Download 2016 Midterm Review Answer Key

BIOLOGY MIDTERM 2016 REVIEW
1. Which element was absent in the early earth’s atmosphere? (carbon dioxide,
Oxygen)
Oxygen
2. What is homeostasis? Homeostasis is maintaining a stable internal
environment.
3. Calculate the total magnification of a microscope using the following
formula:
Total Magnification = magnification of eyepiece x magnification of
objective lens
a. A microscope has an eyepiece lens with a power of 10X. The objective
lens being used has a power of 4X.
Total magnification = 40X
b. A microscope has an eyepiece lens with a power of 10X. The objective
lens being used has a power of 40X
Total magnification = 400X
c. A microscope has an eyepiece lens with a power of 10X. The objective
lens being used has a power of 10X.
Total magnification = 100X
Using the information given below to answer questions 4a and 4b.
You are conducting an experiment to determine if increased ultraviolet
radiation from the decrease in the ozone layer is killing off frog tadpoles.
After examining all of the data available in the library, you decide to go with
a hypothesis that increased ultraviolet radiation from the sun is killing off
the tadpoles. You design an experiment with a control and an experimental
group. Your control group (group 1) involves 100 tadpoles in a five gallon
container of water that is covered by glass (knowing that the glass will filter
out the ultraviolet radiation). The experimental group (group 2) will be set
up exactly like group 1, except that instead of being covered with glass, it is
covered with an acrylic Plexiglas, which will not filter out the U.V.
radiation. You then place the groups outside for a period of a month, and
observe the results.
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Number of tadpoles
started with
Number of tadpoles
finished with
Result
Group 1
Group 2
100
100
96
96
4a. Identify the independent variable and the dependent variable?
The independent variable is the acrylic plexiglass used to cover the
container and dependent variable is the number of tadpoles survived.
4b. Identify the control group and the experimental group?
The control group is the group 1, which was covered with glass and
the experimental group was group 2 that was covered by an acrylic
plexiglass.
5. List the functions of cell membranes.
a. To separate the inside environment of the cell from the outside
environment.
b. To regulate what enters or leaves the cell.
6. How does active transport differ from passive transport?
In active transport substances are moved across the cell membrane against
the concentration gradient using energy whereas in passive transport
substances are moved across the membrane from high to low concentration
without using energy.
7.
In an experiment, a group of students placed several raisins in a container with 100 milliliters of water. They covered the container and
let the raisins sit overnight. The students removed the raisins from the container and observed that they were larger. They also
observed that the volume of water in the container had decreased.
Explain why the raisins became larger? Name and describe the process that caused this change in the raisins.
Raisins became larger by gaining water. Since they had low concentration of
water inside as compared to the outside environment, water moved from
outside (higher conc.) to inside of the raisins. This process is called osmosis
in which water molecules move from an area where they are in high
concentration to an area of lower concentration across a semi-permeable
membrane.
8. Explain why placing peeled carrots in salty water makes them flaccid while
placing them in pure water makes them crisp and crunchy.
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Salty water is hypertonic to the environment inside the carrot cells. In
hypertonic solution, carrots lose water. This situation is reversed when
carrots are placed in pure water because carrots gain water by osmosis when
placed in hypotonic environment.
9. In active transport, molecules are moved against their concentration
gradient, whereas in passive transport molecules are moved with the
concentration gradient.
10.What critical role do enzymes play in the living systems? Can an organism
function normally if an enzyme is either lacking or is dysfunctional? What
could be the cause of a dysfunctional/absence of an enzyme in a living
system?
Enzymes are critical for all living things because they catalyze/speed up
chemical reactions. An organism cannot function normally without an
enzyme or if the enzyme made in the cells is defective/dysfunctional. The
main cause of a dysfunctional/absence of an enzyme is a mutation in the
gene, which codes for that particular enzyme. Mostly frameshift mutations
caused by deletion/insertion or nonsense mutation caused by substitution
result in dysfunctional proteins or for the absence of proteins.
11.True/False: Bacteria are prokaryotic organisms.
12.Identify the illustrations shown below as prokaryotic bacterial cell,
eukaryotic plant cell or eukaryotic animal cell. Circle the cell that can most
likely conduct photosynthesis.
Prokaryotic bacterial cell
Eukaryotic animal cell
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Eukaryotic plant Cell
13.A cell containing a cell wall, chloroplasts and one/two large central vacuole
is a plant cell.
14. A cell that lacks chloroplasts and a cell wall is an animal cell.
15.The products of cellular respiration are CO2, H2O and ATP.
16.Photosynthesis takes place in the chloroplasts of plant cells.
17.The products of photosynthesis are Glucose/C6H12O6 and Oxygen/O2.
18.ATP molecules are used by organisms to transfer/store energy.
19. Oxygen is produced by photosynthesis, which most organisms use to break
down glucose to get energy by a process called cellular respiration.
20.Carbon dioxide is used by photosynthesis, which is produced by
heterotrophic organisms during cellular respiration.
21.True/False: Carbon dioxide concentrations are higher in winter than in
summer because the amount of photosynthesis conducted by plants is lower
in winter than in summer.
22.True/False: The amount of O2 production is lower in an area where there
are many trees.
23.Explain why the concentration of CO2 is lower near the tomato fields as
compared to an area that does not have any plants during day time.
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The concentration of CO2 is lower near the tomato fields as compared to an
area that does not have any plants because plants remove carbon dioxide to
use it as a raw material for photosynthesis. They add oxygen via
photosynthesis to the environment.
24.Summarize the process of Cellular respiration and Photosynthesis in
chemical equations.
Photosynthesis
6CO2 + 6H2O+ Sunlight
C6H12O6 + 6O2
Cellular Respiration
C6H12O6 + 6O2
6CO2 + 6H2O +ATP
25.Can photosynthesis and cellular respiration processes be thought of as
opposite processes? Why?
Yes, the products of photosynthesis are the reactants of cellular respiration
26.Why is cellular respiration and photosynthesis important for maintaining
life?
Cellular respiration and photosynthesis important for maintaining life.
Living things are dependent on plants for food/glucose and oxygen, and they
are dependent on cellular respiration for breaking down glucose to obtain
energy. Carbon dioxide produced as a result of cellular respiration is used by
plants as a reactant for photosynthesis while oxygen produced by plants
through photosynthesis is used for cellular respiration to oxidize glucose.
27.To investigate the processes of photosynthesis and cellular respiration, a
group of students sets up an experiment with four flasks as shown.
Flask 1: 100 mL water, 1 mL bromothymol blue, plant
Flask 2: 100 mL water, 1 mL bromothymol blue, 2 small fish
Flask 3: 100 mL water, 1 mL bromothymol blue, plant and 2 fish
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Flask 4: 100 mL water, 1 mL bromothymol blue
All four flasks are stoppered and placed under floodlight.
a. What color would the solution in each flask be after few hours?
Indicate which process/processes would take place in each flask.
Flask 1: Blue; photosynthesis
Flask 2: Yellow; cellular respiration
Flask 3: Blue/Yellow; both photosynthesis and cellular respiration
Flask 4: Blue; No change in bromothymol color (blue)
b. Explain how the processes that have occurred in each flask result in
the observed color of the bromothymol blue solutions.
Flask 1: Blue; plants will produce oxygen via photosynthesis, which
will not change bromothymol’s color
Flask 2: Yellow; Fish will carry out cellular respiration, as a result of
which carbondioxide will be produced. When carbon dioxide is added
to bromothymol solution, it makes a weak carbonic acid and changes
its blue color to yellow
Flask 3: Blue/Yellow; both photosynthesis and cellular respiration can
take place; the color of bromothymol would depend upon the
concentration of oxygen /carbon dioxide produced.
Flask 4: Blue; No change in bromothymol color (blue) This is a
control set up.
c. Predict what will happen in each flask if placed in dark for 24 hours.
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Since photosynthesis cannot take place in dark, the color of solution in
all flasks except for # 4 will change to yellow color due to CO2
produced by plant and fish as a result of cellular respiration.
28.Organic compounds are composed of Carbon and Hydrogen.
29.Carbohydrates are organic compounds composed of Carbon, Hydrogen and
Oxygen. ( Carbon, Nitrogen, Oxygen, Hydrogen)
30.What will be the number of carbon and oxygen atoms in the following
carbohydrate?
Cx H24 Ox __________________________ (24, 12, 14)
31.Disaccharides and polysaccharides are carbohydrates composed of simple
sugars or monosaccharides. (simple, complex, carbohydrates)
32.Carbohydrates in our diet play an important role in our bodies because they
provide us with energy. (proteins, energy)
33.Lipids function as long term energy storage molecules.
34.Oils, fats and waxes are hydrophobic, meaning they repel water
(hydrophilic, hydrophobic).
35.Oil, fats and waxes are the examples of lipids. (proteins, carbohydrates or
lipids)
36.The monomers that make proteins are amino acids. (monosaccharides,
amino acids, nucleotides)
37.What are enzymes? How do they affect the rate of chemical reactions?
Enzymes are proteins that catalyze/speed up chemical reactions.
38.List the factors that can affect the enzyme action.
 Temperature
 pH
 substrate/enzyme concentration
39.The monomers that make proteins are called amino acids, that are linked in a
chain, which is folded to make a particular protein molecule.
40. If a protein was heated it would experience denaturation , which is the loss
of shape and function of a protein.
41. DNA stores genetic information to make proteins.
42.The sections of DNA that stores genetic/heredity information to make
proteins are called genes.
43.Summarize the flow of genetic information.
DNA
RNA
PROTEIN
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44. The monomers that make DNA are called nucleotides.
45.According to Chargaff’s rule: Adenine = Thymine, Cytosine = Guanine.
46.True/False. All living things contain DNA in their cells.
47.A change in a gene/DNA sequence called a mutation can result in a
defective protein.
48.Mutations in DNA/genes give rise to genetic variations in organisms that
may help them to survive in a certain environment.
49.Nucleotides can only be added to the 3’ (OH) end of a DNA strand. Label
the 5’ and 3’ ends of each DNA strand?
5’
3’
3’
5’
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50.Draw a labelled structure of a DNA molecule that is 4 nucleotides long in
your notebooks.
Practice drawing a DNA molecule that is 4 nucleotides long. Make sure you have
all parts labeled: Sugar phosphate backbone, base pairs, hydrogen bonds,
nucleotide and 3’ and 5’ ends of each strand of DNA.
51.Briefly describe how proteins are made in the cells.
Proteins are made in the cells at the ribosomes. This process is called protein
synthesis that involves two main steps. The first step –transcription is
completed in the nucleus, mRNA is made while transcribing/copying the
gene using the template strand of DNA. The second step- translation takes
place at the ribosome where mRNA codons are translated into a chain of
aminoacids/polypeptide to make a protein.
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Use the codon table provided to answer question # 51.
52.A section of DNA is give below. Determine, from the DNA sequence, what
the amino acid sequence of the protein will be.
5’ ATG CGA TAC TGG CTC CTG TAA 3’
Non Template/Gene
strand
3’ TAC GCT ATG ACC GAG GAC ATT 5’ Template Strand
5’AUG CGA UAC UGG CUC CUG UAA 3’ mRNA
Met- Arg- Tyr- trp- leu- leu- STOP Amino Acids
STOP is not an amino acid.
53.A mutation has occurred in the DNA sequence: T-T-A-G-C-C-A-G-A. The
sequence is now: T-T-A-C-C-C-A-G-A. What type of mutation has
occurred?
Substitution
54.Individuals with one form of lactose intolerance do not produce the enzyme
lactase because the gene coding for the production of lactase is shut off in
their cells. Which process does not occur for the gene?
Protein Synthesis
55.The normal hemoglobin protein consists of 574 amino acids. Approximately
how many base pairs (bp) code for this protein?
a. 191 bp
b. 1,722 bp
c. 287 bp
d. 1,910 bp
56.To code for a particular protein, a gene consists of 12,669 base pairs.
Assuming that 3 base pairs code for the START and 3 base pairs code for
STOP, approximately how many amino acids do we anticipate exist within
the protein?
a. 4223 amino acids
b. 4,222 amino acids
c. 37,989 amino acids
d. 38,007 amino acids
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Since STOP is not an amino acid, subtract 3 base pairs from 12,669.
You must get 12,666 base pairs. Each codon made up of triplet bases
codes for one amino acid.
12,666 /3= 4222 amino acids
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