Concepts of Biology Test 1

Some questions fall outside the realm of science. Which of the following questions could NOT be answered using the scientific method?

Why is it unethical to test newly developed drugs in animals?

A factory with an office that controls the information sent to separate rooms for each of the manufacturing and shipping processes would be analogous to

a eukaryotic cell with a nucleus.

When scientists generate a single informed, logical, and plausible explanation for a question and observations of the natural world, they are proposing a scientific

hypothesis.

The Golgi apparatus

sorts proteins and lipids and sends them to their final destination.

Nitrogen has seven protons, seven neutrons, and seven electrons. What is the atomic mass of nitrogen?

14

Chemists often represent the structure of atoms using p, n, and e to indicate the number of protons, neutrons, and electrons. Which atom would have an atomic weight of 30?

15 p, 15 n, 15 e

The hypothesis that a common ancestor gave rise to all living organisms is strengthened by what observation?

Almost all cells in all living organisms use DNA to direct their structure, function, and behavior.

Some antibiotics used to treat bacterial infections kill the bacteria by chemically punching holes in the cell wall of the bacteria, by preventing the bacteria from replicating their DNA, or by many other actions that ultimately cause cell death. Why do these antibiotics not work to kill viruses and cure people of viral infections?

Antibiotics cannot kill a virus because viruses are not living cells with cell walls to puncture, nor do they have their own organelles to replicate DNA.

Which of the following would be a fact?

Bats with white noses have been observed in the wild.

Which of the following statements most accurately describes a selectively permeable membrane?

Certain solutes move freely across the membrane by simple diffusion while others must be helped across by active or passive transport proteins; some substances are completely excluded from crossing the membrane.

Recently, beekeepers have noticed an alarming and sudden disappearance of honeybees from their hives. Some beekeepers and environmentalists worry that crops genetically engineered to contain the gene for the Bt insecticidal toxin may be killing the bees. Which of these experiments tests the hypothesis that Bt is killing the bees?

Collecting hundreds of bees. Half of the bees would be kept in a facility with plants genetically engineered to contain the gene for Bt toxin while the other half would be kept in a facility with plants not genetically engineered to contain the gene for Bt toxin. The survival rate for both sets of bees would be calculated and compared.

O2, also termed atmospheric oxygen, is considered to be a molecule but not a compound. Why not?

Compounds are defined as molecules constructed from two or more different elements.

1.Which of the following is/are part of accepted cell theory?

Every living organism is composed of one or more cells, and all living cells arise from preexisting cells.

David Blehert and his research team captured 117 healthy bats to study in the laboratory and divided them into 4 groups. Group 1 was housed in an area free from Geomyces destructans. Group 2 was housed in an area that shared the same air as bats infected with WNS, but they did not have direct contact with the infected bats. Group 3 was housed in direct contact with other bats infected with WNS. Group 4 was directly exposed to Geomyces destructans when it was applied to their wings. During the study period the bats were monitored for signs of WNS. What is the specific hypothesis being tested by the inclusion of group 4 in this experiment?

Geomyces destructans causes WNS, and it can be transmitted by direct contact with the fungus; no contact with infected bats is needed for transmission of the fungus.

You are a microbiologist working with a species of bacteria that can perform photosynthesis. You know that the enzymes needed to perform photosynthesis in plant cells are closely associated with the membranes in chloroplasts. Where in the bacteria would you expect to find the enzymes needed to perform photosynthesis?

I would expect to find the photosynthetic enzymes associated with the plasma membrane of the bacteria.

A scientific hypothesis must be constructed with which of the following characteristics?

It provides a reasonable explanation to a question and is consistent with current observations; it must also be testable and falsifiable.

From what substance do liposomes spontaneously form and why are they important?

Liposomes form from phospholipid bilayers and provide a barrier between an external environment and an internal environment; this creates an internal environment where specific chemical reactions needed to establish a living cell can occur separately from the external environment.

Victoria, who is 10 years old, wants to be a zoologist when she grows up because she loves animals. So, she decided to begin her training by "doing something scientific." Specifically, she weighed and measured the lengths of all the earthworms she could find in her yard and recorded the data in a notebook. She then made a graph showing the maximum, minimum, and average weights and heights of the earthworms. Was she doing something scientific?

No, because she had no hypothesis to direct her data collection or interpretation.

Recently, beekeepers have noticed an alarming and sudden disappearance of honeybees from their hives. Some beekeepers and environmentalists worry that crops genetically engineered to contain the gene for the Bt insecticidal toxin may be killing the bees. Without data from a scientific experiment, is it reasonable to state that Bt-containing crops are responsible for the loss of honeybees?

No, because there could be some other unknown or unmentioned factor affecting the survival of honeybees.

Prokaryotes and eukaryotes are primarily distinguished by the absence or presence of internal membrane- enclosed organelles. Are prokaryotic cells at an evolutionary disadvantage because they lack organelles?

No; although prokaryotic cells are comparatively less efficient than eukaryotic cells, they are still able to carry out the processes necessary for survival and reproduction.

Scientific understanding can always be challenged, and even changed, with new ways of observing and with different interpretations. For example, new tools and techniques have resulted in new observations and the discovery of additional information. This has resulted in revised ways of understanding how molecules are moved across the plasma membrane of cells. Hence, there is no certainty in science, only degrees of probability (likelihood) and potential for change. In light of this understanding, which of the following statements is most meaningful?

Scientific knowledge is necessarily contingent knowledge.

Which of the following questions could NOT be used to develop a testable hypothesis?

Should everyone drink bottled water only?

Which of the following would be a theory?

Specific pathogens are directly responsible for specific diseases and conditions.

Dialysis tubing is a selectively permeable membrane that can be filled with a solution to simulate a cell. A piece of dialysis tubing has been filled with a cloudy white solution of 5 percent starch, 5 percent egg albumin (protein), and 5 percent glucose (a small sugar) dissolved in water to simulate a cell. This cell is weighed and then placed in a beaker of 3 percent iodine dissolved in water. When iodine and starch are mixed together, they form a bluish-black compound that is easily seen. After soaking in the yellow iodine-water solution for one hour, the cell is once again weighed. You also notice that the solution inside of the cell is now a dark blue color while the solution in the beaker is still a light yellow color from the iodine. What do you expect to happen to the weight of the cell over time and what can you deduce from the color change?

The cell should gain weight over time because it is hypertonic to the beaker environment and water will enter the cell through osmosis. The color change indicates that the iodine molecules were small enough to diffuse across the membrane and react with the starch inside the cell. No color change in the beaker tells us that the starch was too large to cross the membrane from the cell and into the beaker.

An experiment mixed together oil (lipids), organophosphate-containing detergent in water, and copper ions to act as a catalyst for a chemical reaction. Membranes budded off of the oil in this mixture. Which of the following is a reasonable and possible explanation of the experimental results?

The chemical reaction caused the organophosphates from the detergent to chemically combine with lipids from the oil to form phospholipids with hydrophilic heads and hydrophobic tails. The hydrophobic tails lined up towards each other with their hydrophilic heads pointing out towards the water; this configuration formed a phospholipid bilayer that pulled into a spherical liposome.

How many atoms are present in a single molecule of C8H10N4O2?

The chemical reaction that represents photosynthesis is 6 H2O + 6 CO2 → C6H12O6 + 6 O2. What are the reactants?

A group of researchers conducted an experiment and collected the data presented in this graph. Which of the following statements are supported by the information in this graph?

The hypothesis was supported because all members of the control group survived while most of the members of both treatment groups died by the end of the study.

David Blehert and his research team captured 117 healthy bats to study in the laboratory and divided them into 4 groups. Group 1 was housed in an area free from Geomyces destructans. Group 2 was housed in an area that shared the same air as bats infected with WNS, but they did not have direct contact with the infected bats. Group 3 was housed in direct contact with other bats infected with WNS. Group 4 was directly exposed to Geomyces destructans when it was applied to their wings. During the study period the bats were monitored for signs of WNS. What were the independent and dependent variables in this experiment?

The independent variable was the type of exposure to Geomyces destructans. The dependent variable was whether or not the bats became sick with WNS.

Compare and contrast the nuclear envelope and the plasma membrane.

The nuclear envelope consists of two concentric phospholipid bilayers while the plasma membrane is only one phospholipid bilayer. Both membranes are selectively permeable and have pores.

You buy a bunch of small, round, red radishes at the grocery store; they are on sale because they have been sitting in the produce aisle for a while. When you get home you remove the stems and clean them. With the first bite, you notice their texture is not as crisp and crunchy as you like. Your friend says you should refrigerate them in a bowl of water overnight. The next day the radishes are crisp and crunchy again. What is the most likely explanation of why they became crunchy again after soaking in water?

The radish cells were hypertonic to the water in which they were soaking. So, the water moved by osmosis across the plasma membranes into the radish cells increasing the turgor pressure inside of the cells and making them crunchier.

You are in lab attempting to prepare a slide of cow blood for observation in a wet mount. You place a small drop of the blood on a slide, add a drop of strong saline (salt) solution, and then cover all of it with a coverslip. After returning to your desk, you observe the slide with your microscope and notice that all of the red blood cells (RBCs) do not look like the nice round donut shaped cells in your lab manual. Instead, the RBCs look very shriveled up. Your lab partner has also made a slide, but the RBCs on their slide do look like the ones in the lab manual; your lab partner used a more dilute solution of saline but the same vial of blood. What is the most plausible explanation for the appearance of the blood cells on your slide?

The saline you used was hypertonic to the RBCs; this resulted in water osmosing through the RBC plasma membrane mostly out of the cell.

Which of the following statements is true?

The scientific method or process can help people make informed medical and environmental decisions.

Examine the figure below. If each sugar molecule represents a percentage point of sugar dissolved in the solution, what change would you expect to see in the solution level over time and why?

The solution level on the left side of the figure would rise while the solution level on the right side of the figure would decrease. This is because the solution on the left side of the figure is hypertonic while the solution on the right side of the figure is hypotonic.

If the concentration of sugar molecules in water on side "A" of a selectively permeable membrane is 5 percent, and the concentration of sugar molecules in water on side "B" of a selectively permeable membrane is 15 percent, which way will the water move and why?

The water will mostly move from side "A" to side "B" because the water concentration is higher on side "A."

A researcher wanted to determine if consuming diet sodas causes diabetes. He conducted a study in which subjects were asked to recall how many diet sodas they drank each day, on average; the subjects' blood sugar levels were then measured. The average blood sugar levels were determined in the test subjects. Each group included an equal number of male and female participants and the groups were standardized for average weight and age. Which of these statements most accurately describes what is seen in the graph?

There appears to be a positive correlation between the number of diet sodas consumed each day and the average blood sugar levels measured in mmol/L. However, no definite cause-effect relationship has been established.

Examine the figure below. If each sugar molecule represents a percentage point of sugar dissolved in the solution, what change would you expect to see in the solution level over time and why?

There will be no net movement of water because the solutions are isotonic.

A species of butterflies gradually becomes darker in color over many generations; this is an example of which characteristic of living organisms?

They can evolve as groups.

Which of the following statements is true of chloroplasts?

They capture energy from sunlight.

Why would hydrophilic substances such as sodium ions (Na+ ), hydrogen ions (H+ ), sugars, and amino acids be unable to simply diffuse across a plasma membrane?

They do not readily mix with the hydrophobic tails forming the core of the phospholipid bilayer; therefore, they must move across by facilitated diffusion.

What characteristic is NOT shared by all organisms?

They make their own energy.

Why do scientists repeat their experiments over and over again?

They must make sure the results were not an accident and that they are repeatable.

The roots of a sunflower plant growing downwards while the shoot grows upwards and the flower turns towards the sun are examples of what characteristic of all living organisms?

They sense the environment and respond to it.

Which of the following help increase the selective permeability of a phospholipid bilayer membrane?

Transport proteins, channel proteins, and passive carrier proteins all help increase the selective permeability of a phospholipid bilayer membrane.

Which of the following can be used to accurately describe viruses?

Typically just a piece of genetic material encased in proteins, viruses are small, non- cellular infectious agents that are only capable of reproducing when inside a living cell such as those of plants, animals, fungi, protozoans, or bacteria.

Is it possible for scientists to study events that happened or animals/plants that lived millions of years ago?

Yes. Apply the laws of physics and nature that we know exist today to evaluate the evidence of past events. For example, observe modern animal behavior, structure, and function, and compare them to the structures of fossilized animals to deduce the function of the fossilized structures.

Is it important for scientists to communicate their results to fellow scientists?

Yes. The quality and accuracy of the scientific work can be enhanced by input, further review, and possibly even repetition by other scientists working in the same field.

You are coughing and producing a wheezing sound as you breathe; you also have a fever. You go to the doctor who listens to your chest, takes X-rays of your chest, and determines that you probably have something called croup. Which of the following are the facts in this scenario?

You are coughing, wheezing, and have a fever.

A long piece of ribbon wired along both long edges is twisted into a helix and wrapped around individual pipe cleaners that have been rolled into spools; this grouping is then twisted (super coiled) again to condense it. This could be best used as a simple model for

a chromosome, where the pipe cleaners represent bundles of proteins around which the DNA double helix (wired ribbon) is wrapped.

A tissue is defined as

a group of cells that performs a unique set of tasks in the body.

Which of the following would be the best analogy for the function of the Golgi apparatus?

a worker in a factory who places labels on products and then packs them into a shipping box

Which of the following would be likely to move through a plasma membrane by simple diffusion?

a. water (H2O), carbon dioxide (CO2), oxygen (O2)

Bats use echolocation to orient themselves and locate objects. Doing this requires special adaptations in their inner ear, midbrain, and auditory cortex of their cerebrum. The echolocation system of bats is an example of

an organ system.

Which of the following types of organisms are commonly single-celled (unicellular)?

bacteria, some fungi (yeast), and many protozoans

Experimental studies are an effective way of establishing a ________ relationship between two or more aspects of the natural world because they provide a way of testing predicted interaction(s).

cause-effect

Observational studies typically point out correlations between aspects of the natural world, but they do not establish solid ________ relationships.

cause-effect

Which of the following sequences correctly represents the biological hierarchy of a multicellular organism?

cells → tissues → organs → individual

Which of the following represents conducting an experiment?

dialing a telephone number

The caves in upstate New York, where Alan Hicks' team first noticed the deaths of thousands of bats, represent the

ecosystem where the bats lived.

The subatomic particles that possess a single negative charge and surround the nucleus are the

electrons.

Carbon, hydrogen, and nitrogen are all examples of

elements.

Using the compound light microscope in the lab room, you observe a wet mount slide preparation. You observe layers of cells that have a definite, rigid, rectangular shape; there appears to be a nucleus in all of the cells and there are many oval-shaped green structures that seem to be moving around inside of the cells in an orderly fashion. What general cell type are you most likely observing?

eukaryotic and plant

The human heart pumps blood throughout the blood vessels in the body. This is a scientific

fact.

In 1890, Robert Koch developed a hypothesis regarding the cause of communicable diseases. He designed an experiment and collected data that supported his hypothesis. Later, his experiment was repeated by many other scientists who used other pathogens and documented similar results that not only supported their hypotheses but also supported Koch's original hypothesis. These many experiments that supported multiple hypotheses regarding the cause of communicable diseases contributed to the development of the

germ theory of disease.

David Blehert and his research team captured 117 healthy bats to study in the laboratory and divided them into four groups. Group 1 was housed in an area free from Geomyces destructans. Group 2 was housed in an area that shared the same air as bats infected with WNS, but they did not have direct contact with the infected bats. Group 3 was housed in direct contact with other bats infected with WNS. Group 4 was directly exposed to Geomyces destructans when it was applied to their wings. During the study period the bats were monitored for signs of WNS. Which group is the control group?

group 1

Living organisms maintain a constant internal environment by sensing and responding to their internal conditions. This stable maintenance of internal conditions is known as:

homeostasis.

Phospholipids are large organic molecules with a ________, polar phosphate head connected to ________, nonpolar fatty acid tails. How do these molecules arrange themselves to form a mostly impermeable barrier between a liposome and its environment?

hydrophilic; hydrophobic; They line up hydrophobic tails facing each other at the center line of the membrane with the hydrophilic heads facing outward, away from the center line of the membrane.

You often experience numbness and pain in the thumb and first two fingers on your right hand. You go to the doctor who suspects that carpal tunnel syndrome is the reason for the numbness and pain. The doctor then orders a simple test to see how fast nerve impulses are moving up and down your arm. The doctor's preliminary diagnosis of carpal tunnel syndrome is a(n)

hypothesis.

New medications undergo extensive human testing before receiving FDA approval. These tests represent an experiment and variations in the dosage given to participants represents the

independent variable.

The smooth endoplasmic reticulum

is the site where lipids destined for other cellular compartments are manufactured.

DNA is one of the features common to all known forms of life;

it is the blueprint that guides the growth, development, behavior, and reproduction of all organisms.

Your muscle cells need large amounts of ATP to function in the movement of your body. Which of the following organelles would you expect to be especially abundant in muscle cells?

mitochondria

The boundary that surrounds the contents of the nucleus is the

nuclear envelope.

Adenine (A), thymine (T), guanine (G), and cytosine (C) are the ________ building blocks for DNA; they are organized in different combinations to code for all of the proteins needed to accomplish everything the cell does.

nucleotide

During the process of ________, water diffuses across a semipermeable membrane from an area where water is more concentrated to an area where water is less concentrated (it moves along the water concentration gradient).

osmosis

Cells naturally, without using energy, respond to changes in water concentration through the process of

osmosis.

The leaves of a plant typically have different tissue layers that function in different ways. The epidermis layer functions like a covering of skin to protect the leaf while vascular bundles carry water and nutrients through the leaf. The palisade mesophyll layer is responsible for most of the photosynthesis that occurs while the spongy mesophyll layer underneath it aids in the exchange of gases (CO2 and O2) and water vapor. In which leaf tissues would you expect to find the highest density of chloroplasts?

palisade mesophyll

Scientists are human beings and are, like all human beings, susceptible to personal and group biases that may influence how they interpret evidence. Before original research work is accepted and added to a growing body of scientific understanding, perhaps even contributing to our understanding of an important scientific theory, it must be scrutinized by experts in the field who have no direct connection to the research under review. The main mechanism for doing this is

peer-reviewed publications.

A white blood cell (WBC) encounters bacteria in a scrape on the knee of a child who has fallen off of his bicycle. The WBC's job is to take the bacteria inside of itself and destroy the bacteria. If the bacteria cannot be moved across the WBC membrane, how will the WBC most likely take it in?

phagocytosis

An amoeba, a protozoan that moves by pseudopodia, approaches a smaller protozoan and extends its pseudopodia (extensions of cytoplasm in plasma membrane) around the smaller protozoan. Once the amoeba's pseudopodia completely surrounds the other protozoan, the amoeba's plasma membrane pinches off by folding back into the amoeba and creating a vesicle containing the smaller protozoan. This vesicle is now within the amoeba itself and will soon fuse with other vesicles containing digestive enzymes. This is an example of

phagocytosis.

Living cells have an intact phospholipid bilayer that separates the cell from its external environment; this structure is commonly referred to as the

plasma membrane.

Experimentation is the primary, but not only, means used to verify or refute the ________ made by a hypothesis.

predictions

Ribosomes are very small nonmembranous organelles that can either exist freely in the cytoplasm or be embedded in the endoplasmic reticulum of a cell; they are associated with the synthesis of

proteins.

The plasma membrane of some white blood cells contain ________ that bind with proteins of cells such as bacteria that have invaded the human body. These special proteins tell the white blood cells those bacterial cells do not belong to that particular human and to phagocytize (eat) them.

receptor proteins

A protein molecule, transferrin, embedded in the plasma membrane recognizes iron molecules and causes the plasma membrane to fold in around the iron and take it into the cell. This is an example of

receptor-mediated endocytosis.

Which of these characteristics of living organisms are present in viruses?

reproduce using DNA (or RNA); sense their environment and respond to it; can evolve as groups

You are a scientist observing a membrane through which water and some small hydrophobic molecules can freely pass along a concentration gradient from high to low. However, some sugar molecules are too large to pass through the membrane either way without the assistance of passive transport proteins. Additionally, small Na+ ions and some proteins can pass through the membrane against the concentration gradient, but both require the assistance of active transport proteins. What general type of membrane are you observing?

semipermeable

If a bottle of perfume were spilled in the corner of a large lecture hall, the students sitting near that corner of the room would very quickly smell the perfume. Over time, the students sitting in the far corner of the room would smell the perfume. What phenomenon has occurred to the perfume molecules that have entered the air?

simple diffusion

Which of the following would be likely to require facilitated diffusion to move across the plasma membrane?

sodium ions (Na+ ), hydrogen ions (H+ ), sugars, and amino acids

Once supported by a predictable experimental outcome, a scientific hypothesis

still cannot be considered to have been proven true.

A scientific hypothesis must be ________; if not, science cannot evaluate it.

testable

Many important cellular functions in eukaryotic cells occur within membrane-enclosed organelles, such as cellular respiration occurring within the mitochondria. The membranes of the mitochondria provide a place for enzymes needed for cellular respiration to anchor and function. Prokaryotic cells must also carry out respiration but do not have mitochondria. Where is the most likely place that enzymes needed for cellular respiration are anchored and functioning?

the plasma membrane

A screen door allows breezes to enter and aromas to exit but keeps out insects. Its function most resembles

the plasma membrane.

In science, when a hypothesis or group of hypotheses supported by repeated experimental evidence holds true through time, it can be developed into a ________. It is not a guess. It is not static. It is tentative and dynamic and can be adjusted when new, compelling evidence is discovered. It is typically an overarching explanation that best fits all of the available information or evidence.

theory

Whenever we ________, we are proceeding scientifically.

try to solve a problem by systematically evaluating the plausibility of various solutions