Chapter 28

Which of the following explains why bulk transport allows for a larger body size to be attained?

-Bulk transport allows for waste products to be removed more efficiently. -Bulk transport allows for oxygen to reach interior cells that are located far from the surface of the body. -Bulk transport allows for rapid communication between different parts of the body. -Bulk transport allows for nutrients to be transported over greater distances.

Simple multicellular organisms show which of the following characteristics?

-adhesion of cells -little differentiation of specialized cell types - little communication between cells - little transfer of resources between cells

Differentiation in complex multicellular organisms occurs when:

-different combinations of genes are activated and repressed in different cells. -cells in different environments are exposed to different types of signals. -different combinations of proteins are expressed in different cells. -cells acquire different fates

The field of evo-devo:

-examines the genetic and developmental mechanisms of evolutionary change. -aims to understand the genetic differences that underly differences in form and function between species. -examines the molecular mechanisms that guide development in individual species. -compares the genetic programs for growth and development in different species.

If all animal cells―both embryonic and adult―suddenly possessed cells walls, which of the following processes would be negatively affected?

-the movement of materials through the intestines -the ability of animals to move their limbs (i.e., muscle contraction) -the development of gastrulae during embryogenesis -the ability of the animal hearts to pump blood

Which of the following statements about the evolution of animal cell adhesion molecules is true?

Animal cell adhesion molecules evolved from protein families that originally performed other functions.

Which of the following statements about bulk transport is false?

Bulk transport is found in simple multicellular organisms, but not unicellular organisms.

Which of the following statements are true regarding bulk transport in both animals and plants?

Bulk transport is responsible for the movement of nutrients and hormones in both animals and plants.

What happens during gastrulation?

Cells migrate to form a layered structure.

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

Coenocytic

Which of the following statements contrasting simple versus complex multicellularity is true?

Complex multicellular organisms show a large degree of cellular differentiation, whereas simple multicellular organisms show little differentiation of specialized cell types.

Which of the following statements about plants and animals is false?

Complex multicellularity arose in the common ancestor of plants and animals and was retained in each of these groups.

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

Complex multicellularity evolved independently at least six times in different groups of organisms.

How can two cells in the same complex multicellular organism have different fates?

Different genes are activated and repressed in the two cells.

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

False

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?

Green algae will form multicellular colonies.

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

If a single cell is removed from a simple multicellular organism, it will likely be able to reproduce on its own.

If animals were unable to produce pectin, what effect would this have on their epithelial tissues?

It would have no effect on epithelial tissue structure or function.

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?

The intestine must have a large surface area over which nutrients derived from food can diffuse into the bloodstream.

You are asked to determine whether an unknown tissue specimen comes from a plant or an animal. Closer inspection with an electron microscope reveals that the cells are connected by small openings lined by extensions of the cell membrane and containing tubules connecting the endomembrane systems of adjacent cells. Which of the following conclusions can be drawn from your observations?

The openings are plasmodesmata, so the tissue must come from a plant.

Which of the following statements are true regarding sponges?

The structure of sponges―especially the pores and canals―allows for sponges to achieve sizes of up to a meter (or more).

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?

This plant is coenocytic (the dark spots are actually nuclei) and―given the tropical environment―is likely an example of Caulerpa.

Which of the following represents the correct order of evolution of requirements for complex multicellularity in animals?

adhesion, cell signaling, gap junctions, bulk transport

Which of the following adhesive molecules can be found in all complex multicellular organisms?---cadherins -integrins -pectins -cadherins and integrins

none

Which of the following statements is true regarding plant meristems? -The majority of a plant meristem is composed of differentiated cells; only a few undifferentiated cells exist in this structure. -Plant meristems are typically sandwiched between zones of cell expansion and zones of cell differentiation. -The cells composing plant meristems undergo meiotic cell division and produce haploid cells. -Plant meristems only exist in roots, and are found nowhere else in plants.

none

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

placing metabolically active cells in the interior of an organism and metabolically inert structures along the exterior surface

Which of the following traits of complex multicellular organisms is also shared by some simple multicellular organisms, but not by single-celled organisms?

plasmodesmata

The mesoglea of jellyfish:

provides structural support to the jellyfish body and would be considered a metabolically inactive tissue.

Structures used for bulk transport include all of the following except:

the mesoglea of jellyfish.

Diffusion is best defined as:

the random motion of individual molecules with net movement from areas of higher concentration to areas of lower concentration.

Many of the signaling pathways used for communication between cells in complex multicellular organisms first evolved in:

unicellular eukaryotes.