Question 1

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.

Accepted Answer

In simple multicellular organisms, individual cells often retain the ability to live independently and reproduce on their own if separated from the organism.

Question 2

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.

Accepted Answer

The answer of The evolution from simple multicellular organisms to...

Question 3

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.

Accepted Answer

In the presence of predatory protists, single-celled green algae may evolve to form multicellular colonies as a defense mechanism. This adaptation can help protect individual cells within the colony from being eaten, as the larger, multicellular structure can be more difficult for predators to consume.

Question 4

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

Accepted Answer

The circulatory system is involved in bulk transport of nutrients, oxygen, and signaling molecules through the bloodstream to various organs and tissues in the body. The respiratory system is responsible for gas exchange between the lungs and the bloodstream, but not bulk transport of molecules. The immune system is responsible for protecting the body against pathogens and foreign substances, but not nutrient transport. The digestive system breaks down food and absorbs nutrients, but does not transport these molecules throughout the body in bulk.

Question 5

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.

Accepted Answer

Diffusion is the process of passive movement of molecules/ions from high concentration to low concentration. Active transport involves the use of energy to move molecules/ions against the concentration gradient. Endocytosis is the process of engulfing extracellular materials into the cell. Solubility is not related to the movement of ions or molecules.

Question 6

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

Accepted Answer

Amplification of surface areas, such as the villi in the human intestine or the gills in fish, is a common adaptation among complex multicellular organisms to increase the surface area available for absorption of oxygen and nutrients, facilitating efficient exchange with the environment.

Question 7

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

Accepted Answer

This statement is true. Many taxonomic groups, such as protists and bacteria, include simple multicellular organisms but did not give rise to complex multicellular organisms like animals and plants.

Question 8

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

Accepted Answer

Hemoglobin is a protein in red blood cells that binds to oxygen and transports it throughout the circulatory system.

Question 9

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

Accepted Answer

The organism is one large cell with multiple nuclei, which is characteristic of a coenocytic organism. Coenocytic organisms are unicellular but have multiple nuclei, and their cytoplasm is not divided into individual cells.

Question 10

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.

Accepted Answer

Exterior cells can be less differentiated than interior cells (e.g. skin cells vs. liver cells).

Question 11

What is the main limitation on cell size?
A)diffusion
B)bulk flow
C)oxygen
D)cell membrane strength

Accepted Answer

The main limitation on cell size is diffusion, as larger cells have more difficulty obtaining nutrients and eliminating waste products through simple diffusion alone. This is because larger cells have a smaller surface area to volume ratio, and as a result, the distance for diffusion becomes too great for efficient exchange. Bulk flow and oxygen availability may also be factors, but they are not the main limiting factor for cell size. Cell membrane strength may limit the size of a cell, but it is secondary to the diffusion limitation.

Question 12

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.

Accepted Answer

Complex multicellularity has indeed evolved independently at least six times in different groups of organisms, including animals, fungi, red algae, green algae (which includes land plants), brown algae, and myxogastria (a group of slime molds). This indicates a convergent evolution, where similar features evolve separately in different evolutionary lineages.

Question 13

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

Accepted Answer

Oxygen moves into cells primarily through simple diffusion, as it is a small, nonpolar molecule that can easily pass through the lipid bilayer of the cell membrane without the need for energy or transport proteins.

Question 14

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.

Accepted Answer

Organisms that exhibit complex multicellularity are too large and cells/tissues are not in contact with the environment. This necessitates systems that can overcome the limits of diffusion for basic physiologic processes to occur. Bulk flow allows for the movement of liquid and necessary nutrients throughout the organism.

Question 15

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.

Accepted Answer

Bulk flow systems move substances faster than simple diffusion, which is essential for supplying nutrients and gasses to the cells of complex multicellular organisms that are not in direct contact with the external environment. Plants and animals both use bulk flow systems, but fungi and algae have different mechanisms for moving substances. While animals have specialized organs like a heart to pump fluids, plants use a system of xylem and phloem to transport water, minerals, and sugars.

Question 16

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

Accepted Answer

The presence of multiple highly differentiated cells organized into distinct tissue layers suggests a complex multicellular organization, which is characteristic of higher-level organisms such as animals and plants. The other choices are not the best fit as coenocytic organisms consist of a single cell with multiple nuclei, filamentous organisms have elongated shapes and eukaryotic refers to the presence of a nucleus, which is universal in complex multicellular organisms. Simple multicellular organisms may have multiple cells, but they lack the level of differentiation and organization seen in complex multicellular organisms.

Question 17

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

Accepted Answer

Coenocytic organisms are those which have multiple nuclei in a single, continuous cytoplasmic mass, without any cell walls or cell membranes dividing the cytoplasm into separate cells. Some examples of coenocytic organisms include certain types of fungi and algae. While some multicellular organisms may be coenocytic (such as certain types of fungi), not all coenocytic organisms are multicellular.

Question 18

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.

Accepted Answer

C  Oxygen diffusion is effective only over short distances, so in complex multicellular organisms, bulk flow systems like circulatory systems are necessary to transport oxygen efficiently throughout the body.

Question 19

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).

Accepted Answer

The observation of large cells with several dark spots indicates that this plant is likely coenocytic, meaning it has multiple nuclei within a single cell. The dark spots are actually nuclei and not symbiotic organisms. There is no indication that the plant is a fungus or a tree-fern.

Question 20

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.

Accepted Answer

Complex multicellular organisms have a high degree of cellular differentiation into specialized cell types, while simple multicellular organisms have little differentiation.

Quiz 28: Being Multicellular

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

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

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?

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

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

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?

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

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?

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?

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

What is the main limitation on cell size?

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

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

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

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

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

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

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?

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