UMUC Biology 103

An atom is converted into an ion by adding or removing ___________________.
electrons :When electrons are added or removed from an atom, the charge of the atom changes and the atom becomes an ion.
The positive particle in the atom is the …
proton :Protons are positively charged.
How many electrons does a neon atom have in its second shell?
8 :This second and third shells can hold up to 8 electrons.
Which is the biggest?

Proton
Neutron
Atom
Electron

Atom
The negative particle in the atom is the …
electron
What would be the charge of a beryllium atom that has a full outer shell?

+1
no charge
-1
+2

+2
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Fluorine, F, has an atomic number of 9 and an approximate atomic mass of 19. What would be the charge of fluorine that has a full outer shell?

+2
+1
-1
no charge

-1
Negatively charged particles are found where in an atom?

In the nucleus
In a single layer outside the nucleus
In multiple layers outside the nucleus
Both inside and outside the nucleus

In multiple layers outside the nucleus
Beryllium, Be, has an atomic number of 4 and an atomic mass of approximately 9. How many neutrons does a beryllium atom have?

9
5
4
13

5
Beryllium, Be, has an atomic number of 4 and an atomic mass of approximately 9. How many electrons does a beryllium atom have?

5
13
9
4

4
Fluorine, F, has an atomic number of 9 and an approximate atomic mass of 19. How many electrons does a fluorine atom have?

10
28
9
19

9
Two atoms that have the same number of protons but different numbers of neutrons are called…

isomers
isotopes
ions

isotopes
What would be the charge of a neon atom that has a full outer shell?

-1
+2
no charge
+1

no charge
Zinc is abbreviated Zn. What is the atomic mass of zinc?

35
95
65.39
30

65.39
Gold is abbreviated Au.

How many protons does gold have?

79
197
118
276

79
An element has 43 protons and 50 neutrons. What is the atomic number of this element?

93
43
50

43
Neon has an atomic number of 10 and an atomic mass of approximately 20. How many electrons does neon have in its first shell?

2
10
20
8

2
Zinc is abbreviated Zn. How many electrons does zinc have in its first shell?

79
2
197
8

2
An element has 43 protons and 50 neutrons. What is the ATOMIC MASS of this element?

43
50
93

93
Zinc is abbreviated Zn. How many protons does zinc have?

65.39
35
30
95

30
What is the correct molecular formula for caffeine (shown here)?

C8H9N4O2
C3H9N4O2
C3H10N4O2
C8H10N4O2

C8H10N4O2
A covalent chemical bond is one in which:

Electrons are removed from one atom and transferred to another atom so that the two atoms become oppositely charged

Outer shell electrons are shared by two atoms so as to satisfactorily fill the outer electron shells of both.

Outer shell electrons of one atom are transferred to the inner electron shells of another atom.

Protons or neutrons are shared by two atoms so as to satisfy the requirements of both.

Outer shell electrons are shared by two atoms so as to satisfactorily fill the outer electron shells of both.
The lines on the above drawing of caffeine indicate:

Covalent bonds
Hydrogen bonds
Ionic bonds
Polar bonds

Covalent bonds
Which bond is the weakest?

Covalent bonds
Hydrogen bonds
Ionic bonds
All 3 of these bonds are approximately the same strength.

Hydrogen bonds
A double covalent bond is the sharing of a total of how many electrons?

2
4
6
8

4
A shared pair of electrons is called a: _________.

covalent bond
hydrogen bond
ionic bond
polar bond

covalent bond
The partial negative charge at one end of a water molecule is attracted to the partial positive charge of another water molecule. This attraction is called:

a covalent bond
an ionic bond
a hydrogen bond

a hydrogen bond
What do the four elements most abundant in life – carbon, oxygen, hydrogen and nitrogen – have in common?

They are elements produced only in living cells.
Each element exists in only one isotopic form.
They all have the same number of valence electrons.
They all have unpaired electrons in their valence shells.

They all have unpaired electrons in their valence shells.
Weak chemical bonds that form BETWEEN polar molecules are

Covalent bonds
Hydrogen bonds
Ionic bonds
None of these answers are correct.

Hydrogen bonds
What do atoms form when they share electron pairs?

molecules
isotopes
elements

molecules
What determines the number of covalent bonds formed by an atom?

Orbitals found in the atom
Valence shells in the atom
Electrons in the outer valence shell of the atom
Electrons in each orbital of the atom

Electrons in the outer valence shell of the atom
The partial negative charge at one end of a water molecule is attracted to the partial positive charge of another water molecule. This attraction is called:

a covalent bond
a hydrogen bond
an ionic bond

a hydrogen bond
What bond(s) is (are) disrupted in the presence of water?

atomic
ionic
molecular
covalent

ionic
What do the four elements most abundant in life – carbon, oxygen, hydrogen and nitrogen – have in common?

They all have the same number of valence electrons.
They all have unpaired electrons in their valence shells.
They are elements produced only in living cells.
Each element exists in only one isotopic form.

They all have unpaired electrons in their valence shells.
Table salt is composed of Na+ and Cl- to form NaCl. This type of bond is called: _____________.

Polar
Ionic
Hydrogen
Covalent

Ionic
Compare the liquid and solid states of water. Which statement is true?

Liquid water is more dense
Solid water is more dense

Liquid water is more dense
Polar molecules are hydrophilic.

True
False

true
Which of the following statements is true concerning hydrogen bonding and the liquid and solid states of water?

Only liquid water forms hydrogen bonds.
Only solid water forms hydrogen bonds.
Both liquid and solid states of water form hydrogen bonds.

Both liquid and solid states of water form hydrogen bonds.
Which characteristic of water protects fish when a lake freezes?

water is less dense as a solid
cohesion
water as a solvent
All of the these characteristics.

water is less dense as a solid
Detergents are

neither polar nor nonpolar
nonpolar
amphipathic
polar

amphipathic
Which of the following statements is true?

Water moves up a tree in tubes. These tubes must be polar.
Water moves through a tree mainly using the force of gravity.
Non-polar molecules would move up trees in the same way water does.
All of these are true

Water moves up a tree in tubes. These tubes must be polar.
Which of the following molecules is hydrophilic?

butter
olive oil
table salt

table salt
You are able to fill a glass with water so that the water goes above the rim of the glass. What property of water have you observed?

moderates temperature
density
cohesiveness

cohesiveness
You make a cup of tea. What is the solute?

the tea leaves
the tea leaves and water together
the water

the tea leaves
What is the pH of bleach?

very acidic
slightly acidic
slightly basic
very basic

very basic
Solution A has a lower concentration of H+ than solution B. Solution A is

more acidic
more basic
more neutral

more basic
You test soda (pH 2.5) with blue litmus paper. What color would you expect to see?

Yellow
Green
Red
Blue

Red
You test bleach (pH 13) with red litmus paper. What color would you expect to see?

Blue
Yellow
Red
Green

Blue
A small amount of acid is added to a buffered solution. What will happen?

The pH will change very little, if at all. The buffer will accept the hydrogen ions from the added acid, keeping pH constant.
The pH will increase rapidly after acid is added.
The pH will decrease rapidly after acid is added.
The pH will change very little, if at all. The buffer will donate extra hydrogen ions to the solution to keep the pH constan

The pH will decrease rapidly after acid is added.
Which of the following is the strongest base?

baking soda, pH 8.5
stomach acid, pH 1
ammonia, pH 12
black coffee, pH 5
water, pH 7

ammonia, pH 12
What is the pH of lemon juice?

very acidic
slightly acidic
slightly basic
very basic

very acidic
You have a solution that has a pH of 5 and need it to be pH 8. What do you do?

Add a base
Add water
Add an acid

Add a base
The pH of a substance is determined by measuring the ____________ of the substance.

electrical charge
toxicity
hydrogen ions
chemical reactivity

hydrogen ions
A strong base is dripped into a buffered solution. What will happen as a large amount of base is added to the solution?

At first, the pH will not respond much. Then, when the buffering capacity is “used up,” pH will increase rapidly as more base is added until some limit is reached.
At first, the pH will not respond much. Then, when the buffering capacity is “used up,” pH will decrease rapidly as more base is added.
The pH will start to increase as soon as base is added, and will continue to increase until it reaches 14.
The pH will start to decrease as soon as base is added, and will continue to decrease until it reaches 0.

At first, the pH will not respond much. Then, when the buffering capacity is “used up,” pH will increase rapidly as more base is added until some limit is reached.
Buffers do all of the following EXCEPT:

Help organisms maintain homeostasis.
Donate (provide) hydrogen ions to the solution when an base is added to the solution.
Make a solution strongly acidic
Absorb excess hydrogen ions when an acid is added to a solution.
Maintain a stable pH within a solution.

Make a solution strongly acidic
Solution A has a lower concentration of H+ than solution B. Solution A is

more neutral
more acidic
more basic

more basic
The pH of a substance is determined by measuring the ____________ of the substance.

chemical reactivity
toxicity
electrical charge
hydrogen ions

hydrogen ions
You test soda (pH 2.5) with blue litmus paper. What color would you expect to see?

Green
Yellow
Red
Blue

Red
A solution with a pH of 4 has how many H+ ions compared to a solution with a pH of 6?

1000 times less
100 times more
two thirds as many
1000 times more
100 times less

not 1000 times more or 100 times less
You have a solution that has a pH of 5 and need it to be pH 8. What do you do?

Add water
Add an acid
Add a base

Add a base
Solution A has a higher concentration of H+ than solution B. Solution A is

more acidic
more basic
more neutral

more acidic
pH is a measure of

toxicity
hydrogen ions
chemical reactivity
electrical charge

hydrogen ions
You have a solution that has a pH of 8 and need it to be pH 5. What do you do?

Add a base
Add an acid
Add water

Add an acid
Fluorine, F, has an atomic number of 9 and an approximate atomic mass of 19. How many neutrons does a fluorine atom have?

9
28
10
19

10
Neon has an atomic number of 10 and an atomic mass of approximately 20. How many protons does an atom of neon have?

30
5
10
20

10
What is the monomer that is used to build proteins?

Amino acids
Monosaccharides
Fatty acids
Nucleotides

Amino acids
Complete the sentence: All organic molecules contain ____________.

carbon
oxygen
nitrogen
all of these are true

carbon
Which of these molecules is not organic? Select all that apply.

Water
Fatty acid
Caffeine
Silica dioxide: quartz
Styrene

Silica dioxide: quartz
Which of the following are functions of carbohydrates? Select all that apply.

Energy storage
Structure
Cell recognition
Cell signaling
None of these choices

Energy storage
Structure
Cell recognition
Cell signaling
What do starch and cellulose have in common? Select all that apply.

They both have the same linear structure.
They both have the same function
They are both made of glucose subunits.
They are both made by plants.

They are both made of glucose subunits.
They both have the same linear structure.
Which of the following is the smallest?

Ribose
Lactose
Starch
Sucrose

Ribose
What type of molecule is shown here?

Amino acid
Carbohydrate
Nucleotide
Lipid

Carbohydrate
This carbohydrate is produced by animals for energy storage

Cellulose
Glycogen
Chitin
Starch

Glycogen
Which polysaccharide is most similar to chitin?

Glycogen
Starch
Cellulose
Glucose

Cellulose
What characteristic of carbon makes it a good backbone for creating diverse and durable molecules?

Carbon is a large atom.
Carbon forms four covalent bonds.
Carbon forms hydrogen bonds.
All of these are true.

Carbon forms four covalent bonds
Which of the following is characterized as dietary fiber?

Sucrose
Cellulose
Glycogen
Starch

Cellulose
Which of the following is characteristic of carbohydrates?

Carbohydrates are hydrophobic and have the general formula CH2O.
Carbohydrates are hydrophilic and have the general formula CH2O.
Carbohydrates are hydrophobic and have the general formula CHO.
Carbohydrates are hydrophilic and have the general formula CHO.

Carbohydrates are hydrophilic and have the general formula CH2O.
What is this structure?

cholesterol
saturated fatty acid
unsaturated fatty acid
phospholipid
triglyceride

triglyceride
What is the name of this structure?

unsaturated fatty acid
phospholipid
cholesterol
triglyceride
saturated fatty acid

cholesterol
Which of the following are functions of steroids? Select all that apply.

communication
maintain membrane fluidity
precursors to vitamins
enzymes

communication
maintain membrane fluidity
How many glycerols in a triglyceride?

1
2
3
4

1
What type of lipid is shown here?

Steroid
Fatty acid
Triglyceride
Phospholipid

Steroid
Which lipid is mainly used for energy storage?

phospholipids
steroids
triglycerides
waxes

triglycerides
Which characteristic of trans fats has been linked to an increased risk of heart diseases?

They increase the levels of both HDL and LDL
They increase the levels of LDL
They increase the levels of HDL

They increase the levels of LDL
Which type of lipoprotein is carried to the liver for processing?

LDL
HDL
Both of these

HDL
Which part of the lipid shown is hydrophilic?

The red circle
The entire phospholipid is hydrophobic
The entire phospholipid is hydrophilic
The blue lines

The red circle
Which molecule makes up the bulk of a cell’s membrane?

Polysachharides
Proteins
Phospholipid
Monosaccharides

Phospholipid
Which lipids have fused carbon rings?

Phospholipids
Triglycerides
Steroids
Waxes

Steroids
What type of molecule is shown here?

Carbohydrate
Nucleic Acid
Protein
Lipid

Lipid
Which lipids have 2 long hydrocarbon chains linked by an ester group?

Phospholipids
Triglycerides
Waxes
Steroids

Waxes
Which lipid provides a water protective layer on the surface of some animals and plants?

triglycerides
waxes
phospholipids
steroids

waxes
Which molecule makes up the bulk of a cell’s membrane?

Polysachharides
Monosaccharides
Proteins
Phospholipid

Phospholipid
Where do peptide bonds form?

Between amino acids of two different protein chains.
Between adjacent amino groups on amino acids.
Between adjacent carboxyl groups on amino acids.
Between the carboxyl group of one amino acid and the amino group of another amino acid.

Between the carboxyl group of one amino acid and the amino group of another amino acid.
The amino acid valine is shown with its sidechain atoms highlighted in yellow. Do you think this amino acid is hydrophilic or hydrophobic?
hydrophobic (non-polar)
The following shows the dipeptide alanine-serine. Four atoms are labeled. Which atom is part of the peptide bond that joins the two amino acids?

Atom A
Atom B
Atom C
Atom D

Atom B between the o and the n right in the middle
The sequence and folded form of three different proteins are shown below. Although the sequences are different, the folded structures are the same (S shaped).

Which of the following three structures will be the least stable (white=polar sidechains, black=non-polar sidechains).

protein A
protein B
protein C

protein C wwwwbwbbwwww
Which of the following diagrams represents the correct structure of a protein? Each blue-gray-red box represents an amino acid.
a bgr bgr bgr bgr bgr bgr
* * *
Which of the following changes when a protein denatures?

Length of the entire protein
Amino acid sequence
Three dimensional structure

Three dimensional structure
Which of the following four proteins would bind best to the antibody? The portion of the antibody the binds the protein is shown on the left, the proteins (A, B, C, D) on the right.

Protein A
Protein B
Protein C
Protein D

c :same as diagram
Where do competitive inhibitors bind on an enzyme?

substrate
allosteric site
competitive site
active site

active site
A ligand cannot bind to the active site of an enzyme.

True
False

False
Two enzymes catalyze the same reaction. Enzyme A converts substrate to product twice as fast as enzyme B. Which enzyme has the lower activation energy or energy barrier: A or B?

Enzyme A
Enzyme B

Enzyme A
Amino acids in a protein chain are attached by bonds called
peptide bonds
This amino acid is ______________.

hydrophobic
hydrophilic

hydrophilic
The peptide bond that forms between two amino acids is an example of a(n):

hydrogen bond
ionic bond
covalent bond

covalent bond
Which of the following curves best represents the activity of an enzyme isolated from a bacteria that lives in the hot springs in Yellowstone (water temperature 120 degrees C)?

curve A
curve B
curve C

curve B curves up then down and goes past 120
Which of the following plots more correctly shows the activity of pepsin as a function of pH?

plot A
plot B
plot C
plot D

plot A goes up then down like a volcano starts at 0
An enzyme binds the indicated substrate and converts it to product by removing two hydrogen atoms and forming a double bond between the two middle carbons. Compounds A and B are inhibitors of this enzyme. Which of the two inhibitors is a non-competitive inhibitor?

Compound A
Compound B

Compound B
This is an image of

Deoxyribose pyrimidines
Ribose pyrimidine
Ribose purine
Deoxyribose purine

Deoxyribose pyrimidines
Which nucleotide is at the 3′ end of this nucleic acid?

G
A
T
C

t
Does the DNA in the skin cell have the same backbone as DNA in the brain cell of the same organism?

Yes, all backbones of ALL DNA molecules are the same.
Yes, the backbones of DNA are different for each person, but within the organism – they are the same in all cells.
No, the backbones will be different in each cell type.
No, the backbones will be different because of mutations.

Yes, all backbones of ALL DNA molecules are the same.
Which labeled region is the base?

Blue
Green
Red

Green
How many phosphate groups does ATP have?

1
2
3
4

3
Which of these is NOT a difference between DNA and RNA?

DNA tends to be double stranded, while RNA tends to be single stranded
RNA uses the base thymine while DNA uses the base uracil.
DNA uses the sugar deoxyribose while RNA uses the sugar ribose.
All of these are differences between DNA and RNA.

RNA uses the base thymine while DNA uses the base uracil.
The molecule shown here is: _________________

an amino acid
a carbohydrate
a nucleotide
a lipid

an amino acid
The cells of your body are surrounded by water. The outer layer of these cells is made of many nonpolar molecules. What would happen if the outer layer of these cells was made of mainly polar molecules?

The cells would dissolve.
The cells could not interact with their environment.
The cells would be too heavy to float in the water.
Water could not get in to the cell.

The cells would dissolve.
Which of the following is used for long term energy storage?

Proteins
Nucleic Acids
Carbohydrates
Lipids

Lipids
What type of molecule is shown here:

Carbohydrate
Lipid
Nucleotide
Amino acid

Lipid
Which of these functional groups is hydrophilic?

Alcohols
Carboxyl
Phosphate
All of the other selections.

All of the other selections.
This is an image of

Deoxyribose purine
Deoxyribose pyrimidines
Ribose purine
Ribose pyrimidine

Deoxyribose purine
Enzymes are usually ______________?

carbohydrates
nucleotides
lipids
proteins

proteins
Detergents are ______________.

polar
nonpolar
both polar and nonpolar
neither polar nor nonpolar

both polar and nonpolar
How will lipids respond when immersed in water?

The phospholipids will form crystals at the bottom of the solution
The phospholipid will dissolve evenly in the water
The heads will orient away from the water
The tails will orient away from the water

The tails will orient away from the water
Proteins begin with an amino group and end with a carboxyl group. In the case of nucleic acids:

They begin at the 3′ end and end at the 5′ end.
They begin at the 5′ end and end at the 3′.
It is the same in nucleic acids.
They begin at the 5′ end and end at the 2′ end

They begin at the 5′ end and end at the 3′.
Which of the following is mostly hydrophobic?

Carbohydrates
Proteins
Nucleic acids
Lipids

Lipids
Which is NOT a function of proteins?

Maintains structure of animal cells
Move substances in and out of the cell.
Form the bulk of cellular membranes.
Recognition of specific particles.

Form the bulk of cellular membranes.
Which of the following structures can be found together in eukaryotic cells?

DNA and ribosomes
ribosomes and endoplasmic reticulum
cytoplasm and ribosomes
cytoplasm and plasma membrane

ribosomes and endoplasmic reticulum
Which of the following statements about prokaryotes is incorrect?
Prokaryotes have circular pieces of DNA within their nuclei.
A forensic examination reveals cells containing ribosomes, DNA, a plasma membrane, and a cell wall. What type of cell it is?
bacterium
Which is NOT a difference between prokaryotic and eukaryotic cells?
Eukaryotes are larger than prokaryotes.
Which of these is also called an antibiotic in a medical setting?
Antibacterial
Which is a plausible effect of taking oral antibiotics?
The antibiotics could unintentionally kill good bacteria living in your intestines, leaving you more susceptible to infection by pathogenic bacteria.
What is the concern with overuse of antibiotics?
Bacteria will become antibiotic resistant.
All living things are made of one or more cells: true or false?
True
All cells have ______________?
plasma membrane
An ideal antibiotic damages only bacterial cells but not human cells. Which of the following cellular structures would be a good target for antibiotics?
cell wall
How does the selective permeability of the membrane help the cell.
This allows the cell to regulate what enters and exits
Which substance would be most likely to pass through a lipid bilayer/plasma membrane without embedded proteins?
a steroid hormone
Biological Membranes are:
dynamic.
Which component of the plasma membrane has the widest variety of functions?
proteins
What is the role of carbohydrates in the plasma membrane?
cellular identification
A set of erythrocytes is placed in a beaker of 0.9% NaCl. Nothing appears to happen to the cells. Why?
0.9% NaCl is iostonic to the cells.
All of the following have an effect on the fluidity of a membrane except:
the presence of integral proteins in the membrane
Which of the following can cross the cell’s plasma membrane without the assistance of protein transporters? Select all that apply.
small hydrophobic molecules
gasses
An animal cell placed in a hypotonic solution will __________.
burst
A substance, such as glucose, will enter a cell following its concentration gradient, from the blood and tissues, through the membrane, and into the cytoplasm. Such movement of glucose has a maximal capacity, does not require energy, and is specific only for glucose. How is the entry of glucose into the cell occurring?
By facilitated diffusion
The secretion of materials, such as hormones and neurotransmitters, from inside of a cell to the outside is ___________.
exocytosis
An immune cell would engulf a pathogenic cell using the process of: ________________ ?
endocytosis
A substance, such as glucose, will enter a cell following its concentration gradient, from the blood and tissues, through the membrane, and into the cytoplasm. Such movement of glucose has a maximal capacity, does not require energy, and is specific only for glucose. How is the entry of glucose into the cell occurring?
By facilitated diffusion
Increasing the concentration gradient:
Increases the rate of diffusion
Sodium ions are more highly concentrated outside the cell, in the extracellular fluid. Which process would be used to return any sodium ions that leaked into the cell back to the extracellular fluid?
active transport
Protein transporters that move materials against a concentration gradient are active transport proteins.
True
Active transport could also be called facilitated diffusion.
False
A cell will uptake large molecules from the extracellular fluid by the process of __________.
endocytosis