Endosymbiotic theory explains the origin of organelles, such as mitochondria and chloroplasts in eukaryotes, as once free-living prokaryotes that were later engulfed and became part of the host eukaryote. The following choices support the theory, except which one?
The following sequences show a partial segment of a DNA, wherein the first sequence encodes for the wild-type hypothetical protein, while the second sequence contains a mutation. What could be inferred with the protein encoded by the mutated DNA? #1 5’- GTGATAGCTTTGATAAGCGAAAGTTTGGAGAAGCTG-3’ #2 5’- GTGATAGCTTTGATAAGCTAAAGTTTGGAGAAGCTG-3’ Source: https://www.khanacademy.org/
Editorial convention: treat the displayed 5′→3′ sequences as coding strands, with codons starting at the first shown base.
Protein from mutated DNA has one different amino acid.
Protein from mutated DNA has a shorter amino acid sequence.
Protein from mutated DNA has a longer amino acid sequence.
Protein from mutated DNA has a completely different amino acid sequence.
Although not translated to protein, non-coding RNAs (ncRNAs) play a variety of important functions. Which of the following ncRNAs function in RNA silencing in order to downregulate gene expression?
One of the major types of vaccines developed against the SARS-CoV-2 is the adenovirus vector vaccine. Which of the following statements is not true regarding this vaccine?
It is made up of genetically-engineered adenoviruses which are common cold viruses.
The genetic material of adenoviruses is double-stranded DNA.
The genetic material is transcribed and translated in the cytoplasm to generate the SARS-CoV-2 spike protein.
The genetic material is devoid of replication genes of adenoviruses making the viral vector replication-incompetent.
The Chinese milk scandal happened in 2008 which significantly affected the big milk industry in China and its exports from Asia to Europe and the Americas. In total, 300 000 people fell ill, among them 50 000 babies and 6 deaths. It was reported that milk products, which on average contain 3.2 % protein, were adulterated by melamine (Lewis structure shown below). This artificially increases the reported amount of protein in a sample. Lewis structure of melamine. In any sample of melamine, calculate the average % nitrogen in a given amount of melamine. Use the following atomic weights: N=14, C=12, H=1.
Elemental analysis of a hydrocarbon $\mathrm{C_xH_yO_z}$ yielded showed it contains 54.5 % C and 9.1 % H. Which of the following hydrocarbons could correspond to this sample? (Use the following atomic weights: C=12, O=16, H=1) i. CH₂O ii. C₂H₄O₂ iii. C₂H₄O iv. C₄H₈O₂
A. i only
B. ii only
C. ii and iii
D. ii and iv
Editorial review: assess the printed choices and explain any scientific inconsistency. State any assumptions used.
Molnupiravir (structure shown below) is one of the drugs currently being developed against Covid-19. Which of the following is a correct list of the functional groups present in the compound?
A. Amide, aldehyde, ether, and alcohol
B. Amide, ketone, ether, ether, carboxylic acid, alcohol
C. Amide, aldehyde, ether, ether, carboxylic acid, alcohol
D. Amide, ketone, ether, ester, alcohol
Editorial review: assess the printed choices and explain any scientific inconsistency. State any assumptions used.
Calcium carbonate (CaCO₃) is present in the skeleton of corals, which is much affected by acidification of the ocean because of its reaction with acids that produces carbonic acid (H₂CO₃). The latter in turn decomposes into water and carbon dioxide. In an experiment, a researcher dissolved 2.35 g of CaCO₃ in 167 mL of 0.175 M HCl. How much volume of CO₂ at room temperature (25 C) and ambient pressure would this reaction release? Use the following atomic weights: Ca=40, C=12, O=16, H=1, Cl=35
A. 35.7 mL
B. 71.5 mL
C. 575 mL
D. 1.15 L
Editorial review: assess the printed choices and explain any scientific inconsistency. State any assumptions used.
The Tour de France is a 21-day cycling competition that brings professional athletes around France, passing through different cities and villages through the mountains of the Pyrenees and the Alps and finishing at the Champs Elysees in Paris. A typical biker cycles for six hours in a day, logging a speed record as follows: What is the total distance travelled by the biker during the first half of the 6 hour- cycle?
In 2020, the Nobel Prize in Physics was awarded to Roger Penrose for demonstrating that the formation of black holes can be predicted from what theory?
Smart materials respond to stimuli such as heat or light by changing their properties. For example, new drug carriers are being developed by researchers worldwide for the controlled release of drugs. To illustrate, an active drug (red circle) may be attached to a smart carrier (green triangle). Once the carrier reaches the target organ, light is applied to the organ to locally release the drug. This is especially important for diseases like cancer, where terrible side effects can occur if the drug affects the other parts of the body. In some cases, the carrier is in equilibrium between an active and inactive state (blue triangle), but only the former is sensitive to light while the latter is not: In a system consisting of a large number of carriers, one of these two is more stable than the other. In a trial drug being developed for cancer, the active state is less stable by 1.15 kJ/mol. Given a million pieces of drug carrier, what is the ratio of the number of carriers in the inactive state relative to the inactive state at 25 C?
Editorial correction: the second “inactive state” in the requested ratio is read as “active state”. Interpret the stated stability difference as a molar free-energy difference at the stated temperature.
In the photophysics of solar cells, it is assumed that during light absorption, only the electron density of pigments/sensitizers changes while the nucleus is relatively stationary. This is from what principle in quantum mechanics that says that electronic transitions happen very fast relative to motion of nuclei?
For the following problem, ignore gravity: An electron is placed through a uniform electric field of $1.00\times10^4$ N/C. Calculate the acceleration of the electron. (mass of electron=$9.1\times10^{-31}$ kg, charge of electron=$1.6\times10^{-19}$ C)
