Chapter 5: Cells Are the Fundamental Units of Life (HOMEWORK & QUIZ)

Mitochondria and plastids are believed to have once been independent organisms because they a) contain their own DNA. b) have glyoxysomes. c) have nuclei. d) have flagella. e) make vesicles.

a) contain their own DNA.

An organism made up of many small cells as opposed to one large cell has all of the following properties except a) decreased diffusion between nucleoplasm and cytoplasm. b) increased release of waste products to the environment. c) increased uptake of necessary nutrients from the environment. d) more efficient transport of materials. e) compartmentalization of functions within the organism.

a) decreased diffusion between nucleoplasm and cytoplasm.

Hypothetically, if 3% of all amoebas naturally develop rounded cells, and there is no effect on rate of rounded cells from being raised in the lab or getting a no drug injection, what percentage of rounded cells in the experimental groups outlined in Figure 5.22B are not due to the drugs tested? a) 3% b) 97% c) It depends on the percentage of rounded cells in each group.

a) 3%

A girl who grew up on a farm observed many animal births and deaths. As a result, she became fascinated with the question "What is life"? She decided to pursue this question by studying cell biology in college. What rationale can be used to explain why this course of study was a valid choice to satisfy the student's interests? a) All characteristics of life apply in the same way to cells as they do to larger organisms. b) Concepts taught in cell biology are easier for students new to college to understand. c) Cell biology will prepare the student for biology classes where she will find the Answer to her question. d) Cells are easier to study than multicellular animals due to their smaller size. e) It is not possible to understand the physiologies of large animals without first learning cell biology.

a) All characteristics of life apply in the same way to cells as they do to larger organisms.

Which function is carried out by the cell membrane? a) Materials transport b) Gene regulation c) Protein production d) Energy metabolism e) Information storage

a) Materials transport

Which is the correct order of structures that a macromolecule and its monomers will encounter in the time period between when the macromolecule is engulfed into a cell and when its monomers are used as an energy source? a) Phagosome → secondary lysosome → cytoplasm → mitochondria b) Primary lysosome → peroxisome → secondary lysosome → mitochondria c) Primary lysosome → secondary lysosome → peroxisome → cell membrane d) Rough endoplasmic reticulum → vesicle → Golgi apparatus → mitochondria e) Phagosome → cisternae → secondary lysosome → mitochondria

a) Phagosome → secondary lysosome → cytoplasm → mitochondria

If all the lysosomes within a cell suddenly ruptured, what would be the most likely result? a) Proteins in the cytosol would break down. b) More proteins would be made. c) The DNA in mitochondria would break down. d) The mitochondria and chloroplasts would divide. e) There would be no change in cell function.

a) Proteins in the cytosol would break down.

While using electron microscopy to examine the cell membrane of a bacterium, you have discovered the presence of a complex motor protein assembly. You do not find any evidence of a proper flagellum. You can conclude that the bacterium most likely has lost its ability to make a) flagellin. b) actin. c) myosin. d) keratin. e) tubulin.

a) flagellin.

A prokaryotic cell lacks a _______ and _______. a) nucleus; membrane-bound organelles b) cell wall; membrane-bound organelles c) cell wall; ribosomes nucleus; ribosomes d) nucleus; DNA

a) nucleus; membrane-bound organelles

All of the following molecules can be found in extracellular structures except a) tubulin. b) peptidoglycans. c) collagen. d) cellulose. e) polysaccharides.

a) tubulin.

Scientists have researched methods to transplant stem cells to human heart tissue to repair severe damage by cardiovascular disease. Studies in model systems have shown that if the transplanted stem cells are not washed with a buffered saline solution before transplantation, they adhere, adapt, and survive better. Which statement best explains this observation? a) The microenvironment surrounding stem cells is improved by a washing step before transplantation. b) A supportive environment for stem cell adhesion to existing heart tissue is supplied by the extracellular matrix surrounding the stem cells. c) The extracellular matrix surrounding the damaged heart tissue provides all the necessary proteins and proteoglycans for adherence of transplanted cells. d) Biomolecules necessary for successful transplantation are secreted into the stem cells' extracellular matrix when the cells are stimulated by a washing step before transplantation. e) Transplanted stem cells require certain proteins and proteoglycans present in the extracellular matrix of the damaged heart tissue.

b) A supportive environment for stem cell adhesion to existing heart tissue is supplied by the extracellular matrix surrounding the stem cells.

What type of agent would be most likely to disrupt the structures of microvilli? a) Actin polymerizing agent b) Actin depolymerizing agent c) Microtubule disruptors d) Tubulin polymerization inhibitor e) Actin cross-linking agent

b) Actin depolymerizing agent

Which is not a fundamental concept addressed by cell theory? a) Modern cells evolved from a common ancestor. b) Cells may be classified as either prokaryotic or eukaryotic. c) All cells come from pre-existing cells. d) Cells are the fundamental units of life. e) All living organisms are composed of cells.

b) Cells may be classified as either prokaryotic or eukaryotic.

You discover what looks to be a new organelle that is smaller than a mitochondrion, but you need to do further testing to best determine its cellular function. What would be your best plan of action? a) Use a light microscope under normal culturing conditions, and watch the organelle's movement through the cell. b) Isolate the organelle using cell fractionation, and follow with further biochemical analysis. c) Observe the organelle with freeze-fracture electron microscopy. d) Use a chemical against actin to prevent organelle transport within the cell and observe the resulting cellular function. e) Use a detergent to break up the lipid membrane of the organelle in the cell, and observe the resulting cell function.

b) Isolate the organelle using cell fractionation, and follow with further biochemical analysis.

Which structure is not surrounded by one or more membranes? a) Vacuole b) Ribosome c) Mitochondrion d) Chloroplast e) Peroxisome

b) Ribosome

Louis Pasteur's experiment in which he boiled broth and allowed it to cool under conditions that prevented exposure of the broth to dust provided evidence against spontaneous generation and in support of the cell theory tenet that a) cells are the fundamental units of life. b) all cells come from preexisting cells. c) the smallest unit of life is the cell. d) modern cells evolved from a common ancestor. e) all organisms are composed of cells.

b) all cells come from preexisting cells.

A new protein with a molecular weight of 25,000 daltons is discovered and found to reside only in the nucleus. For this to happen, the protein must a) be made in the nucleolus. b) be transported across the nuclear envelope. c) be synthesized by a unique mechanism. d) contain a large number of hydrophobic amino acids. e) exist in a denatured state.

b) be transported across the nuclear envelope.

A new protein with a molecular weight of 25,000 daltons is discovered and found to reside only in the nucleus. For this to happen, the protein must a) exist in a denatured state. b) be transported across the nuclear envelope. c) be synthesized by a unique mechanism. d) be made in the nucleolus. e) contain a large number of hydrophobic amino acids.

b) be transported across the nuclear envelope.

The cytoskeleton consists of a) internal cell walls. b) microtubules, intermediate filaments, and microfilaments. c) calcified microtubules. d) cilia, flagella, and microfilaments. e) cilia, microtubules, and microfilaments.

b) microtubules, intermediate filaments, and microfilaments.

A dye is injected into one plant cell and is observed to travel into adjacent plant cells. The dye is traveling between cells through a) osmosis. b) plasmodesmata. c) integrin. d) dynein. e) nuclear pores.

b) plasmodesmata.

You examine an unknown organism using freeze-fracture electron microscopy and discover ribosomes in its cytoplasm. You also find that it has inner membranes, but it is difficult to tell whether they are contiguous with the cell membrane or not. Which feature would allow you to classify this organism as a prokaryote? a) A nucleus b) Plastids c) A capsule d) A distinct mitochondrion e) DNA

c) A capsule

Which step is thought to have occurred, according to endosymbiotic theory? a) An independent prokaryotic cell was engulfed by another independent prokaryotic cell, and both continued activities independent of one another. b) An independent prokaryotic cell was engulfed by a dependent prokaryotic cell, allowing the dependent host cell to survive with the help of the engulfed cell. c) An independent prokaryotic cell was engulfed by another independent prokaryotic cell, after which the engulfed cell lost certain functions and became dependent on the host cell. d) A dependent prokaryotic cell was engulfed by another dependent prokaryotic cell, allowing each cell to survive with the help of the other. e) A dependent prokaryotic cell was engulfed by an independent prokaryotic cell, allowing the dependent cell to survive within the independent host cell.

c) An independent prokaryotic cell was engulfed by another independent prokaryotic cell, after which the engulfed cell lost certain functions and became dependent on the host cell.

It has been proposed that integrin proteins undergo conformational changes when they bind to small molecules diffusing into the extracellular matrix. Because integrins are transmembrane proteins, a change in their conformation can be transmitted across the membrane to the portion of the protein that interacts with intracellular structures. What biological role does this allow integrins to play in a cell's function within a multicellular organism? a) Selective filtration b) Structural support c) Cell-cell adhesion d) Cell-cell communication e) Barrier to pathogens

c) Cell-cell adhesion

Which statement can be used as evidence for the endosymbiosis theory? a) In eukaryotes, the endoplasmic reticulum is continuous with the nuclear envelope. b) Internal membranes are the sites of photosynthesis in photosynthetic prokaryotes. c) Mitochondria and plastids have DNA that encodes some proteins used by the organelles. d) Compartmentalization of individual functions in separate organelles allows eukaryotes greater ability to carry out a wide diversity of functions. e) Vacuoles are membrane-bound organelles that store toxic molecules and waste products.

c) Mitochondria and plastids have DNA that encodes some proteins used by the organelles.

Muscle cells need large amounts of calcium and ATP for contraction. Based on these requirements, you would expect that muscle cells would have an increased number of what type of organelles (per unit volume)? a) Chloroplasts and rough endoplasmic reticulum b) Smooth endoplasmic reticulum and vesicles c) Mitochondria and smooth endoplasmic reticulum d) Golgi apparatus and mitochondria Peroxisomes and Golgi apparatus

c) Mitochondria and smooth endoplasmic reticulum

What property of organelles and other subcellular structures is used to separate them using the lab technique known as cell fractionation? a) Charge b) Function c) Size d) Shape e) Composition

c) Size

Which is a difference between a prokaryotic and a eukaryotic cell? a) A prokaryotic cell does not use ribosomes for protein synthesis, whereas a eukaryotic cell does. b) A prokaryotic cell is not enclosed by a cell membrane, and a eukaryotic cell is enclosed. c) The DNA in a prokaryotic cell is not enclosed in a membrane-bound nucleus. d) Cellular processes in a prokaryotic cell are compartmentalized, whereas compartmentalization is absent in a eukaryotic cell. e) A prokaryotic cell does not use DNA as its genetic material.

c) The DNA in a prokaryotic cell is not enclosed in a membrane-bound nucleus.

In the previous question we established the following could be contributing to the 3% rounded cells seen in the no drug group: *3% of all amoebas naturally develop as rounded cells. *The no drug injection causes rounded cells at a rate of 3%. *Something about being raised in the lab environment causes rounded cells at a rate of 3%. How could you determine which of the factors stated in Question #1 contribute to the 3% of rounded cells seen in the no drug group? a) Include a group in the experiment that is not injected at all and count percent of rounded cells. b) Sample amoeba in the wild and count percent of rounded cells. c) both of the above d) There's no way to determine this.

c) both of the above

Ribosomes are not visible under a light microscope, but they can be seen with an electron microscope because a) electron beams have more energy than light beams. b) electron microscopes focus light with magnets. c) electron microscopes have more resolving power than light microscopes. d) electrons have such high energy that they pass through biological samples. e) electron microscopes can be used to observe living cells.

c) electron microscopes have more resolving power than light microscopes.

While using electron microscopy to examine the cell membrane of a bacterium, you have discovered the presence of a complex motor protein assembly. You do not find any evidence of a proper flagellum. You can conclude that the bacterium most likely has lost its ability to make a) actin. b) myosin. c) flagellin. d) keratin. e) tubulin.

c) flagellin.

Some proteins on the surface of a mammalian cell contain carbohydrates. These proteins are synthesized by ______ and the sugars are added in the ________. a) cytoplasmic ribosomes; smooth endoplasmic reticulum b) the Golgi apparatus; rough endoplasmic reticulum c) ribosomes on the rough endoplasmic reticulum; Golgi apparatus d) mitochondrial ribosomes; smooth endoplasmic reticulum e) cytoplasmic ribosomes; cell membrane

c) ribosomes on the rough endoplasmic reticulum; Golgi apparatus

Ribosomes are not found in a) prokaryotic cells. b) mitochondria. c) the Golgi apparatus. d) chloroplasts. e) the rough endoplasmic reticulum.

c) the Golgi apparatus.

Galactose-substituted diglycerides and sulfolipids are the most abundant lipids in the biosphere because of their presence in _______, which are highly abundant in plant cells. a) vegetable oils b) cisternae c) thylakoids d) intracellular matrices e) cristae

c) thylakoids

One benefit of scanning electron microscopy is that it enables researchers to a) follow metabolic reactions inside cells. b) sequence DNA molecules. c) visualize 3-D topography of a cell or tissue sample. d) determine the age of a cell. e) observe cells dividing.

c) visualize 3-D topography of a cell or tissue sample.n,

All else being equal, which cell carries out the most chemical activity within a minute? a) A square cell with sides that are 1 µm in length b) A spherical cell 1 µm in diameter c) A spherical cell 4 µm in diameter that has many infoldings d) A spherical cell 4 µm in diameter e) A square cell with sides that are 4 µm in length

d) A spherical cell 4 µm in diameter

Which structure is present in some prokaryotic cells? a) Nucleus b) Microtubule c) Mitochondrion d) Capsule e) Chloroplast

d) Capsule

Five statements about cell membranes are given. Which statement can be used to explain the importance of the cell membrane to cell survival? a) The cell membrane expands or shrinks by the addition or removal of phospholipid molecules. b) Cell membranes are composed of a phospholipid bilayer embedded with proteins. c) The cell membrane is so small that it is best viewed with an electron microscope. d) Cell membranes are selectively permeable with respect to molecules and ions. e) The cell membranes of prokaryotes and eukaryotes have the same basic structure.

d) Cell membranes are selectively permeable with respect to molecules and ions.

Which statement is true concerning endosymbiosis? a) Endosymbiotic events never occur in modern times. b) The nucleus probably formed through an endosymbiotic event. c) The endomembrane system likely formed as the result of endosymbiosis. d) Endosymbiosis explains the evolution of mitochondria and plastids. e) Endosymbiosis is a theory that has little evidence to support it.

d) Endosymbiosis explains the evolution of mitochondria and plastids.

Which statement about lysosomes is true? a) They may contain anthocyanins that aid in pollination. b) They are found only in plants. c) They provide a site for the storage of starch in plant cells. d) They are the sites where autophagy occurs. e) They may have arisen through endosymbiosis.

d) They are the sites where autophagy occurs.

In the experiment in Figures 5.22A and 5.22B, we saw that microfilaments are necessary for amoeboid cell movement. When drugs are used to prevent microfilaments from forming, cells become rounded and cannot move. However, even in the no drug group, 3% of cells are still rounded. What are some possible reasons for this? a) 3% of all amoebas naturally develop as rounded cells. b) The no drug injection causes rounded cells at a rate of 3%. c) Something about being raised in the lab environment causes rounded cells at a rate of 3%. d) all of the above e) only a and b

d) all of the above

The major factor limiting cell size is the a) presence of membrane-enclosed organelles. b') need for energy. c) composition of the cell membrane. d) ratio of surface area to volume. e) volume of water in the cytoplasm.

d) ratio of surface area to volume.

A vesicle carries a protein to the cell membrane, where it is inserted into the phospholipid bilayer. The vesicle budded off from which subcellular structure before making the trip through the cytoplasm to the cell membrane? a) Rough ER b) medial-Golgi c) cis-Golgi d) trans-Golgi e) Smooth ER

d) trans-Golgi

You examine an unknown organism using freeze-fracture electron microscopy and discover ribosomes in its cytoplasm. You also find that it has inner membranes, but it is difficult to tell whether they are contiguous with the cell membrane or not. Which feature would allow you to classify this organism as a prokaryote? a) Plastids b) A nucleus c) A distinct mitochondrion d) DNA e) A capsule

e) A capsule

Although plant and animal cells are both classified as eukaryotic, they do have some differences. Which pair correctly names an animal and a plant cell structure that serve some of the same functions? a) Animal peroxisome and plant chloroplast b) Animal nuclear pore and plant plasmodesmata c) Animal mitochondrion and plant leucoplast d) Animal cytoskeleton and plant cell wall e) Animal lysosome and plant vacuole

e) Animal lysosome and plant vacuole

Which technique could you use to determine whether the flagellum-like structure you are observing is made of the protein flagellin or the protein tubulin? a) Light microscopy b) Cell culturing techniques c) Videography of living cells d) Cell fractionation e) Biochemical analysis

e) Biochemical analysis

Scientists have been able to culture human cells so that the cells are able to live and reproduce indefinitely. However, it is not possible for any subset of components of a cell to function in this way; only an entire, undisrupted cell can live and reproduce. This observation supports which tenet of the cell theory? a) All cells come from preexisting cells. b) Modern cells evolved from a common ancestor. c) Life is continuous. d) All living organisms are composed of cells. e) Cells are the fundamental units of life.

e) Cells are the fundamental units of life.

Which is an observation that supports the theory of endosymbiosis? a) Mitochondria are present in large numbers in some cells. b) Plastids are organelles found only in plant cells. c) Mitochondria are found in both plant and animal cells. d) Chloroplasts carry out photosynthesis. e) Chloroplasts divide independently of the nucleus.

e) Chloroplasts divide independently of the nucleus.

Some people develop such breakdown and wear to joints that they no longer function properly. Physicians can surgically replace these joints with artificial joints. However, after surgery the artificial joints tend to come loose from their attachment points over time unless they are covered with biological coatings that contain proteins present in the human extracellular matrix. Which function of the extracellular matrix is highlighted in this instance? a) Filtration of materials passing between different tissues b) Providing a medium for chemical signals to move between cells c)Orientation of cell movements during development d) Strengthening of bone, cartilage, and skin e) Recognition of cells and cell-to-cell adhesion

e) Recognition of cells and cell-to-cell adhesion

Some bacteria have a specialized outer structure known as a(n) _______ that protects them from attack by a host's immune system. a) lamina b) envelope c) endoplasmic reticulum d) cell membrane e) capsule

e) capsule

Ribosomes are not visible under a light microscope, but they can be seen with an electron microscope because a) electron beams have more energy than light beams. b) electron microscopes focus light with magnets. c) electron microscopes can be used to observe living cells. d) electrons have such high energy that they pass through biological samples. e) electron microscopes have more resolving power than light microscopes.

e) electron microscopes have more resolving power than light microscopes.

Hair and some intermediate filaments are composed of a) microtubules. b) microfilaments. c) collagen. d) proteoglycans. e) keratin.

e) keratin

Members of the domains Bacteria and Archaea have all of the following except a) cytoplasm. b) cell membranes. c) DNA. d) ribosomes. e) nuclei.

e) nuclei