Chapter 1 Study Questions

Indicate whether the following statements are true or false. If the statement is false, explain why it is false. A. Membrane components in the cell are made in the endoplasmic reticulum. B. The Golgi apparatus is made up of a series of membrane-enclosed compartments throughwhich materials destined for secretion must pass. C. Lysosomes are small organelles where fatty acid synthesis occurs.

A. True B. True C. False, lysosomes house enzymes that break down nutriensts for use by the cell and help recycle materials that arent used, which will be released from the cell

Indicate whether the following statements are true or false. If the statement is false, explain why it is false. A. Oxygen is toxic to certain prokaryotic organisms. B. Mitochondria are thought to have evolved from anaerobic bacteria. C.Photosynthetic bacteria contain chloroplasts.

A. True B. False, Mitochondria use oxygen to generate enger and are though to have evolved from aerobic bacteria C. False, Photosynthetic bacteria have enzyme systems similar to those found in chloroplast allowing them to harvest ligh energu to fix carbon dioxide

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.

are transparent

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.

programmed cell death

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

can rapidly reorganize

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

chromosomes

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.

evolution

Eukaryotic cells are able to trigger the release of material from secretory vesicles to the An example of materials extracellular space using a process called exocytosis.commonly released this way is _____________. (a) hormones. (b) nucleic acids. (c) sugars. (d) cytosolic proteins.

hormones

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 microscope is limited by the __________ of light. (a) absorption (b) intensity (c) filtering (d) wavelength

wavelength

Although there are many distinct prokaryotic species, most have a small range of shapes, sizes, and growth rates. Which of the following characteristics are not observed in prokaryotes? (a) a highly structured cytoplasm (b) endoplasmic reticulum (c) the ability to divide rapidly (d) a cell wall

a highly structured cytoplasm endoplasminc reticulum

By definition, prokaryotic cells do not possess __________. (a) a nucleus. (b) replication machinery. (c) ribosomes. (d) membrane bilayers.

a nucleus

Biologists cannot possibly study all living species. Instead, they try to understand cell behavior by studying a select subset of them. 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

all of the above

Scientists learned that cell death is a normal and even important part of life by studyingthe 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) 70% 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.

c is the best answer because it was the prior developmental studies tracing cell lineages from the egg to the adult that allowed scientists to identify the precise time and location of cells that were being targeted for cell death. It was observed that this cell death was a normal and necessary part of the developmental pathway in the worm. Programmed cell death has since become known to be an important process in all multicellular eukaryotic organisms.

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?

cell

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

cell divison

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. Which of the processes below cannot be studied in yeast? (a) DNA replication (b) cell motility (c) exocytosis (d) cell division

cell mobility

Which of the following choices best describes the role of the lysosome? (a) transport of material to the Golgi (b) clean-up, recycling, and disposal of macromolecules (c) sorting of transport vesicles (d) the storage of excess macromolecules

clean up, recycling, and disposal of macromolecules

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 vesicles and brought into the cell? (a) degradation (b) exocytosis (c) phagocytosis (d) endocytosis

endocytosis

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

endosymbionts

Chloroplasts are found only in eukaryotic cells that carry out photosynthesis: plants and algae. Plants and algae appear green as a result of the presence of chlorophyll. Where is chlorophyll located 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

in the third, innermost membrane

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

insect

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.

is defined as all the genes being used to make protein

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.

it can reproduce in 8-10 weeks

Prokaryotic cells are able to evolve very fast, which helps them to rapidly adapt to new food sources and develop resistance to antibiotics. Which of the options below lists the three main characteristics that 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

large population rapid growth can exchange DNA

What unit of lengthwould you generally use to measure atypical (a) centimeters (b) nanometers (c) millimeters (d) micrometers

micrometers

__________ 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

peroxisomes

The flow of genetic information is controlled by a series of biochemical reactions that result in the production of proteins, each with its own specific order of amino acids.

replication, transcription, translation

Which of the following characteristics would not support the idea that the ancestral eukaryote was a predator cell that captured and consumed other cells? (a) dynamic cytoskeleton (b) large cell size (c) ability to move (d) rigid membrane

rigid membrane

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 livingorganisms. (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 betweenplant and animal tissues. (d) New cells arise from the growth and division of previously existing cells.

scientists came to the conclusion that new cells can form spontaneously from the remnants of ruptered cells

Photosynthesis enables plants to capture the energy from sunlight. In this essentialprocess, 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

sugar

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 material "burned" and the form of energy produced during cellular respiration? (a) fat, ADP (b) sugar, fat (c) sugar, ATP (d) fat, protein

sugar, ATP

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.

sugars

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.

that can be understood based on the principles of mutation and selection

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

0.2 um

Which pair of values best fills in the blanks in this statement: On average, eukaryotic _________ times more volume thancells are __________ times longer and haveprokaryotic cells. (a) 5, 100 (b) 10, 200 (c) 10, 100 (d) 10, 1000

10, 1000

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.1-8 Changes in DNA sequence from one

A mutation is a result of sexual reproduction

Indicate whether the following statements are true or false. If the statement is false, explain why it is false. A. The human genome is roughly 30 times larger than the Arabidopsis genome, but contains approximately the same number of protein-coding genes. B. The variation in genome size among protozoans is larger than that observed across all species of mammals, birds, and reptiles. C. The vast majority of our genome encodes functional RNA molecules or proteins and most of the intervening DNA is nonfunctional.

A. True B. True C. False, it is a relatively small proportion of our DNA that encodes RNA and protein molecules. Majority of non encoding sequences is probably involed in critical regulatory processes.

Given what you know about the differences between prokaryotic cells and eukaryotic cells, rate the following things as "good" or "bad" processes to study in the model organism E. coli. A. formation of the endoplasmic reticulum B. DNA replication C. how the actin cytoskeleton contributes to cell shape D. how cells decode their genetic instructions to make proteins E. how mitochondria get distributed to cells during cell division

A. bad b. good c. bad d. good e. bad

Some prokaryotes can live by utilizing entirely inorganic materials. Which of the following inorganic molecules would you predict to be the predominant building block for fats, sugars, and proteins? (a) O2 (b) N2 (c) CO2 (d) H2

CO2

Many of the mechanisms that cells use for maintenance and reproduction were first studied at the molecular level in bacteria. Which bacterial species had a central role in advancing the field of molecular biology? (a) E. coli (b) D.melanogaster (c) S. pombe (d) C. elegans

E. coli.

How does cellular specialization serve multicellular organisms and how might a high degree of specialization be detrimental?

In a multicellular organism, the specialization of cells creates a division of labor and each type of cell relies on the activities of other cell types for survival. This cooperation between specialized cells is essential for the organism as a whole. If one of these overly specialized cells were removed from the context of the organism, it would not have the capabilities needed to generate offspring and would probably not even live very long.

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 the egg cell and thuspollen grain contributes no chloroplasts to fertilizedto the offspring. What can you deduce from these results?

Your results show that not all of the information required for making a chloroplast is encoded in the chloroplast's own DNA; some, at least, must be encoded in the DNA carried in the nucleus. Genetic information is carried only in DNA, so the defect in the chloroplasts must be due to a mutation in DNA. But all of the chloroplasts in the offspring (and thus all of the chloroplast DNA) must derive from those in the female egg other Hence, all ofcell, since chloroplasts only arise from chloroplasts.the chloroplasts contain undamaged DNA from the female parent's chloroplasts. In all the cells of the offspring, however, half of the nuclear DNA will have come from the male germ-cell nucleus, which combined with the female egg nucleus at fertilization. Since this DNA has been treated with DNA-damaging agents, it must be the source of the heritable chloroplast defect. Thus, some of the information required for making awww.testbanktank.comchloroplast is encoded by the nuclear DNA.

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 the same thickness)

microtubles

Indicate whether the following statements are true or false. If the statement is false, explain why it is false. A. Plants do not require a cytoskeleton because they have a cell wall that lendsstructure and support to the cell. B. The cytoskeleton is used as a transportation grid for the efficient, directional movement of cytosolic components. C. Thermal energy promotes random movement of proteins, vesicles, and small molecules in the cytosol.

A. False, although plant cells do have a cell wall that lends structure and support, they still need a cytoskeletonn which helps with connetions between cells and the transport of vesivles inside the cell B. True C. True

Indicate whether the following statements are true or false. If the statement is false,explain why it is false. A. The terms "prokaryote" and "bacterium" are synonyms. B. Prokaryotes can adopt several different basic shapes, including spherical, rod- shaped, and spiral. C. Some prokaryotes have cell walls surrounding the plasma membrane.

A. False, archaea that are signifigantly different make up a class of prokaryotic organisms different from bacteria. B. True C. True

Indicate whether the following statements are true or false. If the statement is false, explain why it is false. A. With respect to cellular respiration, the only organelles used by animal cells are mitochondria, while plant cells use both mitochondria and chloroplasts. B. The number of mitochondria inside a cell remains constant over the life of the cell.

A. False, in plants only mitochondria perform cellular respiration like in animal cells. Chloroplasts perform photosynthesis where water molecules are split to generate oxygen and fix CO2 molecules B. False, Mitochondria have their own divison cycle and their numbers change based on rate of divison.

Indicate whether the following statements are true or false. If the statement is false,www.testbanktank.comexplain why it is false. A. Primitive plant, animal, and fungal cells probably acquired mitochondria afterthey diverged from a common ancestor. B. Protozoans are single-celled eukaryotes with cell morphologies and behaviors that can be as complex as those of some multicellular organisms. C. The first eukaryotic cells on Earth must have been aerobic; otherwise, they wouldnot have been able to survive when the planet's atmosphere became oxygen-rich.

A. False, the mitochondria in the modern plant, animal, fungal cell are very similar implying that these lines diverged after the mitochondrion was possessed by the ancestral eukaryote. B. True C. False, the first eukaryotic cells likely contained a nucleus but no mitochondria. These ancestral eukaryotes must have adapted to survive in a world filled with oxygen by englufing primitive aerobic prokaryotic cells.

Indicate whether the following statements are true or false. If the statement is false, explain why it is false. A. The nucleus of an animal cell is round, small, and difficult to distinguish using light microscopy. B. The presence of the plasma membrane can be inferred by the well-defined boundary of the cell. C. The cytosol is fairly empty, containing a limited number of organelles, whichallows room for rapid movement via diffusion.

A. False, the nucleus is one of the largest organelles and is the easiest organelle to discern within a typical cell B. True C. False, the cytosol is filled with proteins, protein fibers, membrane systems, vesicles, and small molecules. Though, cellular components do move by diffusion, the rate of the movement is limited by the space and size of the component.

Indicate whether the following statements are true or false. If the statement is false,explain why it is false. A. The Paramecium is a multicellular microorganism covered with hairlike cilia. B. Cells of different types can have different chemical requirements. C. The branchlike extensions that sprout from a single nerve cell in a mammalianbrain can extend over several hundred micrometers.

A. False: the paramecium is a single cell organism B. True C. True

You wish to explore how mutations in specific genes affecting sugar metabolism might alter tooth development. Which organism is likely to provide the best model system for your studies, and why? (a) horses (b) mice (c) E. coli (d) Arabidopsis

b) Mice are likely to provide the best model system. Mice have teeth and have long been used as a model organism. Mice reproduce relatively rapidly and the extensive scientific community that works with mice has developed techniques to facilitate genetic manipulations. E. coli (a bacterium) and Arabidopsis (a plant) do not have teeth. Horses like sugar and have big teeth, but they would not be a good model organism. There is not an extensive scientific community working on the molecular and biochemical mechanisms of cell behaviors in horses; they are expensive and have a long reproduction time, which makes genetic studies costly and slow; and tools for genetic manipulation (other than traditional breeding) have not been developed.

For each of the following sentences, fill in the blanks with the best word or phraseselected from the list below. Not all words or phrases will be used; each word or phrase should be used only once. Cells can be very diverse: superficially, they come in various sizes, ranging from bacterial cells such as Lactobacillus, which is a few __________________ inlength, to larger cells such as a frog's egg, which has a diameter of about one __________________. Despite the diversity, cells resemble each other to anastonishing degree in their chemistry. For example, the same 20__________________ are used to make proteins. Similarly, the geneticinformation of all cells is stored in their __________________. Although __________________ contain the same types of molecules as cells, their inabilityto reproduce themselves by their own efforts means that they are not considered living matter. amino acids micrometer(s) viruses DNA millimeter(s) yeastfatty acids plantsmeter plasma membranes

micrometers, milimeters, amino acids, DNA, viruses

Which of the following organelles has both an outer and an inner membrane? (a) endoplasmic reticulum (b) mitochondrion (c) lysosome (d) peroxisome

mitochondrion

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

nuclear envelope

Eukaryotic cells are bigger and more elaborate than prokaryotic cells. Bydefinition, all eukaryotic cells have a __________________, usually the most prominent organelle. Another organelle found in essentially all eukaryotic cells isthe for the cell. In__________________, which generates the chemical energycontrast, the __________________ is a type of organelle found only in the cellsof plants and algae, and performs photosynthesis. If we were to strip away theplasma membrane from a eukaryotic cell and remove all of its membrane-enclosed organelles, we would be left with the __________________, whichcontains many long, fine filaments of protein that are responsible for cell shape and structure and thereby form the cell's __________________. chloroplast cytosol nucleus chromosome endoplasmic reticulum ribosomescytoskeleton mitochondrion

nucleus, mitochondrion, chloroplast, cytosol, cytoskeleton

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

oxygen