Deck 1: Cells: The Fundamental Units of Life

Question 1

Which three characteristics best support the rapid evolution of prokaryotic populations?

A)microscopic, motile, anaerobic
B)aerobic, motile, rapid growth
C)no organelles, cell wall, can exchange DNA
D)large population, rapid growth, can exchange DNA

Answer 1

D

Question 2

Which statement is NOT true about mutations?

A)A mutation is a change in the DNA that can generate offspring less fit for survival than their parents.
B)A mutation can be a result of imperfect DNA duplication.
C)A mutation is a result of sexual reproduction.
D)A mutation is a change in the DNA that can generate offspring that are as fit for survival as their parents are.

Answer 2

C

Question 3

Mitochondria contain their own genome, are able to duplicate, and actually divide on a different time line from the rest of the cell.Nevertheless, mitochondria cannot function for long when isolated from the cell because they are

A)viruses.
B)parasites.
C)endosymbionts.
D)anaerobes.

Answer 3

C

Question 4

What unit of length would you generally use to measure a typical plant or animal cell?

A)centimeters
B)nanometers
C)millimeters
D)micrometers

Question 5

Select the option that BEST finishes the following statement: Evolution is a process

A)that can be understood based on the principles of mutation and selection.
B)that results from repeated cycles of adaptation over billions of years.
C)by which all present-day cells arose from 4-5 different ancestral cells.
D)that requires hundreds of thousands of years.

Question 6

The __________ __________ is made up of two concentric membranes and is continuous with the membrane of the endoplasmic reticulum.

A)plasma membrane
B)Golgi network
C)mitochondrial membrane
D)nuclear envelope

Question 7

The central dogma provides a framework for thinking about how genetic information is copied and used to produce structural and catalytic components of the cell.From the choices below, select the order of biochemical processes that best correlates with the tenets of the central dogma.

A)replication, transcription, translation
B)replication, translation, transcription
C)translation, transcription, replication
D)translation, replication, transcription

Question 8

The mitochondrial proteins found in the inner membrane are involved in the conversion of ADP to ATP, a source of energy for the cell.This process consumes which of the following substances?

A)oxygen
B)nitrogen
C)sulfur
D)carbon dioxide

Question 9

Changes in DNA sequence from one generation to the next may result in offspring that are altered in fitness compared with their parents.The process of change and selection over the course of many generations is the basis of

A)mutation.
B)evolution.
C)heredity.
D)reproduction.

Question 10

Mitochondria perform cellular respiration, a process that uses oxygen, generates carbon dioxide, and produces chemical energy for the cell.Which answer below indicates a correct pairing of the material "burned" and the form of energy produced during cellular respiration?

A)fat, ADP
B)sugar, fat
C)sugar, ATP
D)fat, protein

Question 11

Prokaryotic cells do not possess

A)a nucleus.
B)replication machinery.
C)ribosomes.
D)membrane bilayers.

Question 12

Which of the following organelles has both an outer and an inner membrane?

A)endoplasmic reticulum
B)mitochondrion
C)lysosome
D)peroxisome

Question 13

Proteins are important architectural and catalytic components within the cell, helping to determine its chemistry, its shape, and its ability to respond to changes in the environment.Remarkably, all of the different proteins in a cell are made from the same 20 __________.By linking them in different sequences, the cell can make protein molecules with different conformations and surface chemistries, and therefore different functions.

A)nucleotides
B)sugars
C)amino acids
D)fatty acids

Question 14

The nucleus, an organelle found in eukaryotic cells, confines the __________, keeping them separated from other components of the cell.

A)lysosomes
B)chromosomes
C)peroxisomes
D)ribosomes

Question 15

Living systems are incredibly diverse in size, shape, environment, and behavior.It is estimated that there are between 10 million and 100 million different species.Despite this wide variety of organisms, it remains difficult to define what it means to say something is alive.Which of the following can be described as the smallest living unit?

A)DNA
B)cell
C)organelle
D)protein

Question 16

Select the option that correctly finishes the following statement: A cell's genome

A)is defined as all the genes being used to make protein.
B)contains all of a cell's DNA.
C)constantly changes, depending upon the cell's environment.
D)is altered during embryonic development.

Question 17

What is the smallest distance two points can be separated and still resolved using light microscopy?

A)20 nm
B)0.2 μm
C)2 μm
D)200 μm

Question 18

Cell biologists employ targeted fluorescent dyes or modified fluorescent proteins in both standard fluorescence microscopy and confocal microscopy to observe specific details in the cell.Even though fluorescence permits better visualization, the resolving power is essentially the same as that of a standard light microscope because the resolving power of a fluorescent microscope is still limited by the __________ of visible light.

A)absorption
B)intensity
C)filtering
D)wavelength

Question 19

Which statement is NOT true about the events/conclusions from studies during the mid-1800s surrounding the discovery of cells?

A)Cells came to be known as the smallest universal building block of living organisms.
B)Scientists came to the conclusion that new cells can form spontaneously from the remnants of ruptured cells.
C)Light microscopy was essential in demonstrating the commonalities between plant and animal tissues.
D)New cells arise from the growth and division of previously existing cells.

Question 20

The world of prokaryotes is divided into two domains (bacteria and archaea), each as different from each other as from eukaryotes.Select the observable characteristic that BEST separates archaea from bacteria.

A)can metabolize inorganic substances
B)are found in extremely harsh environments
C)thrive in anaerobic conditions
D)are photosynthetic organisms

Question 21

__________ are fairly small organelles that provide a safe place within the cell to carry out certain biochemical reactions that generate harmful, highly reactive oxygen species.These chemicals are both generated and broken down in the same location.

A)Nucleosomes
B)Lysosomes
C)Peroxisomes
D)Endosomes

Question 22

Cells that are specialized for the secretion of proteins are likely to have which of the following features?

A)long bundles of actin/myosin proteins
B)small volume of cytoplasm
C)large population of mitochondria
D)enlarged endoplasmic reticulum

Question 23

Scientists learned that cell death is a normal and even important part of life by studying the development of the nematode worm C.elegans.What was the most important feature of C.elegans for the study of programmed cell death?

A)The nematode is smaller and simpler than the fruit fly.
B)Seventy percent of C.elegans genes have homologs in humans.
C)The developmental pathway of each cell in the adult worm was known.
D)Its genome was partially sequenced.

Question 24

Eukaryotic cells are able to trigger the release of material from secretory vesicles to the extracellular space using a process called exocytosis.An example of materials commonly released this way is

A)hormones.
B)nucleic acids.
C)sugars.
D)cytosolic proteins.

Question 25

Which species was the key model organism for the advancement of molecular biology (understanding DNA replication, decoding the DNA to make proteins, etc.)?

A)E.coli
B)D.melanogaster
C)S.pombe
D)C.elegans

Question 26

Zebrafish (Danio rerio) are especially useful in the study of early development because their embryos

A)are exceptionally large.
B)develop slowly.
C)are transparent.
D)are pigmented.

Question 27

Brewer's yeast, apart from being an irreplaceable asset in the brewery and in the bakery, is an experimental organism used to study eukaryotic cells.However, it does have some limitations.Select all the processes below that CANNOT be studied in yeast.

A)differentiation
B)motility
C)exocytosis
D)cell division

Question 29

Drosophila melanogaster is a/an __________.This type of animal is the most abundant of all animal species, making it an appropriate choice as an experimental model.

A)insect
B)bird
C)amphibian
D)mammal

Question 30

Which of the following choices BEST describes the role of the lysosome?

A)transport of material to the Golgi apparatus
B)clean-up, recycling, and disposal of macromolecules
C)sorting of transport vesicles
D)the storage of excess macromolecules

Question 31

The cytoskeleton provides support, structure, motility, and organization, and it forms tracks to direct organelle and vesicle transport.Which of the cytoskeletal elements listed below is the thickest?

A)actin filaments
B)microtubules
C)intermediate filaments
D)none of the above (all have the same thickness)

Question 32

Which pair of values best fills in the blanks in this statement: On average, eukaryotic cells are __________ times longer and have __________ times more volume than prokaryotic cells.

A)5; 100
B)10; 200
C)10; 100
D)10; 1000

Question 33

Photosynthesis enables plants to capture the energy from sunlight.In this essential process, plants incorporate the carbon from CO₂ into high-energy __________ molecules, which the plant cell mitochondria use to produce ATP.

A)fat
B)sugar
C)protein
D)fiber

Question 34

Despite the differences between eukaryotic and prokaryotic cells, prokaryotes have proteins that are distantly related to eukaryotic actin filaments and microtubules.What is likely to be the most ancient function of the cytoskeleton?

A)cell motility
B)vesicle transport
C)membrane support
D)cell division

Question 35

Chloroplasts are complex organelles present in all photosynthesizing eukaryotes.Three different membranes create chemically different environments inside the chloroplast.Precisely where are chlorophyll molecules localized in the chloroplast?

A)in the first, outer membrane
B)in the space between the first and second membranes
C)in the second, inner membrane
D)in the third, innermost membrane

Question 36

Caenorhabditis elegans is a nematode.During its development, it produces more than 1000 cells.However, the adult worm has only 959 somatic cells.The process by which 131 cells are specifically targeted for destruction is called

A)directed cell pruning.
B)programmed cell death.
C)autophagy.
D)necrosis.

Question 37

A.thaliana, or Arabidopsis, is a common weed.Biologists have selected it over hundreds of thousands of other flowering plant species to serve as an experimental model organism because

A)it can withstand extremely cold climates.
B)it can reproduce in 8-10 weeks.
C)it produces thousands of offspring per plant.
D)Both (B) and (C) are true.

Question 38

Choose the phrase that best completes this sentence: Microtubules __________ and are required to pull duplicated chromosomes to opposite poles of dividing cells.

A)generate contractile forces
B)are intermediate in thickness
C)can rapidly reorganize
D)are found in especially large numbers in muscle cells

Question 39

Biologists cannot possibly study all living species.Instead, they try to understand cell behavior by studying a select subset of species.Which of the following characteristics are useful in an organism chosen for use as a model in laboratory studies?

A)amenability to genetic manipulation
B)ability to grow under controlled conditions
C)rapid rate of reproduction
D)all of the above

Question 40

The cell constantly exchanges materials by bringing nutrients in from the external environment and shuttling unwanted by-products back out.Which term describes the process by which external materials are captured inside transport vesicles and brought into the cell?

A)degradation
B)exocytosis
C)phagocytosis
D)endocytosis

Question 41

Evolutionary biologists have always used a broad range of modern organisms to infer the characteristics that ancestral organisms may have possessed.Genomic sequences are now available for an increasing number of species, and scientists studying evolutionary processes can take advantage of this enormous amount of data to bring evolution into the arena of molecular studies.By aligning the sequences of homologous genes and looking for regions of similarity and where changes have occurred, it is possible to infer the sequence of the ancestral gene.
A.What term is used to describe the changes in gene sequences that have occurred? How can we use what we know about this process to construct a time line showing when various sequence changes occurred and when they led to the modern sequences that we know today?
B.It is possible to express an ancestral gene sequence in modern organisms and subsequently compare the function of its product with that of the modern protein.Why might this approach give misleading conclusions?

Question 42

Cellular processes are often regulated by unknown mechanisms.In many cases, biologists work backward in an attempt to understand a process in which they are interested.This was the case when Nurse and Hartwell were trying to understand how cell division is controlled in yeast.Describe the process by which they "broke" the system and then supplied the "missing parts" to get the cell cycle running again.What further evidence did they collect to show that human cells and yeast cells regulate the cell cycle using a similar mechanism?

Question 44

Genes that have homologs in a variety of species have been discovered through the analysis of genome sequences.In fact, it is not uncommon to find a family of homologous genes encoding proteins that are unmistakably similar in amino acid sequence in organisms as diverse as budding yeast, archaea, plants, and humans.Even more remarkably, many of these proteins can substitute functionally for their homologs in other organisms (i.e., if we delete a native gene and replace it with a homologous gene from another species, the protein will be produced and its function preserved).Use your understanding of evolution to explain how this is possible.

Question 45

For each of the following sentences, fill in the blanks with the best word or phrase selected from the list below.Not all words or phrases will be used; each word or phrase should be used only once.
chloroplast cytosol nucleus
chromosome endoplasmic reticulum ribosomes
cytoskeleton mitochondrion
Eukaryotic cells are bigger and more elaborate than prokaryotic cells.By definition, all eukaryotic cells have a __________, usually the most prominent organelle.Another organelle found in essentially all eukaryotic cells is the __________, which generates the chemical energy for the cell.In contrast, the __________ is a type of organelle found only in the cells of plants and algae, and performs photosynthesis.If we were to strip away the plasma membrane from a eukaryotic cell and remove all of its membrane-enclosed organelles, we would be left with the __________, which contains many long, fine filaments of protein that are responsible for cell shape and structure, and thereby form the cell's __________.

Question 46

Generate an analogy to describe the cell as the simplest unit of life to somebody who has not studied biology.Be sure to incorporate the observable features of living organisms, which distinguishes them from inanimate objects.

Question 48

Cellular populations in bacterial colonies and the human body both start with single founder cells, yet these two collections of cells are vastly different.What is the primary reason for these differences?

Question 49

For each of the following sentences, fill in the blanks with the best word or phrase selected from the list below.Not all words or phrases will be used; each word or phrase should be used only once.
$\begin{array}{lll}\text { amino acids } & \text { micrometer(s) } & \text { viruses } \\\text { DNA } & \text { millimeter(s) } & \text { yeast } \\\text { fatty acids } & \text { plants } & \\\text { meter } & \text { plasma membranes } &\end{array}$

Cells can be very diverse: superficially, they come in various sizes, ranging from bacterial cells such as Lactobacillus, which is a few __________ in length, to larger cells such as a frog's egg, which has a diameter of about 1 __________.Despite the diversity, cells resemble each other to an astonishing degree in their chemistry.For example, the same 20 __________ are used to make proteins.Similarly, the genetic information of all cells is stored in their __________.Although __________ contain the same types of molecules as cells, their inability to reproduce themselves by their own efforts means that they are not considered living matter.

Question 52

The protozoan Didinium feeds on other organisms by engulfing them.Describe the cellular characteristics necessary to feed this way and explain why this is not a mechanism by which bacteria can acquire energy.Are bacteria, in general, unable to feed on other cells in this way?

Question 54

Describe the benefits and limitations of utilizing electron microscopy to understand biological systems.

Question 55

Number the following cells based on when they are believed to have evolved.
___ anaerobic eukaryote
___ aerobic prokaryote
___ anaerobic prokaryote
___ photosynthetic eukaryote
___ aerobic eukaryote
___ photosynthetic prokaryote

Question 56

The antibiotic streptomycin inhibits protein synthesis in bacteria.If this antibiotic is added to a culture of animal cells, protein synthesis in the cytosol continues normally.However, over time, the population of mitochondria in the cell becomes depleted.Specifically, it is observed that the protein-synthesis machinery inside the mitochondria is inhibited.
A.Explain this observation based on what you know about the origins of the modern eukaryote.
B.What do you expect to observe if, in a new experiment, animal cells are treated with diphtheria toxin, a compound that is known to block cytosolic protein synthesis but does not have any impact on bacterial growth?

Question 57

You fertilize egg cells from a healthy plant with pollen (which contains the male germ cells) that has been treated with DNA-damaging agents.You find that some of the offspring have defective chloroplasts, and that this characteristic can be passed on to future generations.This surprises you at first because you happen to know that the male germ cell in the pollen grain contributes no chloroplasts to the fertilized egg cell and thus to the offspring.What can you deduce from these results?

Question 58

Employ the principles of evolution discussed in this chapter to explain how the specific features and predatory behaviors of some primitive eukaryotes may have given them a selective advantage over others 1.5 billion years ago.

Question 60

You have been following the recent presidential elections and have heard some candidates disparaging excessive and "unnecessary" federal government expenditures.One particular candidate asks: "Why are we spending millions of dollars studying fruit flies? How can that possibly help us find a cure for cancer?" Use your knowledge of model organisms to explain why studies in D.melanogaster (the fruit fly) are actually an excellent use of research funding.

Question 61

Use the list of structures below to label the schematic drawing of an animal cell in Figure 1-41.
Figure 1-41
A.plasma membrane
B.nuclear envelope
C.cytosol
D.Golgi apparatus
E.endoplasmic reticulum
F.mitochondrion
G.transport vesicles

Question 62

Your friend has just returned from a deep-sea mission and claims to have found a new single-celled life form.He believes this new life form may not have descended from the common ancestor that all types of life on Earth share.You are convinced that he must be wrong, and you manage to extract DNA from the cells he has discovered.He says that the mere presence of DNA is not enough to prove the point: his cells might have adopted DNA as a useful molecule quite independently of all other known life-forms.What could you do to provide additional evidence to support your argument?

Question 63

Identify the appropriate cell type in which the listed structure or molecule can be found.Note that the structure or molecule can be found in more than one type of cell. $\begin{array}{c}\begin{array}{l}\underline{\text { structure or molecule }}\\1 \quad \text { DNA } \\ 2 \quad \text { nucleus } \\3 \quad \text { plasma membrane } \\4 \quad \text { chloroplast } \\5 \quad \text { cell wall } \\6 \quad \text { lysosome } \\7 \quad \text { mitochondrion } \\8 \quad \text { Golgi apparatus }\end{array}\begin{array}{l} \quad\quad\quad\quad\underline{\text { cell type}}\\ \text {animal \quad plant\quad bacterial}\\ \text {animal\quad plant\quad bacterial}\\ \text {animal \quad plant\quad bacterial}\\ \text {animal\quad plant\quad bacterial}\\ \text {animal \quad plant \quad bacterial}\\ \text {animal\quad plant \quad bacterial}\\ \text {animal \quad plant\quad bacterial}\\ \text {animal \quad plant \quad bacterial}\\\end{array}\end{array}$

Figure 1-71

Question 64

Draw and annotate a diagram that explains how living systems are autocatalytic.