SECTION A
MULTIPLE CHOICE QUESTIONS.
( 50 marks )
You are required to answer ALL the questions in this section.
1.
Each element is unique and different from other elements because of the number of protons
in the nuclei of its atoms. Which of the following indicates the number of protons in an atom’s
nucleus?
2.
A
atomic mass
B
atomic weight
C
atomic number
D
mass weight
E
mass number
Calcium has an atomic number of 20 and an atomic mass of 40. Therefore, a calcium atom
must have
3.
4.
A
20 protons.
B
40 electrons.
C
40 neutrons.
D
A and B only
E
A, B, and C
A covalent bond is likely to be polar when
A
one of the atoms sharing electrons is much more electronegative than the other atom.
B
the two atoms sharing electrons are equally electronegative.
C
the two atoms sharing electrons are of the same element.
D
it is between two atoms that are both very strong electron acceptors.
E
the two atoms sharing electrons are different elements.
The sum of all the chemical reactions that occur in the body is known as
A
Anabolism
B
Metabolism
C
Catabolism
D
Differentiation
E
(A) and (B)
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5.
What is the difference between covalent bonds and ionic bonds?
A
Covalent bonds involve the sharing of protons between atoms, and ionic bonds
involve the sharing of electrons between atoms.
B
Covalent bonds involve the sharing of neutrons between atoms, and ionic bonds
involve the sharing of electrons between atoms.
C
Covalent bonds involve the sharing of electrons between atoms, and ionic bonds
involve the electrical attraction between atoms.
D
Covalent bonds involve the sharing of protons between atoms, and ionic bonds
involve the sharing of neutrons between atoms.
E
Covalent bonds involve the transfer of electrons between atoms, and ionic bonds
involve the sharing of neutrons between atoms.
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7
Nucleic acids are polymers composed of monomer units known as
A
Amino acids
B
Nucleosides
C
Nucleotides
D
Nitrogenous bases
E
polynucleotides
In ______ inhibition, another molecule is so close in shape to an enzyme's substrate that this
molecule can compete with the true substrate for the active site of the enzyme.
8.
A
noncompetitive
B
competitive
C
reversible
D
irreversible
E
feedback
The site on the enzyme surface where the reactant fits is the ____________.
A.
binding site
B.
active site
C.
allosteric site
D.
ATP site
E.
competent site
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9
_________________ is the end product of glycolysis and is the starting material for the Kreb's
cycle.
10.
11.
12.
13.
A.
Glucose
B.
Carbon dioxide
C.
Water
D.
Pyruvate
E
Lactate
Which phase of mitosis is associated with formation of the nuclear envelope?
A.
Prophase
B.
Metaphase
C.
Anaphase
D.
Telophase
E
Cytokinesis
The fluid-filled space that surrounds the cristae within a mitochondrion is called a ______.
A
thylakoid
B
stroma
C
matrix
D
grana
E
cytosol
Which organelle converts energy stored in carbohydrates into ATP?
A
lysosome
B
Golgi apparatus
C
chloroplast
D
mitochondria
E
nucleolus
Which of the following sequences represent the hierarchy of biological organization from the
least to the most complex level?
A
organelle, tissue, biosphere, ecosystem, population, organism
B
cell, community, population, organ system, molecule, organelle
C
organism, community, biosphere, molecule, tissue, organ
D
ecosystem, cell, population, tissue, organism, organ system
E
molecule, cell, organ system, population, ecosystem, biosphere
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14.
A species of mice can have gray or black fur and long or short tails. A cross between blackfurred, long-tailed mice and gray-furred, short-tailed mice produce all black-furred, long-tailed
offspring. Using the gene symbols G for black, g for gray, S for long and s for short, what would
be the genotype of a gray-furred, short-tailed mouse?
15.
A
GGSS
B
ggSS
C
ggss
D
GgSs
E
Ggss
If a human who is a tongue roller (T) and has unattached ear lobes (E) marries a person who
cannot roll their tongue and has attached earlobes, could they produce an offspring that was
also a non-tongue roller with attached earlobes? What would be the genotype of the first
parent? the second parent?
16.
A
yes; TtEe; ttee
B
yes; TtEE; ttEe
C
no; TTEE; ttee
D
yes: TTEe; ttee
E
unable to determine from the information given
In a F1 dihybrid cross (WwGg X WwGg) where W = round, w = wrinkled, G = yellow and g =
green, what is the probability of obtaining an individual that is wrinkled, green and truebreeding?
17.
A
1/16
B
9/16
C
3/16
D
¼
E
1/8
The end product of glycolysis is __________.
A
NADH
B
acetyl-CoA
C
lactate
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18.
19.
20
D
pyruvate
E
FADH2
What role does O2 play in aerobic respiration? It___________.
A
combines with acetyl-CoA at the start of the Krebs cycle
B
is given off as a by-product during the oxidation of pyruvate
C
combines with H2O to help drive the formation of ATP
D
is the final electron acceptor at the end of the electron transport chain
E
None of the above
During what stage of cellular respiration is the most ATP synthesized?
A
Glycolysis
B
Krebs cycle
C
Fermentation
D
Oxidative phosphorylation
E
Link reaction
The following events occur in the replication of DNA.
1. bonds between complementary bases break
2. bonds between complementary bases form
3. opposite strands separate
4. sugar-phosphate bonds form
5. free nucleotides pair with complementary nucleotides on each strand
In which order do these events take place?
21.
A
1 
5
4
B
1 
3  4
C
3 
5 
D
51
3
E
21354
2
2
__________signal the initiation of mRNA synthesis.
A
Telomerase
B
Promoters
C
Transcription factors
D
RNA primase
E
UAG or UGA
5
22.
Each element is unique and different from other elements because of the number of protons
in the nuclei of its atoms. Which of the following indicates the number of protons in an atomʹs
nucleus?
23.
24.
A
atomic mass
B
atomic weight
C
atomic number
D
mass weight
E
mass number
In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by
A
hydrogen bonds.
B
nonpolar covalent bonds.
C
polar covalent bonds.
D
ionic bonds.
E
van der Waals interactions
Why does ice float in liquid water ?
A
The high surface tension of liquid water keeps the ice on top.
B
The ionic bonds between the molecules in ice prevent the ice from sinking.
C
Ice always has air bubbles that keep it afloat.
D
Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water
molecules of liquid water.
E
25.
The crystalline lattice of ice causes it to be denser than liquid water.
Which one of the following is not found in prokaryotic cells ?
A
ribosomes
B
a membrane-bound nucleus
C
a cell wall
D
a capsule
E
pili
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SECTION B ( 30 marks ) STRUCTURED QUESTIONS.
You are required to answer ALL the questions in this section.
1.
In humans, acondroplasia “dwarfism” (D) is dominant over normal (d). A homozygous dominant
(DD) person dies before the age of one. A heterozygous (Dd) person is dwarfed. A homozygous
recessive individual is normal. A heterozygous dwarf man marries a dwarf heterozygous
woman. Give the genotype and phenotype ratio of the offspring.
(4 marks )
2.
Galactosaemia is a rare and potentially serious inherited condition. It is caused by a recessive
allele that reduces the ability of the body to break down galactose. A couple is expecting a
second child. Neither parent has galactosaemia but their first child does have galactosaemia
Using the symbols G and g, illustrate using a genetic diagram, determine the probability of the
couple’s second child not having galactosaemia.
3.
a)
b)
( 3 marks )
In eukaryotic cells, the enzymes for the Krebs cycle are located in the __________, and
those for the electron transport system are located in the ________
(2 marks)
In the diagram below, label processes A, B, C and D.
(4 marks )
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4.
a)
During interphase preceding meiosis, each chromosome replicates itself and becomes
two chromatids joined at the centromere. These identical chromatids are known as
sister chromatids. During the first division of meiosis, pairing of homologous
chromosomes takes place. When paired in this way non-sister chromatids from the
two chromosomes exchange segments of genetic material by breaking and
rejoining.
(i)
State the name given to the exchange of segments of chromatids by breaking and
rejoining.
(ii)
(1mark)
Name the stage of the first division of meiosis when this exchange of segments occurs.
(1 mark )
b)
The human ABO blood groups are A, B, AB and O. They are determined by a single
gene with multiple alleles. IA and IB alleles are codominant, but both these alleles are
dominant to the IO allele.
In a maternity ward, the identities of four babies became accidentally mixed up. The
ABO blood groups of the babies were discovered to be O, A, B and AB. The ABO blood
groups of the four sets of parents were determined and are shown in the table below.
Complete the table to match each baby to its parents by indicating :
•
the parental genotypes, using the symbols IA, IB and IO;
•
the blood group of the baby which belongs to each set of parents.
parental blood
groups
parental genotypes
baby blood group
O and O
AB and O
A and O
AB and A
(8 marks)
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5.
Yeast cells are placed in an apparatus with a solution of sugar (a major nutrient for yeast
metabolism). The apparatus detects bubbles of gas released by the yeast cells. The rate of
respiration varies with the surrounding temperatures as indicated by the data below:
Temperature (°C)
0
10
20
30
40
50
60
70
Number of bubbles of gas
produced per minute
0
3
7
12
7
4
1
0
a)
b)
Graph the results on the axes provided.
( 4 marks )
Determine the optimum temperature for respiration in yeast.
( 1 marks )
Respiration is a series of enzyme-catalyzed reactions. Using your knowledge of
enzymes and the data above analyze and explain the results of this experiment based
on the kinetic energy of particles.
( 2 marks )
SECTION C (15 marks ): EXTENDED ANSWER QUESTIONS
You are required to answer ALL the questions in this section.
1.
2.
Explain the structure and function of the following structures in the cell :
a)
Cell membrane
b)
mitochondria
( 10 marks )
a)
State the Law of Independent Assortment.
( 2 marks )
b)
In some chickens, the gene for feather color is controlled by codiminance. The allele
for black is B and the allele for white is W. The heterozygous phenotype is known as
erminette.
i)
If CB CB represents the genotype for black chicks and CW CW represents the
genotype for white chicks, write the genotype for erminette chicks.
( 1 mark )
ii)
If two erminette chickens were crossed, calculate the probability of producing
a black or white chick. ( Draw a Punnette diagram and show your working for
this answer).
( 2 marks )
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