Final Chem Practice Exam

Which compound is not matched with its correct name?

Na3N sodium trinitride

Which are possible consequences of increasing atmospheric concentrations of CO2 and other greenhouse gases?

Ocean acidification and Sea-level rise

The energy change for the reaction shown is -805kJ/mol. We can conclude therefore that energy is ______ during reaction and that CO2 and H2O are _____stable than CH4 and O2.

released; more

Fats are more “fattening” than carbohydrates because…

They provide more energy when metabolized

Breaking chemical bonds _____ energy

Costs

The “super aspirins” Vioxx TM and Celebrex TM…

Block the COX-2 enzyme but not the COX-1 enzyme

If the thymine (T) content of DNA is 29%, what is the content of adenine (A)?

29% because according to Chargaff’s rules: A=T and G=C

The carbon cycle refers to the…

movement of carbon through living organisms, the atmosphere, the oceans, and the Earth

A difference between glycogen and cellulose is…

the amount of branching in the polymer chains

Which orders the entities in terms of increasing size?

Nucleotide, codon, gene, chromosome

Which isotope has the same numbers of protons, neurtons, and electrons?

Si-28, C-12, and N-14

When O3 molecules absorb UV-C radiation…

A covalent bond breaks

A recent Pew research center survey (Fall 2023) of US adults found that 14% stated there was no solid evidence the Earth’s temperature was getting warmer, and 26% said any warming was due to a natural pattern. Pick one person from one of those groups and respond to their stance based on material we discussed this semester.

No warming— I know that the change of temperature is small, but the last 45 years have all been hotter than the 20th century every year. Glaciers are shrinking and ocean temperatures are rising.

Codon

Three consecutive bases in DNA

Triglyceride

An ester of three fatty acids

Enzyme

A protein that acts as a biological catalyst by accelerating chemical reactions

Ammonia (NH3) has a much higher boiling point (-33C) compared to PH3 (-125C) even though it has a lower molecular weight. Explain.

Nitrogen is the one of the most electronegative elements (with O and F) with hydrogen atoms bonded directly to the nitrogen. The large S- (on nitrogen and S+ on hydrogen). The hydrogen bonds that form between NH3 molecules need to be broken in order to boil, requiring a much higher temperature than PH3 requires.

Explain how the mutation of a single base in DNA can cause the wrong protein to be synthesized.

The DNA in each gene is divided up into codons which are three bases in a row. These codons are the “codes” for the order of amino acids in the protein. For RNA, say for example the normal codon UCG. That is the codon for the amino acid—> serine. If the C gets matched to “A”, that is a “stop” codon and would terminate the growing protein chain.

In September in class I predicted the first overnight freeze of the fall would occur on a clear night…and so it was. What was the basis of my prediction?

Clouds are made of H2O (droplets and vapor). H2o is greenhouse gas (Not as powerful as CO2, but more abundant). With clouds present, there is more heat-trapping gases close to the surface which doesn’t allow temperatures to drop as much as when skies are clear.