Deck 28: Being Multicellular

Question 1

Most simple multicellular species belong to which of the following groups?

A)algae
B)fungi
C)slime molds
D)protozoans
E)bacteria

Answer 1

A

Question 2

Cells in the interior of complex multicellular organisms are able to respond to environmental signals through:

A)receptors designed to detect directly changes in the external environment.
B)diffusion of environmental cues through the outer layers of the body.
C)receptors for signals sent from exterior cells that relay information about environmental changes.
D)pH, temperature, or osmolarity receptors in the membranes of interior cells.

Answer 2

C

Question 3

Which of the following describes the anatomy of a coenocytic organism?

A)The body is made of a large cell with many nuclei.
B)The body cells are organized into well-defined tissue layers.
C)The body cells are organized into branching filaments.
D)The body is made up of several different types of highly specialized cells.
E)The body is a hollow ball of flagellated cells.

Answer 3

A

Question 4

Imagine a hypothetical habitat where there are many simple and complex multicellular organisms of roughly the same size. A new predator is introduced into the habitat that feeds by taking bites of the organism, but never consuming the whole thing. Given this, which of the following statements is MOST likely?

A)Complex multicellular organisms will suffer more because vital differentiated cells that the rest of the organism requires will be lost.
B)Complex multicellular organisms will suffer less because their ratio of surface area to volume will increase and they will absorb more nutrients.
C)Simple multicellular organisms will suffer more because exterior cells responsible for nutrient absorption will be lost.
D)Simple multicellular organisms will suffer more because the greater ratio of surface area to volume will decrease rates of diffusion.

Question 5

Examples of organisms with macroscopic bodies and distinct tissue types can be found among both the prokaryotes and the eukaryotes.

Question 6

Simple multicellular organisms show which of the following characteristics?

A)adhesion of cells
B)little differentiation of specialized cell types
C)little signaling between cells
D)little transfer of resources between cells
E)All of these choices are correct.

Question 7

Which one of the following is a selective advantage of simple multicellularity over single-celled organisms?

A)Multicellularity helps organisms avoid predation.
B)Multicellularity results in fundamental changes in metabolic processes.
C)Multicellularity helps organisms utilize more food sources.
D)Multicellularity helps organisms enhance efficiency of reproduction.

Question 8

Like complex multicellularity, coenocytic morphologies evolved multiple times in the eukaryotic tree.

Question 9

Which one of the following organisms has coenocytic organization?

A)humans
B)amphibians
C)plants
D)some green algae

Question 10

A marine biologist discovers a new species of green algae, which under the microscope appears to be multinuclear. Which of the following is likely TRUE of these algae?

A)It is a complex multicellular organism.
B)It harbors parasites.
C)It is coenocytic.
D)It lives suspended in the water column.

Question 11

What features of complex multicellular organisms are also present in their closest single-celled relatives?

A)cell differentiation
B)cell adhesion molecules
C)receptors for cell-cell signaling
D)regulation of gene expression

Question 12

Which one of the following statements CORRECTLY describes features shared by simple multicellular eukaryotes?

A)Cells adhere to one another; most of the cells are capable of a wide range of functions, including reproduction; and the loss of one or more cells usually does not lead to the death of the organism.
B)Cells adhere to one another and engage in extensive communication with one another; most of the cells are capable of a wide range of functions, including reproduction; and the loss of one or more cells usually does not lead to the death of the organism.
C)Cells adhere to one another and most of the cells are capable of a wide range of functions except the ability to reproduce, which means that the loss of certain cells usually leads to the death of the organism.

Question 13

Each of the seven superkingdoms of eukaryotes contains one member that is a complex multicellular organism.

Question 14

An advantage that simple multicellular eukaryotes have over single-celled organisms is the ability:

A)of the cells in the multicellular organism to communicate with one another.
B)of the cells in a group of cells to avoid predation.
C)of autotrophic cells in the multicellular organism to supply heterotrophic cells with nutrients.
D)to respond the external environment more efficiently.

Question 15

Which of the following is a term describing a multinucleated organism made up of a single cell?

A)colonial
B)multicellular
C)differentiated
D)coenocytic

Question 16

Which of the following factors may have favored the evolution of simple multicellularity?

A)increased ability to avoid predation
B)increased ability to maintain a position in the water column
C)increased ability to remain in a location that is favorable for growth
D)increased ability to generate water currents for feeding
E)All of these choices are correct.

Question 17

Coenocytic organization is a shared derived character of simple multicellular organisms exhibiting the trait.

Question 18

Multiple lines of evidence indicate that complex multicellularity has evolved at least six different times. Which of the following superkingdoms include organisms that exhibit complex multicellularity?

A)Opisthokonta, Archaeplastida, Stramenopila
B)Opisthokonta, Amoebozoa, Archaeplastida, Stramenopila
C)plants, animals, fungi, slime molds
D)plants, animals, fungi, slime molds, red algae, green algae, brown algae
E)green algae (and land plants), red algae, brown algae, animals, fungi, slime molds

Question 19

Which of the following is a characteristic of complex multicellular organisms but not simple multicellular organisms?

A)the presence of subsets of cells (tissues)with specialized functions
B)the use of cell-adhesion molecules to allow cells to adhere to one another
C)the presence of a single cell with multiple nuclei
D)the presence of cells that are not in direct contact with the external environment

Question 20

In simple multicellularity:

A)there is extensive communication between cells.
B)cells are highly differentiated and specialized.
C)most cells retain a full range of functions.
D)some cells are not in direct contact with the external environment.

Question 21

Which of the following statements regarding a simple multicellular organism is TRUE?

A)If an individual cell from a single multicellular organism is damaged or dies, the whole organism will likely die.
B)Certain cells of a simple multicellular organism-typically referred to as inner mass cells-are isolated from the external environment.
C)If a single cell is removed from a simple multicellular organism, it may be able to reproduce on its own.
D)Simple multicellular organisms only include algae.
E)All simple multicellular organisms are only multicellular at one stage of their life cycles-the larval or embryonic stage.

Question 22

The evolution from simple multicellular organisms to complex multicellular organisms required:

A)a mechanism of cell-cell adhesion.
B)an ability to respond to the environment.
C)the development of a system that enabled bulk flow.
D)cell-surface receptors.

Question 23

A young student is trying to recapitulate an experiment discussed in the text. She introduces single-celled green algae into a petri dish containing predatory protists. After several generations, what will she observe?

A)The protists will produce multicellular colonies.
B)Green algae will form multicellular colonies.
C)Green algae will remain unicellular (i.e., there is no benefit to forming multicellular structures).
D)Both protists and green algae will remain unicellular.
E)None of the answer options is correct.

Question 24

In humans and many other animals, what organ system is involved in bulk transport of nutrients, oxygen, and signaling molecules?

A)respiratory system
B)circulatory system
C)immune system
D)digestive system

Question 25

The passive movement of ions or molecules from a point of high concentration to a point of low concentration is known as:

A)diffusion.
B)active transport.
C)endocytosis.
D)solubility.

Question 26

Which of the following is an adaptation shared by virtually all complex multicellular organisms that allows the organisms to receive the oxygen and nutrients they need?

A)amplification of surface areas
B)active transporters for oxygen and glucose
C)restricted body size that corresponds to the environment
D)tissues or organs that function as pumps

Question 27

Most taxonomic groups that include simple multicellular organisms never gave rise to complex multicellular descendants.

Question 28

The oxygen needed for respiration moves from the lungs and into capillaries by simple diffusion. Once in the capillaries, what molecule or other component of blood is responsible for transporting oxygen in the circulatory system?

A)There is no transport molecule; oxygen remains free in the blood.
B)white blood cells
C)hemoglobin
D)cadherins

Question 29

While observing a new species of seaweed under the microscope, you determine that the entire organism is one large cell containing several nuclei. Which of the following BEST describes the organization of this organism?

A)coenocytic
B)complex multicellular
C)simple multicellular
D)filamentous
E)eukaryotic

Question 30

Which of the following statements about the organization of complex multicellular organisms is FALSE?

A)Exterior cells are highly differentiated whereas interior cells are not differentiated.
B)Only some cells are in direct contact with the environment.
C)Interior cells cannot grow as fast as exterior cells without mechanisms to transfer nutrients between cells.
D)Exterior cells receive environmental signals directly, whereas interior cells receive environmental signals indirectly.
E)Signals transferred from exterior cells to interior cells can activate or repress gene expression in the interior cells.

Question 31

What is the main limitation on cell size?

A)diffusion
B)bulk flow
C)oxygen
D)cell membrane strength

Question 32

Which of the following statements about the evolution of complex multicellularity is TRUE?

A)Complex multicellularity evolved independently at least six times in different groups of organisms.
B)Complex multicellularity evolved twice: once in the common ancestor of plants and fungi and once in animals.
C)Complex multicellularity evolved once in the common ancestor of all eukaryotic organisms.
D)Complex multicellularity evolved independently in prokaryotes and eukaryotes.
E)Simple multicellular organisms evolved from complex multicellular ancestors.

Question 33

Organisms that are dependent on oxygen for cellular respiration depend on which of the following processes to move oxygen into cells?

A)simple diffusion
B)active transport
C)endocytosis
D)facilitated diffusion

Question 34

In complex multicellular organisms, bulk flow is an important physiologic character. Why is bulk flow a necessary condition of complex multicellularity?

A)Complex multicellularity reflects cell adhesion between cells, and this cannot happen without bulk flow of signaling molecules from the environment.
B)Organisms exhibiting complex multicellularity are large and have cells/tissues that are not in contact with their environment. Systems that can overcome the limits of diffusion must occur for basic physiologic processes to occur.
C)Bulk flow is necessary to move large amounts of liquid through the organism depending on physiologic needs. The tissues can all receive necessary nutrients from the environment, but bulk flow speeds the rate of diffusion.
D)Complex multicellularity is related to the increase in oxygen in the environment. Because bulk flow systems are only related to the delivery of oxygen to tissues, higher environmental oxygen selected for individuals with bulk flow systems.

Question 35

Which of the following statements concerning complex multicellular organisms is TRUE?

A)Plants and animals use bulk flow systems to move gasses and nutrients, but fungi and algae do not.
B)Bulk flow systems require specialized organs like a heart to pump nutrients and dissolved gasses deep into tissues that are not in contact with the external environment.
C)Bulk flow systems move substances faster than simple diffusion.

Question 36

While analyzing a sample of pond water, you discover a new organism whose body is composed of multiple cells. Upon closer inspection you are able to determine that the individual cells are highly differentiated and organized into distinct interior and exterior tissue layers. Which of the following BEST describes the organization of this organism?

A)complex multicellular
B)simple multicellular
C)coenocytic
D)filamentous
E)eukaryotic

Question 37

All simple multicellular organisms are coenocytic, but not all coenocytic organisms are multicellular.

Question 38

Which of the following statements about the movement of oxygen in complex multicellular organisms is TRUE?

A)Its movement by diffusion into and out of cells is limited to just a few layers of cells.
B)It is moved into and out of cells by specific transport proteins.
C)Bulk flow systems are required in macroscopic organisms to facilitate the transport of oxygen.

Question 39

A young boy is staring at the tropical fish tank in his mother's office. He reaches in and pulls out a fern-like plant. When he closely examines this plant, he notices it has very large cells with several dark spots. What is likely TRUE of this plant?

A)It is coenocytic-the dark spots are symbiotic organisms.
B)Given the tropical environment, this plant is likely a fungus.
C)This is likely an example of a terrestrial tree-fern in the aquatic phase.
D)This plant is coenocytic (the dark spots are actually nuclei).

Question 40

Which of the following statements contrasting simple and complex multicellularity is TRUE?

A)Complex multicellular organisms show a large degree of cellular differentiation, whereas simple multicellular organisms show little differentiation into specialized cell types.
B)Cell or tissue loss in a simple multicellular organism can be lethal for the entire organism, whereas cell or tissue loss in a complex multicellular organism does not lead to death of the entire organism.
C)Highly specialized molecular mechanisms allow cells to adhere to one another in simple multicellular organisms, but not in complex multicellular organisms.
D)Only some cells are in direct contact with the environment in simple multicellular organisms, whereas all cells are in direct contact with the environment in complex multicellular organisms.
E)Most or all of the cells in a complex multicellular organism contribute to reproduction, whereas only a subset of cells contributes to reproduction in simple multicellular organisms.

Question 41

Which of the following statements about diffusion is FALSE?

A)It transports materials actively, powered by ATP.
B)It is effective only over small distances.
C)It limits the size of prokaryotic cells.
D)It limits the shape of prokaryotic cells.
E)It supplies key molecules for metabolism.

Question 42

Which of the following statements is TRUE regarding bulk flow in both animals and plants?

A)Bulk flow in both animals and plants relies on osmosis (much like in fungi)or evaporative pumps. In fact, the mammalian heart and lungs could be considered evaporative pumps.
B)The vascular systems of both plants and animals are remarkably similar, with identical cell types being observed in the phloem of plants and in the blood vessels of animals.
C)Bulk flow is responsible for the movement of nutrients and hormones in both animals and plants.
D)The vascular system of plants and the circulatory system of humans have a mesoglea-like arrangement, with these systems being supported and nourished by a jelly-like substance.

Question 43

Which of the following statements is TRUE regarding sponges?

A)Sponges rely on diffusion for nutrients, and as a result are typically a few micrometers to a millimeter in size.
B)The metabolically active cells of sponges are always located in the interior of the sponge (away from the external environment).
C)The structure of sponges-especially the pores and canals-allows sponges to achieve sizes of up to a meter (or more).
D)Sponges contain a diverse array of cell types, and these diverse cell types allow certain species of sponge to attain large size.
E)Despite their name, sponges typically have smooth, nonporous surfaces.

Question 44

Which one of the following is the definition of diffusion?

A)the tendency of molecules to move in space due to kinetic energy
B)the movement of substances from an area of low concentration to an area of high concentration
C)the movement of a substance across a membrane
D)the movement of a substance by osmosis

Question 45

Cell-cell signaling is limited to complex multicellular organisms composed of organs and organ systems.

Question 46

Bulk flow is completely independent of diffusion; diffusion does not occur anywhere in the body of an organism that demonstrates bulk flow.

Question 47

If plants did not produce vascular tissue, they would be limited to a few centimeters in height.

Question 48

The mesoglea of jellyfish:

A)is the most metabolically active tissue in the jellyfish body.
B)is the jelly-like substance that facilitates the diffusion of nutrients to the interior of the jellyfish.
C)provides structural support to the jellyfish body.
D)would be considered a metabolically inactive tissue.
E)provides structural support to the jellyfish body and would be considered a metabolically inactive tissue.

Question 49

Diffusion is BEST defined as:

A)the random motion of individual molecules, with net movement from areas of higher concentration to areas of lower concentration.
B)the random motion of individual molecules, with net movement from areas of lower concentration to areas of higher concentration.
C)the highly ordered movement of large groups of molecules from areas of higher concentration to areas of lower concentration.
D)the highly ordered movement of large groups of molecules from areas of lower concentration to areas of higher concentration.
E)the transition from individual molecules moving in a random manner to groups of molecules moving in a highly ordered manner.

Question 50

Which of the following statements about bulk flow is FALSE?

A)Bulk flow is found in simple multicellular organisms, but not unicellular organisms.
B)Bulk flow is the active transport of molecules throughout an organism's body.
C)Bulk flow moves materials over greater distances than is possible with diffusion.
D)Bulk flow moves materials at faster rates than is possible with diffusion.
E)Bulk flow allows animals and plants to grow very large.

Question 51

Which of the following is an example of diffusion?

A)movement of individual oxygen molecules from the air to the bloodstream
B)movement of large numbers of air molecules into and out of the lungs
C)transport of oxygen throughout the body by means of the circulatory system
D)binding of oxygen to hemoglobin within the red blood cells
E)movement of oxygen molecules from the lungs to the bloodstream AND movement of large numbers of air molecules into and out of the lungs

Question 52

A young medical student has removed a tendon, intestine, and heart from a cadaver. When he flattens all of these structures (and stretches them out to their utmost extent), he notices that the intestine is by far the largest structure. Why?

A)The intestine is the site of all bulk flow carried out in the human body, and must be large in order to supply the entire body with nutrients.
B)The intestine is the source of all materials transported by means of bulk flow (i.e., it produces hormones, absorbs nutrients, and is the site where oxygen diffuses into the bloodstream).
C)The intestine must have a large surface area over which nutrients derived from food can diffuse into the bloodstream.
D)The intestine must have a large surface area to produce hemoglobin, which then binds to food particles and transports them throughout the body.

Question 53

Based on your understanding of genome and organismal complexity, is the following statement true or false? Complex multicellular organisms have a genome similar in scope and size to their single-celled predecessors.

Question 54

Which of the following is NOT a mechanism to circumvent the limits imposed by diffusion?

A)placing metabolically active cells in the interior of an organism and metabolically inert structures along the exterior surface
B)using vascular tissue to transport materials throughout the plant body
C)placing metabolically active cells along a series of canals and pores
D)using a circulatory system to distribute materials throughout the animal body
E)All of these choices are correct.

Question 55

Which of the following is characteristic of complex multicellularity?

A)All cells are exposed to an exterior surface.
B)The interior cells are more tolerant to lower oxygen levels than exterior cells.
C)Interior cells are exposed to a different physical and chemical environment than exterior cells.
D)All cells of complex multicellular organisms express the same genes.

Question 56

Structures used for bulk flow include all of the following EXCEPT:

A)the circulatory system of humans.
B)the vascular tissues of plants.
C)the mesoglea of jellyfish.
D)the tubular cells of giant kelps.
E)All of these choices are structures used for bulk flow.

Question 57

Choanoflagellates are single-celled eukaryotes that feed on bacteria. In the presence of their food bacteria, some choanoflagellates develop multicellular structures in which the individual choanoflagellate cells are attached to one another. Based on this observation, it may be assumed that:

A)the bacterial cells, or a chemical released by the bacteria, bind to a receptor on the plasma membrane of the choanoflagellate cells.
B)the choanoflagellate cells use cadherins to attach to each other.
C)the choanoflagellates use integrins to attach to each other.
D)choanoflagellates are complex multicellular organisms because they alternate between single cell and multicellular states.

Question 58

In animals, fungi, and plants, bulk flow is always an active and ATP-expensive process. This is best evidenced by the need for a heart to beat in order for bulk flow to occur in animals.

Question 59

Which of the following explains why bulk flow allows an organism to attain a larger body size?

A)All of these choices are correct.
B)Bulk flow allows nutrients to be transported over greater distances.
C)Bulk flow allows rapid communication between different parts of the body.
D)Bulk flow allows oxygen to reach interior cells that are located far from the surface of the body.
E)Bulk flow allows waste products to be removed more efficiently.

Question 60

A jellyfish relies on diffusion to provide oxygen to its body cells, and yet it is much larger than the 1 cm limit imposed by diffusion. How can it be so thick and still meet its metabolic demands by diffusion alone?

A)Much of the thickness of a jellyfish consists of metabolically inert materials that do not require oxygen.
B)Jellyfish have specialized tubular cells that facilitate the movement of oxygen throughout the body.
C)The layers of metabolically active tissue are very thick and highly folded, which provides a large surface area for diffusion.
D)Jellyfish maintain a very large concentration gradient for oxygen across their body tissues.
E)Water makes up most of the body of a jellyfish, and oxygen diffuses more rapidly in water than in tissues.

Question 61

Which of the following statements is TRUE?

A)Integrins and cadherins facilitate cell adhesion to extracellular substrates.
B)Cadherins on the surface of animal cells permit cells to adhere to other cells.
C)Cadherins are used in plant cells to attach the plasma membrane to the cell wall.
D)Integrins on one cell attach to cadherins on another cell to promote cell adhesion.

Question 62

Which of the following are adhesion proteins that are present in both choanoflagellates and animals?

A)actins
B)pectins
C)cadherins
D)hemoglobins

Question 63

Some species of choanoflagellates can form multicellular structures in the presence of their desired food bacterium; however, not all choanoflagellate species will form multicellular structures. Multicellularity is induced in some forms of choanoflagellates because of signals released by the bacterium. This variation in the ability to develop multicellular structures is MOST likely the result of:

A)changes in patterns of gene expression resulting in multicellular aggregations in some, but not all choanoflagellates.
B)changes in the pattern of integrin expression in choaoflagellates forming multicellular aggregations.
C)the evolution of genes for cell-adhesion molecules in only in choanoflagellates that form multicellular aggregations.
D)the evolution of differential responses to environmental signals.

Question 64

Which of the following is TRUE of plasmodesmata?

A)They are holes in the cell wall through which the plasma membrane and endoplasmic reticulum of adjacent cells are connected.
B)They are channels in the plasma membrane of plant cells made of transmembrane proteins that allow ions and small molecules to pass between adjacent cells.
C)They are channels in the plasma membrane of animal cells made of transmembrane proteins that allow ions and small molecules to pass between adjacent cells.
D)They provide points of structural support between adjacent plant cells.
E)They provide points of structural support between adjacent animal cells.

Question 65

Animals are to cadherins as plants are to:

A)integrins.
B)epithelia.
C)adhesion.
D)pectins.

Question 66

Which of the following is TRUE of gap junctions?

A)They are holes in the cell wall through which the plasma membrane and endoplasmic reticulum of adjacent cells are connected.
B)They are channels in the plasma membrane of plant cells made of transmembrane proteins that allow ions and small molecules to pass between adjacent cells.
C)They are channels in the plasma membrane of animal cells made of transmembrane proteins that allow ions and small molecules to pass between adjacent cells.
D)They provide points of structural support between adjacent plant cells.
E)They provide points of structural support between adjacent animal cells.

Question 67

The vegetative cells of the simple multicellular organism Volvox function in:

A)reproduction.
B)photosynthesis.
C)oxygen uptake.
D)All of these choices are correct.

Question 68

For multicellularity to develop, there must be a mechanism of signaling among cells in the multicellular organism. Which of the following structures present in the cell membrane receives signals from the environment, or other cells?

A)plasmodesmata
B)receptors
C)gap junctions
D)cadherins

Question 69

Which of the following molecules help maintain cell-cell adhesions in plants?

A)cadherins
B)pectins
C)integrins
D)cellulose

Question 70

Choanoflagellates are:

A)unicellular organisms.
B)simple multicellular organisms.
C)complex multicellular organisms.
D)prokaryotes.

Question 71

Which one of the following induces multicellularity in a choanoflagellate species?

A)the presence of predators in the environment
B)the presence of the preferred prey/food source in the environment
C)the developmental signal molecules that induce differentiation
D)the cell migrations that take place in the developmental phases of growth

Question 72

Cardiac muscle cells have gap junctions between adjacent cells. What is the function of those gap junctions?

A)They maintain isotonic conditions.
B)They facilitate cell-cell adhesion.
C)They are involved in cell-cell signaling of the cells of the heart.
D)They make nutrients, like glucose, readily available to the muscle cells of the entire heart.

Question 73

Three superkingdoms, the opisthokonts, archaeplastids, and stramenopiles all have members with complex multicellularity. What must be TRUE about the members with complex multicellularity in these groups?

A)They have tissues that are not in direct contact with their environment.
B)They form aggregations in the presence of specific signals.
C)They are predatory.
D)They all produce integrins and cadherins.

Question 74

Differentiation of multiple cell types occurs in:

A)animals.
B)fungi.
C)protists.
D)bacteria.

Question 75

Adhesion molecules in choanoflagellates serve the same function as those in their sister group, the animals.

Question 76

The lion's mane jellyfish can be up to 8 feet wide. In spite of its large size, it has no structures for bulk flow to deliver oxygen to its cells. How can it be so large, and lack a mechanism for bulk flow?

A)The jellyfish is surrounded by water, so the concentration gradient between the water and the jellyfish is steep, making the rate of diffusion across tissues very high.
B)The jellyfish is filled with tissue made of structural cells that are not metabolically active. Therefore a mechanism to transport oxygen to its interior is not necessary.
C)The jellyfish body is actually a series of intricate folds, so the ratio of surface area to volume is maximized and diffusion occurs as it would across a tissue one or two cells thick.
D)The jellyfish does not have receptors for sensing the environment, so does not need a mechanism for transmitting signal molecules throughout the body.

Question 77

What structures are used in animal cells to move molecules between cells?

A)plasmodesmata
B)gap junctions
C)cadherins
D)plasma membranes

Question 78

Hormones released by endocrine glands function as signal molecules.

Question 79

How can two cells of a complex multicellular organism have the same genome, but markedly different structures and functions?

A)During differentiation, as cells become specialized, they lose portions of their genome that are no longer needed.
B)Different genes are expressed in different cells.
C)Part of the process of differentiation of cells is to create mutations in the genome.
D)Once differentiation begins, the genome no longer controls cellular functions.

Question 80

Which of the following signals is unlikely to cause a change in gene expression in complex multicellular organisms?

A)oxygen levels
B)nutrients in the environment
C)temperature
D)hormones
E)All of these choices are correct.