USABO Open Exam 2003

Question 1

What enzyme does HIV use to convert RNA to DNA?

Answer 1

Reverse transcriptase

Question 2

The promoter region of a prokaryotic gene is located ______ to the gene and is the binding site for ______.

Answer 2

5’…RNA polymerase

Question 3

Which of the following is TRUE of prokaryotes?
I. Simultaneous transcription and translation
II. Presence of intron sequences
III. Circular DNA

Answer 3

I and III only

Question 4

Integral transmembrane proteins are proteins imbedded in the cell membrane. Which of the following amino acids would you MOST expect to find in the transmembrane region of such proteins?

Answer 4

Tryptophan

Question 5

When the base composition of DNA from bacterium Mycobacterium tuberculosis was determined, 18% of the were found to be adenine. What is the G + C content in M. tuberculosis?

Answer 5

64%

Question 6

The frequency of individuals affected with an autosomally recessive inherited disorder is 1 in 4. Assuming that the population affected by this disease is in Hardy-Weinberg equilibrium, what is the proportion of carrier individuals in this population?

Answer 6

50%

Question 7

The velocity of action potential conduction across a nerve axon is increased by the presence of the myelin sheath. In the peripheral nervous system, what cell myelinates the axon?

Answer 7

Schwann cell

Question 8

The cell bodies of afferent (sensory) nerves involved in somatic reflexes are located in the

Answer 8

Dorsal root ganglion

Question 9

Rods and cones are associated with _____ and _____ vision, respectively.

Answer 9

Light/dark…color

Question 10

Populations that are likely to be living at a density near the limit of their resources, are characterized as

Answer 10

K-selected

Question 11

In many types of cancer, the function of the p53 gene is lost. Wild-type p53 is MOST likely to be a

Answer 11

tumor suppressor

Question 12

What glycolytic product is shuttled to the mitochondria in aerobic respiration?

Answer 12

Pyruvate

Question 13

During human development, which process leads to the formation of three germ layers?

Answer 13

gastrulation

Question 14

Telomerase is responsible for _____ the size of telomeres, and its function is often ____ in carcinogenesis.

Answer 14

maintaining … increased

Question 15

Which of the following is NOT a mode of natural selection?

Answer 15

sexual selection

Question 16

Protostomes have _____ and _____ types of cleavage.

Answer 16

spiral … determinate

Question 17

Which of the following is NOT a characteristic of all chordates?

Answer 17

vertebrae

Question 18

In cardiac muscle, calcium ions can move freely between adjacent cells through which of the following?

Answer 18

gap junctions

Question 19

Unlike most polypeptide hormones, steroid hormones are unique in that they

Answer 19

Diffuse across cell membranes

Question 20

In superoxide dismutase 1, an enzyme implicated in amyotrophic lateral sclerosis (Lou Gehrig’s disease), a copper ion is bound to the active site and is important for enzyme activity. In this enzyme, copper most likely functions as a(n)

Answer 20

cofactor

Question 21

The order of normal blood flow through the human heart is

Answer 21

right atrium, right ventricle, lungs, left atrium, left ventricle, body

Question 22

Allopatric speciation refers to species formed after which type of separation:

Answer 22

geographic

Question 23

Which two functional groups are always found in amino acids?

Answer 23

Carboxyl and amine

Question 24

Movement of ions across the membrane from higher to lower concentrations through a channel protein is an example of

Answer 24

Facilitated diffusion

Question 25

Which group of plants has vascular tissue but does not produce seeds? I. Mosses II. Ferns III. Gymnosperms

Answer 25

II

Question 26

Which of the following is true for transport in xylem?

Answer 26

Movement through xylem depends mainly on transpiration

Question 27

Predation is considered a _________ interaction, while Mutualism is considered a ___________ interaction.

Answer 27

+/-,+/+

Question 28

Which of the following organisms is INCORRECTLY paired with its trophic level?

Answer 28

Beetle - secondary consumer

Question 29

Which of the following is an example of habituation?

Answer 29

Hydra initially contract when gently touched, but soon stop responding.

Question 30

Suppose gene "C" is the gene for color. Its dominant allele has the effect of allowing the production of fur color while its recessive allele interrupts color production. At another locus, there exists another gene that influences color, at which black (B) is dominant to brown (b). What is the relationship between these genes called?

Answer 30

Epistatic

Question 31

``` During migrations, some birds use which of the following as reference frameworks? I. The sun II. Constellations III. Earth's magnetic field I only ```

Answer 31

I,II,andIII

Question 32

Generally, there are more species per square kilometer in which of the following types of ecosystem?

Answer 32

Coral reef

Question 33

RUBP is used and PGA is formed in:

Answer 33

dark reaction (Calvin cycle) of photosynthesis

Question 34

Which is TRUE of the dark reaction (Calvin cycle) of photosynthesis?

Answer 34

It uses carbon dioxide

Question 35

In the fern life cycle, the dominant generation is the:

Answer 35

diploid sporophyte