Bio23 Practice Questions

Hierarchy, Homeostasis & Atomic Structure (I)

1. Which of the following lists the structural hierarchy of life from the smallest to the largest level?

a. cell, organelle, organ, tissue, organ system, organism

b. cell, tissue, organelle, organ, organ system, organism

c. organelle, cell, tissue, organ, organ system, organism

d. tissue, organelle, cell, organ, organ system, organism

2. The diagram above show a homeostatic mechanism called:

a. negative feedback b. negative amplification c. positive feedback d. positive amplification

3. The atomic mass of an atom is the:

a. total number of protons b. total number of protons and electrons

c. total number of protons and neutrons d. total number of protons, neutrons and electrons

4. If the atomic number of an element is 12 and its atomic mass is 25, you could conclude that this element has:

a. 12 neutrons, 13 protons and 13 electrons b. 13 neutrons, 12 protons and 12 electrons

c. 12 neutrons, 13 protons and 12 electrons d. 13 neutrons, 12 protons and 13 electrons

5. Pick the correct statement about atoms:

a. if you change the number of neutrons, then you have a different element

b. if you change the number of electrons, then you create a new isotope of the same atom

c. atoms are electrically neutral because the number of protons is equal to the number of electrons

d. atoms are electrically neutral because the number of protons is equal to the number of neutrons

6. There are three main isotopes of the atom Carbon. Carbon isotopes will:

a. differ in the number of electrons b. differ in their number of protons

c. differ in their number of neutrons d. all of the previous choices are correct

7. A subatomic particle with negligible (very little) mass and a charge of minus 1 is called a(n):

a. Electron b. Proton c. Neutron d. Nucleus

8. Suppose an oxygen atom has 8 protons and 9 neutrons. How many electrons does it have?

a. 1 b. 8 c. 9 d. 17

9. In the picture above, what is the stimulus?

a. blood pressure

b. heart rate

c. glossopharyngeal nerve

d. vagus nerve

10. In the picture above, what is(are) the effector(s)?

a. the brain

b. the heart

c. the blood vessels

d. the vagus nerve

Hierarchy, Homeostasis & Atomic Structure (II)

1. Which of the following is in the correct hierarchical order (smallest to largest)?

a. atom, tissue, cell, macromolecule, organ, organism

b. atom, organelle, molecule, tissue, macromolecule, organ

c. proton, atom, molecule, organelle, cell, system

d. proton, molecule, atom, cell, tissue, organism

2. The diagram above demonstrates:

a. hierarchy b. homeostatic equilibrium c. negative feedback d. positive feedback

3. The weight of an atom is concentrated (found) in the:

a. inner electron shell b. second electron shell c. neutrons d. nucleus

4. The atomic number of sodium is 11 and the atomic mass of sodium is 23. Therefore, you could conclude that:

a. sodium has 11 neutrons and 23 protons b. sodium has 23 neutrons and 11 protons

c. sodium has 11 neutrons and 12 protons d. sodium has 12 neutrons and 11 protons

5. Pick the incorrect statement about atoms:

a. atoms are electrically neutral because the number of protons is equal to the number of neutrons

b. the second energy level (or electron shell) of an atom can hold up to 8 electrons

c. if you change the number of protons, then you essentially change the atom

d. if you change the number of neutrons, then you create a new isotope of the atom

6. There are three main isotopes of the atom Carbon. Carbon isotopes will:

a. differ in their number of electrons b. differ in their number of protons

c. differ in their number of neutrons d. all of the previous choices are correct

7. A subatomic particle with a mass of 1 atomic unit and a charge of 0 is called a(n):

a. electron b. proton c. neutron d. nucleus

8. How many electrons would an atom of Magnesium (atomic number = 12, atomic mass = 24) have

in its second energy level (shell)?

a. 2 b. 8 c. 12 d. 24

9. As shown in the figure above, if blood glucose levels rise as a result of a meal, which of the following represents a homeostatic response?

a. the blood glucose concentration will level off at its new value

b. the blood glucose concentration will eventually return to its original value

c. the blood glucose concentration will continue to rise until illness results

d. the blood glucose concentration will drop below normal levels

10. If you eat jelly donuts for breakfast and insulin is not secreted into the blood what would most

likely happen? (Hint - use information provided in the figure above)

a. blood glucose levels will decrease and the liver will make less glycogen

b. blood glucose levels will decrease and the liver will make more glycogen

c. blood glucose levels will increase and the liver will make less glycogen

d. blood glucose levels will increase and the liver will make more glycogen

Ionic, Covalent & Hydrogen Bonding (I)

1. The chemical reactivity of atoms is mainly determined by:

a. the mass of the atom

b. the number of neutrons

c. the total number of electrons they possess

d. the number of electrons in the outermost (or valence) shell

2. Polar covalent bonds are formed when:

a. atoms share electrons equally

b. electrons are completely transferred from one atom to another

c. a pair of electrons are shared unequally by two atoms

d. two or more atoms lose electrons at the same time

3. An ion is formed when an atom

a. forms a covalent bond with another atom

b. gains or loses an electron

c. gains or loses a proton

d. gains or loses a neutron

4. Which of the following is an ion?

a. NaCl b. Na c. K⁺ d. O₂

5. Lithium chloride (LiCl) is a substance that is held together by:

(Hint: Atomic No. Li = 3; Atomic No. Cl = 17)

a. polar covalent bonds b. non polar covalent bonds

c. ionic bonds d. hydrogen bonds

6. All of the following statements about the structure of water are true EXCEPT:

a. Water is a type of polar covalent molecule

b. Polar covalent bonds are found within the water molecule

c. Hydrogen bonds are found between water molecules

d. The oxygen part of the water molecule carries a partial (small) positive charge

7. Potassium chloride consists of potassium ions (K⁺) and chloride ions (Cl^-) in a crystal.

If potassium chloride is placed in water, which of the following DOES NOT happen?

a. K⁺ ions are attracted to the oxygen atoms in the water molecules

b. Cl^- ions are attracted to the hydrogen atoms in the water molecules

c. KCl dissociates into hydrophilic ions in water

d. KCl forms a hydrophobic complex in water

8. The atomic number of Nitrogen is 7 and its atomic weight (mass) is 14. How many

covalent bonds would Nitrogen be expected to form to obtain stability?

a. 7 b. 14 c. 5 d. 3

9. All chemicals that can resist changes in solution pH when either acids or bases are added are called:

a. sugars b. buffers c. proteins d. isomers e. molecules

10. The increasing acidic indicated in the figure below is associated with:

a. a decrease in the H⁺ concentration and an increase in the pH

b. an increase in the H⁺ concentration and a decrease in the pH

c. a decrease in the H⁺ concentration and a decrease in the pH

d. an increase in the H⁺ concentration and an increase in the pH

Ionic, Covalent & Hydrogen Bonding (II)

1. Which of the following is an ion?

a. MgCl₂ b. Ca c. Cl^- d. CO₂

2. How many valence electrons are there in an atom with an atomic number of 20 and an

atomic weight (mass) of 35?

a. 2 b. 20 c. 35 d. none of the previous choices are correct

3. An atom with an atomic number of 10 would most likely:

a. react with other atoms to form molecules by hydrogen bonding

b. react with other atoms to form molecules by covalent bonding

c. react with other atoms to form molecules by ionic bonding

d. none of the above, this atom would be non-reactive

4. Non-polar covalent bonds are formed when:

a. electrons in the molecule are completely transferred from one atom to another

b. electrons in the molecule are completely transferred from one ion to another

c. pairs of electrons are unequally shared between atoms in the molecule

d. pairs of electrons are equally shared between atoms in the molecule

5. Calcium chloride (CaCl₂) crystals are held together by ionic bonds and consist of Ca⁺⁺

and Cl^- ions. Ca⁺⁺ is:

a. a cation that has two less electrons than a Ca atom

b. an anion that has two less electrons than a Ca atom

c. a cation that has two more protons than a Ca atom

d. an anion that has two more protons than a Ca atom

6. The formula “H₂O” means:

a. This atom contains two hydrogen molecules and one oxygen molecule.

b. This atom contains one hydrogen molecule and two oxygen molecules.

c. This molecule contains two hydrogen atoms and one oxygen atom.

d. This molecule contains one hydrogen atom and two oxygen atoms

7. The single lines shown joining the H atoms to the N or C in the molecule shown above show:

a. single ionic bonds, formed by transferring electrons from one atom to another

b. single covalent bonds, formed by sharing one pair of electrons between the atoms

c. single hydrogen bonds, formed by transferring electrons from one atom to another

d. all of the above

8. The atomic number of Oxygen is 8 and its atomic weight (mass) is 16. How many

covalent bonds would Oxygen be expected to form to obtain stability?

a. 1 b. 2 c. 8 d. 16

Questions 9 & 10: Use the figure below to help figure out the answer

9. Complete the blanks. A solution was made by placing many of the same molecules in unbuffered water. The molecules completely dissociated in the water to give many H⁺ ions. These molecules would be a type of strong _______ and ________ the pH.

a. acid, increase b. acid, decrease

c. base, increase d. base, decrease

10. What would happen to the pH if a large amount of buffer was added to a solution with a starting pH of 6.0?

a. the pH would increase

b. the pH would decrease

c. the pH could increase or decrease

d. the pH would not change because buffers do not change pH

Organic vs. Inorganic, Functional Groups, Monomers & Polymers, Metabolism (I)

1. In a living organism, the class of chemical reactions where smaller molecules are joined

to make larger molecules is called:

a. catabolism b. anabolism c. metabolism d. homeostasis

2. Which of the following elements is often found in organic molecules, but rarely in inorganic molecules?

a. hydrogen b. nitrogen c. carbon d. oxygen

3. Which of the following is an inorganic molecule?

a. C₆H₁₂O₆NS b. C₆H₁₂O₆ c. CH₃(CH₂)₁₄COOH d. Ca₁₀(PO₄)₆(OH)₂

4. In an hydrolysis (decomposition) reaction_____

a. a water molecule is split when a covalent bond between two monomers is formed

b. a water molecule is split when a covalent bond joining two monomers is broken

c. a water molecule splits when a covalent bond between two polymers is formed

d. a water molecule has nothing to do with the reaction

5. The -OH functional group is called a(n) ____ group

a. amino b. carboxyl c. hydroxyl d. oxyaldehyde

6. True or False: If found in body fluids, the substances shown above can be called

organic ions.

7. The chemical reaction shown below is an example of a ____ reaction

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

a. decomposition (catabolic)

b. synthesis (anabolic)

c. exchange

d. reversible

8. Which of the following molecules ARE NOT formed by the reaction shown above?

a. proteins

b. starch

c. fatty acids

d. nucleic acids

9. Which of the following molecules is considered a monomer?

a. water

b. amino acid

c. polysaccharide

d. nucleic acid

10. Inside most cells, the energy required for many cell functions is provided by a molecule

called:

a. ADP b. hemoglobin c. ATP d. oxygen

Organic vs. Inorganic, Functional Groups, Monomers & Polymers, Metabolism (II)

1. Organic molecules always contain the elements__________

a. hydrogen and nitrogen

b. oxygen and nitrogen

c. hydrogen and carbon

d. oxygen and hydrogen

2. Which of the following molecules is NOT organic?

a. C₆H₁₂O₆

b. CH₃(CH₂)₁₄COOH

c. Ca₁₀(PO₄)₆(OH)₂

d. C₆H₁₂O₆NS

3. In a dehydration (condensation) synthesis reaction_____

a. a water molecule is split when a covalent bond between two monomers is formed

b. a water molecule is formed when a covalent bond between two monomers is formed

c. a water molecule is split when an ionic bond between two monomers is formed

d. a water molecule is formed when an ionic bond between two monomers is formed

4. _________is/are functional group(s)

a. amine b. carboxyl c. hydroxyl d. all of these

5. An -NH₂ functional group is called a(n) _____ group:

a. amine

b. carboxyl

c. hydroxyl

d. phosphate

6. Which functional group gives organic molecules the properties of an acid?

a. -OH

b. -COOH

c. -NH₂

d. -CH₃

7. Which functional groups are common to all amino acids and proteins?

a. -NH₂ & -OH

b. -NH₂ & -COOH

c. -CH₃ & -COOH

d. -CH₃ & -OH

Use the picture above to help answer the questions below, as needed

8. In the reaction shown in (a) above the protein molecule shown is a type of:

a. polymer b. monomer c. inorganic compound d. all of these

9. A process called hydrolysis is needed in order for which of the reactions shown above a. amino acids to proteins only

b. glycogen to glucose only

c. both a and b require hydrolysis to occur

d. neither a nor b require hydrolysis to occur

10. Which of the reactions below could be classified as a type of catabolic (decomposition) reaction?

a. HCl → H⁺ + Cl^-

b. C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

c. 3 amino acids → tripeptide + 3 water

molecules molecules

d. NaOH + HCl→ NaCl + H₂O

BIOMOLECULES (I)

1. The monomer below is a type of __________ .

b. amino acid, peptides

c. fatty acid, proteins

d. fatty acid, peptides

4. The secondary structure of a protein is held together by:

a. R- group interactions

b. hydrogen-bonds

c. peptide bonds

d. ionic bonds

5. Catabolism (decomposition) of glycogen would result in an increase in the level of:

a. amino acids

b. fatty acids

c. monosaccharides

d. inorganic compounds

6. The characteristic that all lipids have in common is:

a. they are all made up of fatty acids and glycerol

b. they all contain nitrogen

c. none of them is very high in energy content

d. none of them dissolves in water

7. In the picture above, the whole molecule (A+B) is called a:

a. triglyceride

b. phospholipids

c. steroid

d. complex sugar

8. In the picture above, the part labeled A is said to be a:

a. hydrophobic nonpolar (uncharged) phosphate group

b. hydrophilic polar (charged) phosphate group

c. hydrophobic polar (charged) phosphate group

d. hydrophilic nonpolar (uncharged) phosphate group

9. In the picture above, the part labeled B shows types of:

a. amino acid chains

b. fatty acid molecules

c. triglycerides

d. glycerol

10. Steve noticed that his friend Jon had gained a little weight during the holidays. He commented, “Storing up some ________ for the winter, I see”.

a. polysaccharides

b. triglycerides

c. nucleotides

d. steroids

Biomolecules (II)

Questions 1-3 Refer to the figure below:

1. The molecule labeled B above is a type of:

a. monosaccharide b. amino acid c. fatty acid d. nucleotide

2. The molecule labeled D above is a type of:

a. monosaccharide b. amino acid c. fatty acid d. nucleotide

3. The monomer that joins to form proteins is identified by the letter:

a. A b. B c. C d. D

4. The primary structure of a protein refers to:

a. the sequence of amino acids in the peptide chain

b. the number of alpha helices and beta pleated sheets in the peptide chain

c. the number of hydrogen bonds in the peptide chain

d. all of the above

5. Enzymes are:

a. types of steroids

b. biological catalysts

c. product specific

d. all of the above

6. The four main catergories of macromolecules in a cell are

a. proteins, DNA, RNA and steroids

b. proteins, nucleic acids, carbohydrates, and lipids

c. nucleic acids, carbohydrates, monosaccharides, and proteins

d. RNA, DNA, proteins, and carbohydrates

7. True or False: The part of the molecule labeled B in the picture above is said to be

hydrophobic.

8. True or False: The molecule shown above is also a commonly found stored in adipose (fat) cells around the body.

9. The molecule that acts as an energy store and is found mostly in skeletal muscle and the liver is called:

a. glycogen b. triglyceride c. starch d. myoglobin

10. The macromolecules that perform most cell functions are types of:

a. carbohydrates

b. nucleic acids

c. proteins

d. all of the above are about equal

CELL MEMBRANE (I)

1. Which of the following statements about the cell (plasma) membrane is false?

1. it defines cell boundaries

2. it controls interactions with other cells

3. not all cells have a cell membrane

4. it controls passage of materials in and out of cell

2. ___________ is/are found in the hydrophobic part of the plasma membrane

1. nucleotides b. amino acids c. cholesterol d. monosaccharides

3. Different plasma membrane proteins do all of the following except_______

1. work as receptors b. synthesize mRNA c. work as enzymes d. work as cell adhesion molecules

4. What statement is the most accurate?

1. hydrophobic tails of phospholipids are facing the exterior of the membrane

2. hydrophilic tails of phospholipids are facing the exterior of the membrane

3. hydrophobic heads of phospholipids are facing the exterior of the membrane

4. hydrophilic heads of phospholipids are facing the exterior of the membrane

5. Diffusion is_______________

1. the net movement of water from a place of lower water concentration to a place of higher water concentration

2. the net movement of water from a place of higher solute concentration to a place of lower solute concentration

3. the net movement of particles down their concentration gradient

4. the net movement of particles against (up) their concentration gradient

6. Which of the following statements is true?

a. in general, larger molecules diffuse faster than smaller molecules.

b. in general, higher temperatures increase the speed of diffusion.

c. decreasing the concentration gradient increases the speed of diffusion

d. increasing the energy supply in a cell would increase the speed of diffusion

7. Which of the following factors does not affect the diffusion rate?

a. temperature

b. membrane thickness

c. concentration gradient

d. availability of energy

8. Rebecca mixed some sugar with water. Which of the following statements is the most accurate?

1. sugar is the solute

2. water is the solvent

3. the mixture of sugar and water forms a solution

4. all of them are accurate

9. During diffusion a substance always moves from:

a. outside a cell to inside a cell

b. inside a cell to outside a cell

c. from an area of higher concentration to an area of lower concentration

d. from an area of lower concentration to an area of higher concentration

10. The movement of small nonpolar lipid molecules down their concentration gradient across the

phospholipid part of the cell membrane occurs by a process called:

1. diffusion b. osmosis c. filtration d. active transport

CELL MEMBRANE (II)

1. Which of the following statements is false?

a. The cell membrane separates the extracellular fluid from the intracellular fluid

b. The cell membrane is mostly made of carbohydrates

c. The cell membrane is found in all living cells

d. The cell membrane regulates inflow and out flow from the cell

2. The cell membrane is mainly made of:

a. lipids and proteins b. cellulose and proteins c. cellulose d. lipids only

3. ___________ is/are found on the hydrophilic side of the plasma membrane

a. peripheral proteins b. Nucleotides c. Cholesterol c. Transmembrane proteins

2. Diffusion:

a. requires energy b. is a passive process c. uses ATP d. is an active process

3. A cell placed in a hypertonic solution will:

a. lose water b. gain water c. neither lose nor gain water d. both gain and lose water equally

5. Which of the following would decrease the diffusion rate across a membrane?

a. increasing the temperature b. increasing the membrane thickness

c. increasing the membrane surface area d. increasing the concentration gradient

6. Refer to the picture above. Which of the following statements is true?

a. The cell shown in A is in a hypertonic solution

b. There is a net flow of water into the cell shown in A

c. The cell shown in C is in an isotonic solution

d. There is a net flow of water into the cell shown in B

7. When a cell is placed in distilled (i.e. pure) water; the intracellular fluid would be ______ compared to

the external

environment.

a. hypertonic b. hypotonic c. isotonic d. gin & tonic

8. Which of the following statements is false?

a. oxygen can cross cell membranes by simple diffusion

b. a polar amino acid can cross the membrane by facilitated diffusion

c. a small non polar molecule can cross the membrane by simple diffusion

d. a small monosaccharide can cross the membrane through ion channels

9. __________does not require energy.

a. transport of K⁺ against its concentration gradient

b. transport of glucose up its concentration gradient

c. transport of Cl^- down its concentration gradient

d. endocytosis

10. ________ is/are an example(s) of active transport.

a. transport of Na⁺ down its concentration gradient

b. transport of proline (amino acid) from where it is in a high concentration to where it is in a low concentration

c. transport of Ca⁺ against its concentration gradient

d. all of the above

CELL MEMBRANE-TRANSPORT (II)

1. Active transport:

a. is a process that requires ATP

b. moves substances from an area of low concentration to an area of high concentration

c. involves specific proteins that move different substances

d. all of the previous choices are correct

2. Which of the following is(are) BULK transport process(es) where vesicles are being formed at the cell membrane and taken into the cell?

a. pinocytosis b. phagocytosis c. receptor-mediated endocytosis d. all of these

3. Solution A has a lower concentration of impermeable solutes compared to solution B.

Which of the following statements is correct?

a. Solution A is hypertonic to solution B b. Solution A is hypotonic to solution B

c. Solution B is hypotonic to solution A d. Solution B is isotonic to solution A

4. The movement of water molecules down their concentration gradient across a selectively permeable

membrane is called_______ (Select the most accurate option)

a. Diffusion b. Osmosis c. Active transport d. Equilibrium

5. Small lipid molecules (e.g. steroid hormones) can cross the plasma membrane by _____________.

a. facilitated diffusion through a channel protein b. facilitated diffusion by a carrier protein

c. simple diffusion d. receptor-mediated endocytosis

6. Transport of ________ across a cell membrane requires (needs) energy.

a. K⁺ against its concentration gradient b. glucose down its concentration gradient

c. Cl^- down its concentration gradient d. all of these

7. A cell (e.g. red blood cell) placed in a hypotonic solution would most likely ___________

(You may want to make a drawing to help you find the answer)

a. burst b. shrink c. stay the same size d. any of the previous choices could happen

8. Which of the following transport processes would NOT require ATP?

a. moving glucose from where it is in a low concentration to where it is in a high concentration

b. moving Cl^- ions down their concentration gradient into a cell

c. phagocytosis of a bacterium into macrophages

d. transporting Ca²⁺ ions against their concentration gradient

9. Osmosis is the movement of water across a semipermeable membrane:

a. from areas of high solute to low solute concentration

b. from areas of low solute concentration to high solute concentration

c. that is an active process occurring in any direction

d. that is an active process occurring only in one direction

10. The active transport of molecules across a plasma membrane requires energy.

Movement of sodium ions up their concentration gradient requires energy in the form of ATP.

a. both of these statements are true c. the first statement is true, the second statement is false

b. both of these statements are false d. the first statement is false, the second statement is true

ELECTRICALLY EXCITABLE CELLS (I)

1. All of the following are examples of electrically excitable cells EXCEPT:

a. skeletal muscle fiber (cell)

b. epithelial cell in the skin

c. cardiac muscle fiber (cell)

d. neuron

2. Information between electrically excitable cells is usually transmitted via:

a. chemical messengers

b. voltage changes

c. resting membrane potentials

d. action potentials

3. The resting membrane potential is mainly due to:

a. ligand-gated sodium channels and potassium leak channels

b. sodium potassium pumps and potassium leak channels

c. sodium and potassium leak channels

d. ligand-gated and voltage-gated sodium channels

4. Which of the following is the explanation for repolarization of an excited membrane?

a. Na⁺ moves into the cell

b. Na⁺ moves out of the cell

c. K⁺ moves into the cell

d. K⁺ moves out of the cell

5. The term depolarization means:

a. The membrane potential has just reached threshold

b. The membrane potential has become more negative

c. The membrane potential is moving above the action potential

d. The membrane potential is moving above the resting potential

6. The approximate resting potential of many neurons is about:

a. 0 mV b. +70 mV c. –70 mV d. + 35 mV e. –35 mV

7. In what way does the inside of a resting neuron differ from the external environment?

The interior is:

a. negatively charged and contains more Na+

b. positively charged and contains more Na+

c. negatively charged and contains less Na+

d. positively charged and contains less Na+

8. Upon stimulation of a skeletal muscle cell, a depolarizing change occurs that is usually caused by:

a. calcium ions leaving the cell

b. sodium ions leaving the cell

c. potassium ions leaving the cell

d. none of the previous choices are correct

9. The part labeled “x” is called:

(a) axon hillock

(b) node of Ranvier

(c) dendrite

(d) soma

10. The part labeled “y” is called:

(a) axon hillock

(b) node of Ranvier

(c) dendrite

(d) soma

ELECTRICALLY EXCITABLE CELLS (I)

1. _________________ is an example of an electrically excitable cell:

a. red blood cell

b. epithelial cell lining the digestive tract

c. mature bone cell

d. cardiac muscle cell

2. Which of the following normally causes a cell to depolarize?

a. opening Na⁺-channels

b. opening K⁺-channels

c. closing Na⁺ channels

d. closing K⁺-channels

3. What are the normal levels of sodium and potassium ions in body fluids?

a. both sodium and potassium are high outside of cells

b. both sodium and potassium are high inside of cells

c. sodium is high outside of cells and potassium is high inside of cells

d. sodium is high inside of cells and potassium is high outside of cells

4. The repolarization phase of an action potential is mostly caused by opening:

a. voltage-gated Na⁺-channels

b. voltage-gated K⁺-channels

c. ligand-gated Na⁺-channels

d. ligand-gated K⁺-channels

5. During the resting membrane potential:

a. the inside of the membrane is more negative than the outside

b. Na⁺ diffuses out of the cell via leak channels

c. K⁺ diffuses into the cell via leak channels

d. all of the above are true

6. Local potentials are usually caused by the opening of:

a. ligand-gated channels

b. voltage-gated channels

c. leak channels

d. sodium-potassium pumps

7. The following are characteristics of the local potential EXCEPT:

a. the signal loses strength as it moves away from the point of origin

b. it can only travel short distances

c. it occurs on an all-or-none basis

d. many small stimuli can sum up to a local potential of increased magnitude

8. The term hyperpolarization means that:

a. The membrane potential is above zero

b. The membrane potential is moving towards zero

c. The membrane potential is below the RMP

d. The membrane potential is exactly at zero

9.

10. Arrange the following events (that occur during the establishment of the local

potential) in the correct order:

1. Chemical messenger binds to ligand-gated Na⁺ channels

2. The change in voltage triggers the opening of voltage-gated K⁺ channels

3. Na⁺ ions rush INTO the cell bringing positive charges INTO the cell

4. The membrane depolarizes (the membrane potential moves towards zero)

5. K⁺ ions move DOWN their concentration gradient from inside to OUTSIDE the cell taking positive charges OUT of the cell.

6. Ligand-gated Na⁺ channels open

7. The membrane repolarizes (the membrane potential moves away from zero)

The correct order is:

a. 1,5,4,6,7,2,3

b. 1,6,3,4,2,5,7

c. 1,4,3,5,6,7,2

d. 5,4,6,7,1,2,3