Biology 1
Fall Semester
Examination Review
ANSWER KEY
1.
What is the
difference between inference and observation?
·
An inference is a logical
interpretation based on prior knowledge or experience.
·
An observation involves using the
senses to gather information.
·
Inferences can be supported by
observations.
2.
How would
one determine whether something was living or nonliving?
Anything
lacking one or more of the following characteristics of life is nonliving:
·
Made up of cells
·
Reproduces
·
Based on a universal genetic code
·
Grows and develops
·
Obtains and uses materials and energy
·
Responds to its environment
·
Maintains a stable internal environment
·
Taken as a group, changes over time\
3.
What are
the fur groups of organic compounds found in living things?
The four groups are:
carbohydrates, lipids, nucleic acids, and proteins
4.
Compare
enzyme activity to a lock and key.
In a comparison of the
activity of enzymes to a lock and key, the lock symbolizes the active site of
the enzyme and the key symbolizes the substrate. A specific key can fit into a
specific lock; so, too, does a specific substrate fit into the active site of a
specific enzyme. Without a prefect match, the reaction cannot occur. Likewise,
without the right key, the lock cannot open.
5.
How do
prokaryotes and eukaryotes differ?
Prokaryotes are
generally simpler and smaller than eukaryotes, whereas eukaryotes have a
nucleus and other specialized organelles.
6.
A
hypertonic salt solution has a higher concentration of solutes than a blood
cell. Explain what happens when a blood cell is placed in a hypertonic salt
solution.
When a blood cell is
placed in a hypertonic solution, the water flows from the blood cell, through
the cell membrane, into the solution. As a result of losing water, the cell
shrinks.
7.
Summarize
three statements from the cell theory. Explain the significance of the cell
theory to biology.
The cell theory states
that all living things are composed of cells. It also says that cells are the
basic units of life and new cells come from preexisting cells. The cell theory
is significant to biology because all living things are made of cells.
Differences in the structure and function of different life forms are reflected
in differences in their cell structures.
8.
Discuss the
relationship between autotrophs and heterotrophs. Do heterotrophs depend on
autotrophs for their survival? Explain your answer.
Heterotrophs depend on
autotrophs to obtain energy from the sun. This energy is then passed on to
heterotrophs in form of food. Without autotrophs, the sun’s energy would not be
available to heterotrophs and heterotrophs would eventually die out or find a
new way of obtaining energy.
9.
Identify
three factors that affect the rate of photosynthesis, and explain the effect of
each.
Three of the factors
that affect the rate of photosynthesis are light intensity, temperature, and
water. The rate of photosynthesis increases with light intensity up to a
certain point, then levels off. Photosynthesis slows at extreme temperatures
and usually has an optimal temperature for each kind of plant. Lack of water
slows down photosynthesis.
10. Trace the events that occur in the
thylakoid membrane during the light-dependent reactions.
Electrons in the
pigments in photosystem II absorb energy from light. These electrons then move
through the electron transport chain to photosystem I. H+ ions move
from the stroma into the inner thylakoid membrane. NADP+ becomes
NADPH. The charge difference on either side to the thylakoid membrane provides
the energy to make ATP via ATP synthase.
11. List the main events of glycolysis. How
many ATP molecules are produced and consumed by glycolysis? What effect does
the presence of oxygen have on the events that follow glycolysis?
Glycolysis is the
breakdown of glucose into two molecules of pyruvic acid, producing 4 ATP
molecules. An initial input of 2 ATP molecules is required to start glycolysis;
thus, there is a net gain of 2 ATP molecules. This process produces high-energy
electrons, which are passed to AND+ forming 2 NADH. If oxygen is
present, glycolysis leads to the Krebs cycle and the electron transport chain.
If oxygen is not present, glycolysis is followed by the rest of fermentation.
12. Compare lactic acid fermentation with
alcoholic fermentation. Where does each process occur? What are the products of
each process?
Both main types of
fermentation release energy from food molecules by producing ATP in the absence
of oxygen via glycolysis. Alcoholic fermentation occurs in yeasts and a few
other microorganisms, and its products are alcohol, CO2, and NAD+.
Lactic acid fermentation occurs in muscle cells and some unicellular organism,
and its products are lactic acid and NAD+.
13. What kinds of problems does growth cause
for cells? How does cell division help a cell solve these problems?
As a cell grows, it
functions less efficiently because it places more demands on its DNA and it is
less able to move materials to their proper destinations quickly. Cell division
results in two daughter cells. Each cell has its own copy of the parent cell’s
DNA and has a size that allows it to efficiently exchange materials.
14. List and describe the main events of the
cell cycle. Illustrate your description with a diagram of the cell cycle.
During the G1
phase, the cell grows; during the S phase, the DNA replicates; during the G2
phase, the cell prepares for mitosis. The M phase or cell division includes
mitosis and cytokinesis. Figures should approximate Figure 10-4 on page 245 of
the textbook.
15. Explain why short plants reappeared in
Mendel’s F2 generation of pea plants.
When the heterozygous
tall F1 plants produces gametes, their dominant allele for tallness
segregated from their recessive allele for shortness. As a result, some of
their gametes had the dominant allele, while others had the recessive allele.
When the F1 plants self-pollinated, some male gametes with the
recessive allele fused with female gametes with the recessive allele during
fertilization. The offspring that resulted, which were part of the F2
generation, had two alleles for shortness and were therefore short.
16. The stages of meiosis are classified into
two divisions: meiosis I and meiosis II. Compare and contrast these two divisions.
Both meiosis I and
meiosis II contain a prophase, metaphase, anaphase, and telophase. However,
chromosome replicate prior toe meiosis I but not prior to meiosis II. Also,
during meiosis I, tetrads form and align along the center of the cell. Then,
the homologous chromosomes are separated and two haploid daughter cells form.
During meiosis II, sister chromatids align along the center of the cell and are
then separated. Four haploid daughter cells form.
17. Heterozygous male guinea pigs with black,
rough hair (BbRr) are crossed with heterozygous female guinea pigs with
black, rough hair (BbRr). In guinea pigs, the recessive gene b is
for white hair, and the recessive gene r is for smooth hair. What are
the genotypes and phenotypes of the offspring resulting from this cross?
B
= Black hair R = rough hair
b
= white hair r = smooth hair
|
BR |
Br |
bR |
br |
BR |
BBRR |
BBRr |
BbRR |
BbRr |
Br |
BBRr |
BBrr |
BbRr |
Bbrr |
bR |
BbRR |
BbRr |
BbRR |
BbRr |
br |
BbRr |
Bbrr |
bbRr |
bbrr |
9 black, rough hair
3 black, smooth hair
3 white, rough hair
1 white, smooth hair
18. Red (R) is incompletely dominant
to white (r) in snapdragons. The heterozygous genotype produces a pink
snapdragon. If a red snapdragon (RR) is crossed with a white snapdragon
(rr), what will be the genotypes and phenotypes of the F1 and
the F2 offspring?
RR = red, Rr = pink,
and rr = white
F1 RR x rr
|
r |
r |
4/4 = pink |
R |
Rr |
Rr |
|
R |
Rr |
Rr |
F2 Rr x Rr
|
R |
r |
¼ = red ½ = pink ¼ = white |
R |
RR |
Rr |
|
r |
Rr |
rr |
19. Describe the structure of a DNA molecule.
A DNA molecule ahs the
shape of a double helix, or that of a twisted ladder. Each strand of the helix
is a chain of nucleotides. Each nucleotide is made up of a deoxyribose sugar, a
phosphate group, and a nitrogenous base. The two strands are held together by
hydrogen bonds between the nitrogenous bases of the nucleotides on opposite
strands. The nitrogenous bases form hydrogen bonds with each other in pairs.
Adenine forms hydrogen bonds with thymine, and guanine forms hydrogen bonds
with cytosine.
20. Contrast the functions of the three main
types of RNA.
Messenger RNA carries
copies of instruction for assembling proteins from DNA to the ribosomes.
Ribosomal RNA is component of the ribosomes. Transfer RNA carries amino acids
to the ribosomes for assembly into proteins.