BIO SCI 93 Midterm #1 Exam Questions
with Revised Correct Detailed Answers with
Rationales Guaranteed Pass
What is the difference between an element and a compound?
- ans -an element cannot be broken down to other substances by chemical
reactions & a compound is made up of two or more DIFFERENT elements
What is the difference between a single bond and a double bond?
- ans -a single bond is a pair of shared valence electrons & a double bond is the
sharing of two pairs of valence electrons
What is electronegativity? - ans -the attraction of a particular atom for the
electrons of a covalent bond (think oxygen and hydrogen). non polar covalent
bonds share the electrons equally because the atoms sharing them, are equal in
electronegativity; unlike polar bonds (H2O)
What is a salt? - ans -compounds formed by ionic bonds (NaCl)
What are Van der Waals interactions? - ans -weak forces that occur only when
atom and molecules are very close together. they occur because electrons are not
always evenly distributed. (ex: gecko walking on a wall)
Why does it mean when a reaction has reached chemical equilibrium? - ans -It
mens is has reached the point at which the reactions offset one another exactly.
What is a molecule? - ans -Two or more atoms covalently bonded together
What is the difference between a non-polar covalent bond and polar covalent
bond? - ans -A non polar covalent bond is a bond where the electrons are being
shared equally and the restructure of the molecule is equal if you cut it n half
(CH4). A polar covalent bond is a bond that does not share the electrons Evelyn
because of the difference in electronegativity amongst the atoms (H2O)
,What is an ionic bond? - ans -A bond between a cation (+) and an anion (-) where
an electron is taken/given
What is hydrogen bond? - ans -A weak bond between two molecules resulting
from the attraction between a proton in one molecule and an electronegative
atom in the other (H2O)
What is a chemical reaction? - ans -The making and breaking of chemical bonds,
leading to changes in the composition of matter. The reactant in a reaction is the
stating material and the product is what you get after the reaction.
What is a solution, solvent, and solute, and an aqueous solution? - ans -Solution: a
liquid that is a complete homogenous mixture of two or more substances.
Solvent: a dissolving agent.
Solute: a substance that is dissolved.
Aqueous solution: the solute is dissolved in water; water is the universal solvent
What is the difference between an acid and a base? - ans -Acid: a substance that
increases the hydrogen ion concentration in a solution. Base: a substance that
reduces the hydrogen concentration/increases hydroxide concentration in a
solution (some accept hydrogen ions like NH3 + H+ --> NH4+). Strong acids and
bases don't dissociate completely in water.
What is the pH scale and what is a buffer? - ans -pH scale measure how acidic or
basic a solution is and a buffer is a substance that minimizes changes in [H+] and
[OH-] in a solution. Most buffers contain a weak acid and its corresponding base,
which combines with H+
What is a hypothesis? - ans -a testable explanation to a question (can never be
proven)
What is a prediction? - ans -a statement about an uncertain event
What is an experiment? - ans -a scientific test (to show if the hypothesis was
accepted or rejected), carried out in controlled conditions
, How is a theory different than a hypothesis? - ans -a theory is broader in scope,
general enough to spin a new testable hypothesis, and it is generally supported by
a greater body of evidence
What are functional groups? - ans -Chemical groups that are directly involved in
chemical reactions. Each functional group has different properties; such as shape
and change, that cause it to participate in a certain way.
Hydroxyl group - ans -Forms hydrogen bonds with water because of its polarity
and it helps dissolve compounds like sugar. An example is ethanol which is an
alcohol (its compound name)
Carbonyl group - ans -Compound name: Ketone. Polar. The sugars with ketone
group= ketoses and sugars with aldehydes= aldoses. A ketone is a carbonyl group
within the carbon skeleton. An aldehyde is the carbonyl group at the end of the
carbon skeleton. An example is acetone (simplest ketone) and propanal
(aldehyde).
Carboxyl group - ans -Compound name: organic acid. It is polar and acts as an acid
because it can donate an H+. It is covalently bonded between oxygen an
hydrogen. An example of this is acetic acid, which gives vinegar its sour taste.
Amino group - ans -Compound name; amine. It is polar and acts as a base because
it can pick up an H+ from its surrounding solution. An example of this is glycine, an
amino acid (note its carbonyl group).
Sulfhydryl group - ans -Compound name: thiol. It is nonpolar and when reacted, it
forms a "cross" link that helps stabilize protein structure such as hair. An example
of this is cysteine, a sulfur containing amino acid.
Phosphate group - ans -Compound name: organic phosphate. It is polar and
contributes an negative charge (1- the inside a chain of phosphates; 2- when at
the end of the chain). It releases energy because it reacts with H2O. An example
of the is glycerol phosphate which takes part in chemical reactions.
Methyl group - ans -Compound name: methylated compound. It is non-polar and
affects the expression of genes when on DNA or on proteins bound to DNA. It also
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Essiekarimi. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $11.99. You're not tied to anything after your purchase.
