AP Bio Unit 4 Test

A new mutation that arose in one copy of gene X in a somatic cell resulted in the formation of a tumor. Which of the following pieces of evidence best describes how the new mutation directly caused the tumor? A Protein X normally stimulates cell division, and the mutation created an overactive version of protein X. B Protein X normally activates a growth hormone receptor, and the mutation decreased the stability of protein X. C Protein X normally prevents passage through the cell cycle, and the mutation created an overactive version of protein X. D Protein X normally regulates gene expression, and the mutation created an underactive version of protein X that blocked the cell cycle.

Which of the following occurs in both meiosis and mitosis? A Separation of homologous chromosomes B Reduction of chromosome number C Separation of sister chromatids D Crossing-over between homologous chromosomes E Production of four daughter cells

The process of cytokinesis in plants primarily consists of the A replication of DNA in preparation for mitosis B separation of homologous chromosomes to opposite ends of the cell C separation of sister chromatids to opposite ends of the cell D creation of daughter cells by constriction of the cell membrane E creation of daughter cells by fusion of vesicles at the equator of the cell

Cells that contain only circular chromosomes are most probably which of the following? A Protist cells B Fungal cells C Bacterial cells D Plant cells E Animal cells

Which of the following is true of mitosis? A It is also known as cytokinesis. B It maintains the same chromosome number in the daughter cells as in the parent cell. C It is the last phase of interphase. D It regulates the transfer of genetic information from one daughter cell to another. E It moves homologous chromosomes to opposite poles.

Which of the following occurs during mitosis but not during meiosis I ? A The chromosomes are pulled to opposite poles of the spindle apparatus. B The chromatids of each chromosome are separated. C The nuclear envelope breaks down. D Both synapsis and crossing-over take place. E The diploid number of chromosomes is reduced to the haploid number.

All of the following are true statements about meiosis in mammals EXCEPT: A It serves as a factor in bringing about variation among offspring. B It follows DNA replication. C It occurs only in reproductive structures. D It produces cells with the haploid number of chromosomes. E It produces four genetically identical gametes.

Individuals with an inherited autosomal recessive disorder called primary ciliary dyskinesia (PCD) often have severe respiratory problems due to defective cilia. Males with PCD are often sterile because they produce sperm with defective flagella. Which of the following most likely explains the effect of the recessive allele? A The mitochondria are defective and do not produce sufficient protein to synthesize microtubules in the cilia and flagella. B The plasma membrane of the alveoli is not permeable to carbon dioxide during respiration because it is too hydrophobic. C The Golgi bodies secrete an enzyme that destroys the proteins in the flagella and cilia. D The cells do not produce functional motor proteins in flagella and cilia.

A researcher examining a root tip observes a plant cell with condensed sister chromatids, kinetochores with attached microtubules, and individual chromosomes that are aligned at the equatorial plate of the cell. Which of the following best describes what the next process will be in the cell? A Homologous chromosomes (each with two sister chromatids) will move toward opposite poles of the cell. B Paired chromatids will separate, and the new daughter chromosomes will move toward opposite poles of the cell. C The nuclear envelope will break down, and the spindle will begin to form. D The chromatin will decondense, and the daughter cell will enter interphase.

Gregor Mendel's pioneering genetic experiments with pea plants occurred before the discovery of the structure and function of chromosomes. Which of the following observations about inheritance in pea plants could be explained only after the discovery that genes may be linked on a chromosome? A Pea color and pea shape display independent inheritance patterns. B Offspring of a given cross show all possible combinations of traits in equal proportions. C Most offspring of a given cross have a combination of traits that is identical to that of either one parent or the other. D Recessive phenotypes can skip a generation, showing up only in the parental and F2 generations.

A student in a biology class crossed a male Drosophila melanogaster having a gray body and long wings with a female D. melanogaster having a black body and apterous wings. The following distribution of traits was observed in the offspring. Phenotype / Number of Offspring Gray body, long wings / 42 Black body, apterous wings / 41 Gray body, apterous wings / 9 Black body, long wings / 8 Which of the following is supported by the data? A The alleles for gray body and long wings are dominant. B The alleles for gray body and long wings are recessive. C Genes for the two traits are located on two different chromosomes, and independent assortment occurred. D Genes for the two traits are located close together on the same chromosome, and crossing over occurred between the two gene loci.

If chemical signals in the cytoplasm control the progression of a cell to the M phase of the cell cycle, then fusion of a cell in G1 with a cell in early M phase would most likely result in the A replication of chromosomes only in the G1 cell B exiting of both cells from the cell cycle and into the G0 phase C condensation of chromatin in preparation of nuclear division in both cells D transfer of organelles from the G1 cell to the cell in the M phase

A group of people whose ancestors immigrated to North America 200 years ago have certain allele frequencies that differ significantly from those in surrounding populations in the United States. Which of the following is the most likely explanation for the difference in allele frequencies? A Mutation B Independent assortment C Reproductive isolation D Sex linkage E Gametic isolation

The events listed below generally take place during meiosis. I. Synapsis occurs. II. Crossing-over is completed. III. Condensation of chromosomes begins. IV. Separation of homologous chromosomes begins. Which of the following is the correct sequence of these events? A I, II, III, IV B II, I, III, IV C III, I, II, IV D III, IV, II, I E IV, II, III, I

During mitosis, which of the following normally occurs? A Homologous chromosomes pair. B Replicated chromosomes line up on the equatorial plate. C Tetrads form. D Unreplicated chromosomes become oriented in the center of the cell. E Maternal and paternal chromatids pair.

During mitosis, which of the following normally occurs? A Homologous chromosomes pair. B Replicated chromosomes line up on the equatorial plate. C Tetrads form. D Unreplicated chromosomes become oriented in the center of the cell. E Maternal and paternal chromatids pair.

The vertebrate forelimb initially develops in the embryo as a solid mass of tissue. As development progresses, the solid mass near the end of the forelimb is remodeled into individual digits. Which of the following best explains the role of apoptosis in remodeling of the forelimb? A Apoptosis replaces old cells with new ones that are less likely to contain mutations. B Apoptosis involves the regulated activation of proteins in specific cells of the developing forelimb that leads to the death of those cells. C Apoptosis involves the destruction of extra cells in the developing forelimb, which provides nutrients for phagocytic cells. D Apoptosis in the developing forelimb triggers the differentiation of cells whose fate was not already determined.