Solution Authoring Guidelines · Protein synthesis takes place much more slowly in eukaryotes than in prokaryotes. Give a ... Actin and myosin are also called thin and thick filaments

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Solution Authoring

Guidelines

Version 9.4

September 2016

2 Copyright@2016 chegg.com

Subject-specific Guidelines- Biology

Table of Contents

B1. Technology ................................................................................................. 3

B2. Special points/others .................................................................................. 3

List of changes made over Version 9.1

Removed B1. Content and B4. Conceptual questions ……………..…………Page no.3


Modified the point (b) in B2.Special points/others.....……………..…………Page no.3


Modified B2(b)………………………………………………………………………………….Page no. 3


B1. Technology

a. Use ChemBio/ChemDraw for Chemical structures.

b. Use CorelDraw or Serif DrawPlus for other diagrams.

c. Should you wish to use a different program, please check first with your

Territory Manager.

B2. Special points/others

a. Names of Species and genes should be in italics.

b. The correct option(s) in match the following type questions should be boxed.

c. The symbols for males (♂) and females (♀) should be used for solutions of

genetic books. The symbol for males can be created by holding down ALT and

pressing 11, while the symbol for females can be created by holding down ALT

and pressing 12.

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Sample solutions – Biology


Sample example 3-MCQ type has been added…………….……….Page no. 7

Sample example 4-Fill in the blank type has been added….……….Page no. 8

Sample example 5-True or False type has been added….…….…….Page no.9

Sample example 7- New Very Short Answer Type has been added...Page no.12


Sample example 1- Calculation based has been modified…………..Page no.5


Biology Example 1: Calculation based

Question:

Normal human hemoglobin has an isoelectric point of 6.87. A mutant variety of hemoglobin,

known as sickle-cell hemoglobin, has an isoelectric point of 7.09. The titration curve of

hemoglobin indicates that, in this pH range, 13 groups change ionization states per unit

change in pH range. Calculate the difference in ionic charge between molecules of normal

and sickle-cell hemoglobin.

Solution:

Calculate the difference in the charges between sickle-cell hemoglobin and normal

hemoglobin using the following formula: z n pH

Here, the number of charged groups is n, the change in pH is ΔpH , and the charge is z.

Number of charged groups in Normal hemoglobin, n is 13.

The isoelectric point of the normal hemoglobin is 6.87

The isoelectric point of sickle-cell hemoglobin is 7.09.

Substitute the values in the formula.

Δ ΔpH

13 7.09 6.87

= 2.86 or 3

z n

Thus, the difference of the charges between sickle-cell hemoglobin and normal hemoglobin is

three approximately. Therefore, sickle-cell hemoglobin is three ionic charges less or

negative than normal hemoglobin.


Biology Example 2: Conceptual

Question:

What are the three economically important members of the Moraceae?

Solution:

Moraceae is one of the four Urticalean Rosid families. These families were first a part of the

order Utricales. They are now included in the order Rosales. Moraceae is generally known as

the mulberry family. It consists of monoecious and dioecious trees, shrubs, lianas, and herbs.

Economically important members of Moraceae include the following:

The latex from the bark of Ficus elastica is used to manufacture rubber.

The fruits from the plant Artocarpus altilis is edible and is called the jack fruit or the

breadfruit.

Edible figs are obtained from Ficus carica.

The leaves of Moringa are used as food for the silkmoth. They also have the nutritive

value and can be used as food for humans. The fruits of Moringa are used as

vegetables.

Morus alba or mulberry is used in the manufacture of silk.

The bark of paper mulberry is used for obtaining fibers, which are used in the cloth

manufacturing industry.

Match the following questions:

Match the following questions contain two different or related options, which should be

matched with each other. All the correct options should be boxed.

Example:


Biology Example 3: Multiple Choice Question Type

Question

Prolonged muscle inactivity as in siting causes a(n)_______________

a) Increase in blood lipids

b) Increase in calories burned

c) Decrease in blood glucose

d) All the above

Solution

Sitting inactive for prolonged periods would allow our body to accumulate various

compounds in our body. In specific, there is only one compound that accumulates faster than

any other. Observe this condition option by option in the following steps:

The burning of calories requires enhanced activity but not prolonged inactive state that results

in storage of energy.

Hence, the option (b) is not the correct answer.

Decreased muscle activity leads to under-utilization of the available glucose, increasing its

content in the blood.

Hence, the option (c) is not the correct answer.

As decreased muscle activity increases blood lipids, decreases the number of calories burned,

and increases blood glucose levels. Thus, only the option (a) is correct and all the other

options are not correct.

Thus, the option (d) is also incorrect.

Inactivity of the muscles for extended durations results in the accumulation of excess energy

as lipids. Prolonged sitting is hazardous. During this time, leg muscles relax and decrease the

production of lipoprotein lipase (LPL). LPL is essential for uptake of lipids from the blood

and for production of HDL. As the production of LPL decreases, accumulation of lipids in

the blood increases.

Hence, the correct answer is Option a .


Biology Example 4: Fill in the blank Type

Question:

A common type of knee injury seen in football, usually caused by a hard blow to the lateral

side of the knee while the foot is fixed on the ground, involves the rupture of the

____________and tearing of the __________and the _________and is also known as

‘unhappy triad’.

Solution:

A general type of knee injury, which produces swelling and leakage of blood from injured

blood vessels, is also responsible for the ruptures of the closed areas near to injury.

The damaged regions around the injured blood vessels are synovial membrane, collateral

ligament, anterior cruciate ligament and menisci.

Tearing of ligament produces tearing of the meniscus. Tearing of ligaments is observed in

football and rugby when the knee experiences a hit from the lateral side when the foot is at

rest. When the three parts of the knee joint get injured along with the injury of medial

meniscus, anterior cruciate ligament, and tibial collateral ligament, it is termed as unhappy

triad.

So, first blank can be filled with anterior cruciate ligament. The second blank can be filled

with ligament and the third blank can be filled with Meniscus.


Biology Example 5: True or False Type

Question

Provide correct answer for the following statement, whether it is true/false

“The major cause of intellectual disability is a neurologic disease.”

Solution

Intellectual disability refers to significant limitation in intellectual functioning and adaptive

behaviour.

The factors are prenatal factors, environmental factors, and neurological diseases (like Down

syndrome, Fragile X syndrome, and Fetal Alcohol Spectrum Disorder (FASD)).

These factors may alter the cognitive function that results in mental retardation. Profound

intellectual disability is caused due to neurological diseases which occur in 2% of the cases.

So, neurological disease cannot be considered as major cause of intellectual disability.

Hence, the above statement is false.


Biology Example 6: Structure based

Question:

Explain how MIT, DIT, T3, and T4 relate to each other structurally?

Solution:

MIT is the monoiodotyrosine. It is the precursor of thyroid hormone. It is formed when

iodine is added to the tyrosine molecule, and has the following structure:

DIT is the diiodotyrosine. It is formed by addition of two atoms of iodine to the tyrosine or

by addition of iodine to MIT. DIT has the following structure:


T4 or thyroxine is synthesized when two DIT molecules combine. Two iodines on each DIT

molecule add to a total of four iodines to the T4 molecule.

T3 or triiodothyronine is formed when one molecule of MIT combines with one molecule of

DIT. Therefore, T3, on the whole contains 3 iodines in its structure.

Therefore, by observing the structures of MIT, DIT, T3, and T4, it can be inferred that all of

them are the derivatives of the amino acid, tyrosine. Also, MIT and DIT are the main

precursors of the hormone, thyroxine.


Biology Example 7: Very Short answer Type

Question:

Protein synthesis takes place much more slowly in eukaryotes than in prokaryotes. Give a

reason why.

Solution:

Protein synthesis takes place much more slowly in eukaryotes than in prokaryotes because of

the following reasons:

Translation in prokaryotes is coupled with transcription which indicates that as soon as the

mRNA is transcribed, ribosomes attach to it and start the process of translation. This

simultaneous process of transcription and translation occurs because there is no defined

nucleus in prokaryotes.

In eukaryotes, the mRNA is produced in the nucleus, which then undergoes modification, and

finally enters the cytoplasm where protein synthesis occurs. This separation of transcription

and translation occurs in space and time.


Biology Example 8: Diagrammatic

Question:

Explain how the cellular and subcellular structure of skeletal muscle relates to the sliding

filament theory of muscle contraction.

Solution:

A sarcomere is the fundamental unit of skeletal muscle and includes repeating segments of

the proteins actin and myosin. The sarcomere is the cellular structure of the skeletal muscle,

while the actin and myosin filaments are the subcellular structures. The following diagram

represents the sarcomere:

The sliding filament theory of skeletal muscle contraction was based on observable

differences made between contracted and relaxed muscle tissue. To understand the filament

theory, it is necessary to know the anatomy of a muscle cell.

Muscle cells, also known as muscle fibers, are made up of bundles of cylindrical organelles

called myofibrils. Myofibrils are surrounded by other organelles such as the sarcoplasmic

reticulum, mitochondria, granules, and a plasma membrane (sarcolemma). Myofibrils contain

two rod-shaped proteins called actin and myosin that lie parallel to each other in an

overlapping pattern. Actin and myosin are also called thin and thick filaments respectively,

because of their relative thickness (that is, actin is thin and myosin is thick). Actin filaments

are joined together at a structure called the Z-line, also known as the Z-disk. In the middle of

the myosin is the M-line, which is also the anchor point for myosin. The repeating pattern

from the Z-line of one actin filament to the Z-line of an adjacent actin filament is defined as a

sarcomere.

The sarcomere is the fundamental unit of skeletal muscle tissue. The area of a sarcomere,

where myosin is not overlapping with actin is called the H-zone and is observably lighter in

color than the rest of the sarcomere under a microscope. This is what gives the skeletal

muscle, its striated or banded appearance. The area that spans the length of the myosin

filament is called the A-band. The area where actin is not overlapping with myosin is called

the I-band.


The sliding filament theory of skeletal muscle contraction was developed, when scientists

observed that a contracted sarcomere had different length, than a sarcomere at rest. In a

contracted muscle fiber, the H-zone decreased to almost nothing, the I-band decreased in size,

and the Z-lines and A-bands were closer together. The sliding filament theory is that the

interaction between actin and myosin filaments during contraction caused the sarcomere to

decrease in size, as adjacent actin and myosin filaments pulled closer together.

The anatomy of actin and myosin filaments further demonstrates the sliding filament theory.

Each myosin filament contains numerous strands of myosin molecules with globular heads.

The myosin heads have a site for ATP (adenosine triphosphate), the ability to break down

ATP for energy, and a site for binding with actin filament. Actin filaments have sites for

binding with the myosin heads and structures that cover these binding sites to prevent

interaction with myosin heads when at rest. When actin and myosin are bound together, a

cross-bridge is formed and then energy from the use of ATP is used to slide the actin

filaments closer together.

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Solution Authoring Guidelines · Protein synthesis takes place much more slowly in eukaryotes than in prokaryotes. Give a ... Actin and myosin are also called thin and thick filaments