
C) actins
D) fibronectins

Accepted Answer

Integrins are transmembrane proteins that act as receptors for extracellular matrix components such as fibronectin and collagen. They can transmit signals from the ECM to the developing cells and influence gene expression, differentiation, and cell proliferation. Therefore, integrins are the best choice for the kind of induction described in the question.

Question 16

H. V. Wilson worked with sponges to gain some insight into exactly what was responsible for holding adjacent cells together. He exposed two species of differently pigmented sponges to a chemical that disrupted the cell-cell interaction (cell junctions), and the cells of the sponges dissociated. Wilson then mixed the cells of the two species and removed the chemical that caused the cells to dissociate. Wilson found that the sponges reassembled into two separate species. The cells from one species did not interact or form associations with the cells of the other species. How do you explain the results of Wilson's experiments?
A) The two species of sponge had different enzymes that functioned in the reassembly process.
B) The molecules responsible for cell-cell adhesion (cell junctions) were irreversibly destroyed during the experiment.
C) The molecules responsible for cell-cell adhesion (cell junctions) differed between the two species of sponge.
D) One cell functioned as the nucleus for each organism, thereby attracting only cells of the same pigment.

Accepted Answer

Wilson's experiments suggest that the molecules responsible for cell-cell adhesion (cell junctions) differed between the two species of sponge, as the cells from one species did not interact or form associations with the cells of the other species. This indicates that the molecules involved in cell junctions were specific to each species, and did not allow for interaction between them.

Question 17

What is a major difference between the extracellular matrix (ECM) of a plant cell and the ECM of an animal cell?
A) Plant ECM is composed primarily of proteins, whereas animal ECM is mainly carbohydrates.
B) Plant ECM is primarily carbohydrate in nature, whereas animal ECM is mainly proteins.
C) Plant and animal ECMs are quite similar in structure and function.
D) ECM components in plant cells are released extracellularly by the Golgi stacks, whereas lysosomes do this in animal cells.

Accepted Answer

The major difference between the ECM of a plant cell and an animal cell is that the plant ECM is primarily carbohydrate in nature, while the animal ECM is mainly composed of proteins. Plant cells produce a complex ECM called the cell wall, which is composed mainly of cellulose, hemicellulose, and pectin. In contrast, animal cells secrete and assemble a diverse array of ECM proteins, including collagen, fibronectin, and laminins, among others.

Question 18

For a tissue or an organ to function as a unit, ________.
A) there must be a signal molecule recognized by all cells in the tissue or organ
B) there must be cell-cell communication among the cells within a tissue or organ
C) the tissue or organ must perform similar functions
D) the tissue or organ must be composed of all of the same type of cells

Accepted Answer

Cell-cell communication is necessary for cells to coordinate their activities and function as a unit within a tissue or organ. This communication can occur through direct contact between cells or through signals transmitted through the extracellular matrix or via chemical messengers like hormones. Therefore, option B is the correct answer. Option A is incorrect because signal molecules are not always required for cells to function as a unit. Option C is incorrect because tissues and organs can perform diverse functions and still function as a unit (e.g., liver performs roles in digestion, metabolism, and storage). Option D is incorrect because different cell types can work together within a single organ or tissue to perform a specific function.

Question 19

Integrins are integral membrane proteins. They are often attached to ________.
A) the membranes of intracellular organelles
B) cytoskeletal proteins and proteins in the extracellular matrix
C) the outside of the plasma membrane
D) glycogen molecules and other types of cellular inclusions

Accepted Answer

Integrins are often attached to cytoskeletal proteins and proteins in the extracellular matrix, playing a crucial role in maintaining cell structure and signaling between cells and their environment. They are not typically attached to intracellular organelles, the outside of the plasma membrane or glycogen molecules.

Question 20

The extracellular matrix is thought to participate in the regulation of animal cell behavior by communicating information from the outside to the inside of the cell via which of the following?
A) gap junctions
B) the nucleus
C) DNA and RNA
D) integrins
E) plasmodesmata

Accepted Answer

Integrins are membrane proteins that span the plasma membrane and connect the extracellular matrix to the cytoskeleton inside the cell. They can transmit signals bidirectionally, from the extracellular to the intracellular space, and vice versa. Thus, integrins enable the extracellular matrix to affect cell behavior by sending signals to the inside of the cell. Gap junctions, plasmodesmata, and DNA/RNA do not have direct roles in communicating information from the outside to the inside of the cell, while the nucleus primarily controls gene expression and is not involved in signal transduction from the extracellular matrix.

Quiz 11: Cellcell Interactions

Where would you expect to find tight junctions?

Which of the following statements is FALSE?

What do the cell walls of plants and the extracellular matrix of animal cells have in common?

One characteristic of life and living systems is that they are able to adapt. In general, cells interact with other cells and their environment through the action of their ________.

For the following question(s) , match the labeled component of the cell membrane in the figure with its description. -Which component is a protein fiber of the extracellular matrix?

Plasmodesmata in plant cells are most similar in function to which of the following structures in animal cells?

The cell walls of bacteria, fungi, and plant cells and the extracellular matrix of animal cells are all external to the plasma membrane. Which of the following is a characteristic common to all of these extracellular structures?

Signals from the extracellular matrix to the cytoskeleton may be transmitted by ________.

A mutation that disrupts the ability of an animal cell to add polysaccharide modifications to proteins would most likely cause defects in its ________.

Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through ________.

All of the following proteins may be found in the extracellular matrix of animal cells EXCEPT ________.

Osteocytes are bone cells. Collagen fibers and calcium salts are found in abundance between and among the osteocytes. The collagen and calcium salts are ________.

Which of the following would you NOT find in a plant cell?

In plant cells, the middle lamella ________.

What is a major difference between the extracellular matrix (ECM) of a plant cell and the ECM of an animal cell?

For a tissue or an organ to function as a unit, ________.

Integrins are integral membrane proteins. They are often attached to ________.

The extracellular matrix is thought to participate in the regulation of animal cell behavior by communicating information from the outside to the inside of the cell via which of the following?