Description
Notes: Although there is a minimum word count of 3500 words for this exam, you will find that it is likely going to require more than the minimum to fully answer the question. You may not copy or quote from any source. All information must be re-written in your own words. Answer all questions.
Question 01: Blood Circulation Patterns (875 words)
Describe the functional changes in blood circulation patterns of chordates from the most primitive to the most advanced. Include in
your answer:
a. the pattern of circulation and function of blood in the Lancelet, Branchiostoma lanceolatum
b. the general blood circulation pattern of fishes and the special case of fishes with lungs or swim bladders
c. the transition in blood circulation pattern from tadpole to adult frog during metamorphosis
d. the blood circulatory adaptations of reptiles, birds and mammals
Question 02: From Amniote Egg to Mammals (875 words) Describe amniote eggs and the transition from animals that lay eggs to placental mammals. Include in your answer:
a. the functions of the amniote egg membranes
b. the production of bird eggs and the structure and function of the calcified shells of bird eggs,
c. the adaptations seen in the fossil record that supported the transition from pre-mammal synapsid egg-layers to modern,
placental mammals that nurse their young
Question 03: Bird Flight: Mechanics, Weight, Balance and Power (875 words) Describe flight mechanics and adaptations for flight in birds. Include in your answer:
a. the modern explanation of flight mechanics as described in the text,
b. descriptions of adaptations for flight that reduce weight and those that contribute to balance around the center of gravity,
c. descriptions of mechanisms that increase power (physiological and structural properties, such as food selection, respiratory
refinements, heart rate, mechanical leverage, etc.).
Question 04: Kidneys, Rats and Otters (875 words) Describe the specialized mechanisms for conserving water while ridding the body of nitrogenous metabolic wastes. Include in your answer:
a. the structure and function of organs of excretion of increasing complexity for flatworms, annelids, and insects
b. the special adaptations for water conservation of Sea Otters in ocean waters and Kangaroo Rats in deserts
c. the mechanisms and structural adaptations of the vertebrate kidney for eliminating urea and controlling water loss
References
Immediately following the essay, two lines below the last line of your essay, list all sources used in writing your essay to
answer the question. Do not use in-text citations and do not use footnotes. Simply list your sources in this “References”
section. You must have a References section with at least five references which you have used in preparing your answers:
Explanation & Answer
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Running head: ZOOLOGY
Zoology
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Blood Circulation Patterns
Chordates are a group of animals that belong to the phylum Chordata which have
definable characteristics of the presence of a dorsal nerve cord, pharyngeal slits which are
present in fish and post anal tails. They are usually bilaterally symmetric which means that they
can be cut into two equal parts through the center and for the vertebrates; the dorsal nerve chord
is usually replaced by a vertebral column. This phylum includes such organisms as birds,
mammals, fish, and reptiles as well as a squirt in the Tunicata subgroup. In this phylum the
organisms have a circulatory system that is closed which means their circulatory system id
closed. The blood flows through veins, blood vessels, and arteries and is pumped by the heart.
Also, there is the presence of smaller vessels known as capillaries which help in transport of
diffused gases into the respiratory systems for oxygen and out of the systems for carbon IV
oxide. Unlike the open circulatory system where blood flows through the cavities inside the
body, the closed circulatory system does not have cavities rather it has specific organs which
help in the transport of blood. The heart of these chordates is usually divided into four parts, that
is, a four chambered heart which helps in separate circulation of blood for the respiratory
systems and that for the other body parts, a process known as systemic circulation.
Lancelets which are also known as Amphioxi are a group of marine creatures which are
fishlike in appearance under Chordates. They are usually found in temperate and tropical marine
usually appearing half buried in the sand. They are of the phylum Chordata, sub phylum
Cephalochordata, class Leptocardii and of order Amphioxiformes. Since they have a circulatory
system that is closed, they lack a heart. The heart is essential for pumping blood in closed
systems but for these organisms, blood flows in the body by pulsation which is a coordination of
rhythmic contraction and expansion of the vessels. Notably, the blood of these organisms does
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not have pigments or cells and the blood functions mainly to distribute nutrients in the body
rather than using it for respiratory activities or gaseous exchange.
The circulatory system in fish is of single circuit nature as opposed to that of mammals
which are of a double nature. Fish have a two chambered heart, the ventricle and the atrium. The
atrium collects blood from all over the body organs while the ventricle pumps blood from the
heart to the gills. Here the process of gaseous exchange takes place where oxygen is added into
it, re-oxygenation, a process known as gill circulation. From here, the blood then travels through
the other body parts and eventually ends up in the atrium, a process known as systemic
circulation. In this systemic circulation process, there is the development of a gradient between
the two blood types, the oxygenated and deoxygenated. This results in a deficiency of the
oxygen reaching most of the fish body parts which creates a slowdown in body metabolism. The
circulatory system also consists of the Sinus venous which is a typical venous system where the
merging of blood occurs form several veins just before it enters the heart. The main function of
this part is to regulate and coordinate the heart beat through the presence of a cardiac muscle
present in the organ. The valves present between the Sinus Venosus helps in ensuring that blood
flows only in one direction. There are special types of fish which have an organ known as a
swim bladder usually presents between the gut and the kidneys, occupying the same position as
the lungs in other fish species and is homologous to the heart. There is a major difference
between the swim bladder and the lung in relation to the blood supply and the origin where the
former originates from the gut’s dorsal wall and is supplied blood by the dorsal aorta while the
lung usually originates from the ventral wall of the pharynx and blood is supplied from the sixth
aortic arch. This organ, that is the swim bladder, acts as a hydrostatic organ.
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A tadpole usually spends all its life time under water, therefore, its circulatory system is
closely related to that of a fish. Just like the fish, its heart has two chambers as well, with one
ventricle and one atrium. The blood in its body follows a systemic path where the blood from all
body organs first ...