BCLN BIOLOGY 11 – Rev July 2014
Unit 13 ~ Learning Guide
Name: _______________
INSTRUCTIONS
Complete the following notes and questions as you work through the related lessons.
You are required to have this package completed BEFORE you write your unit test. Do
your best and ask questions about anything that you don't understand BEFORE you
write the unit test.
13.1 NOTES: CHORDATES
General Characteristics of Phylum Chordata
Although not the largest, Chordates are the most diverse phylum in the animal kingdom.
Chordates have _____________________________ at some stage of the life cycle and
have __________________________ made from an outgrowth of the digestive tube.
All chordates are deuterosomes and the blastopore during embryonic development
forms the anus. They show body segmentation and other characteristics present in the
more advanced animals.
In order to be classified as a chordate an animal must have the characteristics listed
below. Although it may seem as if many chordates do not possess these characteristics,
they do at some point during embryonic development.
1. Notochord
__________________________
__________________________
_________________________.
The function of the notochord is
to provide support and protection
to the nerve chord. In the higher
chordates, the vertebrates, the
notochord
is
present
in
embryonic development and
__________________________
_______________________________________________________________.
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BCLN BIOLOGY 11 – Rev July 2014
2. Dorsal Tubular Nerve Chord
The _________________________________________________ is exactly
what its name suggests. The term dorsal means it is on the back side of the
animal. The term tubular means it is hollow. It is the nerve chord of the animal.
The hollow portion of the nerve chord is filled with fluid that nourishes the nerve
cells. ___________________________________________________________
________________________________________________________________
_______________________________.
3. Pharyngeal Pouches
________________________________________________________________
________________________________________________________________
________________________________________________________________.
In water-breathing animals the pharyngeal pouches become the gills or gill slits.
In air- breathing animals the pharyngeal pouches take on a number of functions.
None of the pharyngeal pouches are involved in respiration in humans.
4. Post Anal Tail
The ______________________________________ is simply an extension of the
nerve chord and body ___________________________________.
There are three sub-phyla that will be discussed in the lessons to follow:
1. Subphylum Urochordata
2. Subphylum Cephalochordata
3. Subphylum Vertebrata
Endoskeletons
All of the chordates have an _______________________________________. The
skeleton of chordates varies greatly from the ________________________________
_________________________________ to the ______________________________
___________________________________ and the bony skeletons of humans.
The endoskeleton possesses advantages and disadvantages to the previously studied
exoskeleton of Arthropods. The endoskeleton doesn't provide the overall protection to
the body that the exoskeleton does. Where protection of a certain internal organ is very
important it is well protected by the endoskeleton. In humans, the skull, spine, and rib
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BCLN BIOLOGY 11 – Rev July 2014
cage would be examples of bones that are providing effective protection for organs like
the brain, spinal cord and heart.
The endoskeleton has a ________________________________________________
__________________________________________. Likely, the most important
improvement over the exoskeleton is its _____________________________________.
The exoskeleton must be periodically shed and regrown. This leaves the animal
vulnerable for a short time while it is re-growing its exoskeleton and is also very costly in
terms of energy. With the endoskeleton's ability to grow along with the animal, these
animals can grow much larger and energy can be expended on the development of
other organs.
13.1 PRACTICE: CHORDATES
1. In the diagram below, identify and label the 4 characteristics that are common to
all chordates. (4 marks)
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BCLN BIOLOGY 11 – Rev July 2014
2. Members of Phylum Chordata have ______________________ symmetry and a
_______________________ (which means they have a body cavity which is
completely lined with mesoderm). (2 marks)
3. In Chordates the blastopore becomes the anus:
a. Organisms
that
develop
this
way
_________________________________. (1 mark)
are
termed
b. Identify at least one other animal phylum, studied in Biology 11, that has a
similar developmental pattern. (1 mark)
4. All chordates have an endoskeleton:
a. Define endoskeleton. (1 mark)
b. Explain two ways that an endoskeleton might provide a selective
advantage over either lacking a skeleton altogether or over an
exoskeleton. Remember to answer this question properly you must
compare the exoskeleton to the alternatives. (2 marks)
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13.2 NOTES: PROCHORDATES
General Characteristics of Prochordates
____________________________________________________
___________________________ are those animals in which
___________________________________________________
__________________________________ during development.
The
two
subphyla
of
prochordate
are
the
________________________ (subphylum Cephalochordata;
pictured top right) and the ____________________ (subphylum
Urochordata; pictured bottom right).
1. Lancelets
_________________________
(subphylum
Cephalochordata)
_______________
________________________________________________________________
___________________________________________. The ________________
_______________________________________________________________
_______________________________________________. A lancelet is very
mobile and powers its way through the water with muscles that use the
notochord as a point of attachment. The tentacles around the mouth are for
searching through mud for microscopic food particles that will filter out of the
constant water stream that is moving through the animal.
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PLEASE LABEL THE ANATOMY OF A LANCELET
DIAGRAM BELOW BEFORE PROCEEDING ANY FURTHER!
2. Tunicates
_______________________________________________
______________________________________________.
There are an estimated 2000 species of tunicates that are
commonly called “Tunics” meaning tough covering.
_______________________________________________
___________________. Tunicates are hermaphrodites.
The adult tunicate (subphylum Urochordata) looks more
like an invertebrate than a chordate since the only retained
trait from the larval stage are the gill slits. Tunicate larva
possesses all of the chordate characteristics. The tadpolelike larvae is bilaterally symmetrical and free swimming
which is ideal for the dispersal stage of the tunicate life
cycle. __________________________________________
_______________________________________________
______________________________________________.
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The sessile tunicate will filter feeder by drawing in water thought its incurrent
siphon and past the gill slits to filter out oxygen and food. The larvaceans (class
Appendicularia) are a group of tunicates that remain in the larval form and do not
become the sessile adult. ____________________________________________
_________________________________________________________________
________________________________________________________________.
13.2 PRACTICE: PROCHORDATES
1. What is the defining characteristic of a prochordate? (1 mark)
2. The lancelet is considered the prototypical chordate.
a. Define prototypical. (1 mark)
b. Why is the lancelet considered the prototypical chordate? (1 mark)
3. It is difficult to recognize an adult tunicate as a chordate.
a. Explain why. (1 mark)
b. Explain why scientists classify it as chordate. (1 mark)
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13.3 NOTES: VERTEBRATES
Diversity of Vertebrates
The anatomy and physiology of humans is
the focus of Biology 12. For this reason, the
study of the vertebrates in Biology 11 will
be an introduction to the diversity of the
classes within the phylum. The vertebrates
are the animals that are more typically used
to represent the chordate phylum. With
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
vertebrates are the most advanced of all
organisms.
Vertebrates are distinguished from other
chordates by:
1. _____________________________________________________________ that
surround and protect the dorsal nerve cord. The vertebrae form a vertebral
column or spine.
2. A cranium or _____________________________________________________
3. An _____________________________________________________________
Features of Vertebrates
Vertebrates also have:
1. A living endoskeleton with vertebral column that can grow.
2. __________________________________________________
3. Paired appendages.
4. Efficient respiration and excretion.
5. __________________________________________________
6. Adapted to active lifestyles.
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Proposed Vertebrate Lineages
Fishes
Vertebrates first appear in the fossil record
______________________________________.
Today there are an estimated 45,000 species of
vertebrates. More than 24,000 of these are fish
species. _______________________________
______________________:
1. _________________________________
_________________________________
2. _________________________________
_________________________________
3. _________________________________
________________________________
General Characteristics of Fishes
Fish have a stream-lined shape for to reduce drag with paired fins that allow movement
left or right. Secretion of a mucus layer helps to reduce friction. Fish have an air bladder
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which stores carbon dioxide to control their buoyancy in the water. Gills allow for gas
exchange between the blood stream and water. Fish also have a lateral line or row of
sensory structures along the side of the body that can detect vibrations in the water.
1. Jawless Fishes
It is predicted that the ______________________
________________________________________ since
they are the most similar to the prochordates and are
the oldest known vertebrate fossils. Jawless fishes have
____________________________________________
_____________________. They rely on external
fertilization for reproduction. Examples of these fishes
include the ___________________________________.
Both of these fishes rely on symbiotic relationships.
_______________________ are deep sea bottom
dwellers named for their slimy coat. They take part in a
commensalistic relationship as _______________
____________________________________________
____________________________________________
___________________________________________.
The circular rasping teeth of the lamprey attach to a
fish. Rasping at the flesh of the host fish the lamprey
will feed off of the blood. Lampreys are an exotic
species introduced into the Great Lakes through the
discharge of ballast tanks from ships. They devastated
native fish populations in the 1970's and 1980's.
2. Cartilaginous Fishes
The next group of fishes are the ____________
______________________________________.
This class includes sharks, skates and rays.
______________________________________
______________________________________.
The cartilaginous fishes are all marine and all
are carnivorous except the whale shark. They
have jaws, paired appendages, visceral arches, three semi-circular canals,
paired nasal cavities, and placoid scales that feel like sandpaper, and a wellPage 10 of 30
developed sense of smell. As their
name suggests they have an
endoskeleton
made
entirely
of
cartilage. Other features include no
swim bladder or lung, a heterocercal or
asymmetrical tail, and respiration by
means of five to seven pairs of gills
with gill slits. These fish have separate
sexes and utilize several reproductive
strategies. Some species are oviparous (eggs hatch outside the body), others
are ovovivparous (eggs hatch inside the body), and others are viviparous (young
are cared forcompletely internally).
____________________ have very well developed senses that are used to
locate prey.
In fact, they actually have seven senses. The two extra senses are the ability to
detect slight electric currents in water which could be caused by the muscle
contractions of another animal and the ability to detect changes in pressure in
water currents with their lateral line. Sharks have 6-20 rows of teeth that are
continually being replaced and may use over 20,000 teeth in a lifetime. The
paired pectoral fins in sharks are located just behind the head and jut out from
the body like wings on a plane to provide lift when swimming.
______________________________________ have flattened bodies, paired
wing like pectoral fins, and some species have a whip like tail. Rays have
diamond shaped bodies while skates have triangular shaped bodies. Both are
bottom dwellers and their flat shape and color camouflage them with the ocean
floor.
3. Bony Fishes
_____________________________________________
have a ________________________________________
_____________________________________. Bony fish
are characterized by three key features; bone, lungs or
swim bladder, and scales. The tail is usually homocercal
or symmetrical on the top and bottom. They have skin
with mucous glands and embedded dermal scales. The
operculum, a bony plate that protects the gills, is found in bony fishes.
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These are the fishes that we generally think
of when we think of fish. From the fish that
we eat to the ones we keep as pets in a
fish tank. One of the most unique organs in
the bony fishes is the swim bladder. This is
a relatively large air sac within the fish that
increases in size when the fish wants to go
up and decreases in size when the fish
wants to go down. Most of the bony fishes
are ray-finned fish. However, a very
important group of fish in terms of
evolution are the lobe-finned fishes.
__________________________________
__________________________________
__________________________________
_________________________________.
These fishes not only had fleshy
appendages instead of flat fins, but they
also had a lung that could be used for
respiration. Lobe-finned fish were long
thought to be extinct, but in 1938 a lobefinned fish called a coelacanth was caught
off the coast of Madagascar. These are the
only known living lobe-finned fish.
Bony fish all have a very similar internal anatomy. The circulatory system
consists of a ________________________________________ with separate
arterial and venous systems and four aortic arches. The nervous system consists
of a well-developed brain with well-developed olfactory and optic lobes. Most
species are oviparous and fertilization is external.
Life in the Water
Scales found in fishes prevent diffusion through body tissues so gills are needed
for gas exchange. In marine fish water is continually leaving the body by osmosis
and ions are continually entering. To keep from dehydrating they must drink large
amounts of water and produce a small amount of concentrated urine. Their gills
are also adapted to lose salt. In freshwater fish water is continually entering the
body of the fish by osmosis so they do not drink water and produce large
amounts of dilute urine.
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Amphibians
Amphibians are the most primitive of the animals to possess true limbs and are
tetrapods with four legs. Other features are _______________________________
______________________________________________________________________
_____________________________________________________________________.
Frogs, toads, newts and salamanders all undergo metamorphosis from a ___________
__________________________________________________________. Amphibians
must lay their eggs in a place where they will hatch in water. Respiration occurs in the
_____________________________________________________________________.
Amphibian/vertebrate Adaptation to Land
There are two hypotheses:
1. Aquatic vertebrates first moved onto land as shallow pools of water began drying
up. This theory is no longer accepted.
2. More likely that ancestors of amphibians left the water to escape predation,
competition and gain access to the abundance of resources on land.
Characteristics of Early Amphibians
Amphibians ___________________________________________________________.
Four strong limbs developed from fins. The adaptations for living on land included sense
organs for detecting scents and sound. 360-286 million years ago early amphibians split
into two main evolutionary lines that led to modern amphibians and reptiles.
Diversification of Amphibians
Today there are an estimated 4,500 species of amphibians in
three Orders. Modern amphibians share the five key
characteristics of metamorphosis, __________________
___________________________________________________
___________________________________________________
___________________________________________________
___________________________________________________
___________________________________________________
___________________________________________________
___________________________________________________
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Amphibians – Order Anura
The Order Anura includes frogs and toads. They are found worldwide except in polar
climates. Frogs and toads live in a variety of habitats. The term “toad” is commonly used
for any anuran that has rough bumpy skin. The term “frog” is commonly used when
anurans have smooth moist skin.
Frogs and toads spend part of their life in water (if not all). They are characterized by a
body adapted for jumping and are carnivores (some have a sticky tongue). Many return
to the water to reproduce where their eggs hatch into larvae called tadpoles.
Amphibians – Order Urodela
The Order Urodela includes salamanders that are characterized by elongated bodies,
long tails, and moist skin. Most salamanders have four limbs and are aquatic and
terrestrial. They are carnivores who are mainly active at night.
Most of them live in North America and Central America.
The Family Plethodontidae or ________________________________________ with
more than 300 species is the largest group of salamanders. _____________________
____________________________________________________________________
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___________________. Fertilization is internal and they lay eggs in water (larval
stage) or in moist land environments (no larval stage).
Amphibians – Order Apoda
The Order Apoda includes caecilian or legless amphibians as the name suggests. They
resemble small snakes and are often blind. Caecilians are rarely seen and little is
known about their ecology and behavior. Most of them burrow in soil and some are
aquatic. All species have teeth and eat worms and other invertebrates that they detect
using chemosensory tentacles on the side of their head. They can be found in Asia,
Africa and South America.
Reproduction in Amphibians
The reproductive system of the male frog includes two bean shaped testes located near
the kidneys. During the breeding season sperm develop in the testes and pass through
the tubes to the kidneys and urinary ducts. During mating sperm leaves the body
through the _________________________ opening.
The reproductive system of the female frog includes a pair of
large, lobed ovaries containing thousands of tiny immature eggs
that lie near the kidneys. During the breeding season the eggs
enlarge, mature and burst through the thin ovarian walls into the
body cavity. Cilia move the egg forward into a funnel like opening
of the oviducts. As eggs pass through the oviduct they are coated
with jelly like material. The eggs exit through the cloaca to the
external environment where fertilization occurs.
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Amphibian Courtship and Fertilization
In early spring frogs emerge from hibernation and migrate to
ponds and slow moving streams. Males call to attract females
and warn off other males. Each species has its own mating
call. When a mating pair find each other, the male frog climbs
onto the females back in an embrace called amplexus that
may last for days. The female leases legs into the water and
the male discharges sperm over them called direct external
fertilization.
Amphibian Metamorphosis
Increasing levels of a hormone called thyroxine which
circulates throughout the bloodstream stimulates
metamorphosis. Within a few days of fertilization
tadpoles emerge. They live off the yolk stored in their
body. Tadpoles grows larger and develop three pairs
of gills. Eventually the mouth opens and allows it to
feed. A process of change called metamorphosis
results in the legs growing and the tail and gills
disappearing. The mouth broadens and develops
teeth and jaws. The lungs then become functional.
Amphibian Parental Care
Parental care is common among amphibians. Eggs and larvae are vulnerable to
predators so parental care increases the likelihood that offspring will survive. Most often
the male remains with eggs to guard them. Darwin’s males take young into their mouth.
Female gastric-brooding frogs swallow their eggs. Both appear to have become extinct!!
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Reptiles
Reptiles are ___________________________
______________________________________
by the Permian period. Reptiles have a
______________________________________
that is keratinized and __________________
___________________. They are usually
tetrapods and have ______________________
_____________________________________.
Reptiles have evolved to be completely
terrestrial in many cases and are no longer
dependent upon water for the laying of eggs.
This is because of the ____________________
_____________________________. This egg
is developed from _______________________
______________________________________
______________________________________
______________________________________
______________________________________________________________________
______________________________________________________________________
_____________________________________________________________________.
Reptiles, fish and amphibians are cold blooded or ________________________. This
does not mean that their blood is cold. The body temperature of an ectotherm is
____________________________________________________________. Therefore,
ectothermic animals regulate their body temperature by regulating their surroundings.
They will lie in the sun if it is cold out, and shade themselves if they are hot. Ectotherms
must still regulate their body temperature in order for normal internal body functions to
take place.
The above right image above shows the American Alligator, Garter snake close up,
Gopherus polyphemus, and the Collared Lizard.
Birds
Birds
are
__________________________________.
Often
referred
to
as
__________________________________, birds and other endothermic animals regulate their
body temperature internally. By maintaining a constant internal body temperature bodily
functions occur at optimum levels of efficiency. This self-regulation is known as
______________________________. This is important for animals such as birds that require a
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great deal of energy for flight. Birds also have other adaptations for flight such as
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________.
Since we can see a bird’s beak, we can easily hypothesize what it might eat. We can watch
birds catch, handle, and swallow different foods to test our hypotheses based on the shape of
the bill. The sharp thin bill of herons and egrets spear fish. The hooked bills of hawks and owls
grab and rip apart prey and the short conical bills of sparrows crack seeds.
Flight is very efficient but requires a lot of energy. Flying birds have 5-20 times their
resting metabolic rate while running mammals only have 2-4 times their resting
metabolic rate. To produce the level of energy required for flight, birds have incredibly
efficient and ___________________________________________________________
______________________________________________. These systems allow both
fast flight and long distance migration.
In addition, ___________________________________________________________
_________________________ that greatly aid in flight.
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__________________________________
__________________________________
__________________________________
__________________________________
________________________. Air passes
through bird lungs ___________________
_____________ into posterior __________
__________________________________
___________________ by a different
route. As a result, there are two passes of
air in each respiratory cycle and because of
countercurrent flow the oxygen extraction is
very high. Birds have a _______________
__________________________________
_____________________________________________________________________.
This efficiency of respiration and circulation enables birds to fly over the Himalayans at
the altitude of Mount Everest.
Mammals
Mammals are thought to have
evolved during the Mesozoic Era
from therapsids. The mammalian
skull accommodates a larger brain
relative to its body size and
differentiated teeth. Mammals are
characterized by having __________
_____________________________
__________________.
Mammals
have a high level of infant care,
because the young are fed by means
of the mammary glands. The adults
must expend a lot of energy in the young, but it increases the chances of having
successful offspring. This high-energy load on the mother means fewer offspring are
produced. Mammals share other characteristics with birds. For example, efficient
circulatory and respiratory systems, a ____________________________________
and being ______________________________ are characteristic shared by both.
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Mammals are divided into three groups;
1. monotremes
2. marsupials
3. placental mammals
1. Monotremes
The _________________________________
____________________________________
____________________________________
____________________________________.
They are different from the other mammals in
that they ____________________________
__________________________ and have a cloaca. Interestingly, the platypus
lacks a true stomach and digests its food in an enlarged area of the esophagus.
2. Marsupials
Marsupials (like the wombat above) are found
mainly in Australia, but some marsupials are
found in South and Central America as well.
The only marsupial living in North America is
the opossum. These opossums, although not
native to the area, are found as far north as
Hornby Island, British Columbia. In Australia,
marsupials have filled many of the niches held
by placental mammals in the rest of the world.
Marsupials spend comparatively less time with
pregnancy and they are born very immature. Once born they enter a pouch on
the mother. Fed by the mammary glands the newborn will remain in the pouch
until mature. The vast majority of marsupial fossils have been found in Australia
including those of a huge ten foot tall kangaroo ancestor.
3. Placental Mammals
Due to the presence of the __________________________________________
________________________________________________________________
______________________________________, a longer pregnancy is possible.
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The increased gestation time allows more energy to be used for the development
of the nervous system. As a result of this development, placental mammals have
the largest brain to body weight ratio. Even after the lengthy pregnancy brain
development continues under parental care. The larger brain has resulted in
social development and communication in many mammals. Placental mammals
are very widely distributed around the world and have members in almost every
niche. Bats have taken to the air, whales to the water, and many examples exist
on land. Placental mammals can be ___________________________________
_______________________________________.
Major Orders of Placental Mammals include:
 Perissodactyla = Horses
 Artiodactyla = Deer
 Carnivora = Cats
 Primates = Monkeys
 Cetacea = Whales
 Chiroptera = Bats
 Rodentia = Mice
 Proboscidea = Elephants
 Lagomorpha = Rabbits
13.3 PRACTICE: VERTEBRATES
1. What three characteristics distinguish vertebrates from prochordates? (3 marks)
2. There are three main classes of fish, listed in proposed evolutionary order, they
are:
a. Class _____________________________ which include jawless fish such
as the lamprey and _______________________. (2 marks)
b. Class _____________________________ which includes cartilaginous
fishes such as __________________, rays and skates. (2 marks)
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c. Class _____________________________ which include bony fishes such
as the ones we eat and keep as pets. (2 marks)
3. Lobe-finned fish from Class Osteichthyes are thought to be the evolutionary
forerunner to __________________________. (1 mark)
4. Amphibians live both in water and on land.
a. What features of their respiratory system make them well-adapted for
such a life style? (3 marks)
b. Using our current understanding of Darwin's theory of evolution, please
explain how such adaptions likely came to be. (4 marks)
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5. Reptiles are hypothesized to have evolved from ________________________
ancestors. (1 mark)
6. Reptiles lay leathery shelled amniotic eggs.
a. Define amniotic egg. (1 mark)
b. Identify two selective advantages associated with an amniotic egg. (2
marks)
7. Reptiles, fish and amphibians are ectothermic.
a. Explain what ectothermic means (cold-blooded is not a sufficient or correct
answer). (1 mark)
b. How does being ectothermic impact an organism's behavior? (1 mark)
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8. Birds and mammals are endothermic.
a. Explain what endothermic means (warm-blooded is not a sufficient
answer). (1 mark)
b. What is the term for when an organism self-regulates its internal
conditions such as temperature? (1 mark)
9. Identify and explain at least four adaptations that enable birds to meet and/or
limit the metabolic demands of flight. (4 marks)
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10. Mammals are characterized by having ___________ and __________________
_________________________ as well as having a larger _________________
relative to body size. (3 marks)
11. Three main groups of mammals include:
a. The ______________________________ which include the duck-billed
platypus and echidna and which are unique in that they lay hard-shelled
amniotic eggs. (1 mark)
b. The ______________________________ which include kangaroos,
wombats and opossums which are all have pouches for rearing their
young. (1 mark)
c. The ____________________________________________ which include
humans, bats and whales, all characterized by having a
__________________________ that assists in exchange of nutrients
between a mother and her developing fetus(es). (1 mark)
~ END OF BIOLOGY 11 UNIT 13 LEARNING GUIDE ~
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UNIT 13 ANSWER KEY
13.1 PRACTICE: CHORDATES
1. In the diagram below, identify and label the 4 characteristics that are common to all chordates. (4
marks)
2. Members of Phylum Chordata have ______________________ symmetry and a
_______________________ (which means they have a body cavity which is completely lined
with mesoderm). (2 marks)
3. In Chordates the blastopore becomes the anus:
a. Organisms that develop this way are termed _________________________________.
(1 mark)
b. Identify at least one other animal phylum, studied in Biology 11, that has a similar
developmental pattern. (1 mark)
- Echinoderms
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4. All chordates have an endoskeleton:
a. Define endoskeleton. (1 mark)
-
internal skeleton
b. Explain two ways that an endoskeleton might provide a selective advantage over either
lacking a skeleton altogether or over an exoskeleton. Remember to answer this question
properly you must compare the exoskeleton to the alternatives. (2 marks)
- an endoskeleton is advantageous in many situations compared to no
skeleton as it serves to protect organs and it acts as levers for muscles
and movement
-
an endoskeleton is advantageous in many situations compared to an
exoskeleton as it grows with the organism and thus, does not need to be
shed such that the organism is periodically vulnerable and because it is
lighter than an exoskeleton and thus, does not limit the potential size of
an organism
13.2 PRACTICE: PROCHORDATES
1. What is the defining characteristic of a prochordate? (1 mark)
- the notochord remains intact throughout development as opposed to being replaced
with a vertebral column
2. The lancelet is considered the prototypical chordate.
a. Define prototypical. (1 mark)
- representing the original form after which all other related organisms are
patterned
b. Why is the lancelet considered the prototypical chordate? (1 mark)
-
the lancet is considered prototypical as it clearly displays all 4
characteristics of a chordate (notochord, dorsal tubular nerve cord,
pharyngeal slits and post anal tail) throughout its entire life cycle
-
all other chordates go through an embryonic state that closely replicates
the adult lancet form
3. It is difficult to recognize an adult tunicate as a chordate.
a. Explain why. (1 mark)
- as larva, tunicates clearly possess the 4 key characteristics of chordates
but as the tunicate matures to adult stage these characteristics are no
longer apparent
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b. Explain why scientists classify it as chordate. (1 mark)
- based on the fact that their larval stage has the four key characteristics
of chordates
13.3 PRACTICE: VERTEBRATES
1. What three characteristics distinguish vertebrates from prochordates? (3 marks)
- have vertebrate made of bone or cartilage that surround and protect the
dorsal nerve cord
-
have a cranium (skull) to protect brain
-
have an endoskeleton of bone or cartilage
2. There are three main classes of fish, listed in proposed evolutionary order, they are:
a. Class _____________________________ which include jawless fish such as the
lamprey and _______________________. (2 marks)
b. Class _____________________________ which includes cartilaginous fishes such as
__________________, rays and skates. (2 marks)
c. Class _____________________________ which include bony fishes such as the ones
we eat and keep as pets. (2 mark
3. Lobe-finned fish from Class Osteichthyes are thought to be the evolutionary forerunner to
__________________________. (1 mark)
4. Amphibians live both in water and on land.
a. What features of their respiratory system make them well-adapted for such a life style? (3
marks)
-
can exchange gas via moist skin, gills and/or lungs enabling them to survive
on both land and water
b. Using our current understanding of Darwin's theory of evolution, please explain how such
adaptions likely came to be. (4 marks)
-
As per previous answers to similar questions…
o
random variation (via mutation and genetic recombination)
o
if variation is beneficial it helps organism to survive natural selection
o
if organism survives natural selection and reproduces it passes on
the random, beneficial variation
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5. Reptiles are hypothesized to have evolved from ________________________ ancestors. (1
mark)
6. Reptiles lay leathery shelled amniotic eggs.
a. Define amniotic egg. (1 mark)
- Egg that is surrounded by amniotic fluid
b. Identify two selective advantages associated with an amniotic egg. (2 marks)
-
allows embryo to develop on land independent of water and thus, opens up
an entirely new niche for reptiles as compared to amphibians which must
reproduce near or in water
-
allows embryo to be well-developed and relatively independent of water
when hatched again opening up a new niche (dry land)
7. Reptiles, fish and amphibians are ectothermic.
a. Explain what ectothermic means (cold-blooded is not a sufficient or correct answer). (1
mark)
- Ectothermic = refers to animals whose body temperatures fluctuate with
that of the surrounding environment…if in shade their body temperature
lowers and if in sun their body temperature rises
b. How does being ectothermic impact an organism's behavior? (1 mark)
- metabolic rates are typically influenced by body temperature with warmer
temperatures resulting in greater metabolic rates, ectothermic organisms
will regulate their body temperature and thus, their metabolic rated by
either seeking out cold or hot locations in their environment
8. Birds and mammals are endothermic.
a. Explain what endothermic means (warm-blooded is not a sufficient answer). (1 mark)
- Endothermic = refers to animals whose are able to internally regulate their
body temperatures
b. What is the term for when an organism self-regulates its internal conditions such as
temperature? (1 mark)
- homeostasis
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9. Identify and explain at least four adaptations that enable birds to meet and/or limit the metabolic
demands of flight. (4 marks)
- light, hollow bones = less energy required
-
efficient circulatory system = rabid delivery of O2 to and removal of CO2
from muscles
-
efficient respiratory system allows for continual flow of oxygenated air
through the system
-
feathers to maximize lift
-
strong muscles
10. Mammals are characterized by having ___________ and __________________
_________________________ as well as having a larger _________________ relative to body
size. (3 marks)
11. Three main groups of mammals include:
a. The ______________________________ which include the duck-billed platypus and
echidna and which are unique in that they lay hard-shelled amniotic eggs. (1 mark)
b. The ______________________________ which include kangaroos, wombats and
opossums which are all have pouches for rearing their young. (1 mark)
c. The ____________________________________________ which include humans, bats
and whales, all characterized by having a __________________________ that assists in
exchange of nutrients between a mother and her developing fetus(es). (1 mark)
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