Exam #2

Question 1

What is an epitope?

Answer 1

An epitope, or antigenic determinant, is the region of a macromolecule on the surface of an invading pathogen that the host immune system recognizes as foreign.

Question 2

Where does prokaryotic DNA replication occur opposed to eukaryotic DNA replication?

Answer 2

Prokaryote = cytosol

Eukaryote = nucleus

Question 3

A swollen abdomen can often accompany severe malnutrition due to insufficient dietary protein. What is a logical explanation for a swollen abdominal region in a person lacking protein in their diet?

Answer 3

The form of malnutrition this question refers to is commonly known as kwashiorkor. This question requires that you apply the information provided to logically deduce the answer. Why might insufficient protein cause a swollen abdomen? You should realize that blood proteins are the primary mechanism for reclaiming fluid from the interstitial space in humans. Without sufficient protein, the osmotic pressure that moves fluid into the lumen of blood vessels is greatly reduced and therefore remains in the interstitial space. This inability to adequately reclaim fluid from the interstitial space can result in a swollen abdominal region. Note: There are a variety of physiological explanations that could contribute to a swollen abdominal region in a person with insufficient protein in their diet.

Question 4

What are the 3 sections of the small intestine?

Answer 4

duodenum, jejunum, ilium

Question 5

Which of the following choices is correctly associated with sugar movement in plants?

A. multidirectional
B. source to sink
C. Companion cells
D. Energy is used

Answer 5

All of the options in this question are correctly associated with sugar movement in plants. Sugar moves via translocation from sources, which have a high concentration of sugar, to sinks, which have a low concentration of sugar (B). Depending on the nutritional requirements throughout the year, various parts of a plant can either be sources or sinks making translocation multidirectional (A). Companion cells (C) use energy (D) to import sucrose from source cells prior to its entrance into the phloem.

Question 6

The only way to ensure that a totally new, previously non-existent, allele arises in a population is by

A. natural selection
B. gene flow
C. genetic drift
D. mutation
E. directional selection

Answer 6

D. mutation

Question 7

In ecology, the term community describes

Answer 7

The sum total of all living species, living in the same area, at the same time.

In ecology, the term community describes the sum total of all living species in the same area at the same time. Choice A is incorrect because the option correctly defines the term population, not community. Choice B is incorrect because the option describes two different populations of the same species. Choice D is incorrect because the option defines an ecosystem, not a community. An ecosystem includes both the community and abiotic factors, such as sunlight or temperature. Choice E is incorrect because this option defines the term biosphere, not community.

Question 8

Sertoli cells provide nutritional and structural support to spermatogonium and spermatocytes in male human beings. Where would you expect to see abundant Sertoli cells?

Answer 8

Sertoli cells can be found abundantly in the seminiferous tubules of a human male. Spermatogenesis occurs in the seminiferous tubules, which are tightly coiled structures located in the testes. Sertoli cells aid developing sperm by providing nutritional support and serving a structural role by forming the blood-testes barrier. Since one of the functions of a Sertoli cell is stated in the question stem, the correct answer can be derived through the sole knowledge of the location of spermatogenesis.

Question 9

During translation, _______________ is synthesized from an RNA template.

Answer 9

protein

Question 10

By altering internal and external Na+ and K+ concentrations, Na+/K+ pumps in red blood cell ghosts can operate in reverse. What is likely directly produced in the cytosol from these manipulated Na+/K+ pumps embedded in the plasma membrane of red blood cell ghosts?

A. NaCl
B. glucose
C. ATP
D. NADH
E. DNA

Answer 10

C. ATP

It is highly unlikely you have ever encountered a question in your general studies regarding the reverse operation of a Na+/K+ pump. However, by applying fundamental biology knowledge regarding the normal function of a Na+/K+ pump the correct answer can be derived. Na+/K+ pumps serve critical functions in the maintenance of overall cell homeostasis by maintaining the electrochemical gradient necessary to transport ions and molecular matter into and out of a cell. Much of the total energy used within a cell goes towards proper Na+/K+ pump function. Normally, Na+/K+ pumps hydrolyze a single molecule of ATP to transport three Na+ ions out of a cell and two K+ ions into a cell against their respective electrochemical gradients. However, by concentrating Na+ outside a red blood cell ghost and K+ in the cytosol, Na+/K+ pumps can be manipulated to operate in reverse thereby synthesizing ATP rather than hydrolyzing it.

Question 11

A cancer causing gene is also called

Answer 11

oncogene

A cancer causing gene is also called an oncogene. Typical, non-cancerous genes, are called proto-oncogenes and can become oncogenes through a variety of different mechanisms. Tumor suppressor genes, such as the p53 gene, function to minimize uncontrolled cell growth and thus are not cancer causing genes. However, knockout mutations of the p53 gene can result in cancer. Choice C is incorrect because an operon is a sequence of nucleotides that can be categorized into a promoter, an operator, and one or more structural genes. Operons are transcribed as a single unit and are commonly found in prokaryotes.

Question 12

Inserting a normal allele into a single defective gene for the purpose of curing certain heritable diseases is known as

Answer 12

gene therapy

Inserting a normal allele into a single defective gene for the purpose of curing a disease that you can inherit is known as gene therapy. Proteomics (A) refers to the study of the entire array of proteins that could be possibly produced by an organism’s genome. Eugenics (B) refers to the deliberate attempt to control the genetic makeup of entire populations. Genomics (D) refers to the study of the entire genetic makeup of a particular species. DNA fingerprinting (E) refers to the analysis of distinguishing characteristics of a person’s genome.

Question 13

Penicillin is a commonly prescribed antibiotic that exerts its protective function by interfering with the cross linking of peptidoglycan. Which microorganisms are likely to be most susceptible to penicillin?

A. staphylococcus 
B. mycoplasma
C. Platyhelminths
D. ascomycota
E. Ciliates

Answer 13

A. staphylococcus

Microorganisms of the genus Staphylococcus are most likely to be susceptible to the penicillin. Peptidoglycan is a polymer found in the cell wall of most bacteria. Peptidoglycan is not found in eukaryotes, archeae, viruses, or the few kinds of bacteria that lack a cell wall. This distinguishing characteristic allows penicillin to be a selectively toxic antibiotic, capable of harming bacteria without harming the host. Penicillin is particularly effective against gram positive bacteria, such as bacteria of the genus Staphylococcus (A). Gram negative bacteria are more resistant to pencillin due to the presence of an extra membrane around their peptidoglycan. It would be ridiculous for official test writers to expect you to know the exact classification of every living organism. However, the correct answer to this question can be deduced by carefully analyzing the answer choices. Choice C and Choice E can be immediately eliminated because Platyhelminths are animals and Ciliates are protists. Protists are eukaryotes and therefore do not have peptidoglycan. Choice D can almost as easily be eliminated because Ascomycota is a phylum of fungi. Like protists, fungi are eukaryotes and therefore do not have peptidoglycan. You should be aware that “myco” and “myces” can literally be translated to mean “fungi”. Ascomycota, Deuteromycota, Zygomycota, Basidiomycota, Saccharomyces are all examples of fungi classifications. Lastly, Choice B can be eliminated by knowing that mycoplasma lack cell walls and therefore do not have peptidoglycan.

Question 14

Which option below best describes eukaryotic DNA replication on the leading strand?

Answer 14

In eukaryotes, DNA replication on the leading strand occurs continuously. However, DNA replication on the lagging strand occurs semidiscontinuously.

Question 15

Which characteristics determine if something is living or non-living?

l. independent metabolism
ll. the ability to self replicate
lll. the ability to produce gametes

Answer 15

l and ll

Most scientists today agree that distinguishing between life and non-life is based on two key characteristics; the presence or absence of independent metabolism and the ability or inability to self replicate. An entity is considered “alive” if it is capable of independent metabolism (which excludes viruses) and is capable of self replication. Statement III is not a steadfast parameter in determining if something is living or non-living. Many organisms found on Earth today are capable of independent metabolism and self-replication but do not produce gametes.

Question 16

Which embryological germ layer are muscles derived from?

Answer 16

mesoderm

Question 17

Where does fertilization usually occur in the female reproductive system?

A. Ovaries
B. mammary glands
C. interstitial space
D. oviduct
E. uterus

Answer 17

D. oviduct

Question 18

The oviduct can also be referred to as …

Answer 18

the fallopian tubes.

Question 19

Hb curve shifts:

Answer 19

An increase in blood temperature typically results in a right shift, as shown by the dashed oxygen-hemoglobin disassociation curve. Under such conditions, hemoglobin is more able to unload oxygen into active, warmer, oxygen-depleted tissues. Remember that high blood pH means less H+ in the bloodstream, which in turn means less CO2 in the bloodstream. With less CO2 in the blood stream the curve would shift to the left because the hemoglobin would not need to “dump” more oxygen into the tissues. The table below outlines the oxygen-hemoglobin binding effect associated with various physiological changes.

Question 20

A male mammals fitness is predominately dictated by his ability to find

Answer 20

a mate

Although very controversial, many evolutionary biologists assert that male and females are typically presented with different challenges when attempting to increase their own fitness. Under most circumstances, but not all, a male’s fitness is predominately dictated by the ability to find a mate. In contrast, females typically must exert enormous amounts of energy during child development and therefore their fitness is predominately dictated by the ability to gain sufficient resources to successfully reproduce. It is important to note that these roles are sometimes reversed.

Question 21

What is the most species rich class of animals on Earth?

A. Reptilia
B. Aves
C. Amphibia
D. Insecta
E. Mammalia

Answer 21

D. insecta

There are more species of insects than any other class of animals on Earth. Unique reproductive cycles have lead to the abundance and divergence of many different species of insects.

Question 22

What pathway allows water to move from root hairs to vascular tissue through the cell walls of plant cells prior to reaching the Casparian strip?

Answer 22

Apoplastic pathway

There are two major pathways by which water moves from root hairs to the vascular tissue in plants. These two routes are the apoplastic and symplastic pathways.

apoplastic: allows water to move through interconnected cell walls of plant cells until reaching the more centrally located Casparian strip. The waxy Casparian strip re-directs water back through the plasma membrane where it can enter vascular tissue via plasmodesmata.

symplastic pathway: does not consist of water flowing through the cell wall of plant cells. Rather, water flows continuously from root hairs to vascular tissue via plasmodesmata.

Question 23

The point where a muscle attaches to the more movable end of a bone is called the

A. Joint
B. epiphysis
C. epiphyseal plate
D. origin
E. insertion

Answer 23

E. insertion

In contrast, the origin is the location where a muscle attaches to the less movable end of a bone.

Question 24

Where would you look if you were interested in viewing an abundance of apocrine sweat glands?

Answer 24

armpits

For the official, you should be aware of two different types of sweat glands.
Apocrine sweat glands are highly concentrated in regions of the body that contain an abundance of hair, such as the armpits or pubic area.

In contrast, eccrine sweat glands can be found over the entire surface of the human body and are especially abundant in areas such as the palms of your hands, your forehead, and the soles of your feet.

Question 25

Insulin dependent diabetes mellitus (IDDM) is an autoimmune disease that can result in insufficient insulin release into the bloodstream. Which cells are likely recognized as foreign to the immune system of a person suffering from this dangerous condition?

Answer 25

pancreatic beta cells

Question 26

Frequency of genetic recombination of two linked genes during prophase of meiosis is most directly correlated with

Answer 26

The frequency of genetic recombination between two linked genes is directly correlated with the distance along the length of the chromosome between them.

The greater the distance between two genes along a particular chromosome the more likely they are to genetically recombine by crossing over.

Genes that are located very closely to one another are less likely to recombine.

Question 27

In eukaryotic cells the Krebs cycle occurs in the mitochondrial matrix but in prokaryotic cells it occurs in the

Answer 27

cytosol,
while the electron transport chain occurs along the plasma membrane.

In eukaryotic cells glycolysis, occurs in the cytosol and the Krebs cycle occurs in the mitochondrial matrix. The electron transport chain in eukaryotes occurs across the inner mitochondrial membrane.

Question 28

What is the order of the 3 main components of the vertebral column?

Answer 28

(TOP) Cervical = 7

                Thoracic = 11

(BOTTOM) Lumbar = 5

The sacrum and coccyx are also considered sections of the human vertebral column.

Question 29

A late-stage mammalian blastula is more commonly referred to as

Answer 29

a blastocyst

Question 30

Like many other lipids, cholesterol is synthesized

Answer 30

in the smooth ER

The smooth endoplasmic reticulum serves many functions including: synthesizing lipids, detoxifying poisons, and storing calcium ions. Cholesterol is vital to our survival as well as potentially harmful. Cholesterol is a precursor for the synthesis of many important sex hormones, the formation of bile salts in the liver, and maintaining the fluidity of the plasma membrane of cells. However, cholesterol also has the potential to lead to dangerous conditions such as atherosclerosis.

Question 31

Which of the following are primary components of nucleotides?

Answer 31

l. nitrogenous base
ll. five carbon sugar
lll. phosphate

Question 32

Which valve(s) is/are located in the human heart?

Answer 32

The human heart has several valves that help promote unidirectional movement of blood.

The bicuspid valve, also known as mitral valve, is located between the left atrium and left ventricle.

The tricuspid valve is located between the right atrium and right ventricle.

A semilunar valve is located at the junction between the pulmonary artery and right ventricle. An additional semilunar valve is located at the junction of the left ventricle and aortic arch.