AP Bio Semester Final

Basic structure of a biological membrane contains?

Phospholipid bilayer

DNA replication occurs when in the cell cycle?

S phase

Which of the following best describes how the amount of DNA in the cell changes during M phase?

The amount of DNA is halved as the cell divides into two daughter cells.

Figure 1 represents part of a process essential to gene expression. Which of the following best explains what strand X represents?

The antisense strand, because it is serving as a template

DNA and RNA are nucleic acids that can store biological information based on the sequence of their nucleotide monomers. Figure 1 shows a short segment of each of the two types of nucleic acids. Which of the following best describes a structural difference between DNA and RNA?

The backbones ofDNA and RNA are composed of an alternating sugar and base. In DNA, the sugar is deoxyribose, whereas the sugar in RNA is ribose.

Figure 1 represents part of a process that occurs in eukaryotic cells. There are untranslated regions (UTR) in this sequence. Which of the following best explains the process represented by Figure 1 ?

The enzyme-regulated processing of pre‑mRNA into mature mRNA

What is the expected percent change in the DNA content of a typical eukaryotic cell as it progresses through the cell cycle from the start of the G1 phase to the end of the G2 phase?

+100%

A group of researchers cultured yeast cells in a nutrient-rich environment and a nutrient-poor environment and observed the duration of the stages of their cell cycles. The results of their study are summarized in Table 1. The cell cycle of yeast cells grown in the nutrient-poor environment is approximately what percent of the cell cycle of yeast cells grown in the nutrient-rich environment?

168

An experiment was performed to determine the mode of inheritance of two mouse genes, one for fur color and one for fur length. It is known that black fur (B) is dominant over white fur (b) and that long fur (L) is dominant over short fur (l). To determine how the genes are inherited, a cross was performed between two true-breeding mice, one with long black fur and one with short white fur. Their progeny, the F1 generation, all had long black fur. Five F1 male-female pairs were then crossed with one another. The F2 generation phenotypes for each cross are shown in Table·1. Which of the following is the mean number per cross of F2 generation offspring that are the result of crossing over?

2.2

Pigeons demonstrate ZW sex determination, such that a ZZ genotype produces a male and a ZW genotype produces a female. The gene for feather color is located on the Z chromosome, and the red allele is dominant over the brown allele. Three crosses between brown male pigeons and red female pigeons were performed, and the results are shown below. Which of the following is the mean number of male offspring produced by the three crosses?

9

Researchers determined the average amount of time that a particular type of eukaryotic cell spends in each phase of the cell cycle. The data collected by the researchers are represented in Figure 1. Based on Figure 1, what percent of the time required to complete a full cycle do the cells typically spend in interphase?

95%

Allosteric inhibitor

An allosteric inhibitor is a molecule that binds to the enzyme at an allosteric site. Upon binding with the inhibitor, the enzyme changes its 3D shape. Allosteric inhibition is a form of noncompetitive inhibition. This means that the inhibitor is not directly competing with the substrate at the active site.

How would you permanently block the function of an enzyme?

A chemical that blocks enzyme activity by binding to the active site is called a competitive inhibitor. These types of chemicals have similar shapes with the substrate of the enzyme. This similarity allows the chemical to compete with the substrate for who gets to attach to the active site on the enzyme.

A researcher claims that the synthesis of ATP from ADP and inorganic phosphate (Pi) is essential to cellular function. Which of the following statements best helps justify the researcher's claim?

ATP hydrolysis is an energy-releasing reaction that is often coupled with reactions that require an input of energy.

Muscle contraction depends on ATP hydrolysis. During periods of intense exercise, muscle cells rely on the ATP supplied by three metabolic pathways: glycolysis, mitochondrial respiration, and the phosphagen system. Figure 1 shows the rates at which the three metabolic pathways produce ATP following the start of an intense period of exercise. Which of the following correctly uses the data to justify the claim that the phosphagen system is an immediate, short-term source of ATP for muscle cells?

ATP production by the phosphagen system increases and decreases rapidly following the start of the exercise period.

Dihybrid cross

AaBb x aaBb

Which of the following best describes the numbered areas?

Areas 1 and 3 are polar, since the membrane molecules are aligned with water molecules.

A researcher claims that only a portion of the light energy captured by green plants is available for growth and repair. Which of the following observations best helps justify the researcher's claim?

As light energy is converted to chemical energy by metabolic processes, some of the energy is lost as heat.

Trisomy 21 is a condition in which a child is born with an extra chromosome in pair 21. Researchers assessed the frequency of children born with trisomy 21 by age of the mothers at birth (maternal age) and primary cause of the error leading to trisomy 21. The findings are presented in Figure 1. Based on the data in Figure 1, which of the following is most likely the primary cause of the pattern of frequency of trisomy 21 births in the selected maternal age-groups?

At older maternal ages, the incidence of errors in meiosis during egg production increases, which leads to an increase in nondisjunction.

Why/how are plants green?

Chlorophyll gives plants their green color because it does not absorb the green wavelengths of white light. That particular light wavelength is reflected from the plant, so it appears green.

Figure 1 shows the number of chromosomes observed in an actively dividing human cell at each stage of cell division. Which of the following presents a correct interpretation of the changes in chromosome number depicted in Figure 1 ?

Chromosomes enter metaphase containing two chromatids attached by a centromere. During anaphase, the chromatids are separated, each becoming a chromosome. Cytokinesis distributes the chromosomes into two separate cells.

Which of the following outcomes will most likely result from the irreversible binding of GDP to the G protein?

Concentration of glycogen will increase

Which of the following statements best helps explain the reaction specificity of an enzyme?

The shape and charge of the substrates are compatible with the active site of the enzyme.

Which of the following correctly explains where DNADNA replication will begin on the strand oriented 5'→3', reading from left to right?

DNA replication will be initiated immediately to the left of the RNA, since DNA polymerase requires an RNA primer.

Protons are pumped across a membrane during what in both photosynthesis and cellular respiration?

Electron transport

Single six-sided ring structure

Glucose

The enzyme hexokinase catalyzes the conversion of glucose to glucose-6-phosphate, which is an important step in glycolysis. The reaction involves the transfer of a phosphate group from ATP to glucose. Either a glucose molecule or a water molecule can fit in the active site of hexokinase. The presence of a water molecule in hexokinase's active site would result in the hydrolysis of ATP to ADP instead of the conversion of glucose to glucose-6-phosphate. Which of the following statements best helps explain the reaction specificity of hexokinase?

Glucose has the right shape and charge to cause hexokinase to undergo a structural change needed for catalysis, whereas water does not.

Hydrogen bond stability within DNA strands.

Hydrogen bonds are weak, noncovalent interactions, but the large number of hydrogen bonds between complementary base pairs in a DNA double helix combine to provide great stability for the structure.

Competitive and allosteric enzyme inhibitors differ how?

In competitive inhibition, an inhibitor molecule competes with a substrate by binding to the enzyme 's active site so the substrate is blocked. In allosteric inhibition, an inhibitor binds to an allosteric site; the substrate can still bind to the enzyme, but the enzyme is no longer in optimal position to catalyze the reaction.

Researchers performed an experiment to determine the effect of certain genetic mutations on mitosis in tropical fruit fly embryos. They determined the percentage of cells in each of four phases of mitosis as shown in Figure 1. Which of the following patterns is shown by the data?

In mutant 3 cells, more time is spent in prophase/prometaphase than in the later stages of mitosis.

A model that represents a process occurring in a cell of a particular organism is shown in Figure 1. Which of the following correctly explains the process shown in Figure 1 ?

Initiation of transcription is occurring because a strand of RNA is being produced from a DNA template strand.

Which statement best explains why correct protein folding is critical in the transmembrane protein shown above?

Interactions of the hydrophobic and hydrophilic amino acids help to anchor the protein in the membrane.

A model of a process involving nucleic acids is shown in Figure 1. Which of the following best explains what process is represented in Figure 1 ?

New DNA strands are being synthesized in the 5' to 3' direction from their DNA templates.

Which of the following conclusions is most clearly supported by the representations of nucleic acid #1 and nucleic acid #2 ?

Nucleic acid #1 contains adenine-thymine base pairs, whereas nucleic acid #2 does not.

A student carries out a genetics experiment with fruit flies to investigate the inheritance pattern of the white eye trait. The student crosses a homozygous white-eyed female with a wild-type male and records observations about the flies in the F1 generation. The student plans to use the F1 data to perform a chi-square goodness-of-fit test for a model based on an X-linked recessive pattern of inheritance. The student will use one degree of freedom and a significance level of p=0.05. The setup for the student's chi-square goodness-of-fit test is presented in Table 1. The student calculates a chi-square value of 0.36. Which of the following statements best completes the student's chi-square goodness-of-fit test?

The critical value is 3.84, and the student cannot reject the null hypothesis.

A researcher proposes a model of an enzyme-catalyzed reaction in which a reactant is converted to a product. The model is based on the idea that the reactant passes through a transition state within the enzyme-substrate complex before the reactant is converted to the product. Which of the following statements best helps explain how the enzyme speeds up the reaction?

The enzyme's active site binds to and stabilizes the transition state, which decreases the activation energy of the reaction.

Which of the following statements best predicts the effect of a mutation that results in a loss of the glucocorticoid receptor's ligand binding function?

The glucocorticoid receptor will remain associated with the accessory proteins.

Which statement best explains the orientation of the phospholipid molecules in this model?

The hydrophilic phosphate groups of the phospholipid molecules are attracted to the aqueous internal and external environments.

Which of the following characteristics of Figure 1 best shows that the fragment is RNA and not DNA?

The identity of the nitrogenous base.

Which feature of model 1 best illustrates how biological information is coded in a DNA molecule?

The linear sequence of the base pairs.

A DNA mutation changes the shape of the extracellular domain of transmembrane receptor protein A produced by the cell. Which of the following predictions is the most likely consequence of the mutation?

The molecule that normally binds to protein AA will no longer attach, deactivating the cellular response.

In fruit flies, sepia eyes and ebony body are traits that display autosomal recessive patterns of inheritance. To investigate whether the traits are genetically linked, students cross wild-type flies with a line of flies that have sepia eyes and ebony bodies. The students observe that all the flies in the F1 generation have normal eyes and normal bodies. The students allow the flies in the F1 generation to mate and produce an F2 generation. The students then record observations for the flies in the F2 generation and use the data to perform a chi-square goodness-of-fit test for a model of independent assortment. The setup for the chi-square goodness-of-fit test is presented in Table 1. The students calculate a chi-squared value of 92.86 and compare it with a critical value of 7.82. Which of the following best completes the chi-square goodness-of-fit test?

The null hypothesis can be rejected, and the students should conclude that the data may have resulted from genetic linkage.

In order to determine the effects of age on the accumulation of mitochondrial mutations, mitochondrial DNA samples from young mice (3 months) and old mice (30 months) were observed for mutations. Which of the following is a correct analysis of this data set?

There is an increase in the mean number of mutations for the two age groups of 9.0 mutations per 10^6 base pairs. This is more critical in male mammals since mitochondria are paternally inherited.

A gene that influences coat color in domestic cats is located on the X chromosome. A female cat that is heterozygous for the gene (XBXO) has a calico-colored coat. In a genetics experiment, researchers mate a calico-colored female cat (XBXO) with an orange-colored male cat (XOY) to produce an F1 generation. The researchers record observations for the cats in the F1F1 generation and plan to use the data to perform a chi-square goodness-of-fit test for a model of X-linked inheritance. The data for the chi-square goodness-of-fit test are presented in Table 1. The researchers calculate a chi-square value of 4.6 and choose a significance level of p=0.05. Which of the following statements best completes the chi-square goodness-of-fit test?

The null hypothesis cannot be rejected because the chi-square value is less than the critical value.

The features of this model provide evidence for which explanation of why all growing strands are synthesized in a 5′ to 3′ direction?

The phosphate group, attached to the 5′ carbon of the dTMP, forms a covalent bond with the oxygen atom attached to the 3′ carbon of the growing strand.

What are lipids roles and functions?

They serve as structural components of cell membranes, function as energy storehouses, and function as important signaling molecules. The three main types of lipids are triacylglycerols (also called triglycerides), phospholipids, and sterols.

Monohybrid cross

Tt x Tt

DNA strand is ____.

antiparallel

Osmosis moves water from what to what?

higher concentration to lower concentration

Genetic material is passed on to offspring in eukaryotes during asexual reproduction when?

mitosis

Nondisjuction

the failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, usually resulting in an abnormal distribution of chromosomes in the daughter nuclei.

Transcription

the process of making an RNA copy of a gene sequence. This copy, called a messenger RNA (mRNA) molecule, leaves the cell nucleus and enters the cytoplasm, where it directs the synthesis of the protein, which it encodes.

Translation

the process of translating the sequence of a messenger RNA (mRNA) molecule to a sequence of amino acids during protein synthesis. The genetic code describes the relationship between the sequence of base pairs in a gene and the corresponding amino acid sequence that it encodes. In the cell cytoplasm, the ribosome reads the sequence of the mRNA in groups of three bases to assemble the protein.

Half of all newborns in humans are males because?

the segregation of the X and Y chromosomes during male meiosis.