Section 1 Check

Question 1 How did the invention of the microscope

impact society's understanding of disease?

B. Microscopes were invented after the development of the cell theory.

A. Scientists were able to view microorganisms that were previously unknown.

D. Scientists could view membrane-bound organelles of prokaryotes.

C. It was once believed that viruses, not bacteria, caused diseases.

How did the invention of the microscope impact society's understanding of disease?

Question 1

The answer is A. Before microscopes were invented, people believed that curses and supernatural spirits caused diseases. Microscopes enabled scientists to view cells, which led to the discovery that microorganisms cause some diseases.

Which of the following uses a beam of light and a series of lenses to magnify objects in steps?

Question 2

D. simple light microscope

C. transmission electron microscope

B. scanning electron microscope

A. compound light microscope

The answer is A. Most microscopes use at least two convex lenses. Compound light microscopes use a light beam and a series of lenses and can magnify objects up to about 1500 times. Electron microscopes use a beam of electrons and can magnify structures up to 500 000 times.

Plasma membrane

Nucleus

Nucleolus

Chromosomes

Organelles

Question 3 What makes this cell eukaryotic?

A. Because it has a cell wall.

B. Because it contains DNA.

Plasma membrane

Nucleus

Nucleolus

Chromosomes

Organelles

Question 3 What makes this cell eukaryotic?

C. Because it has membrane-bound organelles.

D. Because it does not have DNA.

Plasma membrane

Nucleus

Nucleolus

Chromosomes

Organelles

Question 3 The Answer is C. Eukaryotic cells contain

membrane-bound organelles that have specific functions in the cell; prokaryotic cells do not.

Which of the following best describes the plasma membrane's mechanism in maintaining homeostasis?

Question 1

A. protein synthesis

B. selective permeability

C. fluid composition

D. structural protein attachment

The answer is B. Selective permeability is the process in which the membrane allows some molecules to pass through, while keeping others out.

Describe the structure of the plasma membrane.

Question 2

The plasma membrane is composed of a phospholipid bilayer, which has two layers of phospholipids back-to-back. The polar heads of phospholipid molecules contain phosphate groups and face outward.

Why is the phosphate group of a phospholipid important to the plasma membrane?

Question 3

Polar head (includes phosphate group)

Nonpolar tails (fatty acids)

Phospholipid molecule

When phospholipid molecules form a bilayer, the phosphate groups lie to the outside. Because phosphate groups are polar, they allow the cell membrane to interact with its watery (polar) environments inside and outside the cell.

Polar head (includes phosphate group)Nonpolar

tails (fatty acids)

Phospholipid molecule

Explain why the model of the plasma membrane is called the fluid mosaic model.

Question 4

It is fluid because the phospholipid molecules move within the membrane. Proteins in the membrane that move among the phospholipids create the mosaic pattern.

What is the primary function of the cell wall?

Question 1

D. acquire nutrients from environment

C. control activity of organelles

B. provide support

A. act as selectively permeable membrane

The answer is B. The cell wall is an inflexible, porous barrier that provides support but does not select which molecules can enter the cell.

Question 2

DNA

Plasma membrane

Cell wall

Describe the control center of a prokaryotic cell.

Ribosomes

DNA

Plasma membrane

Cell wall

Prokaryotic cells do not have true nuclei; their DNA is not separated from the rest of the cell by a membrane.

Ribosomes

Which of the following structures is the site of protein synthesis?

Question 3

D. Lysosome

C. Vacuole

B. Ribosome

A. Golgi apparatus

The answer is B. Ribosomes are the sites where the cell produces proteins according to the directions of DNA. They can be attached to the surface of the endoplasmic reticulum or float freely in the cytoplasm.

What is the advantage of having numerous folds in the ER?

Question 4

B. It can create more vesicles in a smaller space.

A. It enables the ER to lie snugly against the nucleolus.

D. A large amount of work can be done in a small space.

What is the advantage of having numerous folds in the ER?

Question 4

C. It can capture more light energy with more folds.

The answer is D. The ER is arranged in a series of folded membranes, which, if spread out, would take up tremendous space.

B. It contains a greater number of plastids.

What could you predict about a plant cell that contains fewer chloroplasts than other plant cells?

Question 5

A. It contains less chlorophyll.

D. It will appear darker green in color.

C. It will have an increased rate of light energy capture.

The answer is A. Chloroplasts are among the plant organelles known as plastids and contain the green pigment chlorophyll. Chlorophyll traps light energy from the Sun and gives leaves and stems their green color.

A mutation results in the inner membranes of a liver cell's mitochondria being smooth, rather than folded. Which of the following would you expect?

Question 6

B. It can create more vesicles in a smaller space

A. more efficient storage of cellular energy

A mutation results in the inner membranes of a liver cell's mitochondria being smooth, rather than folded. Which of the following would you expect?

Question 6

D. fewer ribosomes available for protein synthesis

C. decreased energy available to the cell

The answer is C. Mitochondria transform energy for the cell. A highly folded inner membrane provides a greater surface area for producing energy-storing molecules.

Question 1

B. endocytosis A. active transport

The diffusion of water across a selectively permeable membrane is called __________. (TX Obj 2; 4B)

Water moleculeSugar moleculeSelectively

permeable membrane

Question 1

D. osmosis C. exocytosis

Water moleculeSugar moleculeSelectively

permeable membrane

The diffusion of water across a selectively permeable membrane is called __________. (TX Obj 2; 4B)

The answer is D, osmosis. Regulating the water flow through the plasma membrane is an important factor in maintaining homeostasis within the cell.

Water moleculeSugar moleculeSelectively

permeable membrane

Before osmosis After osmosis

What is the expected result of having an animal cell in a hypertonic solution? (TX Obj 2; 4B)

Question 2

D. The cell retains its normal shape.

C. The cell swells up.

A. The cell shrivels up.

B. The plasma membrane shrinks away from

the cell wall.

The answer is A. In a hypertonic solution, cells experience osmosis of water out of the cell. Animal cells shrivel because of decreased pressure in the cells.

H2OH2O

Water moleculeSugar molecule

A grocer mists the celery display with water to keep it looking fresh. What type of solution is the celery now in? (TX Obj 2; 4B)

Question 3

D. exotonic

C. hypertonic

B. hypotonic

A. isotonic

The answer is B. Plant cells contain a rigid cell wall and do not burst even in a hypotonic solution.

Plasma membrane

Question 4

B. simple diffusion

A. osmosis Concentration

gradient

Channel proteins

Transport of materials across the plasma membrane that does not require energy from the cell but does use transport proteins is called __________. (TX Obj 2; 4B)

Question 4

D. active transport

C. facilitated diffusion Plasma

membraneConcentration

gradient

Channel proteins

Transport of materials across the plasma membrane that does not require energy from the cell but does use transport proteins is called __________. (TX Obj 2; 4B)

The answer is C. Facilitated diffusion is a type of passive transport and requires no energy from the cell.

Plasma membrane

Concentration gradient

Channel proteins

The stringy structures in the cell nucleus that contain DNA are __________. (TX Obj 2; 4B)

Question 1

D. chlorophylls

C. genes

B. chromosomes

A. centromeres

The answer is B. Chromosomes are the carriers of the genetic material of the cell. A gene is a segment of DNA that controls the production of a protein.

Look at the diagram and identify the stage of mitosis that is depicted. (TX Obj 2; 4B)

Question 2

D. telophase C. anaphase

B. metaphase A. prophase

Centromere

Sister chromatids

The answer is B. Metaphase is the short second phase of mitosis, during which the chromosomes begin to line up on the equator of the spindle.

Centromere

Sister chromatids

What is the process by which a cell's cytoplasm divides? (TX Obj 2; 4B)

Question 3

D. mitosis

C. meiosis

B. telekinesis

A. cytokinesis

The answer is A. Cytokinesis follows telophase and allows the two new cells to separate.

In multicellular organisms, groups of cells that work together to perform a specific function are called __________. (TX Obj 2; 10B)

Question 4

D. cell cycles

C. tissues

B. organs

A. organ systems

The answer is C. Tissues organize to form organs, which work with other organs to form organ systems.

Explain cancer in terms of cell growth.(TX Obj 2; 4B, 6C)

Question 1

AnswerCancer is a malignant growth resulting from uncontrolled cell division. The loss of control may be caused by environmental factors or changes in enzyme production that result from defective or changed genetic material. Cancerous cells form masses of tissue called tumors that deprive normal cells of nutrients.

A(n) __________ is a segment of DNA that controls the production of a protein. (TX Obj 2; 4B, 6C)

Question 2

D. chromosome

C. enzyme

B. cyclin

A. gene

The answer is A. Genes control the production of proteins. Scientists think that cancer results from changes in one or more of the genes that produce substances controlling the cell cycle.

Which of the following is thought to reduce the risk of developing cancer? (TX Obj 2; 4B)

Question 3

D. decrease dietary minerals

C. decrease dietary fiber

B. increase dietary fiber

A. increase dietary fat

The answer is B. Health professionals believe that diets low in fat and high in fiber content can reduce the risk of many types of cancer.

Question 1 What is the primary difference in the ways

that plants and animals obtain energy?(TX Obj 2; 8C, TX Obj 3; 13A)

Answer All living organisms need energy. Plants can

trap light energy in sunlight and store it for later use. Animals cannot trap energy from sunlight and must eat plants that contain stored energy.

Question 2 Why does the formation of ATP require

energy? (TX Obj 2; 4B)

One molecule of ATP contains three phosphate groups, which are charged particles. Energy is required to bond the phosphate groups onto the same molecule because they behave the same way that the poles of magnets do and repel groups with like charges. When the ATP molecule is broken down, the chemical energy stored in it becomes available to the cell for life processes.

Question 3 A molecule of adenosine that has one

phosphate group bonded to it is ______.(TX Obj 2; 4B)

A. AMP

B. ADPC. ATPD. ACP

The answer is A. AMP is adenosine monophosphate.

The addition and release of a phosphate group on adenosine diphosphate creates a cycle of ATP formation and breakdown.

Adenosine

Adenosine

P P P

PP

P P

Adenosine triphosphate (ATP)

Adenosine diphosphate (ADP)

Question 4 What is the function of the protein molecule

shown in this diagram? (TX Obj 2; 4B)ATP

ADP

ADP

Protein P Energy

This protein molecule has a specific binding site for ATP. In order to access the energy stored ATP, the protein molecule binds the ATP and uncouples one phosphate group. This action releases energy that is then available to the cell.

ATP

ADP

ADP

Protein P Energy

The process that uses the sun’s energy to make simple sugars is ________. (TX Obj 2; 4B, 8CTX Obj 3; 9D)

Question 1

D. photolysis

C. photosynthesis

B. glycolysisA. cellular respiration

The answer is C. Photosynthesis happens in two phases to make simple sugars and convert the sugars into complex carbohydrates for energy storage.

The function accomplished by the light-dependent reactions is ________. (TX Obj 2; 4B, 8C, TX Obj 3; 9D)

Question 2

D. conversion of sugar to PGAL

C. carbon fixation

B. sugar production

A. energy storage

The answer is A. The light-dependent reactions transfer energy from the sun to chlorophyll, and pass energized electrons to proteins embedded in the thylakoid membrane for storage in ATP and NADPH molecules.

Sun

Chlorophyll passes energy down through the electron transport chain.

for the use in light-independent reactions

bonds P to ADPforming

ATPoxygenreleased

splitsH2O

H+

NADP+

NADPH

Light energy transfers to chlorophyll.

Energized electrons provide energy that

The first step in the Calvin cycle is the ________.(TX Obj 2; 4B, 8C, TX Obj 3; 9D)

Question 3

D. Bonding of carbon to ribulose biphosphate

C. Splitting of six-carbon sugar into two three-carbon molecules

B. production of phosphoglyceraldehydeA. replenishing of ribulose biphosphate

The answer is D. The carbon atom from CO2 bonds with a five-carbon sugar to form an unstable six-carbon sugar. This molecule then splits to form two three-carbon molecules.

How many rounds of the Calvin cycle must occur in order for one molecule of PGAL to be transferred to the cell’s cytoplasm?(TX Obj 2; 4B, 8C, TX Obj 3; 9D)

Question 4

D. 4C. 3B. 2A. 1

The answer is C. Each round of the Calvin cycle produces two molecules of PGAL.

What do the Calvin cycle and the Citric acid cycle have in common? (TX Obj 2; 4B, 8C,TX Obj 3; 9D)

Question 1

D. From every turn of the cycle, two molecules of carbon dioxide are produced.

C. Both generate ADP.B. Both require input of ATP molecules.

A. The molecule used in the first reaction is also one of the end products.

The answer is A. In the Calvin cycle, RuBP bonds to carbon in the first step and is produced in the last step. In the citric acid cycle, oxaloacetic acid reacts in the first step and is recycled in the last step.

The process by which mitochondria break down food molecules to produce ATP is called ________. (TX Obj 2; 4B, 8CTX Obj 3; 9D)

Question 2

D. the Calvin cycleC. the light-independent reactionB. cellular respirationA. photosynthesis

The answer is B. Photosynthesis, light-independent reactions, and the Calvin cycle all occur in plants.

The three stages of cellular respiration are ________. (TX Obj 2; 4B, 8C, TX Obj 3; 9D)

Question 3

B. carbon fixation, the citric acid cycle, and the electron transport chain

A. glycolysis, the Calvin cycle, and the electron transport chain

The three stages of cellular respiration are ________. (TX Obj 2; 4B, 8C, TX Obj 3; 9D)

Question 3

D. the light-dependent reactions, the citric acid cycle and the electron transport chain

C. glycolysis, the citric acid cycle, and the electron transport chain

The answer is C. The first stage is anaerobic, but the last two stages require oxygen to be completed.

Which of the following yields the greatest net ATP? TX Obj 2; 4B, 8C, TX Obj 3; 9D)

Question 4

D. Cellular respiration

C. Calvin cycle

B. Alcoholic fermentation

A. Lactic acid fermentation

The answer is D. Cellular respiration is far more efficient in ATP production than the fermentation reactions.

Comparison of Fermentation to Cellular RespirationLactic Acid Alcoholic Cellular respiration

glucose

glycolysis (pyruvic acid)

lactic acid

2 ATP

glucose glucose

glycolysis (pyruvic acid) glycolysis (pyruvic acid)

carbon dioxide

alcohol

2 ATP 38 ATP

water

carbon dioxide