Download Unit 1: The Science of Biology

Unit 1: The Science of Biology
• Q1: Define Biology
• A1: Biology is the study of living things
• Q2: List and describe the 5 major steps of the scientific
method
• A2: Although the exact number of steps may vary, the
process of science should follow the same basic steps of
the scientific method:
– State the problem or question
– Make observations and/or gather information (research)
– Make a HYPOTHESIS – based on your observations/research,
make a prediction of what you think will happen
– Design and conduct a controlled experiment
– Analyze data and draw a conclusion – determine WHY the
results of the experiment occurred and communicate your
findings
Unit 1: The Science of Biology
• Q3: Compare and contrast the terms
independent and dependent variable and give an
example of each
• A3: Independent variable is the condition of the
experiment that the scientist chooses to change
or do differently, while the dependent variable is
whatever is measured, observed, or recorded.
– For example, if I do an experiment to test the effects
of various types of fertilizer on the height of plants,
the TYPE OF fertilizer is the independent variable,
while the height of the plants is the dependent
variable
Unit 1: The Science of Biology
• Q4: What is a control, and what is its purpose in
the experiment?
• A4: The control (or CONTROL GROUP) is the part
of the experiment that you do NOT test. In other
words, it is the thing that you leave alone. For
example, in the experiment described in Q3, the
control group would be a group of plants that
received NO fertilizer. It is needed so that I can
compare my results to what is “normal.”
Unit 1: The Science of Biology
• Q5: List and describe the 5 characteristics of a living thing
• A5: Although the number of characteristics can vary, all
living organisms have the following basic characteristics:
– Organization: All organisms are made of one or more cells,
and each of these cells contains DNA
– Reproduction: All living things can make more living things of
the same species
– Growth & Development: All living things increase in size/mass
and change over time
– Maintenance of Homeostasis: All living things use energy
(metabolism) and respond to stimuli in their environment to
maintain stable internal conditions
– Adaptations formed through Evolution: All living things have
inherited characteristics and/or behaviors that help them
survive in their environment
Unit 1: The Science of Biology
• Q6: Define SCIENTIFIC THEORY
• A6: A scientific theory is an explanation of the
natural world that is based on evidence,
observations, and experimental data. It is a
logical explanation of how something works, for
which all the current evidence and research says
it is correct. REMEMBER, in science, a theory is
NOT “just a theory”!
Unit 2: Ecology
• Q7: Define ECOLOGY
• A7: Ecology is the scientific
study of the
interrelationships between
organisms and their
environment
• Q8: Distinguish between
populations, communities,
ecosystems, biomes, and
biosphere
• A8: (See Figure)
Unit 2: Ecology
• Q9: Draw and interpret food
chains and food webs
• A9: A food chain is a simple
diagram of one set of feeding
relationships in an
ecosystem, while a food web
is a more complex diagram,
showing ALL of the feeding
relationships in an ecosystem
Unit 2: Ecology
• Q10: Draw and interpret
energy pyramids based upon
mass
• A10: The amount of energy
that flows through can
ecosystem can be measured
using the BIOMASS of the
organisms in the food chain.
The biomass is the mass (or
weight) of living material in
each trophic level. Only 10% of
the biomass is transferred from
one trophic level to the next
(10% RULE)
Unit 2: Ecology
• Q11: Identify the various
TROPHIC LEVELS
• A11: A trophic level refers
to a “feeding level” in a
food chain. Producers
(autotrophs) make up the
1st trophic level, followed
by primary consumers
(heterotrophs), secondary
consumers, and top
(tertiary) consumers
Unit 2: Ecology
• Q12: Follow the energy
transfers through
ecosystems
• A12: THE 10% RULE says
that only 10% of the
energy that is captured in
the first trophic level
(plants) is passed on to the
next trophic level. The
other 90% of the energy is
used up by the organism
for its own metabolism, or
given off as heat
Unit 2: Ecology
• Q13: Differentiate
between biotic and abiotic
factors in various
ecosystems/biomes
• A13: Biotic factors are the
LIVING things in the
environment, while abiotic
factors are the NONLIVING thing in the
environment.
– For this question, be sure
to know how these factors
differ in the different
biomes (tundra, taiga,
deciduous forest, desert,
grassland, tropical rain
forest)!
Unit 3: Biochemistry
• Q14: List the 3 parts of an atom and
give their charge
• A14: An atom contains protons
(positive charge), neutrons (no
charge), and electrons (negative
charge)
• Q15: Define the following terms
and give an example – element,
compound
• A15: An element is a substance
made of only one type of atom that
cannot be broken down into any
simpler substance, such as carbon.
A compound is a substance made of
molecules, consisting of 2 or more
kinds of atoms, such as water
Unit 3: Biochemistry
• Q16: Define the term ion. How are
they formed?
• A16: An ION is an atom that has an
overall positive or negative charge
because it has gained or lost
electrons
• Q17: Compare and contrast ionic
and covalent bonding. Which one is
stronger?
• A18: A covalent bond is formed
when atoms share electrons (such as
in water molecules), while an ionic
bond is formed when atoms gain or
lose electrons, and are then
attracted because of opposite
charges. Ionic bonds are stronger
Unit 3: Biochemistry
• Q18: List 3 properties of water that make it
special
• A18: Water has the following properties (be
sure that you know what each of these means!)
– High heat of vaporization
– Capillary action
– Surface tension
– Expands when frozen
– Universal solvent
Unit 3: Biochemistry
• Q19: Define polarity
• A19: Polarity occurs when a molecule (such as
water) has a slight positive charge on one end and
a slight negative charge on the other end. This
causes the polar molecules to attract
• Q20: Define the following terms and describe how
they relate to each other: solution, solute, and
solvent
• A20: A solution is a mixture formed when one
substance is evenly dissolved in another substance,
such as salt water. The substance that is dissolved
is the solvent (salt), while the solvent is the
substance doing the dissolving (water)
Unit 3: Biochemistry
• Q21: Define pH. Compare/contrast acids &
bases
• A21: The pH of a substance is a measure of the
concentration of Hydrogen ions dissolved in the
substance. It is essentially a measure of how
acidic or basic a substance is. The pH scale goes
from 0-14. Anything with a pH below 7 is an
ACID; anything with a pH above 7 is a BASE.
Substances with a ph of 7 are NEUTRAL.
Unit 3: Biochemistry
• Q22: Define monomer & polymer
• A22: A POLYMER is a large molecule made up of
many smaller molecules or subunits. The smaller
molecule or subunit is the MONOMER
• Q23: List the 4 macromolecules. Give a function
for each. Describe what each one is made up of.
• A23: Polymer
Monomer
Function
(Macromolecule)
Carbohydrate
Glucose
Used for quick energy
Lipids
Fatty Acids
Used for energy
storage & insulation
Proteins
Amino Acids
Enzymes & building
structures
Nucleic Acids
Nucleotides
DNA & RNA
Unit 3: Biochemistry
• Q24: Define chemical reaction. List the parts of
a chemical reaction and give example.
• A24: A chemical reaction is process in which
chemical bonds are formed or broken. The
REACTANTS are what goes into a reaction; the
PRODUCTS are what is made from a reaction
• In the photosynthesis reaction below, the
reactants are water and carbon dioxide, while
the products are glucose and oxygen
Unit 3: Biochemistry
• Q25: Compare and contrast exothermic and
endothermic reactions
• A25: Exothermic reactions are chemical reactions
in which energy is released or given off (chemical
bonds are broken), while endothermic reactions
are chemical reactions in which energy must be
put into the reaction (chemical bonds are formed)
• Q26: Explain what activation energy is and how is
it used
• A26: Activation energy is the initial energy needed
to start a chemical reaction, similar to the “spark”
needed to ignite a fire
Unit 3: Biochemistry
• Q27 & Q28: Define catalyst. How are they used
in reactions? Why are enzymes called biological
catalysts?
• A27 & A28: A CATALYST is anything that speeds
up a chemical reaction, but is not used up in the
reaction. ENZYMES are a special type of protein
that act as a biological catalyst. They help to
start and/or speed up reactions in living things.
Unit 3: Biochemistry
• Q29: Explain the enzyme substrate complex and how it
works. Why is it compared to a lock and key model?
• A29: An enzyme bonds to a specific molecule (the
substrate) at a specific location on the molecule (known as
the active site). The enzyme and substrate molecules fit
together like a lock and key. Once bonded together, the
enzyme helps to break down the substrate into the
products.
Unit 4: Cells
• Q30: State the 3 parts of the cell theory.
• A30: The Cell Theory states that:
– All cells must come from preexisting cells
– The cell is the basic unit of structure and function
in all organisms
– All organisms are made of one or more cells
Unit 4: Cells
• Q31: Give the contributions of the following
scientists to the cell theory: Hooke, Leewenhoek,
Schleiden, Schwann and Virchow.
• A31: Cell Scientists
– Robert Hooke – examined cork cells; first to use the
word “cell”
– Anton van Leewenhoek – first to see living cells;
developed early microscope
– Schleiden – Examine plant cells; stated that all plants
are made of cells
– Schwann – Examined animal cells; stated that all
animals are made of cells
– Rudolf Virchow – 1st to see the nucleus and its role in
cell reproduction; concluded that all cells must come
from pre-existing cells
Unit 4: Cells
• Q32: Compare and contrast eukaryotic &
prokaryotic cells
• A32: Prokaryotes are BACTERIA only – they are
small, simple cells with NO ORGANELLES and NO
NUCLEUS. Eukaryotes are everything else except
for bacteria (plants, animals, etc.). The cells are
larger and more complex, and contain a nucleus
and other organelles.
• Q33: Define the term organelle and give the
function of each of the following organelles:
• A33: Please see the chart on page 199 of “zebra
book”, or follow the link below:
• http://www.biologyjunction.com/cell_functions.htm
Unit 4: Cells
• Q34: Compare and contrast
plant and animal cells.
• A34: Plant cells have a cell wall
and chloroplasts. Their cell wall
gives them more of a
rectangular shape, and they are
often larger. Animal cells have
centrioles, are more round in
shape, and they are typically
smaller
• Q35: List the parts of the cell
membrane and their functions.
• A35: The cell membrane
consists of 2 layers of
phospholipids, proteins,
carbohydrates and cholesterol
Unit 4: Cells
• Q36: Give the name of the current accepted model of the
cell membrane.
• A36: The currently accepted model of the Cell Membrane
is known as the Fluid Mosaic Model. It is referred to as
“fluid” because it is flexible, and a “mosaic” because it is
made of many different pieces (molecules)
• Q37: Compare active and passive transport including:
diffusion, osmosis, facilitative diffusion, endocytosis and
exocytosis.
• A37: Passive transport does NOT require energy because
the molecules are moving from an area of high
concentration to low concentration. Diffusion, osmosis,
and facilitated diffusion are types of passive transport.
Active transport does require energy because the
molecules are moving from low to high concentration.
Endocytosis and exocytosis are types of active transport
Unit 4: Cells
• Q38: Describe what happens to a cell in each of the following
solutions: hypotonic, isotonic and hypertonic. Draw an example of
each
• A38:
– Isotonic – concentration of water and solutes is equal inside and
outside of the cell; the cell has no net movement of water
– Hypertonic – The concentration of water inside the cell is HIGHER than
the concentration of water outside of the cell. Water will move OUT
of the cell
– Hypotonic – The concentration of water inside the cell is LOWER than
the concentration of water outside of the cell. Water will move into
the cell.
Unit 5: Cellular Reproduction
• Q39-Q41: List and describe each of the major
phases of the cell cycle. Explain the 3 steps of
interphase. Explain the 4 steps of Mitosis.
• A39-41: The Cell Cycle is the life cycle of the cell.
It consists of 3 main phases: Interphase, the time
when a cell is not dividing, but is doing all other
metabolic activities; mitosis, the process of cell
division; and Cytokinesis, the brief phase when
the 2 newly formed cells are cut apart.
• Interphase consists of 3 “sub-phases: G1 Phase
(the 1st growth phase), S Phase (when the cell is
SYNTHESIZING new DNA), and G2 Phase (the 2nd
growth phase).
• Mitosis consists of 4 phases:
– Prophase: when the cell PREPARES to divide
– Metaphase: when the chromosomes line up in the
MIDDLE of the cell
– Anaphase: when the sister chromatids are pulled
APART
– Telophase: when the TWO new cells begin to form
Unit 5: Cellular Reproduction
• Q42: Give 3 reasons that cells are limited on how large they can
grow before they must divide.
• A42: Cells must remain small because of 3 factors:
– Surface-Area-to-Volume: as a cell’s size increases, its volume
increases at a much faster rate than its surface are, and the cell
membrane cannot move molecule in and our quickly enough to
maintain homeostasis
– DNA: The DNA works like a set of instructions in the nucleus; if the
cell becomes too large, the DNA cannot control all of the cell’s
activities
– Diffusion: Diffusion is a SLOW process, so if the cell is large,
molecules cannot diffuse fast enough through the cell to maintain
homeostasis
Unit 5: Cellular Reproduction
• Q43: Define the follow terms and explain how they
are related to one another: chromosome, chromatin.
• A43: Chromatin and chromosomes are both DNA,
just in different forms. Normally, DNA is uncoiled in
the nucleus. This “relaxed” form of DNA is
CHROMATIN. When a cell prepares to divide in
Prophase, the DNA coils up very tightly. This tightly
coiled DNA is a CHROMSOME
• Q44:Name the 2 factors that regulate the cell cycle.
• A44: The cell cycle is regulated primarily by
ENZYMES. These enzymes (known as cyclindependent kinases) monitor the cell cycle and trigger
the process of cell division. These enzymes bind to
specialized proteins called CYCLINS to control cell
division
Unit 5: Cellular Reproduction
• Q45: What happens when the cell cycle grows out of control?
• A45: When a cell grows out of control, this abnormal cell
growth can potentially lead to the growth of a cancerous tumor
• Q46: What are stem cells? How are stems cells beneficial in
research?
• A46: Stem cells are cells that are undifferentiated, meaning
they have not yet started to develop into a specific type of cell.
Stem cells are particularly promising for researchers because
they could be used to generate any type of cell, which could
then be used to treat an injury (like a spinal cord injury) or cure
a disease (such as Sickle Cell Anemia)
• Q47: Name the levels of organization within an organism( start
with cells and build up)
• A 47: Cells  Tissues  Organs  Organ Systems  Organism
Unit 5: Cellular Reproduction
• Q48: What is the difference between gametes and somatic cells?
• A48: Somatic cells are “regular” body cells, such as skin, bone, or
muscle cells. Somatic cells are made through MITOSIS. Gametes are
reproductive cells: sperm or egg cells. These cells are made through
MEIOSIS, so they contain HALF the number of chromosomes (haploid)
• Q49: What is the difference between autosomes and sex chromosomes?
Which numbered pairs in humans are autosomes? Which pair are sex
chromosomes?
• A49: Autosomes are “regular” chromosomes. In humans, the
autosomes are pairs 1-22. Sex chromosomes are the pair of
chromosomes that differ in males and females. In humans, this is pair
23. Females have 2 X-chromosomes, and males have 1 X-chromosome
and 1 Y-chromosome.
• Q50: Define sexual reproduction and give it’s advantages.
• A50: Sexual reproduction involves the exchange of genetic material
between 2 organisms. The resulting offspring are genetically different
from the parents. Sexual reproduction gives an advantage to the species
because it provides GENETIC VARIATION. This diversity make the species
less susceptible to disease, and allows the species to become better
adapted to its environment.
Unit 5: Cellular Reproduction
• Q51: Explain the
process of meiosis.
Explain each step of
meiosis. How many
cells do you start
with? Are they
diploid or haploid?
How many daughter
cells do you end
with? Are they
haploid or diploid?
• A51: Meiosis is the
process that
produces gametes
(reproductive cells).
It involves TWO cell
divisions. The end
result is 4
genetically different
HAPLOID gamete
cells.
Unit 6: Cellular Energy
• Q1: Explain the difference between ATP & ADP
molecules.
• A1: ATP (Adenosine Triphosphate) is the
molecule that all cells use for energy (it is like
your cell’s fuel). Energy is stored in the bonds
between the 3 phosphates of this molecule.
When a cell needs to release this stored energy,
a phosphate is broken off to produce ADP
(Adenosine Diphosphate), a molecule with just 2
phosphates.
Unit 6: Cellular Energy
• Q2-Q3: Explain the process of
photosynthesis and include the following
information: organelle where it takes
place, the 2 major reactions and their
locations within the organelle and the
overall chemical reaction of
photosynthesis. (know what goes in, what
comes out). What is the role of
chlorophyll in the photosynthetic
reaction?
• A2-A3: Photosynthesis has two major
steps, which take place in the cholorplast.
Step one is the Light-dependent reactions.
Sunlight is absorbed by the chlorophyll,
and this energy is used to split a water
molecule. ATP and NADPH (another
energy storing molecule) are produced
and sent to the 2nd step. The 2nd step is
the Light-Independent reactions. The
products of the first step are used, and
carbon dioxide is take in. As a result,
sugars (glucose) are produced.
Unit 6: Cellular Energy
• Q4-Q5: Explain the process of glycolysis
including: where it takes place, what it
produces and if it requires oxygen. Explain the
process of cellular respiration include the
following information: organelle where it
takes place, the 2 major reactions and their
locations within organelle, and the overall
chemical reaction of cellular respiration.
• A4-A5: Cellular Respiration is the process that
breaks down the glucose in your food to make
ATP (energy). Glycolysis is the 1st step of
cellular respiration. It occurs in the
mitochondria and does NOT require oxygen
(anaerobic). Glucose is broken down to
produce ATP and NADH (an energy-carrying
molecule). After glycolysis, the 2nd and 3rd
steps of cellular respiration happen in the
mitochondria. The products of glycolysis are
sent to the mitochondria for the 2nd step,
which is Krebs Cycle (or Citric Acid Cycle). The
3rd step is the Electron Transport Chain. This
last step is the most important step because it
produces approximately 32 ATP.
Unit 6: Cellular Energy
• Q6: Explain the 2 different types of fermentation
and where they take place. Do they require
oxygen?
• A6: Fermentation is ANAEROBIC respiration,
meaning they do not require oxygen. They each
break down glucose to make 2 ATP molecules.
– Lactic Acid Fermentation – occurs in your muscle cells
when oxygen is not available; glucose is broken down to
produce 2 ATP and lactic acid as a waste product (which
causes muscle soreness)
– Alcoholic Fermentation – used by bacteria or yeast;
glucose is broken down to make 2 ATP, carbon dioxide,
and ethyl alcohol.
Unit 6: Cellular Energy
• Q7: Explain how photosynthesis
and cellular respiration are
related, (why one must rely on
the other to exist).
• A7: Photosynthesis uses carbon
dioxide and water (and sunlight)
to make glucose and oxygen.
Respiration uses what
photosynthesis makes (glucose
and oxygen) to produce what
photosynthesis needs (carbon
dioxide and water). They are
essentially opposite reactions;
the products of one are the
reactants of the other.
Unit 7: Genetics
• Q8: Define the following terms:
–
–
–
–
–
–
–
–
–
–
–
Genetics – The science of heredity
traits – an inherited characteristic
Heredity – the study of how traits are inherited over time
Gene – a section of DNA that controls a trait
allele – A form of a gene
homozygous – when an organism has 2 of the SAME allele
heterozygous - when an organism has 2 DIFFERENT alleles
Genome – the entire collection of genes in an organism
Genotype – the combination of genes and organism has
phenotype – the actual physical appearance or trait
Dominant – the “stronger” trait that hides or masks the other
trait
– recessive – the “weaker” trait that is hidden by the other trait
Unit 7: Genetics
• Q9:What is Mendel’s contribution to genetics?
• A9: Gregor Mendel was an Austrian monk who used
pea plants to study heredity in the 1860’s. He is
referred to as the Father of Genetics because he
developed important laws of heredity
– Law of Independent Assortment – The genes for each trait
separate independently from one another
– Law of Segregation – During Meiosis, the two alleles for
each trait separate, so that each parent passes on only
one allele for each trait
– Rule of Dominance – If an organism inherits both the
dominant allele and the recessive allele, the dominant
trait is shown
Unit 7: Genetics
• Q10: In the following problem, identify the genotype and
phenotype of the offspring. A red flower is crossed with a
blue flower. Red is dominant to blue. The red flower is
heterozygous and the blue flower is homozygous. Draw a
punnett square to show their offspring.
• A10: R = red; r = blue
– Heterozygous red = Rr
– Homozygous blue = rr
–
R
r
r
Rr
rr
r
Rr
rr
Unit 7: Genetics
• Q11: Define monohybrid cross? Dihybrid cross?
• A11: A monohybrid cross is a cross involving just
one trait. A dihybrid cross involves 2 traits
Unit 7: Genetics
• Q12: State the law of independent assortment? Whose
law is it?
• A12: Gregor Mendel developed the Law of independent
assortment, which states that the genes for each different
trait separate independently from one another (i.e., one
trait has nothing to do with another trait)
• Q13: Explain sex-linked genes, how are traits carried and
passed on.
• A13: Sex-linked traits are traits that are controlled by
genes found only on the X-chromosome. Because females
have two X-chromosomes, they have two copies of these
traits. Males only have one X-chromosome, so they only
have one copy of these traits. These traits can be passed
from a mother to her children.
Unit 7: Genetics
• Q14: Compare and contrast co-dominance and
incomplete dominance. Write a problem and draw a
punnett square for each type of dominance.
• A14: Codominance is when neither trait is
dominant; instead, BOTH traits are expressed in
equal amounts at the same time. Incomplete
Dominance is when neither trait is dominant, but the
traits BLEND to produce something that is half-way
between the other traits. (Please see this Complex
Patterns of Inheritance PowerPoint from the class
website for examples)
Unit 7: Genetics
• Q15: List the four kinds of blood types and
explain which ones are dominant, heterozygous
and recessive.
• A15: 4 possible phenotypes – Type A, B, AB, O
• Type A and Type B are CODOMINANT; Type O is
RECESSIVE to A and B
Unit 7: Genetics
• Q16: Can a man be the father of an O blood type
child if he has AB blood and the mother has A type
blood?
• A16: NO! Be sure to show a Punnett Square to
prove your answer (Parents: IAIB x IAi)
• Q17: Are males able to be carriers of X-linked
disorders? Are females? Why or why not?
• A17: Males can NOT be carriers of a sex-linked trait.
Because males only have one x-chromosome, they
only have 1 copy of the gene and cannot, therefore,
be carriers. Females, on the other hand, have 2 xchromosomes, so they can be carriers of a sex-linked
trait.
Unit 7: Genetics
• Q18: What is a pedigree and how is it used? What
does each symbol on a pedigree represent? Include:
shaded, unshaded and partial shaded symbols.
• A18: A pedigree is essentially a family tree that
shows the inheritance of a genetic trait over many
generations. Pedigrees are used to help determine
how a trait is inherited.
Unit 7: Genetics
• Q18: What is a pedigree and how is it used? What
does each symbol on a pedigree represent? Include:
shaded, unshaded and partial shaded symbols.
• A18: A pedigree is essentially a family tree that
shows the inheritance of a genetic trait over many
generations. Pedigrees are used to help determine
how a trait is inherited.
Unit 8: DNA
• Q19: What is the structure and
function of DNA, (be specific and
include: the nitrogen base
possibilities, sugar and backbone)?
• A19: DNA is composed of two strands
of nucleotides. Each nucleotide
consists of a deoxyribose sugar, a
phosphate, and one of 4 nitrogen
bases. The shape of a DNA molecule is
like a twisted ladder, and it is called a
double helix. The sides of the ladder
are made of of alternating sugars and
phosphates (the sugar-phosphate
backbone), and the “rungs of the
ladder are made up of the pair
nitrogen bases (Adenine, Thymine,
Cytosine, and Guanine)
Unit 8: DNA
• Q20: Name the scientists responsible for
identifying the structure of DNA.
• A20: The scientists who received the Nobel Prize
for their work in determining the structure of
DNA are James Watson and Francis Crick.
• Q21: Who is given credit for the base pair rules
of DNA and what are those rules?
• A21: Erwin Chargaff determined that Adenine
always pairs with Thymine, and Cytosine always
pairs with Guanine.
Unit 8: DNA
• Q22: Describe the structure of RNA.
• A22: RNA is a single-strand of nucleotides (single
helix). It contains the sugar RIBOSE, and does not
contain the base thymine
• Q23: Name the 3 types of RNA and their functions.
• A23: The three type of RNA are:
– Messenger RNA (mRNA) – delivers the message (gene) to
the ribosome
– Transfer RNA (tRNA) - brings the amino acid to the
ribosome
– Ribosomal RNA (rRNA) – makes up the ribosome; helps to
assemble the protein
Unit 8: DNA
• Q24: What base is found only in RNA and not DNA?
• A24: RNA does not contain Thymine (T). Instead, it
contains the base Uracil (U)
• Q25: Explain the process in detail of DNA
replication, include the enzymes involved, products
made and where it takes place.
• A25: DNA replication copies DNA in the nucleus.
First, an enzyme (helicase) unwinds the DNA and
separates the bases. The original strands are used
as a template, and new nucleotides are correctly
paired. Another enzyme, DNA POLYMERASE, helps
bond the two new molecules together.
Unit 8: DNA
• Q26: Explain the process of
transcription in detail and include
the enzyme involved, products made
and where it also takes place.
• A26:
• In transcription, a segment of DNA
(gene) in the nucleus is unwound by
the enzyme helicase to expose the
bases
• The DNA is used as a template to
make the strand of RNA
• RNA nucleotides arrange themselves
in order, according to the order of
bases on the DNA strand to make a
strand of MESSENGER RNA (mRNA)
• This mRNA will then leave the
nucleus and travel through the
cytoplasm to the ribosome to direct
the making of the protein
Unit 8: DNA
• Q27: Explain the process of Translation in detail and include where it
takes place and products made.
• A27:
• The tRNAs, each carrying an amino acid, come to the ribosome and hunt
for the correct place on the mRNA strand to put their amino acid
• Once they find the correct codon on the mRNA, they leave their amino
acid behind, adding it to the growing chain
• This process repeats, assembling the correct sequence of amino acids,
until a STOP codon is reached
• A STOP codon is a 3-base sequence on the mRNA that tells the ribosome
to stop adding amino acids to the chain
• The amino acids are bonded together using peptide bonds, and a protein
(polypeptide) is made!
• The CENTRAL DOGMA of Biology:
– DNA  RNA  PROTEIN  TRAIT
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Unit 8: Genetics
Q28: Define codon. Give the start
codon and a stop codon. Define anticodon. When does it get used?
A28:
Transfer RNA is the molecule that
carries the amino acids to the
ribosome to be added to the protein
tRNA “reads” the code on the mRNA
to make sure that the amino acids are
assembled in the correct order
On one end of the tRNA molecule,
there is a special three-base
sequence, known as the ANTI-CODON
This anti-codon on the tRNA will bond
only with is matching 3-base sequence
on the mRNA strand (which is called a
CODON).
The Start Codon is AUG – it tells the
process of protein synthesis to get
started
The STOP codon tells the process of
protein synthesis to STOP.
Transfer RNA is an RNA
molecule that is ‘bent’
into a unique shape. On
one end it carries a
specific amino acid, and
on the other end is the
anti-codon that will
determine where in the
protein chain that amino
acid is placed
Unit 8: Genetics
• Q29: Explain what a mutation is and how it can occur.
• A29: A mutation is any change in a DNA sequence. This is often a
random mistake that occurs in a cell when the DNA is being
synthesized.
• Q30: Explain the difference between the 2 types of gene mutations:
point and frame shift mutations. Give an example of each.
• A30: A point mutation is when only one base in the DNA is changed
(substitution). A frameshift mutation occurs when one or more DNA
bases is inserted or deleted. This “shifts” the decoding of the gene,
and often results in the production of the wrong protein. Therefore,
frameshift mutations are often more severe.
• Q31: Explain what a silent mutation is and why it is hard to detect.
• A31: A “silent mutation” refers to a point mutation that does NOT
result in the production of an incorrect amino acid, and therefore has
no effect on the organism. They are difficult to detect because they do
not change the protein that is being made and the organism remains
unaffected.
Unit 8: Genetics
• Q32: What is a karyotype and how is it used?
• A32: A karyotype is essentially a picture of a person’s chromosomes,
arranged in their homologous pairs. A karyotype is used to detect
disorders caused by chromosomal abnormalities.
Unit 9: Evolution
• Q33: Explain the theory of evolution.
• A33: Evolution is the gradual accumulation of
adaptations in a population over time so that the
species becomes better adapted to its environment.
• Q34: Distinguish between evolution by means of
inheritance of acquired characteristics and evolution
by means of Natural Selection
• A34: Lamarck stated that organisms could gain the
traits they needed, then pass those traits on to their
offspring (think of stretchy-necked giraffes). Darwin
theorized that organisms with the beneficial traits
survived and passed on these traits, while those with
the traits not suited to the environment did not
survive and reproduce
Unit 9: Evolution
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Q35: Explain Darwin’s Theory of Natural
Selection.
A35: Darwin proposed that a process
he called Natural Selection causes
species to change over time
1. Organisms produce more offspring
than can survive, which causes
competition for resources(food, water,
shelter, mates, etc)
2. There is variation within a species
3. Some variations help the organism
better survive in its environment.
These organisms are more likely to
survive and reproduce, passing their
genes on to the next generation
4. Over time, there will be more and
more individuals in the population with
the favorable trait. So, the whole
population gradually changes
(EVOLVES) over time to become better
adapted to its environment.
Unit 9: Evolution
• Q36:Describe common misconceptions regarding
evolution.
• A36: A common misconception about evolution is
related to time. Remember, evolution happens very
slowly over MILLIONS of years. These huge
timescales sometimes make it hard for us to “see”
evolution clearly.
• One of the most common misconceptions about
evolution is that it is a linear process; for example, a
monkey “turns in to a human.” This is NOT the case.
Evolution is NOT a straight line; it is much better to
think of it more as a bush or a tree with many
branches
• Another common misconception is that individual can
adapt and evolve (like Lamarck’s stretchy-necked
giraffes). This is NOT how evolution works. Evolution
only affects the whole SPECIES, not the individual.
Natural Selection is what causes a species to evolve.
Unit 9: Evolution
• Q37: Identify and explain
different types of scientific
evidence that supports the
theory of evolution.
• A37: Darwin’s Theory is
supported by many different
types of scientific evidence,
such as:
• Fossils clearly show that many
species have changed over
time; some fossils show
transitional forms
(intermediate species between
the old and new species)
• Continued on next slide…
More Evidence for Evolution
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Homologous Structures – many species
with common ancestry show similar
structures. For instance, the forelimbs of
many mammals show similar bone
structure, implying that there are all
modified versions of structures that
occurred in a common ancestor
Analogous Structures – unrelated species
living in similar habitats often have similar
structures that serve the same function,
such as the fins of a dolphin and a shark
Vestigial Structures – many species have
body parts that no longer serve any useful
purpose, like the pelvic bones of a whale,
or your appendix
Genetic Evidence – Today, similarities in
DNA and amino acid sequences show how
species may be related. For example,
humans and chimpanzees (our closest
living relative) share over 98% of our DNA