Answer: Adsorption is the attachment of a compound to particles of the stationary phase. In TLC, separation is based on the relative differences in this absorption.
Question: You are given an unknown white solid to recrystallize in lab. The white solid could be Compound A (melting point 110-112°C), Compound B (melting point 165-167°C) or Compound C (melting point 154-157°C). Compound A, B and C are significantly soluble in butyl acetate (bp: 126°C), even at room temperature and not very soluble in water (bp: 100°C) or in n-butanol (bp: 117°C) (large difference in solubility of solid in water and n-butanol is significant). Butyl acetate is miscible with n-butanol but not with water.
Answer: Answer 1: hot butyl acetate
Answer 2: n-butanol
Answer 3: first signs of cloudiness
Answer 4: A
Question: Km represents the…
Answer Options:
formation of ES
formation of EP
the back reaction of product to ES
Kcat
Answer: the back reaction of product to ES
Question: Why would water not be used to elute a column [besides its polarity] in column chromatography?
Answer: It would dissolve the silica gel in the column.
Question: The chemical properties of organic molecules are determined by specific arrangements of atoms called Structures Bonds Functional groups Radicals Molecules
Answer: Functional groups
Question: Select the appropriate choice for the blanks in the question below: When comparing 2 hydrocarbons, the larger, higher molecular weight molecule would have melting point because of .
Answer Options:
Higher, increased attractive forces
Lower, increased attractive forces
Higher, decreased attractive forces
Lower, decreased attractive forces
Answer: Higher, increased attractive forces
Question: Local folding of a protein occurs at what defined level of protein folding?
Answer Options:
Primary
Secondary
Tertiary
Quaternary
All of the above
Answer: Secondary
Question: Where should you work when transferring irritating or poisonous substances?
Answer: Under a working exhaust hood.
Question: The macromolecules that serve in the storage and transmission of genetic information are:
Answer Options:
carbohydrates.
lipids.
membranes.
nucleic acids.
proteins.
Answer: nucleic acids.
Question: What process is required to change an object from a protostar into a zero age main-sequence star?
Answer Options:
The core reaches a high enough surface temperature and a high enough luminosity so that it’s not obscured between the T Tauri and Herbig Ae/Be stage.
The object begins to outshine all neighboring objects indicating it has grown to a sufficient infrared brightness to be considered a star.
The core temperature of the protostar reaches 10 million K and fusion of hydrogen into helium begins in the core.
Answer: The core temperature of the protostar reaches 10 million K and fusion of hydrogen into helium begins in the core.
Question: Which of the following groups of molecules can participate in a hydrogen bond as a hydrogen bond donor?
Answer Options:
NH3+
CH3
C=O
C≡N
Answer: NH3+
Question: Which of the following carbohydrates is a nonreducing sugar?
Answer Options:
Glucose
Fructose
Lactose
Sucrose
Ribose
Answer: Sucrose
Question: Which of the following polysaccharides can bind exceptionally large amounts of water?
Answer Options:
Cellulose
Glycogen
Starch
Heparin
Amylose
Answer: Heparin
Question: Which of the following are true about disks around protostars? [More than one]
Answer Options:
Protostars all form a flattened disk, but by the time the star reaches the main sequence the disk has grown to be spherical.
By the time a star is about 10 million years old, the densest parts of most disks have been blown away by the central star.
The solar wind is weaker toward the equator of a disk of a star more so with cooler stars. The polar regions to be clear of dust. But the edge of a disk has more debris where the stellar wind is weakest.
Collapsing molecular clouds rotate slower so they condense and the central protostar becomes more massive. This is due to the conservation of angular momentum.
A protostar that is more than about 3 million years old will have a disk of gas and dust, but little dust will reside in the outer part of the disk. The inner region is clear of most dust.
Answer: By the time a star is about 10 million years old, the densest parts of most disks have been blown away by the central star.
A protostar that is more than about 3 million years old will have a disk of gas and dust, but little dust will reside in the outer part of the disk. The inner region is clear of most dust.
Question: What should you always do if you have to leave the lab for fuel or need a classmate who is unwell while in the midst of carrying out an experiment?
Answer: Inform lab instructor/TA.
Question: What functional group are present on this molecule?
Answer Options:
Ether and aldehyde
Hydrate and aldehyde
Hydrate and carboxylic acid
Hydrate and ester
Hydrate and ketone
Answer: Hydrate and aldehyde
Question: What actions should you take if the fire alarm goes off?
Answer: Stop all work and leave all chemicals and equipment in the lab. Follow the lab instructor’s instructions and exit the building as soon as possible. Assemble outside the building in the area directed by the lab instructor.
Question: What is the function of a lyase enzyme?
Answer Options:
To assist the substrate by binding to the enzyme, enabling substrate to achieve site engagement
To facilitate a reaction of one substrate to form new products with the use of water
To facilitate a reaction of one substrate to form two products without the use of water
To flip this
Answer: To facilitate a reaction of one substrate to form two products without the use of water
Question: In place of a nucleus a prokaryotic cell has a __________.
Answer Options:
Mesosome
Carboxysome
Nucleoid
Ribozyme
Reticulosome
Answer: Nucleoid
Question: Determine the pH of the following solutions who’s moles of H+ are 0.002 in a total volume of 5L.
Answer Options:
2.60
3.60
3.40
4.30
7.00
Answer: 3.60