Download Grade 12 Review Answers

Unit 1: Biochemistry
Try these questions:
1. Channel proteins are located in this part of a cell:
a) nucleus
b) cell wall
c) membranes
d) cytoskeleton
2. Hydrogen bonding occurs between:
a) water and water
b) water and a polar molecule
c) two hydrogen-containing polar molecules d)
a polar hydrogen
and a polar oxygen
e) all of the above
3. A piece of celery is placed in a bowl of cold water. Which of the following best
describes what happens to the cells of the celery?
a) they shrivel
b) water moves out of the cells by osmosis
c) water moves into the cells by osmosis, and the cells become more plump
d) water moves into the cells by active transport, and the cells become more plump
e) nothing happens
4. Which of the following functional groups are uniquely associated with amino acids?
a) amine
b) hydroxyl
c) carboxyl
d) none of these
5. Facilitated diffusion requires:
a) specific proteins in the cell membrane
b) ATP
c) several ions moving down their concentration gradient
d) sugar or similar energy source
e) cholesterol
6. Many biological molecules are polymers. List three types of polymers commonly
found in cells. Identify the monomers of each.
Polymer
Starch
DNA or RNA
Protein
Lipids
Monomer
Glucose
Nucleotide
Amino acids
Fatty acids
7. Name the types of chemical reactions that occur in biological systems, and give an
example for each.
Type of Reaction
Example
Condensation
Connecting monomers to form polymers
(ex. connecting many glucose molecules
together to form a starch molecule)
Hydrolysis
Breaking polymers apart to form
monomers (ex. breaking a protein apart to
form many amino acids)
Neutralization
Carbonic acid / hydrogen carbonate buffer
system which regulates blood pH
Oxidation-Reduction reactions
Oxidation of glucose and reduction of
oxygen in cellular respiration
8. What is exocytosis?
Exocytosis occurs when a vesicle (container)
merges with the cell membrane and ejects its
contents into the extracellular space. The contents
might be wastes or materials (like hormones) that
are needed in a different part of the body.
9. Describe the two types of endocytosis.
Phagocytosis is when solid materials (food, bacteria) are taken in to a cell and
pinocytosis is when liquids are taken in. In both cases, the cell membrane surrounds
the material to be ingested and a vesicle forms to contain them.
10. Should a hypertonic, hypotonic or an isotonic solution be used to produce a wet
raisin from a grape? Justify your selection and predict any potential problems with
this procedure.
In order for a grape to turn into a raisin, water would need to exit the cells of the grape
so that it shrinks. The concentration of water inside the grape cells would need to be
higher than in the solution surrounding the grape. This is a hypertonic solution.
Potential problems: what is the concentration of water inside grape cells? As water
flows out of the grape cells, the relative concentrations of water inside and outside will
be changing.
11. Draw the structure of a phospholipid and indicate the fatty acid tails and head group.
Identify each part as polar/nonpolar and hydrophobic/hydrophilic. Describe how
these properties contribute to cell membrane structure.
The hydrophilic heads like to be near water (the fluid inside
and surrounding the cell) and the hydrophobic tails want to
avoid water. The easiest way to achieve these goals is to
form two layers, with the tails all pointing inwards towards
each other and the heads forming an outer surface.
12. Illustrate an enzyme-substrate complex and label key features of the structure.
The enzyme is a biological catalyst.
The substrate is the material or
materials that are undergoing a
reaction. The shape of the protein’s
active site is an exact match for the
substrate(s) whose reaction it
catalyzes. They fit together like a
lock and key.
13. Identify each of the following in the figure below:
a) the type(s) of biological macromolecule(s) in the reactants
b) the type(s) of biological macromolecule(s) in the products
c) the type(s) of biochemical reaction(s) that occur
Reactants
Products
Triglyceride + Water
Glycerol + Fatty Acids
Type of reaction: Hydrolysis
Text pp. 86 – 87 # 7, 8, 11, 12, 17, 18, and pp. 196 – 199 # 6, 12
Unit 2: Metabolic Processes
Try these questions:
1. ATP supplies the energy that drives most cellular activities. The ultimate source of
the energy contained in ATP is:
a) glucose
b) sunlight
c) ADP
d) ATP synthase
e) carbohydrates
2. Which of the following compounds binds to CO2 during the Calvin cycle?
a) ribulose bisphosphate
b) glyceraldehyde-3-phosphate
c) adenosine triphosphate
d) ATP synthase
3. In cellular respiration, the energy released by the electron transport chain pumps
hydrogen ions across the membrane from:
a) matrix to cytoplasm
b) cytoplasm to matrix
c) intermembrane space to matrix
d) matrix to intermembrane space
e) cytoplasm to intermembrane space
4. Why do leaves appear green?
a) the green portion of the light that strikes them is converted to heat
b) the green portion of the light that strikes them is absorbed
c) the green portion of the light that strikes them is destroyed
d) the green portion of the light that strikes them is reflected
e) the green portion of the light that strikes them is converted to other colours
5. List the end products of the following:
a) glycolysis – pyruvate
b) Krebs cycle – NADH, FADH2, ATP
d) Calvin cycle – G3P (which makes glucose and other products)
6. What is the relationship between aerobic cellular respiration, glucose, and oxygen?
Aerobic cellular respiration is the process used to turn glucose and oxygen into energy
(in the form of ATP) to carry out cellular functions.
7. Draw a diagram that shows the roles of the
mitochondria and chloroplasts in cellular
respiration and photosynthesis in plants, and how
the two are linked. Include the organelles
involved, the reactants and final products of each
overall reaction, the electron carriers involved,
and where ATP is produced.
Electron carriers:
Mitochondria: NADH, FADH2, ETC
Chloroplast: NADPH, ETC
ATP Production:
Respiration: glycolysis (cytoplasm); Krebs
cycle (mitochondrial matrix); ETC (inner
mitochondrial membrane)
Photosynthesis : ETC (thylakoid
membrane of chloroplast)
8. Use a Venn diagram to compare and contrast the products of the type of
fermentation that occurs in your cells with the products of fermentation that occurs in
yeast cells.
Human body cells
Organism is aerobic
Pyruvate is converted to
lactic acid
Both
Glycolysis converts
glucose to pyruvate
Produces 2 ATP
NADH is an electron
carrier
Yeast
pyruvate is converted to
ethanol (alcohol)
9. Pyruvate is available as a dietary supplement. Its reported benefits are
controversial, but include enhanced weight loss and increased endurance levels
during physical exercise. Infer how taking pyruvate as a dietary supplement could
lead to these effects.
Pyruvate is the end product of glycolysis and the starting reactant for the Krebs cycle
Miss out on production of 2 ATP from glucose in glycolysis
Don’t need to consume as many calories to produce energy, so taking
pyruvate supplements would mean that your body requires less food intake to
produce 2 ATP from Krebs cycle and up to 34 ATP from ETC.
Lots of energy produced with less food consumed
Text pp.196 – 199 # 13, 15, 16, 17, 18, 23, 24, 27, 45
Unit 3: Molecular Genetics
Try these questions:
1.
What is the name of the process that transfers information from DNA to RNA?
a) translation
b) synthesis
c) replication
d) transcription
e) elongation
2.
What is the corresponding anticodon for the mRNA codon CGA?
a) 5’-GCT-3’
b) 5’-GCU-3’
c) 3’-CGA-5’
d) 3’-GCT-5’
e) 3’-GCA-5’
3.
Which type of mutation would occur if there was a change in the sequence GUUCAU-UUG that caused UUG to become UAG?
a) frameshift
b) substitution
c) silent
d) deletion
e) beneficial
4.
Why does replication occur in opposite directions?
A new strand can only be made in the 5’ to 3’ direction
because the 3’ end of the DNA strand has an –OH
group, which can be used to attach new nucleotides.
The 5’ end has a phosphate group, which does not
easily bond to new molecules. The two DNA strands
are antiparallel, meaning that the 5’ end of one strand is
hydrogen bonded to the 3’ end of the other, so
replication need s to occur in two directions at once.
5.
If the bases on the opposite strands of DNA paired through covalent bonds, what
effect would this have on DNA replication?
Covalent bonds are much stronger than hydrogen bonds, which is what holds the
opposite strands together. Therefore, covalent bonds would be harder for helicase to
break, which would make DNA replication and the transcription stage of protein
synthesis much more energy-intensive for cells.
6.
“A mutation in a gene’s exons is more damaging than a mutation in a gene’s
introns.” Do you agree or disagree? Explain why.
Exons code for a particular part of a protein (i.e. they contain genes) while introns are
actually removed before protein synthesis because they don’t actually code for
anything. A mutation in exons is therefore much more damaging than a mutation in an
intron (which would essentially be a silent, or neutral, mutation).
7.
A sample of DNA has 26% thymine. What do you expect would be the
approximate proportion of adenine, cytosine, and guanine in the sample?
Thymine pairs with Adenine, so there would be an equal amount (26% each) of A & T
(52% total of the DNA). The remaining 48% would be split evenly between cytosine and
guanine, which pair together, so there would be 24% of each of C & G.
8.
THE DOG WAS MAD.
a) How might the sentence change if it were subjected to a frameshift mutation?
THE DOW ASM AD (deletion) or THE DOG SWA SMA D (addition)
b) How might the sentence change if it were subjected to a substitution mutation?
THE DOG WAS BAD
c) How might the sentence change if it were subjected to a deletion mutation?
THE OGW ASM AD
9.
The coding strand of a segment of DNA has the sequence 5’-GTTAAAGGC-3’.
a) What is the corresponding mRNA codon sequence?
3’-CAA UUU CCG-5’
b) What is the anti-codon sequence?
5’-GUU AAA GGC-3’
c) What is the polypeptide sequence?
Gln – Phe - Pro
10. Describe/define each of the following and draw and/or label them on the diagram to
the right.
a) Okazaki fragments –short fragments of DNA
that form during replication of the lagging strand
b) leading strand – new strand that is synthesized
continuously
c) lagging strand – new strand that is synthesized
in fragments
d) DNA polymerase – enzyme that synthesizes new
strands of DNA by bonding the proper nucleotides
(located at the arrow end of new strands of DNA)
e) Helicase – enzyme that separates double-stranded DNA into two single strands
for replication (located at the “fork” of the two DNA strands)
f) Primase – enzyme that builds RNA primers, which are the starting points for
new DNA strands to form (located on DNA template wherever a new strand is
about to be synthesized)
g) Ligase – enzyme that removes RNA primers and joins Okazaki fragments
together (located on new strand between two completed Okazaki fragments)
11. The coding strand of a segment of DNA in a bacterial chromosome has the
following base sequence: 5’-TACACATGCATC-3’.
a) Draw a section of the double-stranded DNA molecule that includes this
segment.
5’ – TACACATGCATC – 3’
3’ – ATGTGTACGTAG – 5’
b) Which end of the segment has a free –OH group?
3’ end
c) Show how a nucleotide substitution could result in a silent mutation of this gene.
mRNA: 3’ – AUG UGU ACG UAG – 5’
Polypeptide: Start – Cys – Thr – Stop
So… because Thr could also be coded by ACU, ACC, or ACA, a substitution in
the DNA that would be completely neutral (silent) could be:
5’-TACACATGGATC-3’
Text pp. 324 – 327 # 3, 4, 5, 6, 7, 10, 40
You will be provided with a
table similar to this one to use
during your exam.
Unit 4: Population Dynamics
Try these questions:
1. A biology student wants to determine the population of sea gulls on a small island in
the middle of a lake. Which is the best method for the student to use?
a) mark-recapture b) nest monitoring c) quadrats
d) scats
e) transects
2. On the graph below, what does the dashed line at the top indicate?
a) carrying capacity b) growth rate
c) lag phase
d) linear growth
e) rapid growth
3. Life strategies of various populations can be represented as r-selected or Kselected. Which of the following is not a characteristic of an r-selected population
a) the growth rate is unpredictable
b) the organisms have a short life span
c) there is little parental care
d) the population size rarely exceeds the carrying capacity of its environment
e) all of these are characteristics of r-selected populations
4. The growth of a population of paramecia is limited by heating the culture. Which of
these is true?
a) heat is a density-dependent limiting factor
b) heat is a density-independent limiting factor
c) paramecia grow at its biotic potential when heated
d) the warm temperature is optimal for the growth of the paramecium
e) none of these is true
5. The population whose age pyramid is shown below does not have which of these?
a) a high birth rate
b) a high death rate
c) a long life expectancy
d) a large number of children
e) a high percentage of young people
6. A parasitic mistletoe plant attaches its roots to an oak tree and absorbs nutrients
from the tree. What effect will the mistletoe have on the oak?
Negative. The tree will have fewer nutrients available to it and may be weak, small,
susceptible to disease, and it may die.
7. List three consequences of the expanding size of the human population.
Increased competition for resources, increased pollution, more rapid spread of disease.
There are many more possible answers here!
8. A population of 500 fish faced a problem of biomagnification resulting in a large
number of deaths. At the same time, 200 births took place, 27 fish immigrated into
the population and 15 fish migrated out. If the final population size was 350 fish,
how many deaths took place?
Population change = [(b+i)-(d+e)]
150 = [(200+27)-(d+15)]
150 = 227-(d+15)
150-227 = -d-15
-77+15 = -d
-139=-d
d=139
9. A species of rabbit shares the same physical environment as a species of tortoise.
The tortoises take time to grow a hard shell as a shield from predators and develop
a slow metabolism to survive for periods without food. The rabbits are easily killed
by predators and by temporary periods without food. Classify these species as rselected or K-selected and explain your classifications.
Rabbit: r-selected – short life span and quick reproduction (early maturity, lots of
babies, lots of reproductive cycles)
Tortoise: K-selected – long life span and well-adapted for environmental conditions
Remember: tortoises don’t give much parental care, but in comparison to the rabbits in
this situation, tortoises are K-selected
10. The per capita growth rate for a certain population is -4.5%. Explain what this
means, and what processes might account for these changes.
This means that the population is shrinking by 4.5% every year (i.e. for every 1000
people in the population, 45 people are lost from the population). Processes leading to
this depend on a lot of factors, like the species, the geographic region, etc., but may
include scarcity of resources, introduction of a predator, pollutants that affect
reproduction or life span, etc.
Text pp. 756 – 759 # 1, 2,
3, 4, 6, 10, 11, 14, 22, 23,
27
The following formulae will
be provided on your exam.
Unit 5: Homeostasis
Big Ideas:
Organisms have strict limits on the internal conditions that they can tolerate.
Systems that maintain homeostasis rely on feedback mechanisms.
Environmental factors can affect homeostasis.
Overall Expectations: You should be able to…
evaluate the impact on the human body of selected chemical substances and of
environmental factors related to human activity;
investigate the feedback mechanisms that maintain homeostasis in living
organisms;
demonstrate an understanding of the anatomy and physiology of human body
systems, and explain the mechanisms that enable the body to maintain
homeostasis.
Try these questions:
1. The organization of neurons that enable you to react rapidly and involuntarily in
times of danger is called:
a) a sensory pathway
b)
a positive feedback
loop
c) the central nervous system
d) a reflex arc
e) the autonomic nervous system
2. Suppose a person is relaxing in front of the television after eating a large meal.
Which component of the autonomic nervous system is activated when the body is
calm and at rest?
a) central NS
b) peripheral NS
c) somatic NS
d) sympathetic NS
e) parasympathetic NS
3. Which list represents the correct order of structures through which urine flows to
reach the external environment?
a) renal medulla, renal artery, renal cortex
b) renal cortex, renal vein, renal medulla
c) kidneys, ureters, urinary bladder, urethra
d) urethra, urinary bladder, ureters, kidneys
e) renal vein, glomerulus, Bowman’s capsule, collecting duct
4. Which structure is correctly matched to its function?
a) Bowman’s capsule –reabsorption
b) Glomerulus – secretion
c) Collecting duct – secretion
d) Glomerulus – filtration
e) Bowman’s capsule – water reabsorption
5. Clearly distinguish among the three processes (filtration, reabsorption, and
secretion) involved in the production of urine.
Filtration: moves water and solutes from blood plasma into the nephron
Reabsorption: moves useful substances back into the blood stream from the
filtrate
Secretion: moves additional wastes and excess substances from the blood into
the filtrate
6. Suppose you stub your toe on a chair leg. Your foot recoils before you feel any pain.
a) Draw a flowchart of the nerve pathway that is involved in this reaction
b) What is this reaction called? Reflex arc
c) How does this reaction protect you? Shortens the amount of time required for
a reaction because the message that you are in imminent danger (ex. from
putting your hand on a hot stove, or that something is about to hit you in
the eye) doesn’t need to travel all the way to the brain before your body
reacts (ex. by pulling your hand away or closing your eyes). Your brain will
receive the pain signal after the protective reflex has already occurred.
7. On a dare, a high school student drinks 4 L of water in 20 min.
a) How would this affect the concentration of substances in the student’s blood?
Concentration of water in the blood would be high, meaning that the
concentration of solutes (glucose, salts, etc.) would be lower.
b) Describe how homeostasis could be restored. As blood gets more dilute,
fluids enter the hypothalamus, where osmoregulators sense a change.
Nerve messages to the pituitary gland stop the release of ADH (antidiuretic
hormone), and less water is reabsorbed from the nephrons, which means
more water continues to the bladder (increased urination).
Text pp. 500 – 503 # 1, 2, 14, 24, 25