Question 1

In mitosis, chromosomes become aligned at the middle of the cell during

Accepted Answer

Metaphase. In metaphase, the spindle is formed and chromosomes become aligned along spindles in the middle of the cell.
Key Takeaway: Mitosis is the process by which a mother cell divides into two identical daughter cells. Mitosis begins with prophase, in which centrioles move to opposite ends of the cell. This is followed by metaphase, where chromosomes become aligned at the center of the cell. Chromosomes move to the oppose ends of the cell in anaphase. During telophase, the chromosomes are enclosed a nuclear membrane. Interphase describes the processes that take place before mitosis such as DNA replication that are essential to the mitotic process.

Question 2

Blood typing can often be used to determine biological fatherhood. Three men, X, Y, and Z, are all possible fathers for child with bood type B. Blood testing determines that the mother's blood type is O. Which blood type must a candidate father have to be eliminated as a possible father?

Accepted Answer

A blood type. If the mother's blood type is O, the child must inherit the B blood antigen and blood type from its father. In this scenario, the father must have a B or AB blood type.
Key Takeaway: Blood type is inherited from both parents. A and B blood type are co-dominant over O blood type. Therefore, if one parent has O blood type, the child will receive the blood type based solely on the other parent. In this scenario, if the child's blood type was A instead of B, the child's father would have to have either A or AB blood type.

Question 3

Blood type O is considered:

Accepted Answer

Recessive: A child can only have O blood type if both parents have O blood type or are heterozygous for A or B blood type.
Key takeaway: Blood type A and blood type B are co-dominant in humans. If a child receives the antigen for blood type A from one parent and B from the other, the child's blood type is no either A or B, but a combined AB. In this system, a child can only have blood type O if it does not receive a blood type antigen from either parent. This is only possible if the parents are homozygous for O blood type or heterozygous for A or B blood type.

Question 4

If the father's blood type is AB and the mother's blood type is homozygous B, what is the percent likelihood that their offspring blood type will be B?
A)0%
B)25%
C)50%
D)75%

Accepted Answer

50%. There is a two out of four chance that the child will have B blood type.
Key takeaway: Using the Punnett square, it is immediately evident that the child will only have B or AB blood type. The father can donate either an A allele or a B allele, whereas the mother can only donate a B allele. It is shown below that the child is 50% likely to have a B blood type.
A | B
B AB | BB
-------- | -------
B AB | BB

Question 5

The father's blood type is AB and the child's blood type is homozygous B.
Which of the following statements must be true about the mother of the child described above?

Accepted Answer

The mother's blood type cannot be homozygous A. If the mother's blood type is homozygous A, the child's blood type can only be A or AB.
Key Takeaway: Blood type A and blood type B are co-dominant. If the mother's blood type is AB, she could potentially donate a B allele to the child. Likewise, if the mother's blood type is O, the child could still have blood type B if it receives the B allele from the father. The immune system will reject blood that does not match the blood of the recipient. If the mother's and child's blood posses different antigens, then they cannot serve as donors or recipients for each other.

Question 6

A child was born with blood type B. Three candidate fathers, X, Y, and Z, were found to have blood types A, B, and O, respectively. Which of the candidate fathers cannot be a blood donor to the child above?

Accepted Answer

candidate X. Blood with the A antigen will cause an immune response if donated to an individual with the B antigen.
Key Takeaway: Blood can only be donated to an individual if that blood will not cause an immune reaction in the recipient. Since O type blood does not possess any antigens, it will not cause an immune response and can be donated to anyone regardless of blood type. Since the child has blood type B, he or she can receive blood from an individual with blood type B. Blood with only the A antigen will cause an immune reaction in the recipient, and cannot be used for a blood donation.

Question 7

What is the mechanism by which glucose enters the cell?

Accepted Answer

Facilitated diffusion is the process by which glucose enters the cell.
Key Takeaway: When glucose concentrations are higher outside the cell than inside the cell, passive transport through diffusion allows glucose to enter the cell without any expenditure of energy. Glucose is large molecule and transfer must be supported by a transfer protein.

Question 8

What is the most likely explanation for leaves wrapped in white construction paper having the lowest amount of chlorophyll?

Accepted Answer

The white paper prevented sunlight from being absorbed by the leaves.
Key Takeaway: The color of an item is the result of what shade of light it absorbs. All other shades are light are reflected. Items appear white only when they reflect all colors of light and absorb none. Since the white paper is reflecting all spectrums of light, no light will reach the leaves to promote photosynthesis.

Question 9

In order of increasing wavelength, the color spectrum ranges in the order of blue-yellow-orange-red. Which of the following statements is true about the relationship between wavelength and photosynthesis?

Accepted Answer

When wavelength increases, photosynthesis decreases, then increases. Photosynthesis is stimulated most by red and blue light, which exist on opposite ends of the wavelength spectrum
Key Takeaway: The wavelength of visible light ranges from about 380-750 nm. Blue light is on the lower end of the scale, and red light on the higher end of the scale. Yellow and orange are in the middle. Since the data indicate that yellow and orange have the smallest effect on photosynthesis, the effect of light on photosynthesis decreases and increases as the wavelength of light increases.

Question 10

A leaf stored in an indigo sleeve is most likely to produce levels of chlorophyll similar to:

Accepted Answer

blue. Indigo is more similar to blue than any of the other colors.
Key Takeaway: Indigo is similar in color to purple. On the color spectrum, purple is more similar to blue than it is to yellow, red, or orange. Therefore, it is most likely that indigo light has an effect on photosynthesis most similar to blue light.

Question 11

What is the corresponding mRNA sequence to the following DNA sequence AGTCCATGCACAAT?

Accepted Answer

UCAGGUACGUGUUA. Transcription is the process to produce RNA from the DNA template, with fixed base paring rules.
Key Takeaway: In transcription, A pairs with U, T with A, G with C, and C with G. RNA does not use thymine, so all other answers other than B can be immediately eliminated.

Question 12

When a DNA sequence is used to synthesize mRNA, the process is called _________.

Accepted Answer

Transcription. In transcription, mRNA is created using DNA as a template.
Key Takeaway: Translation is the process by which proteins are produced using RNA as a transcript. Translocation describes the process by which neighboring chromosomes swap genetic information. Transduction is the process by which DNA is transferred from one bacterium to another by a virus. Translucent describes a material that allows for a free passage of light.

Question 13

Where in the eukaryotic cell does RNA synthesis occur?

Accepted Answer

Nucleus. DNA is transcribed into RNA inside the nucleus
Key Takeaway: The key point to understand is that while RNA does move in and out of the nucleus, DNA does not. Therefore, for RNA to be synthesized from DNA, it must take place inside the nucleus.

Question 14

Which of the following bases is not used in RNA?

Accepted Answer

Thymine. RNA does not use thymine as one of its nitrogenous bases.
Key Takeaway: In DNA, the four nitrogenous bases are adenine, thymine, cytosine, and guanine. In RNA, the four nitrogenous bases are adenine, uracil, cytosine, and guanine.

Question 15

An mRNA sequence is divided into three nucleotide sequences called:

Accepted Answer

Codons. Each codon codes for a single amino acid or as a stop signal to end translation.
Key Takeaway: Anticodons are three nucleotides sequences in tRNA that correspond to codons in mRNA. Genes and alleles are both only associated with DNA. A splice site is the point where a DNA or RNA transcript will be cut.

Question 16

Adenine and guanine are examples of:

Accepted Answer

Purines. Adenine and guanine are the purine bases used in DNA.
Key Takeaway: Purines and pyrimidines are the two classes of nitrogenous bases used in DNA and RNA. Thymine, cytosine, and uracil are all examples of pyrimidines, and uracil replaces thymine in RNA. This means RNA is comprised of one purine and three pyrimidines.

Question 17

Over the course of 150 years, an area filled with weeds becomes more diverse and weeds are replaced by grasses, shrubs, and ultimately oaks. This process is defined as

Accepted Answer

Succession. Succession is the ordered shift in composition and structure of an ecological community.
Key Takeaway: Of the choices, only succession can define a change in an environment. Mutation, adaptation, divergence, and convergence all describe changes in an individual or group of organisms.

Question 18

As the dominant plant of the area changes, the total biomass of the community __________.

Accepted Answer

increases. As a community moves through a succession, each change brings forth an increase in total biomass.
Key Takeaway: As a community moves through a succession, it is characterized by an increase in total biomass, a greater capacity to retain nutrients in the system, increasing species diversity, and increasing size and lifespan of organisms.

Question 19

When oaks become the dominant plant in the area, the mixture of populations no longer creates changes in the environment. The community is now a climax community. Which of the following events could restart succession?

Accepted Answer

All of the above. A climax community is characterized by no environmental change without an outside stimulus.
Key Takeaway: In a climax community, the community has reached a point where the mixture of populations creates no new environmental changes. This equilibrium will not become unbalanced without some outside event. Fires, volcanic activity, human logging, and landslides are all examples of outside forces that can restart succession.

Question 20

Which of the following is NOT a characteristic of a climax community?

Accepted Answer

The essential makeup of the populations within the community is in constant flux.
Key Takeaway: The primary characteristic of a climax community is stability. There is no change in environment, no change in population mixture, and no change in biomass. Species diversity has reached the highest level the region can support. Lifespan and organism size has reached its maximum. Since it is an area of stability, the balance between energy production and consumption propels the equilibrium.

Quiz 11: (AP) Biology : Biology: Part A