AP Bio COVID assignments 3 From: Mrs. Verhovsek

Hello AP Bio Students:

Hope you are all still healthy and safe. We are sending home a third packet of assignments at this time. I am moving forward with information that we should be covering during the fourth marking period. I feel it is important to cover this information for those of you taking the AP exam…however, many of you not taking the exam will be moving on to taking biology courses in college…you will need this information as well. So with that understanding, here is what I would like you do to in the next two weeks.

1. Complete the practice FRQs from Units 4-6. These are included in the mail-home packet OR can be accessed by the link provided on my web page titled AP COVID assignment 3.

2. Attend our class sessions on ZOOM (M,W,F 11:30). These are in order to go over the class PowerPoints for the Chapters that I need to still cover. If you cannot attend the ZOOM class…the PowerPoints have been posted on my web page…You will need to go to the “Notes and Presentations” tab in order to access them. I have posted three new PowerPoints: Chapter 19: Viruses , Chapter 27: Bacteria and a third that is a combination of information from several chapters that covers Organ Systems. Please view these…take notes on them if you would like.

3. I have provided some supplemental videos on this information…links to those are also on my web page. Please view them as well…They are from Bozman Science (Mr. Anderson). He does a good job streamlining the important information.

4. Take the Virus and Bacteria Test…this will be open note/open book. You may view the PowerPoint while you take the test. I just need to see that you have spent some amount of time looking at and “digesting” this information.

Unit 4: Cell Communication and Cell Cycle

1. Scientists used cells called fibroblasts to study factors that cause non-dividing cells in the G0 stage of the cell cycle to reenter the cell cycle and undergo mitosis. In a laboratory, fibroblasts typically grow and divide when they are cultured in a growth medium that contains 10% serum (the liquid part of blood that remains after blood clots). If fibroblasts are cultured for 48 hours in the absence of serum (serum-starvation), they stop dividing and enter the G0 stage of the cell cycle.

The scientists divided serum-starved fibroblasts into groups to which they added no serum, 10% serum, or 0.1% serum. Each of the groups with 0.1% serum was also treated to block the production of only one or combinations of four proteins (p16, p18, p21, and p27) that are inhibitors of cyclin-dependent kinases. The scientists grew the fibroblasts for 48 hours and then measured the amount of DNA replication taking place to determine whether the cells had reentered the cell cycle. The scientists compared each group of cells to the group cultured with 10% serum and plotted the data (Figure 1)

0

20

40

60

80

100

120DNA Replication (percent of 10% serum)

Serum 0% 10% 0.1% 0.1% 0.1% 0.1% 0.1%P16 + + - + + + +P18 + + + + - + -P21 + + + - - - -P27 + + + + + - -Group # 1 2 3 4 5 6 7

Figure 1. DNA replication by treated fibroblasts relative to DNA replication by fibroblasts cultured with 10% serum. The treatment of each group of cells is shown in the table directly under the graph. + means the protein is present; - means the protein is absent.

a) Based on the data for the groups of cells cultured with 0.1% serum (groups 3-7), identify which of the four proteins tested do (does) not appear to play a role in blocking cell cycle entry by fibroblasts.

b) Based on the data for the groups of cells cultured with 0.1% serum (groups 3-7), identify the group(s) most likely to include cells undergoing mitosis.

c) Neurons (nerve cells) of the central nervous system (brain and spinal cord) are in the G0 of the cell cycle and generally do not divide in response to an injury. The scientists predict that they can use the data from this experiment to help them treat individuals who suffer from spinal cord injuries. Provide reasoning to support the scientists’ prediction.

d) Interactions between cyclins and cyclin-dependent kinases control the cell cycle. Explain how the presence or absence of inhibitors of cyclin-dependent kinases might play a role in normal cells becoming cancer cells.

Unit 5: Heredity FRQs

1. The sex of an organism is typically determined genetically, but environmental factors can also play a role. Scientists examined the roles of genes and environmental temperature in the sex determination of a lizard species. Individuals with a ZW pair of chromosomes are always female (ZWf), while individuals with a ZZ pair of chromosomes can be either male (ZZm) or female (ZZf). Scientists mated ZWf or ZZf females with ZZm males and incubated the eggs produced in 20 clutches at temperatures ranging from 23oC to 36oC. When the young hatched, the scientists determined their sexes (Table 1). Among the eggs that did not hatch, the mortality of embryonic lizards was approximately the same for both males and females.

Table 1. Fraction of female progeny produced as a function of egg incubation temperature.

Egg Incubation Temperature (oC) ZZm x ZWf Crosses: Fraction of Female Progeny ± 2SEM

ZZM x ZZf Crosses: Fraction of Female Progeny ±2SEM

23 0.5 ± .08 024 0.5 ± .02 026 0.5 ± .07 028 0.5 ± .03 030 0.5 ± .01 0.03 ± .0132 0.5 ± .03 0.2 ± .0233 0.58 ± .03 0.52 ± .0534 0.74 ± .04 0.88 ± .0435 0.93 ± .03 0.97 ± 0.236 1.0 ± 0.0 1.0 ± 0.0

a) If a particular gene is located on the Z chromosome of this lizard species, describe why a lizard with a ZW genotype has a greater probability of expressing the phenotype for the trait than a lizard with a ZZ genotype does.

b) Construct an appropriately labeled graph, including error bars, to represent the data in Table 1. Based on the data, compare the ZZm x ZWf crosses and the ZZm x ZZf crosses to determine whether there is a significant difference between the two crosses in the fraction of female progeny produced at 24oC, 32oC, and 36oC.

c) For each cross, describe whether genetics or temperature determines the sex of progeny produced from eggs incubated at 35oC. For each cross, describe whether genetics or temperature determines the sex of progeny produced from eggs incubated at 24oC.

d) Predict the effect of increasing global temperatures on the continued presence of the W chromosome in this species of lizard. Scientists claim that, in this species, the W chromosome is unimportant in sex determination. Instead, proteins that are encoded by a gene or genes on the Z chromosome, and that are maximally expressed only at certain temperatures, are responsible for determining whether embryos will develop as females or males. Use the data to support this claim.

2. Primary spermatocytes are diploid (2n) cells with all of the organelles typically found in eukaryotic animal cells. A representation of spermatogenesis from a primary spermatocyte with six chromosomes is shown in Figure 1.

Figure 1. A representation of spermatogenesis

a) Describe the process in meiosis that ensures that both maternal and paternal chromosomes are passed on to each spermatozoon.

b) Explain why the genetic content of individual chromosomes in a spermatozoon most likely differs from the genetic content of individual chromosomes in a primary spermatocyte.

c) In some instances, meiosis of a primary spermatocyte with six chromosomes results in two spermatozoa that contain four chromosomes and two spermatozoa that contain two chromosomes. Predict the most likely cause.

d) A student claims that if the animal producing the spermatozoa has a mutation in a mitochondrial gene, the probability that any offspring will inherit the mutation is zero. Provide evidence to support this claim.

Unit 6: Gene Expression and Regulation

1. DNA replication in eukaryotes and prokaryotes starts when a complex of proteins binds to an origin of replication (Figure 1A) and separates the two strands of the double helix to form a replication bubble with replication forks at each end (Figure 1B). In order for replication to proceed, the enzyme topoisomerase binds to the DNA immediately in front of the advancing replication forks. Figure 1. DNA replication starts when the two strands of the double helix separate at an origin of replication. Topoisomerase binding sites are indicated.

a) Describe how the structure of a prokaryotic chromosome differs from the structure of a eukaryotic chromosome.

b) Explain why DNA replication cannot proceed to the regions of the chromosome labeled as I in Figure 1 unless topoisomerase binds ahead of each advancing replication fork in region II.

c) Use the template of a replication fork to draw arrows that represent both continuous and discontinuous DNA synthesis. Draw one long arrow to show continuous DNA synthesis and three arrows to show discontinuous DNA synthesis. The arrows should point in the direction of nucleotide addition, and the three arrows showing discontinuous synthesis should be numbered 1,2, and 3, in the order of fragment synthesis.

d) Referring to Figure 1, explain why any newly synthesized strand of DNA is the result of both continuous and discontinuous DNA synthesis

Replication forks

Topoisomerase Binding Sites

II

II[

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AP Biology Test Name: ________________________________________Viruses and Bacteria

1. _____ Why are viruses referred to as obligate intracellular parasites?A. They cannot reproduce outside of a host cell. C. They invariably kill any cell they infect.B. Viral DNA always inserts itself into host DNA. D. They must use enzymes encoded by the virus itself.

2. _____ A virus identifies its host cell by which of the following;A. the proteins on its surface and that of the host. C. the proteins in the host’s cytoplasmB. whether its nucleic acid is DNA or RNA. D. the enzymes carried by the virus.

3. _____ Which of the following explains why someone who has had a herpes virus-mediated cold sore, continues to have flare-ups for the rest of their life?

A. re-infection by the same herpes virus strainB. copies of the herpes virus genome permanently maintained in host cells’ cytoplasm or nucleiC. re-infection by a closely related herpes virus of a different strainD. co-infection with an unrelated virus that causes the same symptoms

4. ______ What is the name given to viruses that are single-stranded RNA that acts as a template for DNA synthesis?A. viroid B. proviruses C. retrovirus D. prions

5. _____ Why do RNA viruses appear to have higher rates of mutation?A. RNA nucleotides are more unstable than DNA nucleotidesB. Replication of their genomes does not involve the proofreading steps of DNA replicationC. RNA viruses replicate faster.D. RNA viruses are more sensitive to mutagens.

6. _____ Which of the following can be effective in preventing viral infections in humans?A. getting vaccinated C. applying antisepticsB. taking antibiotics D. taking nucleoside analogs that inhibit transcription

7. _____ Antiviral drugs that have become useful are usually associated with which of the following properties?A. ability to remove all viruses from the infected host C. prevention of the host from becoming infectedB. interference with the viral reproduction D. removal of viral proteins

8. _____ Which of the following characteristics, structures, or processes is common to both bacteria and viruses?A. metabolism B. ribosomes C. cell division D. nucleic acids

9. _____ What are prions?A. a mobile segment of DNA C. viruses that invade bacteriaB. tiny molecules of RNA that infect plants D. misfolded versions of normal brain protein

10. _____ Which of the following terms describes bacteriophage DNA that has become integrated into the host cell chromosome?A. Transposons B. plasmids C. prophages D. retrophages

DiagramsPlace the following labels on the diagram below and briefly describe what is happening at each numbered step. Lytic Cycle Lysogenic Cycle

Short AnswerExplain why the reproductive cycle of many enveloped viruses does not necessarily kill the host cell, while the lytic cycle of phages almost always kills the host cell.______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Two opposing thoughts exist concerning the evolution of viruses. One is that they evolved, possibly multiple times, only after living cells appeared. The other is that they evolved from a pre-cellular form of life. Choose one of these positions and defend it with evidence that could explain the source of viral genomes.______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Label the following diagram: Use the following word bank:Viral RNA DNA HIV Virus Reverse transcriptaseProvirus mRNA copied viral RNA New HIV virus

36. _____ Which of these is the most common compound in the cell walls of gram-positive bacteria?A. cellulose B. chitin C. peptidoglycan D. lignin

37. _____ Not present in all bacteria, this structure enables those that possess it to germinate after exposure to harsh conditions, such as boiling.

A. endospore B. cell wall C. capsule D. flagellum

38. _____ Not present in all bacteria, this structure enables those that possess it to resist the defenses of host organisms.

A. endospore B. cell wall C. capsule D. flagellum

39. _____ Genetic variation in bacterial populations can result from all of the following exceptA. Transduction and transformation C. conjugationB. Mutation D. Meiosis

40. _____ What is the primary ecological role of prokaryotes?A. Parasitizing eukaryotes, thus causing diseaseB. Breaking down organic matterC. Adding methane to the atmosphereD. Serving as primary producers in terrestrial environments

41. _____ Which of the following are responsible for high levels of oxygen in Earth’s atmosphere?A. photoautotrophs B. photoheterotrophs C. chemoautotrophs D. chemoheterotrophs

42. _____ Which of these statements about prokaryotes is correct?A. Bacterial cells conjugate to mutually exchange genetic material.B. Their genetic material is confined within a nuclear envelope.C. They divide by binary fission, without mitosis or meiosis.D. Since they reproduce asexually, there is virtually no genetic variation in bacteria.

43. _____ Penicillin is an antibiotic that inhibits enzymes from catalyzing the synthesis of peptidoglycan, so which prokaryotes should be most vulnerable to the effects of penicillin?

A. archaea B. gram-positive C. gram-negative D. endospores

44. _____ Assuming that each of these possesses a cell wall, which prokaryotes should be expected to be the most resistant to plasmolysis in hypertonic environments?

A. extreme halophiles B. extreme thermophiles C. methanogens D. cyanobacteria

45. _____ Many physicians administer antibiotics to patients at the first sign of any disease symptoms. Why can this practice cause more problems for these patients, and for others not yet infected?

A. The antibiotic may kill viruses that had been keeping the bacteria in check.B. Antibiotics may cause other side effects in patients.C. Overuse of antibiotics can select for antibiotic-resistant strains of bacteria.D. Patients may be allergic to the antibiotic.