Practice Test Questions

A student poses the question: How does the presence of dissolved salt affect the freezing point of water? To answer this question, the student set up two conditions. In the first condition, the student added salt to water in a container and referred to this condition as the variable. In the second condition, the student did not add any salt to water in a second container and referred to this condition as the control. The student took both containers and attempted to freeze the water at various temperatures to assess the freezing point. Would this be a valid experiment?

Yes, because there is one variable and a control

A scientific theory is:

a concept that is supported by experimental evidence that explains the facts in an area of study.

The covalent bonds connecting monomer units in sugars can be formed by the removal of a water molecule. This reaction is referred to as:

a dehydration reaction

If water were non-polar it would not form hydrogen bonds. At normal room temperatures this non-polar water would be _____.

a gas

It is known that many trees lose their leaves in response to decreasing day length. As a result, you think that Gingko trees may also lose their leaves in response to decreasing day length. This statement is an example of:

a hypothesis

Multiple independent experiments have demonstrated that phytochrome helps trigger seasonal change responses in the plant such as changing color and loosening of leaves. Plants have the ability adapt to seasonal changes in their surroundings. This statement is an example of:

a theory

If you were to design a long-term research study to determine why there are no human births in Lapland during the months of August, September, and October, you would need to also examine a comparison population of humans in which births took place every month. The primary reason for including a comparison population within the design of this experiment would be to:

act as a control that would ensure that the results obtained are due to a difference in only one variable

The peptidoglycan of bacterial cell walls contains a carbohydrate matrix linked together by short chains of:

amino acids

Plants are raised under artificial lights turned off and on by an electric clock. Some are given long periods of light, others short periods. This is an example of:

an experiment

After taking your biology exam, you return to your car only to find that you had left the lights on and now the car battery is dead. Your friend offers to jump-start your car, but when you go to hook up the jumper cables you find that the battery terminals are covered with corrosion due to battery acid condensation. Based off your knowledge, what substance could be used to clean the corrosion?

baking soda (pH of 9)

A team of researchers is studying the external structures on the dorsal (back) surface of a spider mite. The spider mite seems to be the habitat of an even smaller mite, which is approximately 0.05mm. While they can see the dorsal surface of the spider mite with their naked eye, they cannot see the mite clearly. The researchers are writing a grant to provide support for a microscope to use to study these new mites. They need to purchase a microscope with a high magnification to observe the new mites on their habitat. Based on the information given, what type of microscope would you suggest?

binocular compound light microscope

When looking at plant and animal cells with an electron microscope, you notice that the plant cells have more Golgi membranes than the animal cells. This is most likely because unlike in animal cells, in plant cells the Golgi apparatus is involved in the production of:

cell walls

What polysaccharide forms the long, tough fibers found in plant cell walls?

cellulose

Humans are unable to get metabolic energy from cellulose because:

cellulose digesting enzymes are absent from the human gut.

The distinctive feature of chloroplasts is that they contain a green pigment called:

chlorophyll

The semi-fluid matrix that surrounds organelles in a cell is called the

cytoplasm

Gingko trees are known to lose their leaves at a certain time each year throughout the United States. Based on this information, Gingko trees in China must behave the same way. These statements are an example of:

deductive reasoning

Luke went to a pediatrician when he was 6 months old. The pediatrician consulted a graph and concluded that Luke was in the 97th percentile for height, weight and length. The pediatrician predicted that Luke would be tall when he reached adulthood. What type of logic is being used when the pediatrician uses the graph to make conclusions about Luke's progress?

deductive reasoning

Your microwave will not turn on, and you speculate that a circuit breaker in the house has been tripped. In scientific terminology, the steps would be described as:

developing a hypothesis based on an observation.

A dish of cells is treated with centrinone, a centriole inhibitor. These cells would no longer be able to ___.

divide

Two oxygen atoms joined to each other by the sharing of two pairs of electrons form a(n):

double covalent bond

When a vesicle moves along microtubules toward the center of the cell, the molecular motor(s) _____ are used?

dynein

Organic molecules have a carbon backbone and _____ such as -OH and -NH2 that affect their chemical properties.

functional groups

A monosaccharide that plays an important role in energy storage is a six-carbon sugar called:

glucose

Nitrogen has a higher electronegativity than hydrogen. As a result you would expect that ammonia (NH3) molecules can form ____ with each other.

hydrogen bonds

Sue was monitoring the oil spill into the Gulf of Mexico from an oil tanker. From her observations, she noted that the oil was moving as large patches in the water. It did not appear as though the oil was dissolving into the water. Why did the oil not dissolve into the water?

hydrophobic interactions

A suggested explanation that might be true and is subject to testing by further observations is a(n):

hypothesis

A yellow jacket, an insect in the order Hymenoptera, stung me. A wasp, an insect in Hymenoptera, stung me. A hornet, an insect in Hymenoptera, stung me. I see a pattern. All insects in this order must have stingers. What type of reasoning does this represent?

inductive reasoning

Both walnut and Gingko trees lose their leaves in the fall when day length starts decreasing. Based on these observations one may conclude that many tree species will lose their leaves in the fall in response to decreasing day length. This statement is an example of:

inductive reasoning

Luke went to a pediatrician when he was 6 months old. The pediatrician consulted a graph and concluded that Luke was in the 97th percentile for height, weight and length. The pediatrician predicted that Luke would be tall when he reached adulthood. What type of reasoning did the pediatrician use to generate her prediction about Luke's future growth in height?

inductive reasoning

The method of reasoning that uses construction of general principles by careful examination of many specific cases is called:

inductive reasoning

In the crystal matrix of ordinary salt, the sodium and chlorine are held together by:

ionic bonds

Atoms of a single element that possess different numbers of neutrons are called:

isotopes

Carbohydrates are polymers formed of structural units called:

monosaccharides

You arrive late to a biological seminar. However, just as you enter the room, you hear the speaker referring to the "five-prime end" and the "three-prime end" of a macromolecule. Immediately, you know that they are talking about a:

nucleic acid

The "X" shaped chromosomal hereditary material can be packaged in this organelle in eukaryotic cells but not in prokaryotic cells. This organelle is the:

nucleus

Karl Popper suggested that scientists use "imaginative preconception," which means that successful scientists:

often predict the outcome of experiments.

The area around a nucleus where an electron is most likely to be found is the:

orbital

The reaction (H2 + F2 → 2HF) is an example of a redox reaction. In reality, two half reactions are occurring. The half reaction (H2 → 2H+ + 2e-) is a(n):

oxidation reaction

Oxygen-16 is abundant and has 8 protons and 8 neutrons. Oxygen-18 has two extra neutrons. These two forms are:

oxygen isotopes.

Denaturation disrupts the secondary and tertiary structure of proteins. However, denaturation is not strong enough to disrupt what interaction that is relevant to protein structure?

peptide bonds

A polymer with the sequence 5' ACGTACGAATAG 3' is a:

piece of DNA

Because oxygen is more electronegative than hydrogen, the water molecule is:

polar

Amino acids are linked together by peptide bonds in a ____

polypeptide

The specific amino acid sequence of a protein is its ____.

primary structure

The digestive enzyme pepsin works in the acidic environment of the stomach to hydrolyze peptide bonds. As a result, pepsin affects which macromolecule?

protein

You label cells with a radioactive isotope of sulfur (35S). The only molecules that would be radioactively labeled in these cells are:

proteins

Based on the literature, you hypothesize that students in traditional biology lectures will have the same grades as students in online biology lectures. You decide to test your hypothesis by comparing grades of students in traditional and online biology lectures over a semester. As a result of the experiment, you observe that the grades in the traditional lectures and the grades in the online lectures are not significantly different. What do these observations allow you to do?

reject the null hypotheses

Given what is known about the minimal essential functions of cellular life, if you could create an artificial cell, what cellular structures must you include?

ribosomes

All atoms tend to fill their outer energy levels with the maximum number of electrons, usually eight. Depending on whether atoms satisfy the octet rule will predict:

the chemical behavior of the atoms.

Fructose and galactose both have six carbon atoms, twelve hydrogen atoms and six oxygen atoms, just like glucose. A friend of yours says: "Since those sugars have the same number of atoms, they should have the same name." You answer: "While they do have the same number and type of atoms,

they are named differently because they are alternate forms of the monosaccharide, glucose."

A nucleic acid contains thymine, allowing you to conclude that:

this nucleic acid is DNA.

A nucleic acid contains uracil, allowing you to conclude that:

this nucleic acid is RNA.

α - glucose is present in potatoes and β - glucose is present in wood. Both are glucose molecules but one can be used by humans to synthesize ATP and one cannot. Based on this information, what is the best explanation on why humans can only digest one of the glucose types?

α - glucose and β - glucose are stereoisomers with OH groups oriented differently.

Dennis had a history of heart disease in his family and was reducing his intake of saturated fats. Saturated means each carbon atom is bonded to as many hydrogen atoms as it can accept. If a carbon were bonded to two carbons, how many hydrogens could it accept?

2

How many hydrogen bonds can a water molecule form?

4

When water ionizes, it produces equal amounts of hydrogen and hydroxide ions that can reassociate with each other. The pH of water is:

7

What is the difference in the bonding between alpha-helix and beta sheets?

Hydrogen bonding occurs between the amides of adjacent chains in the sheets instead of between the amides in different parts of the helices.

Who first described cells?

Robert Hooke

What characteristic would the R groups of amino acids have if they are located within the interior of biological membranes?

The R groups would hydrophobic.

Phospholipids are made up of:

a phosphate, two fatty acids and a glycerol

Proteins are polymers formed of structural units called:

amino acids

Which element's isotope is commonly used to determine when biological samples such as fossils, were formed?

carbon

At the pH of most bodily fluids, which functional group will lose a proton and which functional group will accept a proton?

carboxyl; amino

Experiments are carried out to test a hypothesis by changing one variable at a time and including an unchanged variable termed a(n) _____.

control

When two atoms share a pair of electrons, the bonding is referred to as:

covalent

These biological compounds are non-polar and insoluble in water:

lipids

Biological membranes contain bilayers containing mostly ______.

phospholipids

During which cellular process do all three forms of RNA associate?

protein synthesis

Cl + e- → Cl- is an example of a:

reduction

Three fatty acids bonded together with a glycerol are found in a(n):

triglyceride

The nitrogenous base that is only found in RNA and not DNA is:

uracil

Sodium has 11 electrons arranged in three energy levels. In order to become stable, sodium forms an ion with:

+1 charge.

Regardless of its shape, a given orbital may contain no more than:

2 electrons

A double stranded DNA strand contains 26 pyrimidines. How many purines will the copied strand contain?

26

How many water molecules are produced during the formation of a triglyceride from fatty acids and glycerol?

3

The half-life of Carbon-14 is approximately 5,700 years. Using this information scientists have been able to determine the age of some artifacts left by humans. A scientist wants to know approximately how old a piece of wood was that she found on the floor in an old cave that had recently been discovered. She removed the wood (with permission) to her laboratory. Her wood sample contained 2 grams of Carbon-14. If the age of the wood was determined to be 22,800 years old, how much Carbon-14 originally existed in this piece of wood?

32 grams

An atom has 20 electrons and 20 neutrons. What is the mass of this atom?

40

A chemist adds a chemical to pure water and there is a 100 fold increase in the concentration of hydrogen ions. What is the best approximation of the new pH value?

5

Your dog becomes ill and you rush him to the veterinarian's office. A technician draws blood from your dog's leg for a vet-ordered lab test. After a few minutes the lab results are given to the vet, who immediately grabs a bottle from a shelf and begins to fill a syringe with an unknown fluid. You inquire about the fluid, and the vet informs you that the fluid is necessary to manage your dog's metabolic acidosis. Based on the information provided, what is acidosis, and what is the likely effect of the veterinarian's injection?

Acidosis means that your dog's blood pH has decreased from its normal level, and an injection of buffering solution is required to reverse the condition.

Acyclovir is an antiviral chemical that resembles a nucleotide but lacks a 3' OH group and cannot form phosphodiester bonds. Why is Acyclovir useful in treating some viral infections?

Acyclovir halts viral DNA replication.

To increase the rate of a reaction you could:

Add more reactants.

Sulfolobus are archaea that are commonly found in geothermal environments, with an optimum growth temperature of about 80°C. What feature allows archaea to thrive at such temperatures?

Archaeal membranes contain special lipids.

Consider the following electronegativity values: Boron (B) = 1.8 Carbon (C) = 2.5 Chlorine (Cl) = 3.2 Selenium (Se) = 2.6 Which of the following bonds is the most polar?

B-Cl

You have recently identified a novel protein and obtained its sequence. How could you use this sequence to predict the function of the protein?

By looking for conserved domains.

The formula for glucose is C6H12O6. What is the formula for a polymer made by linking ten glucose molecules together by dehydration synthesis?

C60H102O51

A phosphorus shortage in soil would make it difficult for plants to produce:

DNA

According to most car mechanics, plain water is the best coolant to use in an engine provided the engine is not being exposed to freezing temperatures. If the car is subject to freezing temperatures then a mixture of water and ethylene glycol (antifreeze) is recommended but it does not cool as efficiently as plain water. Why would ethylene glycol reduce the cooling efficiency of water?

Ethylene glycol has a lower heat capacity than water.

How is the bond in F2 different from the bond in KCl?

F2 is covalent and KCl is ionic

Proteins are three dimensional molecules made of strands of amino acids (imagine a ball of string). There are 20 different amino acids used in proteins found in living organisms. Some of these amino acids are polar and others are non-polar. Where would a series of non-polar amino acids most likely be located in a protein that is found in the cytosol of an animal cell?

In the interior of the protein

The pH of your small intestines is around 7.5 and the pH of your large intestine can be 5.5. As substances travel from the small intestines to the large intestine, what would happen to the H+ ion concentration?

It increases by 100 fold.

You recently discovered a new element, and find that this particular element has one electron in its outer energy level. What would you expect will happen to an atom of this element if placed in water?

It will lose an electron forming a positive ion.

Magnesium chloride is a salt formed with ionic bonds between one magnesium ion and two chloride ions. Magnesium has two electrons in its outer shell and chlorine has seven electrons in its outer shell. How are the electrons transferred between these atoms?

Magnesium is oxidized and chlorine is reduced.

The myoglobin protein, which carries oxygen in muscle cells, has only the first three levels of protein structure. What can you infer about myoglobin?

Myoglobin is made of only one polypeptide chain

As you and a friend are entering a chemistry laboratory at your university, you see a sign that states: DANGER—RADIOACTIVE ISOTOPES IN USE. Your friend is an accounting major and has not had any science courses yet. She asks you what a radioactive isotope is and you respond correctly with:

Radioactive isotopes are atoms that are unstable and as a result emit energy in a process called radioactive decay.

The carbonic acid and bicarbonate buffer in blood is extremely important to help maintain homeostasis. What would happen to the pH of the blood if bicarbonate were removed?

Removing bicarbonate from the blood would decrease the pH

Dr. Edward Jenner realized that cows have a disease called cowpox, which is like a disease that infects humans called smallpox; Jenner noticed that milkmaids whose hands were infected with cowpox were not contracting smallpox. Jenner infected a child with the pus from a cowpox blister, and found that the child did not contract smallpox. Which statement represents a supporting hypothesis?

The cowpox infection will prevent the child from being infected by the small pox virus.

Water is most dense and thus heaviest at 4°C. At 0°C, ice forms and can float on liquid water. Suppose ice were most dense at 0°C. What would happen in a lake at this temperature?

The ice would cover the bottom of the aquatic system and would build up in layers over time.

A student set up an experiment to test if plants give off water vapor. Fifty pea plants, growing in pots, were covered with individual glass containers and left overnight. The next morning, the inside of each lid was covered in droplets of water. The lab student concluded that plants generally give off water vapor. What critique would you make of the experimental design?

There was no control so the water could have come from other sources such as air in the jar or the soil.

Vitamin D can be synthesized by the body from a derivative of cholesterol. Given this information, predict vitamin D's solubility.

Vitamin D is fat-soluble.