2024 AQA A-LEVEL BIOLOGY
BIOLOGICAL MOLECULES TOPIC 1
EXAM WITH CORRECT ANSWERS
What are monomers? - CORRECT-ANSWERSMonomers are *small units*
which are the components of larger molecules.
What are polymers? - CORRECT-ANSWERSPolymers are molecules made
from *many monomers* joined together.
What are examples of monomers? - CORRECT-ANSWERS*Monosaccharides,
amino acids* and *nucleotides*
What are examples of polymers? - CORRECT-ANSWERS*Polysaccharides,
polypeptides* and *polynucleotides*
What is a competitive inhibitor? - CORRECT-ANSWERSA substance with a
*similar shape* to the substrate and a *complementary shape* to the
enzyme's active site.
What is a non-competitive inhibitor? - CORRECT-ANSWERSA substance, *with
a different shape* that *binds to another site* on the enzyme other than the
active site.
How does the concentration of competitive inhibitors affect the enzyme
activity? - CORRECT-ANSWERSA competitive inhibitor binds to the active site,
blocking substrates to bind instead, *preventing enzyme-substrate complex*
to form, and rate of reaction increases at a lower rate.
How does the concentration of non-competitive inhibitors affect the enzyme
activity? - CORRECT-ANSWERSA non-competitive inhibitor binds to the
another site on the enzyme and this *causes the active site's shape* to
change, meaning that the substrate is not complementary and less enzyme-
substrate complexes are formed, meaning that rate of reaction is at a lower
rate.
Describe the structure of a nucleotide - CORRECT-ANSWERSMade up of a
*pentose sugar, a nitrogen-containing base and a phosphate group*.
, How is a polynucleotide formed? - CORRECT-ANSWERSA polynucleotide is
formed when two nucleotides join together by a *condensation reaction*
between the phosphate group of one nucleotide and the sugar of another.
The chain of phosphates and sugars is known as the *sugar-phosphate
backbone*.
What is the bond formed between two nucleotides? - CORRECT-ANSWERSA
*phosphodiester bond*.
What is DNA? - CORRECT-ANSWERSDNA (Deoxyribonucleic acid) is a
molecule found in all organisms. It *holds all the genetic information*.
What is the structure of each DNA nucleotide? - CORRECT-ANSWERSEach
DNA nucleotide consists of a *deoxyribose sugar*, an *organic base* and a
*phosphate group*.
What is the structure of a DNA molecule. - CORRECT-ANSWERSA DNA
molecule is twisted into a *double helix* composed of *two separate strands*
of polynucleotides joined together by a *hydrogen bonds between
complementary bases*.
What are the 4 possible bases that can be found in a DNA molecule and
which bases are complementary to each other. - CORRECT-ANSWERSThe
possible bases are *adenine, guanine, cytosine and thymine*.
*Adenine pairs with thymine* and *guanine pairs with cytosine*.through
complementary base pairing.
How does the structure of the DNA lead to their properties? - CORRECT-
ANSWERSThe *double stranded* feature helps DNA to become *more stable*
and act as template in semi-conservative replication.
The *coiled feature* helps the DNA to be *more compact*.
The complementary base pairing ensures semi-conservative replication to
occur as the *hydrogen bonds* between the bases are *weak* and can
*easily be broken* during semi-conservative replication.
Describe the process of DNA replication. - CORRECT-ANSWERSDNA
replication occurs in interphase by *semi-conservative replication*.
*DNA helicase* is used *separate strands and break the hydrogen bonds*
between both strands.
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