Chapter 1

True or False: Lysosomes are small organelles where fatty acid synthesis occurs.

False. Lysosomes house enzymes that breakdown nutrients for use by the cell and help recycle materials that cannot be used, which will later be excreted from the cell.

True or False: Mitochondria are thought to have evolved from anaerobic bacteria.

False. Mitochondria use oxygen to generate energy and are thought to have evolved from aerobic bacteria.

True or False: Although bacteria use a variety of organic substances as food, bacteria are not able live on inorganic substances.

False. Some bacteria can live by consuming exclusively inorganic substances such as CO2, N2, water, and minerals.

True or False: Primitive plant, animal, and fungal cells probably acquired mitochondria after they diverged from a common ancestor.

False. The mitochondria in modern plant, animal, and fungal cells are very similar, implying that these lines diverged after the mitochondrion was acquired by the ancestral eucaryote.

True or False: Animal, plant, fungal, and bacterial cells all possess cell walls.

False. The outermost layer in animal cells is the plasma membrane.

1-10 By definition, procaryotic cells do not possess __________. (a) a nucleus (b) replication machinery (c) ribosomes (d) membrane bilayers

a

1-20 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

a

1-4 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. Choose the correct series biochemical reactions from the options presented here. (a) replication, transcription, translation (b) replication, translation, transcription (c) translation, transcription, replication (d) translation, replication, transcription

a

1-11 Although there are many distinct procaryotic species, most have a small range of shapes, sizes, and growth rates. Which of the following characteristics are not observed in procaryotes? (a) a highly structured cytoplasm (b) endoplasmic reticulum (c) the ability to divide rapidly (d) a cell wall

a, b

1-1 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

b

1-16 The nucleus, an organelle found in eucaryotic cells, confines the __________, keeping them separated from other components of the cell. (a) lysosomes (b) chromosomes (c) peroxisomes (d) ribosomes

b

1-17 Which of the following organelles has both an outer and an inner membrane? (a) endoplasmic reticulum (b) mitochondrion (c) lysosome (d) peroxisome

b

1-22 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

b

1-28 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)

b

1-6 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

b

1-19 Mitochondria contain their own genome, are able to duplicate, and actually divide on a different timeline 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.

c

1-27 __________ 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

c

1-5 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

c

1-15 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

d

1-21 Chloroplasts are found only in eucaryotic 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

d

1-26 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 of by which external materials are captured inside vesicles and brought into the cell? (a) degradation (b) exocytosis (c) phagocytosis (d) endocytosis

d

1-29 Despite the differences between eucaryotic and procaryotic cells, procaryotes have proteins that are distantly related to eucaryotic 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

d

1-30 Which of the following characteristics would not support the idea that the ancestral eucaryote was a predator cell that captured and consumed other cells? (a) dynamic cytoskeleton (b) large cell size (c) ability to move (d) rigid membrane

d

True or False: Protozoans are single-celled eucaryotes with cell morphologies and behaviors that can be as complex as those of some multicellular organisms.

true

True or False: The Golgi apparatus is made up of a series of membrane-enclosed compartments through which materials destined for secretion must pass.

true

True or False: Membrane components in the cell are made in the endoplasmic reticulum.

true

True or False: Oxygen is toxic to certain procaryotic organisms.

true

True or False A virus is a living organism.

False. A virus lacks the full machinery required to copy itself and is therefore not considered a living organism.

True or False Cells of different types can have different chemical requirements.

true

True or False A human white blood cell is larger than a Paramecium cell.

False. A human white blood cell is about 10 μm in diameter. The single-celled paramecium is roughly 10 times that size.