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15.9: Chapter 9 exercises - Biology


6.1: Viruses

Viruses are generally ultramicroscopic, typically from 20 nm to 900 nm in length. Viruses are obligate intracellular parasites.

Multiple Choice

The component(s) of a virus that is/are extended from the envelope for attachment is/are the:

A. capsomeres
B. spikes
C. nucleic acid
D. viral whiskers

Which of the following does a virus lack? Select all that apply.

A. ribosomes
B. metabolic processes
C. glycoprotein

The envelope of a virus is derived from the host’s

A. nucleic acids
B. membrane structures
C. cytoplasm
D. genome

In naming viruses, the family name ends with ________ and genus name ends with _________.

A. −virus; −viridae
B. −viridae; −virus
C. −virion; virus
D. −virus; virion

What is another name for a nonenveloped virus?

A. enveloped virus
B. provirus
C. naked virus
D. latent virus

True/False

True or False: Scientists have identified viruses that are able to infect fungal cells.

Fill in the Blank

A virus that infects a bacterium is called a/an ___________________.

A/an __________ virus possesses characteristics of both a polyhedral and helical virus.

A virus containing only nucleic acid and a capsid is called a/an ___________________ virus or __________________ virus.

The ____________ _____________ on the bacteriophage allow for binding to the bacterial cell.

Short Answer

Discuss the geometric differences among helical, polyhedral, and complex viruses.

What was the meaning of the word “virus” in the 1880s and why was it used to describe the cause of tobacco mosaic disease?

Critical Thinking

Name each labeled part of the illustrated bacteriophage.

In terms of evolution, which do you think arises first? The virus or the host? Explain your answer.

Do you think it is possible to create a virus in the lab? Imagine that you are a mad scientist. Describe how you would go about creating a new virus.

6.2: The Viral Life Cycle

Many viruses target specific hosts or tissues. Some may have more than one host. Many viruses follow several stages to infect host cells. These stages include attachment, penetration, uncoating, biosynthesis, maturation, and release. Bacteriophages have a lytic or lysogenic cycle. The lytic cycle leads to the death of the host, whereas the lysogenic cycle leads to integration of phage into the host genome.

Multiple Choice

Which of the following leads to the destruction of the host cells?

A. lysogenic cycle
B. lytic cycle
C. prophage
D. temperate phage

A virus obtains its envelope during which of the following phases?

A. attachment
B. penetration
C. assembly
D. release

Which of the following components is brought into a cell by HIV?

A. a DNA-dependent DNA polymerase
B. RNA polymerase
C. ribosome
D. reverse transcriptase

A positive-strand RNA virus:

A. must first be converted to a mRNA before it can be translated.
B. can be used directly to translate viral proteins.
C. will be degraded by host enzymes.
D. is not recognized by host ribosomes.

What is the name for the transfer of genetic information from one bacterium to another bacterium by a phage?

A. transduction
B. excision
D. translation

Fill in the Blank

An enzyme from HIV that can make a copy of DNA from RNA is called _______________________.

For lytic viruses, _________________ is a phase during a viral growth curve when the virus is not detected.

Short Answer

Briefly explain the difference between the mechanism of entry of a T-even bacteriophage and an animal virus.

Discuss the difference between generalized and specialized transduction.

Differentiate between lytic and lysogenic cycles.

Critical Thinking

Label the five stages of a bacteriophage infection in the figure:

Bacteriophages have lytic and lysogenic cycles. Discuss the advantages and disadvantages for the phage.

How does reverse transcriptase aid a retrovirus in establishing a chronic infection?

Discuss some methods by which plant viruses are transmitted from a diseased plant to a healthy one.

6.3: Isolation, Culture, and Identification of Viruses

Viral cultivation requires the presence of some form of host cell (whole organism, embryo, or cell culture). Viruses can be isolated from samples by filtration. Viral filtrate is a rich source of released virions. Bacteriophages are detected by presence of clear plaques on bacterial lawn. Animal and plant viruses are detected by cytopathic effects, molecular techniques (PCR, RT-PCR), enzyme immunoassays, and serological assays (hemagglutination assay, hemagglutination inhibition assay).

Multiple Choice

Which of the followings cannot be used to culture viruses?

A. tissue culture
B. liquid medium only
C. embryo
D. animal host

Which of the following tests can be used to detect the presence of a specific virus?

A. EIA
B. RT-PCR
C. PCR
D. all of the above

Which of the following is NOT a cytopathic effect?

A. transformation
B. cell fusion
C. mononucleated cell
D. inclusion bodies

Fill in the Blank

Viruses can be diagnosed and observed using a(n) _____________ microscope.

Cell abnormalities resulting from a viral infection are called ____________ _____________.

Short Answer

Briefly explain the various methods of culturing viruses.

Critical Thinking

Label the components indicated by arrows.

(credit: modification of work by American Society for Microbiology)

What are some characteristics of the viruses that are similar to a computer virus?

6.4: Viroids, Virusoids, and Prions

Other acellular agents such as viroids, virusoids, and prions also cause diseases. Viroids consist of small, naked ssRNAs that cause diseases in plants. Virusoids are ssRNAs that require other helper viruses to establish an infection. Prions are proteinaceous infectious particles that cause transmissible spongiform encephalopathies. Prions are extremely resistant to chemicals, heat, and radiation.

Multiple Choice

Which of these infectious agents do not have nucleic acid?

A. viroids
B. viruses
C. bacteria
D. prions

Which of the following is true of prions?

A. They can be inactivated by boiling at 100 °C.
B. They contain a capsid.
C. They are a rogue form of protein, PrP.
D. They can be reliably inactivated by an autoclave.

Fill in the Blank

Both viroids and virusoids have a(n) _________ genome, but virusoids require a(n) _________ to reproduce.

Short Answer

Describe the disease symptoms observed in animals infected with prions.

Critical Thinking

Does a prion replicate? Explain.


NCERT Solutions For Class 9 Science Chapter 15 Improvement in Food Resources

NCERT Solutions Class 9 Science Chapter 15 Improvement in Food Resources – Here are all the NCERT solutions for Class 9 Science Chapter 15. This solution contains questions, answers, images, step by step explanations of the complete Chapter 15 titled Improvement in Food Resources of Science taught in class 9. If you are a student of class 9 who is using NCERT Textbook to study Science, then you must come across Chapter 15 Improvement in Food Resources. After you have studied lesson, you must be looking for answers of its questions. Here you can get complete NCERT Solutions for Class 9 Science Chapter 15 Improvement in Food Resources in one place. For a better understanding of this chapter, you should also see Chapter 15 Improvement in Food Resources Class 9 notes , Science.


15.9 Exercises

Your company is in the process of hiring a benefits specialist. As a future peer of the person to be hired, you will be one of the interviewers and will talk to all candidates. The company you are working for is a small organization that was acquired. The job advertisement for the position talks about the high level of autonomy that will be available to the job incumbent. Moreover, your manager wants you to sell the position by highlighting the opportunities that come from being a part of a Fortune 500, such as career growth and the opportunity to gain global expertise. The problem is that you do not believe being part of a larger company is such a benefit. In fact, since the company has been acquired by the Fortune 500, the way business is being conducted has changed dramatically. Now there are many rules and regulations that prevent employees from making important decisions autonomously. Moreover, no one from this branch was ever considered for a position in the headquarters or for any global openings. In other words, the picture being painted by the hiring managers and the company’s HR department in the job advertisements is inflated and not realistic. Your manager feels you should sell the job and the company because your competitors are doing the same thing, and being honest might mean losing great candidates. You know that you and your manager will interview several candidates together.

Is this unethical? Why or why not? What would you do before and during the interview to address this dilemma?

Individual Exercise

Impact of HR Practices on Organizational Culture

Below are scenarios of critical decisions you may need to make as a manager. Read each question and select one from each pair of statements. Then, think about the impact your choice would have on the company’s culture.

  1. You need to lay off 10 people. Would you
    1. lay off the newest 10 people?
    2. lay off the 10 people who have the lowest performance evaluations?
    1. ask employees to use their best judgment?
    2. create a detailed dress code highlighting what is proper and improper?
    1. not monitor them because they are professionals and you trust them?
    2. install a program monitoring their Web usage to ensure that they are spending work hours actually doing work?
    1. evaluate people on the basis of their behaviors?
    2. evaluate people on the basis of their results (numerical sales figures and so on)?
    1. seniority?
    2. objective performance?

    Group Exercise

    Recruiting Employees Who Fit the Culture

    You are an employee of a local bookstore. The store currently employs 50 employees and is growing. This is a family-owned business, and employees feel a sense of belonging to this company. Business is conducted in an informal manner, there are not many rules, and people feel like they are part of a family. There are many friendships at work, and employees feel that they have a lot of autonomy regarding how they perform their jobs. Customer service is also very important in this company. Employees on the sales floor often chat with their customers about books and recommend readings they might like. Because the company is growing, they will need to hire several employees over the next months. They want to establish recruitment and selection practices so that they can hire people who have a high degree of fit with the current culture.

    Working within groups, discuss the effectiveness of the following recruitment tools. Evaluate each recruitment source. Which ones would yield candidates with a high degree of fit with the company’s current culture?

    1. Newspaper advertisements
    2. Magazine advertisements
    3. Radio advertisements
    4. Hiring customers
    5. Hiring walk-ins
    6. Employee referrals
    7. Using the state unemployment agency

    Next, create interview questions for a person who will work on the sales floor. What types of questions would you ask during the interview to assess person-organization fit? How would you conduct the interview (who would be involved in the interviewing process, where would you conduct the interview, and so on) to maximize the chances of someone with a high person-organization fit?


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    15.9: Exercises

    • Contributed by Allen B. Downey
    • Professor (Computer Science) at Olin College
    • Sourced from Green Tea Press

    The code for this chapter is in the ch07 directory of ThinkJavaCode . See [Section 0.4] for instructions on how to download the repository. Before you start the exercises, we recommend that you compile and run the examples.

    If you have not already read Appendix A.5, now might be a good time. It describes Checkstyle, a tool that analyzes many aspects of your source code.

    Consider the following methods:

    1. Draw a table that shows the value of the variables i and n during the execution of loop . The table should contain one column for each variable and one line for each iteration.
    2. What is the output of this program?
    3. Can you prove that this loop terminates for any positive value of n ?

    Let&rsquos say you are given a number, a, and you want to find its square root. One way to do that is to start with a rough guess about the answer, x0, and then improve the guess using this formula:

    For example, if we want to find the square root of 9, and we start with (x_ <0>= 6), then (x_ <1>= (6 + 9/6) / 2 = 3.75), which is closer. We can repeat the procedure, using (x_<1>) to calculate (x_<2>), and so on. In this case, (x_ <2>= 3.075 ) and (x_ <3>= 3.00091). So it converges quickly on the correct answer.

    Write a method called squareRoot that takes a double and returns an approximation of the square root of the parameter, using this technique. You should not use Math.sqrt .

    As your initial guess, you should use (a/2). Your method should iterate until it gets two consecutive estimates that differ by less than (0.0001). You can use Math.abs to calculate the absolute value of the difference.

    In Exercise 6.11.9 we wrote a recursive version of power , which takes a double x and an integer n and returns (x^). Now write an iterative method to perform the same calculation.

    Section 6.7 presents a recursive method that computes the factorial function. Write an iterative version of factorial .

    One way to calculate (e^) is to use the infinite series expansion:

    [e^ = 1 + x + x^ <2>/ 2! + x^ <3>/ 3! + x^ <4>/ 4! + dots onumber ]

    1. Write a method called myexp that takes x and n as parameters and estimates (e^ )by adding the first n terms of this series. You can use the factorial method from Section 6.7 or your iterative version from the previous exercise.
    2. You can make this method more efficient if you realize that the numerator of each term is the same as its predecessor multiplied by x , and the denominator is the same as its predecessor multiplied by i . Use this observation to eliminate the use of Math.pow and factorial , and check that you get the same result.
    3. Write a method called check that takes a parameter, x , and displays x , myexp(x) , and Math.exp(x) . The output should look something like:

    You can use the escape sequence " " to put a tab character between columns of a table.

    One way to evaluate ( exp(-x^<2>) ) is to use the infinite series expansion:

    [ exp(-x^<2>) = 1 - x^ <2>+ x^<4>/2 - x^<6>/6 + dots onumber ]

    The ith term in this series is ((-1)^ x^ <2i>/ i!). Write a method named gauss that takes x and n as arguments and returns the sum of the first n terms of the series. You should not use factorial or pow .


    NCERT Solutions for Class 11 Biology Chapter 9 – Biomolecules

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    You can download CBSE NCERT Solutions for Class 11 Biology Chapter 9 from below.


    15.9: Exercises

    • Contributed by Allen B. Downey
    • Professor (Computer Science) at Olin College
    • Sourced from Green Tea Press

    Write a definition for a class named Circle with attributes center and radius , where center is a Point object and radius is a number.

    Instantiate a Circle object that represents a circle with its center at ( (150,100) ) and radius (75).

    Write a function named point_in_circle that takes a Circle and a Point and returns True if the Point lies in or on the boundary of the circle.

    Write a function named rect_in_circle that takes a Circle and a Rectangle and returns True if the Rectangle lies entirely in or on the boundary of the circle.

    Write a function named rect_circle_overlap that takes a Circle and a Rectangle and returns True if any of the corners of the Rectangle fall inside the circle. Or as a more challenging version, return True if any part of the Rectangle falls inside the circle.

    Write a function called draw_rect that takes a Turtle object and a Rectangle and uses the Turtle to draw the Rectangle. See Chapter 4 for examples using Turtle objects.

    Write a function called draw_circle that takes a Turtle and a Circle and draws the Circle.


    Solving the Biomolecules Multiple Choice Questions of Class 11 Biology Chapter 9 MCQ can be of extreme help as you will be aware of all the concepts. These MCQ Questions on Biomolecules Class 11 with answers pave for a quick revision of the Chapter thereby helping you to enhance subject knowledge. Have a glance at the MCQ of Chapter 9 Biology Class 11 and cross-check your answers during preparation.

    I. Select the correct answer from the following questions:

    Question 1.
    Glucose is a
    (a) Ketose hexose sugar
    (b) Pyronose pentose sugar
    (c) Aldose hexose sugar
    (d) Furanose pentose sugar.

    Answer: (c) Aldose hexose sugar.

    Question 2.
    Lactose molecule is composed of
    (a) Fructose+Fructose
    (b) Glucose+Fructose
    (c) Glucose+Glucose
    (d) Glucose+Galactose.

    Answer: (d) Glucose+ Galactose.

    Question 3.
    Which group contains all polysaccharides?
    (a) Glycogen, sucrose and maltose
    (b) Maltose, lactose and sucrose
    (c) Glycogen, glucose and sucrose
    (d) Glycogen, cellulose and starch.

    Answer: (d) Glycogen, cellulose and starch.

    Question 4.
    Amino acids are formed from
    (a) Proteins
    (b) Fatty acids
    (c) Volatile acid
    (d) α < -keto acids.

    Question 5.
    A nucleoside is formed of
    (a) Phosphate and nitrogen base
    (b) Pentose sugar and phosphate
    (c) Pentose sugar, phosphate and nitrogen base
    (d) Pentose sugar and nitrogen base.

    Answer: (d) Pentose sugar and nitrogen base.

    Question 6.
    The most abundant component of a cell is
    (a) Lipid
    (b) Protein
    (c) Water
    (d) Cellulose

    Question 7.
    Maximum amount of iron occures in
    (a) Proteins
    (b) Bone cells
    (c) Leucocytes
    (d) Erythrocytes.

    Question 8.
    Calcium is required for
    (a) Blood clotting
    (b) Bone formation
    (c) Muscle contraction
    (d) All of these.

    Question 9.
    Immediate source of energy is
    (a) ATP
    (b) Glucose
    (c) NADH
    (d) Pyruvic acid.

    Question 10.
    An amino acid without an asymetrical carbon atoms
    (a) Glycine
    (b) Threonine.
    (c) Proline
    (d) Histidine.

    Question 11.
    The most abundant protein is
    (a) Glycine
    (b) Valine
    (c) Arginine
    (d) Collagen

    Question 12.
    Basic unit of nucleic acid is
    (a) Pentose sugar
    (b) Nucleotide
    (c) Phosphoric acid
    (d) Nitrogen base.

    Question 13.
    The amino acids which are not synthesized in our body are called
    (a) Deaminated
    (b) Non-essential
    (c) Essential
    (d) Proteinaceous.

    Question 14.
    Which of the following is a non-reducing sugar?
    (a) Lactose
    (b) Glucose
    (c) Maltose
    (d) Sucrose.

    Question 15.
    The primary structure of a protein is due to
    (a) ionic bonds
    (b) hydrogen
    (c) Peptide bonds
    (d) S-S linkage

    Question 16.
    A source of maximum energy in a cell is
    (a) proteins
    (b) Vitamins
    (c) Fats
    (d) Carbohydrates.

    Question 17.
    Starch is a polymer of a basic unit of starch is
    (a) Maltose
    (b) Sucrose
    (c) Glucose
    (d) Fructose.

    Question 18.
    Glycogen is a polymer of
    (a) Galactose
    (b) Glucose
    (c) Sucrose
    (d) Fructose.

    Question 19.
    Cellulose occurs in
    (a) Cell wall
    (b) Cell membrane
    (c) Cell interior
    (d) Tunicates.

    Question 20.
    Protein/enzyme is formed by chemically bonding together of
    (a) Lipases
    (b) Carbohydrates
    (c) Amino acids
    (d) CO2

    Question 21.
    The most diverse molecules in a cell are
    (a) Carbohydrates
    (b) Proteins
    (c) Lipids
    (d) Mineral salts.

    Question 22.
    Besides having, C,H,O which of the following also contains S and P?
    (a) Fats
    (b) Vitamins
    (c) Carbohydrates
    (d) Proteins.

    Question 23.
    Natural silk fibre is
    (a) Polyester
    (b) Polysaccharide
    (c) Polyamide
    (d) Polyacid.

    Question 24.
    The enzymes having slightly different molecular structure but similar catalytic reaction are called
    (a) Coenzyme
    (b) Holoenzyme
    (c) Proenzyme
    (d) Isoenzyme.

    Question 25.
    Enzyme that functions at pH = 2.0 is
    (a) Lipase
    (b) Ptyalin
    (c) Pepsin
    (d) Trypsin.

    Question 26.
    Enzymes are polymers of
    (a) Fatty acids
    (b) Chromosomes
    (c) Amino acids
    (d) Nucleus and ribosomes.

    Question 1.
    All the elements present in a sample of ………….. are also present in a sample of living tissue.

    Question 2.
    One is called the filtrate or more technically, the acid soluble, peol, and the second, the retentate or the acid insoluble ………..

    Question 4.
    Amino acids are ……………… containing an amino group and an acidic group as substituents on the some carbon i.e., the α < -carbon

    Question 5.
    The …………… and ………… properties of amino acids are essentially of the amino, carboxyl and the ‘R’ functional groups.

    Question 6.
    ………… are generally water insoluble.

    Answer: Phosphorous, Phosphorylated

    Question 8.
    When found attached to a sugar, they are called …………..

    Question 9.
    ………….. are not strictly macromolecules.

    Question 11.
    ………….. are long chains of sugars.

    Question 12.
    …………, is a polymer of fructose.

    Question 14.
    The most important form of energy currency in living systems is the bond energy in a chemical called ……………. .

    Answer: adenosine triphosphate(ATP)

    Question 15.
    The living state is a ……………. steady state to be able to perform work.

    III. Mark the statement true (T) or false (F)

    Question 1.
    Biomacromolecules are polymers. They are made of building blocks which are different.

    Question 2.
    Proteins are heteropolymers made of starch acids.

    Question 3.
    Nucleic acids (RNA and DNA) are composed of nucleotides.

    Question 4.
    Enzyme, are composed of one or several polypeptide chains.

    Question 5.
    When the binding of the chemical shuts off enzyme activity, the process is called inhibition and the chemical is called an inhibitor.

    Question 6.
    When the inhibitor closely resembles the substrate in its mo-lecular structure and inhibits the activity of the enzyme, it is known as competitive inhibitor.

    Question 7.
    Almost all enzymes are proteins. There are some nucleic acids that behave like enzymes. These are called ribozymes.

    Question 8.
    The latter constitute degradation and hence are called catabolic pathways.

    Question 9.
    The most important form of energy currency in living systems is the bond energy in a chemical called adenosine triphosphate (ATP).

    Question 10.
    Together all these chemical reactions are called metabolism.

    Question 11.
    The pitch would be 34Å. The rise perbase pair would be 3.4Å. This form of DNA with the above mentioned salient features is called B-DNA.

    .
    Question 12.
    In a polysaccharide the individual mono saccharides are linked by a glycosidic bond. This bond is also formed by dehydration.

    Question 13.
    In addition, the long protein chain is also folded upon itself like a hollow wollen ball, giving rise to the secondary structure.

    Question 14.
    Other regions of the protein thread are folded into other forms in what is called the tertiary structure.

    Question 15.
    We can take any living tissue (a vegetable or a piece of liver etc.) and grind it in trichloroacetic acid (CI13 CCOOH) using a mortar and a pestle.

    IV. Match the items of column I with the items of column II

    Column I Column II
    (a) Trichloroacetic acid 1. Consist of nucleotides only.
    (b) Inorganic compounds like 2. Uridine and cytidine are nucleotides.
    (c) Inorganic elements like 3. Polypeptides.
    (d) Nucleic acid like DNA and RNA 4. CL13 CCOOH
    (e) Adenosine, guanosine, thymidine 5. Cellulose
    (f) In addition, the long protein chain is also folded upon itself like a hollow 6. Wollen ball, giving rise to the tertiary structure.
    (g) Together all these chemical reactions are called 7. is the bond energy in a chemical called adenosine triphosphate (ATP).
    (h) Proteins are 8. sulphate, phosphate.
    (i) Plant cell walls are made of 9. calcium, magnesium.
    (j) Cotton fibre is 10. Includes all enzmes catalysing inter-conversion of optical, geometric or positional isomers.
    (k) The most important form of energy currency in living systems 11. molecular structure and inhibits the activity of the enzyme, it is known as competitive inhibitor.
    (l) Adult human haemoglobin 12. meta bolism
    (m) The chemical which is 13. Cellulose.
    (n) Isomerares 14. Consists of 4 subunits.
    (o) When the inhibitor closely resembles the substrate in its 15. converted into a product called a ‘substrate’
    Answer

    Column I Column II
    (a) Trichloroacetic acid 4. CL13 CCOOH
    (b) Inorganic compounds like 8. sulphate, phosphate.
    (c) Inorganic elements like 9. calcium, magnesium.
    (d) Nucleic acid like DNA and RNA 1. Consist of nucleotides only.
    (e) Adenosine, guanosine, thymidine 2. Uridine and cytidine are nucleotides.
    (f) In addition, the long protein chain is also folded upon itself like a hollow 6. Wollen ball, giving rise to the tertiary structure.
    (g) Together all these chemical reactions are called 12. metabolism
    (h) Proteins are 3. Polypeptides.
    (i) Plant cell walls are made of 5. Cellulose
    (j) Cotton fibre is 13. Cellulose.
    (k) The most important form of energy currency in living systems 7. is the bond energy in a chemical called adenosine triphosphate (ATP).
    (l) Adult human haemoglobin 14. Consists of 4 subunits.
    (m) The chemical which is 15. converted into a product called a ‘substrate’
    (n) Isomerares 10. Includes all enzmes catalysing inter-conversion of optical, geomet ric or positional isomers.
    (o) When the inhibitor closely resembles the substrate in its 11. molecular structure and inhibits the activity of the enzyme, it is known as competitive inhibitor.

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    Watch the video: Biology in Focus Chapter 9: The Cell Cycle (January 2022).