BIOL 235 Assignment 1 FINAL QUESTIONS AND ANSWERS 2022
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Course
BIOL 235
Institution
BIOL 235
Maintenance of calcium ion is critical to neurological, cardiac and skeletal muscle function. Consider the
roles of 2 hormones involved in the regulation of the concentration of calcium ions in the blood.
Parathyroid hormone increases the concentration of calcium ions in the blood, while calciton...
1) Maintenance of calcium ion is critical to neurological, cardiac and skeletal muscle function. Consider the
roles of 2 hormones involved in the regulation of the concentration of calcium ions in the blood.
Parathyroid hormone increases the concentration of calcium ions in the blood, while calcitonin decreases
the concentration. Based on this information predict the bod’s response to restore calcium balance if a
person swallowed 100 antacid tablets made up of a calcium compounds in 10 minutes. Include in your
answer the definition of homeostasis, the type of feedback loop involved and all the components of a
feedback loop.
Homeostasis is defined as the state of equilibrium (balance) in the body’s internal environment with respect to the
constant interaction of the body’s many regulatory process. In response to any changing conditions, the body’s
equilibrium can shift and the idea of homeostasis is to help maintain the body’s regulatory processes at optimal
level. In this case, since a person has swallowed 100 antacid tablets made of calcium compound in 10 minutes,
the body now has more calcium than is needed in its body, which is disrupting its calcium homeostasis. In
response to this stimulus, a negative feedback loop would be activated where the hormone, calcitonin will
decrease the concentration of calcium hence reversing the change of increased calcium levels in the body until it
reaches its optimal state.
The stimulus in the body is recognized as the calcium blood levels rise above normal, which is affecting the
controlled condition. In response to this change, parafollicular cells in the thyroid gland secrete calcitonin. This
hormone specifically inhibits activity of osteoclasts (the effector in this negative feedback loop), which are the cells
responsible for bone resorption (breaking down bone). Calcitonin also speeds blood calcium reuptake and
accelerates calcium deposition into bones. All these factors result in calcitonin promoting bone formation and
decreasing the overall blood calcium level ultimately reaching a state of a balanced calcium homeostasis.
2) Provide one important example (in the human body) of each of the following:
a. A molecule containing ionic bond
An ionic bond is the force of attraction that holds together ions with opposite charge. One example would
be salt, composed of sodium, Na+ and chlorine, Cl-.
b. A molecule containing covalent bonds
A covalent bond forms where two or more atoms share electrons rather than gaining or losing them.
These bonds can form between atoms of the same element or between atoms of different elements. One
example would be glucose.
c. A molecule containing hydrogen bonds
A hydrogen bond forms when a hydrogen atom with a partial positive charge attracts the partial negative
charge of neighbouring electronegative atoms, usually larger oxygen or nitrogen atoms. Hydrogen bonds
are responsible for holding the base pairs in the middle of the DNA structure thus creating a double helix
structure.
What is the function of each of these three molecules you have identified in the human body? Explain
why each of these three molecules must have its specific types of bonds in order to perform that
molecule’s function.
Sodium chloride is important for maintaining fluid balance. It also plays a role in nerve impulse transmissions. In
an ionic bond, sodium donates an electron to the chlorine to form a bond, the net result is salt, which can be
easily dissolved in water. Further, the ions Na and Cl can be found in sweat that is produced by the eccrine sweat
gland.
Glucose is an important source of energy in the human body. It is broken down and used by our brain to perform
basic functions and higher order executive functions. However, as too little glucose may cause mental fatigue,
excess glucose is also not healthy for the body.
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DNA is important as it holds the genetic information, it is the “blueprint” of our body. The hydrogen bonds in DNA
strengthen it and can be found between each of the atoms. Collectively, hydrogen bonds provide considerable
strength and stability and help determine the 3D shape of large molecules.
3) Define mitosis and meiosis, and describe the differences between these two processes.
Mitosis is the categorization of somatic cell division that a cell undergoes followed by cytokinesis to produce 2
genetically identical cells each with the same number of chromosomes as the original cell. Mitosis is significant as
it replaces injured or dead cell and adds new cells for tissue growth. It involves 4 stages described as prophase,
metaphase, anaphase and telophase.
Meiosis is the reproductive cell division that occurs in the gonads (ovaries and testes) producing gametes, which
are the cells needed to form the next generation of sexually reproducing organisms. Meiosis consists of 2
successive stages known as meiosis I and meiosis II. As a result, the chromosomes are reduced by half where
each gamete containing a single set of 23 chromosomes.
The major differences between mitosis and meiosis are listed below in the table:
Mitosis Meiosis
Somatic cell division Gamete cell division
Copies DNA in interphase stage Copies DNA in interphase 1, but not in interphase 2
Produces 2 diploid daughter cells Produces 4 haploid (23 chromosomes) gametes
4) List the skin glands and write details about their functions. What would be the consequences if a person’s
skin glands stopped functioning?
There are 3 different types of skin glands: sebaceous (oil) glands, sudoriferous (sweat) glands and ceremonious
glands
1. Sebaceous (Oil) Glands:
Simple branched acinar (rounded) glands that are connected to hair follicles. The secreting portion of the
gland is found in the dermis and usually opens into the neck of the hair follicle whereas in other locations it
opens directly onto the surface of the skin. The sebaceous glands secrete sebum, which is categorized as an
oily substance. Sebum helps to coat the surface of hairs, which helps keep them from drying and becoming
brittle. It also prevents excessive evaporation of water from the skin, which allows the skin to say soft and
pliable. If these glands were to stop functioning, a person’s hair and skin would not be properly moisturized,
which would completely dry the skin. Further, sebum also helps to inhibit growth of some bacteria meaning it
can also contribute to the prevention of infections.
When an adolescent reaches puberty, androgens stimulate the sebaceous glands to increase in size and
produce more sebum. Acne occurs when a sebaceous gland undergoes inflammation, which usually begins
around puberty. A condition called cystic acne which is caused by an infection of a cyst or sac of connective
tissue cells can destroy epidermal cells causing permanent scarring of the epidermis.
2. Sudoriferous (Sweat) Glands:
Cells of sudoriferous gland release perspiration or sweat onto the surface of the skin through pores or into
hair follicles. There are 2 different types of sweat glands, eccrine and apocrine glands that are differentiated
by their structure and type of secretion.
Eccrine glands are more common than apocrine glands and are distributed throughout most regions of the
body, especially in the skin of the forehead, palms and soles. In the deep dermis, the secretly portion of the
eccrine gland can be found and the sweat that is produced consists primarily of water with small amounts of
ion (Na and Cl), urea, uric acid, ammonia, amino acids, glucose and lactic acid. The main function of the
endocrine sweat glands is to help regulate body temperature through evaporation. As the sweat evaporates,
large quantities of heat energy also leave the body surface. This homeostatic regulation is known as
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