Question 1

Plasmodesmata are cell- cell junctions that can be found between

Accepted Answer

A)  cells of connective tissue in animals. 
B)  skeletal muscle cells. 
C)  plant cells. 
D)  none of the above. 
A)  cells of connective tissue in animals. 
B)  skeletal muscle cells. 
C)  plant cells. 
D)  none of the above.

Question 2

Hormones function as

Accepted Answer

A)  signal molecules. 
B)  cell receptors. 
C)  second messengers. 
D)  neurotransmitters. 
A)  signal molecules. 
B)  cell receptors. 
C)  second messengers. 
D)  neurotransmitters.

Question 3

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

Accepted Answer

A)  deposited by the circulatory system and are not associated with the osteocytes. 
B)  extensions of the endoplasmic reticulum. 
C)  part of the extracellular matrix. 
D)  components of the plasma membrane of osteocytes. 
A)  deposited by the circulatory system and are not associated with the osteocytes. 
B)  extensions of the endoplasmic reticulum. 
C)  part of the extracellular matrix. 
D)  components of the plasma membrane of osteocytes.

Question 4

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. The cells of the sponges dissociated. Wilson mixed the cells of the two species and removed the chemical that caused the cells to dissociate. Wilson found 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?

Accepted Answer

A)  The disassembled cells formed bonds with any of the cells in the mixture. However, once the organism was completely assembled, an enzyme changed all cells to the same pigment. 
B)  The molecules responsible for cell- cell adhesion were different in the two different species of sponge. 
C)  There are enzymes involved in the assembly of the sponge organism, and the two different species had two different enzymes functioning in reassembly. 
D)  One cell functions as the nucleus for each organism, attracting only cells of the same pigment. 
A)  The disassembled cells formed bonds with any of the cells in the mixture. However, once the organism was completely assembled, an enzyme changed all cells to the same pigment. 
B)  The molecules responsible for cell- cell adhesion were different in the two different species of sponge. 
C)  There are enzymes involved in the assembly of the sponge organism, and the two different species had two different enzymes functioning in reassembly. 
D)  One cell functions as the nucleus for each organism, attracting only cells of the same pigment.

Question 5

Second messengers

Accepted Answer

A)  are intracellular non- protein signalling molecules. 
B)  are intracellular kinases which lead to a cellular response. 
C)  can synthesize cAMP from AMP and ADP. 
D)  are signalling molecules which bind directly to the G- protein coupled receptor. 
A)  are intracellular non- protein signalling molecules. 
B)  are intracellular kinases which lead to a cellular response. 
C)  can synthesize cAMP from AMP and ADP. 
D)  are signalling molecules which bind directly to the G- protein coupled receptor.

Question 6

Intercalated disks are cell- cell junctions found between cardiac muscle cells. A feature of intercalated disks is a large number of gap junctions. This means

Accepted Answer

A)  an extension of smooth endoplasmic reticulum goes through the gap junction, making it continuous from one cardiac muscle cell to the next. 
B)  water and small ions can readily pass from one cardiac muscle cell to the next. 
C)  RNA from one cardiac muscle cell can be transported into an adjacent cell through the gap junction. 
D)  the plasma membrane encompasses multiple cardiac muscle cells. 
A)  an extension of smooth endoplasmic reticulum goes through the gap junction, making it continuous from one cardiac muscle cell to the next. 
B)  water and small ions can readily pass from one cardiac muscle cell to the next. 
C)  RNA from one cardiac muscle cell can be transported into an adjacent cell through the gap junction. 
D)  the plasma membrane encompasses multiple cardiac muscle cells.

Question 7

What does it mean to say that a signal is transduced?

Accepted Answer

A)  The physical form of the signal changes from one form to another. 
B)  The signal triggers a sequence of phosphorylation events inside the cell. 
C)  The signal is amplified, such that even a single molecule evokes a large response. 
D)  The signal enters the cell directly and binds to a receptor inside. 
E)  The signal molecule passes through the cell membrane. 
A)  The physical form of the signal changes from one form to another. 
B)  The signal triggers a sequence of phosphorylation events inside the cell. 
C)  The signal is amplified, such that even a single molecule evokes a large response. 
D)  The signal enters the cell directly and binds to a receptor inside. 
E)  The signal molecule passes through the cell membrane.

Question 8

Pseudomonas aeruginosa is a bacterium that can settle on human lung cells. P. aeruginosa can secrete a signalling molecule that recruits other P. aeruginosa cells. The result of this secretion is the formation of a

Accepted Answer

A)  slime layer. 
B)  biofilm. 
C)  capsule. 
A)  slime layer. 
B)  biofilm. 
C)  capsule.

Question 9

Hormones are chemical substances produced in one organ that are released into the bloodstream and affect the function of a target organ. For the target organ to respond to a particular hormone, it must

Accepted Answer

A)  be from the same cell type as the organ that produced the hormone. 
B)  have receptors that recognize and bind the hormone molecule. 
C)  have the same genetic makeup. 
D)  be experiencing a disruption in homeostasis. 
A)  be from the same cell type as the organ that produced the hormone. 
B)  have receptors that recognize and bind the hormone molecule. 
C)  have the same genetic makeup. 
D)  be experiencing a disruption in homeostasis.

Question 10

Insulin is a hormone produced by the pancreas. When insulin binds to its receptor, which of the following will occur?

Accepted Answer

A)  The G- protein will become active when GTP is replaced by GDP. 
B)  A receptor tyrosine kinase will change its conformation i.e. form a dimer) thereby allowing phosphorylation to occur. 
C)  A G- protein will change its conformation to the "on" position thereby allowing the effector to be activated. 
D)  A receptor tyrosine kinase will dissociate into two monomers thereby allowing phosphorylation to occur. 
A)  The G- protein will become active when GTP is replaced by GDP. 
B)  A receptor tyrosine kinase will change its conformation i.e. form a dimer) thereby allowing phosphorylation to occur. 
C)  A G- protein will change its conformation to the "on" position thereby allowing the effector to be activated. 
D)  A receptor tyrosine kinase will dissociate into two monomers thereby allowing phosphorylation to occur.

Question 11

A gap junction is a channel that connects adjacent cells. What kinds of substances can pass through a gap junction?

Accepted Answer

A)  ions that can regulate heartbeat 
B)  subunits of nucleic acids 
C)  raw materials for protein synthesis 
D)  all of these substances 
A)  ions that can regulate heartbeat 
B)  subunits of nucleic acids 
C)  raw materials for protein synthesis 
D)  all of these substances

Question 12

What is a major difference in the extracellular matrix ECM) between plant and animal cells?

Accepted Answer

A)  Plant ECM components are released extracellularly by the Golgi stacks, whereas lysosomes function in this capacity in animal cells. 
B)  Plant ECM is primarily carbohydrate in nature, whereas animal ECM is largely protein based. 
C)  Plant ECM is composed primarily of proteins, whereas animal ECM is mainly carbohydrates. 
D)  Plant and animal ECMs are quite similar in structure and function. 
A)  Plant ECM components are released extracellularly by the Golgi stacks, whereas lysosomes function in this capacity in animal cells. 
B)  Plant ECM is primarily carbohydrate in nature, whereas animal ECM is largely protein based. 
C)  Plant ECM is composed primarily of proteins, whereas animal ECM is mainly carbohydrates. 
D)  Plant and animal ECMs are quite similar in structure and function.

Question 13

A G- protein receptor with GTP bound to it

Accepted Answer

A)  directly affects gene expression. 
B)  autophosphorylates its tyrosine residues. 
C)  will use cGMP as a second messenger. 
D)  is in its active state. 
A)  directly affects gene expression. 
B)  autophosphorylates its tyrosine residues. 
C)  will use cGMP as a second messenger. 
D)  is in its active state.

Question 14

Tight junctions are cell- cell junctions found between adjacent cells of the epithelium that lines the small intestine. What is the function of these cellular junctions?

Accepted Answer

A)  to attach epithelial cells to a basement membrane 
B)  to recognize pathogenic organisms present in the lumen of the small intestine 
C)  to seal the epithelium and prevent movement of substances between cells 
D)  to release digestive enzymes into the intestinal lumen 
A)  to attach epithelial cells to a basement membrane 
B)  to recognize pathogenic organisms present in the lumen of the small intestine 
C)  to seal the epithelium and prevent movement of substances between cells 
D)  to release digestive enzymes into the intestinal lumen

Question 15

Cells of capillaries that nourish the cells of the central nervous system are joined by tight junctions, whereas the capillaries to most other organs are characterized by having large openings or clefts between adjacent cells. How would the difference in cell- cell connections affect their functions?

Accepted Answer

A)  There is more pressure on the blood passing through the central nervous system than to other organs. 
B)  The blood-brain barrier is more selective regarding the types of molecules that can pass out of circulation. 
C)  Capillaries of the blood-brain barrier are more likely to rupture. 
D)  Capillaries of the central nervous system are more tightly anchored to adjacent tissues. 
A)  There is more pressure on the blood passing through the central nervous system than to other organs. 
B)  The blood-brain barrier is more selective regarding the types of molecules that can pass out of circulation. 
C)  Capillaries of the blood-brain barrier are more likely to rupture. 
D)  Capillaries of the central nervous system are more tightly anchored to adjacent tissues.

Question 16

Acetylcholine is a neurotransmitter that binds to receptors on skeletal muscle cells. The receptor- signal complex brings about a series of events that result in contraction of skeletal muscle. Venom from black widow spiders causes an explosive release of acetylcholine. What would that do to its victims?

Accepted Answer

A)  Muscles would be unable to relax. 
B)  Cell receptors would no longer be able to bind regulatory hormones. 
C)  G- protein receptors would all be inactivated. 
D)  Muscles would be unable to contract. 
A)  Muscles would be unable to relax. 
B)  Cell receptors would no longer be able to bind regulatory hormones. 
C)  G- protein receptors would all be inactivated. 
D)  Muscles would be unable to contract.

Question 17

Scientists have found that extracellular matrix components may induce specific gene expression in embryonic tissues such as the liver and testis. 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?

Accepted Answer

A)  actins 
B)  integrins 
C)  fibronectins 
D)  collagens 
A)  actins 
B)  integrins 
C)  fibronectins 
D)  collagens

Question 18

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

Accepted Answer

A)  extracellular matrix 
B)  tight junctions 
C)  gap junctions 
D)  desmosomes 
E)  peroxisomes 
A)  extracellular matrix 
B)  tight junctions 
C)  gap junctions 
D)  desmosomes 
E)  peroxisomes

Exam 11: Cellcell Interactions

Plasmodesmata are cell- cell junctions that can be found between

Hormones function as

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

Second messengers

Intercalated disks are cell- cell junctions found between cardiac muscle cells. A feature of intercalated disks is a large number of gap junctions. This means

What does it mean to say that a signal is transduced?

Pseudomonas aeruginosa is a bacterium that can settle on human lung cells. P. aeruginosa can secrete a signalling molecule that recruits other P. aeruginosa cells. The result of this secretion is the formation of a

Hormones are chemical substances produced in one organ that are released into the bloodstream and affect the function of a target organ. For the target organ to respond to a particular hormone, it must

Insulin is a hormone produced by the pancreas. When insulin binds to its receptor, which of the following will occur?

A gap junction is a channel that connects adjacent cells. What kinds of substances can pass through a gap junction?

What is a major difference in the extracellular matrix ECM) between plant and animal cells?

A G- protein receptor with GTP bound to it

Tight junctions are cell- cell junctions found between adjacent cells of the epithelium that lines the small intestine. What is the function of these cellular junctions?

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

Biology and the Tree of Life

Water and Carbon: the Chemical Basis of Life

Protein Structure and Function

Nucleic Acids and the Rna World

An Introduction to Carbohydrates

Lipids, Membranes, and the First Cells

Inside the Cell

Energy and Enzymes

Cellular Respiration and Fermentation

Photosynthesis

The Cell Cycle

Meiosis

Mendel and the Gene

Dna and the Gene: Synthesis and Repair

How Genes Work

Transcription, Rna Processing, and Translation

Control of Gene Expression in Bacteria

Control of Gene Expression in Eukaryotes

The Molecular Revolution: Biotechnology and Beyond

Gene Structure and Development

Evolution by Natural Selection

Evolutionary Processes

Speciation

Phylogenies and the History of Life

Bacteria and Archaea

Protists

Green Algae and Land Plants

Fungi

An Introduction to Animals

Protostome Animals

Deuterostome Animals

Viruses

Plant Form and Function

Water and Sugar Transport in Plants

Plant Nutrition

Plant Sensory Systems, Signals, and Responses

Plant Reproduction and Development

Animal Form and Function

Water and Electrolyte Balance in Animals

Animal Nutrition

Gas Exchange and Circulation

Animal Nervous Systems

Animal Sensory Systems

Animal Movement

Chemical Signals in Animals

Animal Reproduction and Development

The Immune System in Animals

An Introduction to Ecology

Behavioural Ecology

Population Ecology

Community Ecology

Ecosystems and Global Ecology

Biodiversity and Conservation Biology

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