LAB PRACTICAL 1 EXERCISE #1-9
EXAM QUESTIONS AND ANSWERS
Are controls necessary? Why or why not? - ANSWER-Yes, because it helps eliminate
other variables and allow better measurements
What is a phospholipid? What functions do phospholipids have in cells? - ANSWER-A
phospholipid is a lipid that helps form the membrane in the cell.
What does "dehydration synthesis" do? - ANSWER-Dehydration synthesis removes
water from subunits to form a covalent bond.
Define prokaryotes - ANSWER-Bacteria; do not contain a membrane-bound nucleus or
any other membrane-bound organelles.
Define spectrophotometry. - ANSWER-Measures the amount of light absorbed and
transmitted by a dissolved chemical.
Define sample as it relates to spectrophotometry. - ANSWER-solution contained in a
clear test tube or cuvette made of glass or quartz
Define blank as it relates to spectrophotometry. - ANSWER-test tube or cuvette
containing only the solvent used to dissolve the chemical you are analyzing.
What is the difference between an absorption spectrum and a standard curve? -
ANSWER-Absorption spectrum is the pattern of the wavelengths absorbed; fingerprint.
The standard curve is the chemicals concentration versus its absorbance of a
wavelength of light
Define solution, solute, solvent. - ANSWER-A solution is a solute or solutes dissolved in
a solvent. Solutes are dissolved substances. Solvents are substances that dissolve
solutes.
Define molecular weight - ANSWER-It is a mass of the molecule
What do buffers do and why are they important in biological systems? - ANSWER-
Buffers keep pH neutral and is important to keep biochemical processes working at a
close to 7 pH.
Our stomachs secrete hydrochloric acid. Knowing the function of antacids, what do you
think causes most "upset stomachs?" - ANSWER-too much acid.
What functions does this hydrochloric acid serve? - ANSWER-They help with the
breakdown of food for digestion.
, Define positive control - ANSWER-The variable for which one tests; it reacts positively
and demonstrates the test's ability to detect what you expect.
Define negative control - ANSWER-Does not contain the variable which one is looking
for; shows you what a negative result looks like.
What is the importance of a positive control? What is the importance of a negative
control? - ANSWER-Positive control gives us a positive expected result and negatives
give us a negative expected result. They are both used together to eliminate potential
variables.
Why is it important to use standards or to develop a standard curve in
spectrophotometry? - ANSWER-to figure out solution concentration.
Define Brownian movement. - ANSWER-When small particles move after they collide
with moving molecules
Define diffusion. - ANSWER-Movement of molecules through solutions and across
membranes in a predictable direction.
Define osmosis. - ANSWER-Diffusion of water across a differentially permeable
membrane.
Know hypotonic, hypertonic, and isotonic solutions and relate it to Figure 8.7. -
ANSWER-Hypotonic describes a solution with a lower concentration of solutes,
hypertonic refers to a solution with a high concentration of solutes, and isotonic refers to
two solutions that have equal concentrations of solutes.
What is the difference between molecular motion and diffusion? - ANSWER-Molecular
motion is random and diffusion can be predicted.
Define enzymes - ANSWER-proteins; they are biocatalysts that accelerate metabolic
reactions to biologically useful rates.
Define substrate. - ANSWER-reacting molecules that bond with enzymes.
Define transition state. - ANSWER-Substrate becomes more reactive and the metabolic
reaction accelerates
Define energy of activation. - ANSWER-energy needed to form a transition state
Define active site. - ANSWER-Where the binding takes place
More substrate increases the probability that an enzyme will contact substrate and
should increase the enzymatic reaction rate. How do you explain the increase in time to
EXAM QUESTIONS AND ANSWERS
Are controls necessary? Why or why not? - ANSWER-Yes, because it helps eliminate
other variables and allow better measurements
What is a phospholipid? What functions do phospholipids have in cells? - ANSWER-A
phospholipid is a lipid that helps form the membrane in the cell.
What does "dehydration synthesis" do? - ANSWER-Dehydration synthesis removes
water from subunits to form a covalent bond.
Define prokaryotes - ANSWER-Bacteria; do not contain a membrane-bound nucleus or
any other membrane-bound organelles.
Define spectrophotometry. - ANSWER-Measures the amount of light absorbed and
transmitted by a dissolved chemical.
Define sample as it relates to spectrophotometry. - ANSWER-solution contained in a
clear test tube or cuvette made of glass or quartz
Define blank as it relates to spectrophotometry. - ANSWER-test tube or cuvette
containing only the solvent used to dissolve the chemical you are analyzing.
What is the difference between an absorption spectrum and a standard curve? -
ANSWER-Absorption spectrum is the pattern of the wavelengths absorbed; fingerprint.
The standard curve is the chemicals concentration versus its absorbance of a
wavelength of light
Define solution, solute, solvent. - ANSWER-A solution is a solute or solutes dissolved in
a solvent. Solutes are dissolved substances. Solvents are substances that dissolve
solutes.
Define molecular weight - ANSWER-It is a mass of the molecule
What do buffers do and why are they important in biological systems? - ANSWER-
Buffers keep pH neutral and is important to keep biochemical processes working at a
close to 7 pH.
Our stomachs secrete hydrochloric acid. Knowing the function of antacids, what do you
think causes most "upset stomachs?" - ANSWER-too much acid.
What functions does this hydrochloric acid serve? - ANSWER-They help with the
breakdown of food for digestion.
, Define positive control - ANSWER-The variable for which one tests; it reacts positively
and demonstrates the test's ability to detect what you expect.
Define negative control - ANSWER-Does not contain the variable which one is looking
for; shows you what a negative result looks like.
What is the importance of a positive control? What is the importance of a negative
control? - ANSWER-Positive control gives us a positive expected result and negatives
give us a negative expected result. They are both used together to eliminate potential
variables.
Why is it important to use standards or to develop a standard curve in
spectrophotometry? - ANSWER-to figure out solution concentration.
Define Brownian movement. - ANSWER-When small particles move after they collide
with moving molecules
Define diffusion. - ANSWER-Movement of molecules through solutions and across
membranes in a predictable direction.
Define osmosis. - ANSWER-Diffusion of water across a differentially permeable
membrane.
Know hypotonic, hypertonic, and isotonic solutions and relate it to Figure 8.7. -
ANSWER-Hypotonic describes a solution with a lower concentration of solutes,
hypertonic refers to a solution with a high concentration of solutes, and isotonic refers to
two solutions that have equal concentrations of solutes.
What is the difference between molecular motion and diffusion? - ANSWER-Molecular
motion is random and diffusion can be predicted.
Define enzymes - ANSWER-proteins; they are biocatalysts that accelerate metabolic
reactions to biologically useful rates.
Define substrate. - ANSWER-reacting molecules that bond with enzymes.
Define transition state. - ANSWER-Substrate becomes more reactive and the metabolic
reaction accelerates
Define energy of activation. - ANSWER-energy needed to form a transition state
Define active site. - ANSWER-Where the binding takes place
More substrate increases the probability that an enzyme will contact substrate and
should increase the enzymatic reaction rate. How do you explain the increase in time to
