1
Q
Which part of the gastrula embryo develops into the gastrovascular cavity? What kind of animal would have a gastrovascular cavity as an adult? (2)
A
- Gastrula invaginates into blastopore.
- Cnidaria and Platyhelminthes (flatworms).
2
Q
How did the evolution of a septum separating the left and right sides of the heart’s ventricle benefit the fitness of the animals that underwent this change? (4)
A
- prevented mixing of deoxygenated from oxygenated blood
- provides a higher concentration of oxygen to working muscles
- allowing for stronger muscular contractions
- more work to be accomplished by those muscles.
3
Q
Which animals have complete ventricular septa and which have incomplete/partial septa?
A
- The crocodilians, birds and mammals with origins some 100 million years apart, however, have a complete ventricular septa
- Modern reptiles don’t have a complete septa, and do not have the capacity for rapid sustained activity.
4
Q
How did global climate change over the Devonian and into the Carboniferous, and what was the cause? (8)
A
- In the Devonian period, the world was experiencing super greenhouse climate conditions
- it was very warm, there probably were no ice caps, there was a lot carbon dioxide in the atmosphere (4,000 ppm)
- plant communities expanded onto land to form the first forests, they depleted the carbon dioxide (CO2) that was in the atmosphere
- CO2 levels dropped to 400 ppm toward the end of the Devonian, it got colder
- There were glaciation events and the rapid change in the climate caused severe extinction in the tropics and the existing coral reefs became extinct.
- the world’s current CO2 level is very close to 400 ppm.
- in the Devonian period, North America and Europe were very close to each other
- During the carboniferous period, massive amounts of photosynthesis removed CO2 from the atmosphere leading to an ice age
5
Q
How is the hemoglobin in human fetal blood is different from that in the blood of adults? (3)
A
- The affinity curve of hemoglobin (adult vs. fetal), for oxygen shows in low oxygen conditions likely found in the uterus that fetal hemoglobin will grab onto oxygen from the mother.
- The different structures of hemoglobin mean that it will more or less strongly attract oxygen at the conditions that the organism most needs for it to grab onto the oxygen.
- For human adults, the atmospheric concentration of oxygen is much higher than in the uterus so that adult hemoglobin does not have as strong an affinity for oxygen as the fetus.
6
Q
What are Hox genes generally, and what is special about those genes specifically identified as the Hox cluster genes? What is the “colinear organization” of these Hox genes? (7)
A
- Homeobox genes are a large group of similar genes that direct the formation of many body structures during early embryonic development.
- In humans, the homeobox gene group contains an estimated 235 functional genes and 65 pseudogenes (structurally similar genes that do not provide instructions for making proteins).
- These genes are characterized by identifiable promoters called homeobox promoters.
- The sequence order of these genes along a chromosome mirrors the order in which they determine which body parts are coded at which segments of the adult organism.
- Hox genes are arranged in clusters
- their order on the chromosome is the same as the order in which they appear along the body.
- the genes on the left control patterning in the head, and the genes on the right control patterning in the tail.
7
Q
Briefly describe the anatomy of the avian respiratory system, and explain its advantages relative to the mammalian respiratory tree. (3)
A
- the exchange occurs in a system of tubes located between an anterior and posterior air sacs, in which the concentration of oxygen is the same as the atmosphere (19-21%)
- with one way passage of air from the posterior air sac, through the exchange tissue (lungs) to the anterior air sac.
- air can pass through the lungs, from the posterior to the anterior air sacs, means that birds have a more efficient respiratory system and can generate enough force to fly
8
Q
How does the mammalian kidney respond to dehydration? (3)
A
- The kidneys can adjust the concentration of the urine to reflect the body’s water needs, conserving water if the body is dehydrated or making urine more dilute to expel excess water when necessary.
- ADH is a hormone that helps the body to retain water by increasing water re-absorption by the kidneys.
- conserve water, aquaporins are inserted into the basolateral plasma membrane.
9
Q
What is the relationship between the diet of an animal and the amount of nitrogenous waste that it produces? Why is a bird better suited for elimination of nitrogenous waste without losing a lot of water, relative to a mammal? (6)
A
- the higher the nitrogen content in an animal’s diet, the greater amount of nitrogenous waste is produced, often in the form of urea (humans), or uric acid (chickens).
- Meat has a relatively high protein content.
- Proteins are composed of amino acids with a high nitrogen content.
- a carnivorous animal has much higher nitrogen waste content than an herbivore.
- in an amniotic egg, the urea may reach high concentrations toxic to the developing embryo.
- Uric acid, on the other hand precipitates out of solution, and thus embryos inside amniotic eggs can excrete uric acid, accumulate at the bottom of the egg, without polluting the “internal pond”.
10
Q
What is the anatomical difference between a synapsid and a diapsid? Into what animals did each of these evolve? (2)
A
- Synapsids are a class of animals that includes mammals and everything more closely related to mammals than to reptiles and birds; have single skull opening (called the temporal fenestra) behind each eye.
- Diapsids are a group of reptiles that developed two holes on each side of their skulls.
11
Q
What animals gave rise to the sponges? (4)
A
- single-celled choanoflagellates resemble the choanocyte cells of sponges which are used to drive their water flow systems and capture most of their food
- early studies suggest sponges are the sister group to the rest of animals
- sponges do not form a monophyletic group, in other words, do not include all and only the descendants of a common ancestor
- recent phylogenetic analyses suggest that comb jellies rather than sponges are the sister group to the rest of animals
12
Q
What group of animals based on overall species diversity, biomass, and the number of individuals is the most successful?
A
Ecdysozoans, which include the arthropods and nemotoda, are the most successful group based on overall species diversity, biomass, and numbers of individuals, and include insects and crustaceans.
13
Q
What is the hypothesis for the evolution of jaws? From what did they differentiate? (10)
A
- Jaws probably originated in the pharyngeal arches supporting the gills of jawless fish.
- The earliest jaws appeared in now extinct placoderms and spiny sharks during the Silurian, about 430 million years ago.
- The original selective advantage offered by the jaw was probably not related to feeding, but to increased respiration efficiency
- the jaws were used in the buccal pump to pump water across the gills.
- The familiar use of jaws for feeding would then have developed as a secondary function before becoming the primary function in many vertebrates
- All vertebrate jaws, including the human jaw, evolved from early fish jaws.
- The appearance of the early vertebrate jaw has been described as “perhaps the most profound and radical evolutionary step in the vertebrate history”.
- Fish without jaws had more difficulty surviving than fish with jaws, and most jawless fish became extinct.
- Jaws originated from gill arches of the fishes, the cartilaginous supports between the gill openings.
- if the anterior gill arches moved forward, and hardened, they could easily evolve into the supports for the jaws.
14
Q
What is brown fat, and how is its metabolism different from white fat? (5)
Where do you typically find brown fat? (4)
A
- is a special type of body fat that is turned on (activated) when you get cold
- produces heat to help maintain your body temperature in cold conditions.
- contains many more mitochondria than does white fat (these mitochondria are the “engines” in brown fat that burn calories to produce heat)
- it appears to be able to use regular body fat as fuel
- exercise may stimulate hormones that activate brown fat
- found in highly vascularized deposits in somewhat consistent anatomical locations, such as between the shoulder blades, surrounding the kidneys, the neck, and along the spinal cord
15
Q
Briefly identify and describe 3 synapomorphies of the Chordata
A
- notochord: a flexible rod like structure that forms the main support of the body in the lowest chordates; a primitive spine
- nerve cord: a dorsal tubular cord of nervous tissue above the notochord of a chordate
- pharyngeal slit: filter-feeding organs found in non-vertebrate chordates (lancelets and tunicates) and hemichordates living in aquatic environments
16
Q
Into what tissues does the endoderm typically differentiate (3)
A
- it’s the innermost of the three germ layers
- Cells derived from the endoderm eventually form many of the internal linings of the body, including the lining of most of the gastrointestinal tract, lungs, liver, pancreas and other glands that open into the gastrointestinal tract, and certain other organs, such as the upper urogenital tract and female vagina.
- Endoderm cells give rise to certain organs, among them the colon, stomach, intestines, lungs, liver, and the pancreas.
17
Q
Into what tissues does the ectoderm typically differentiate (2)
A
- forms certain “outer linings” of the body, including the epidermis (outermost skin layer) and hair
- is the precursor to mammary glands and the central and peripheral nervous systems
18
Q
Into what tissues does the mesoderm typically differentiate (4)
A
- is the germ layer that distinguishes evolutionary higher life-forms (those with bilateral symmetry) from lower life-forms (those with radial body symmetry)
- allows more highly evolved organisms to have an internal body cavity that houses
- protects organs, bathing them in fluids and supporting them with connective tissue
- Cells derived from the mesoderm, which lies between the endoderm and ectoderm, give rise to all other tissues of the body, including the dermis of the skin, the heart, the muscle system, urogenital system, the bones, and the bone marrow (and therefore the blood)
19
Q
What are the Reptiliomorpha? What are their distinguishing features? (5)
A
- Reptiliomorpha is a clade containing the amniotes and those tetrapods that share a more recent common ancestor with amniotes than with living amphibians (lissamphibians)
- two post-orbital fenestrae on either side of their skulls.
- skull loosely attacked to cheek
- tabular large and attacked to parietal
- well developed limbs
- 5 digits
20
Q
Know the time of the origin of sponges (5)
A
- Porifera
- simple multi-cellular animals
- are about 5000 to 10,000 of species of Porifera that are known today
- only 150 species live in fresh water
- Sponges are very primitive creatures that evolved around 500 million years ago
21
Q
Based on overall species diversity, biomass, and number of individuals, the most successful group of animals on Planet Earth is the….
A
Ecdysozoa
22
Q
Which of the following is not an ecdysozoan?
A) sea urchin B) butterfly
C) crab D) spider
E) roundworm
A
A) sea urchin
23
Q
You find a complete vertebrate skull from the early Permian with relatively unspecialized teeth, a small nasal cavity, a single postorbital fenestra (opening behind the eye socket), and a lower jaw comprised of multiple bones and articulating with the upper jaw at the back of the auricular (i.e., not the dentary). Based on this information you conclude that this skull belongs to…
A) an early human—probably Ardipithecus
B) an early dinosaur—perhaps Herrerasaurus
C) an early synapsid—possibly Dimetrodon
D) an early turtle—likely Donatello
E) All of the above are equally likely, based on the description given.
A
C) an early synapsid—possibly Dimetrodon
24
Q
The predominant large (visible to the naked eye) fossils from late Proterozoic (Ediacarian/Vendian) assemblages are mostly….
A) non-dinosaur amniotes like Crocodylus
B) various things that are not likely to be bilaterian
C) heavily armored fish-like animals resembling sharks
D) jawless fish and octopuses with shells
E) cylindrical worms and the tracks they left behind them
A
B) various things that are not likely to be bilaterian
25
... is considered a synapomorphy of the Gnathostomata, and it was likely a game-changer in the evolution of vertebrates.
```
A) a heterocercal tail
B) endochondral bone
C) the jaw
D) myoglobin-rich adipose tissue
E) a true, mesodermally lined coelomic cavity
```
C) the jaw
26
"Evolutionary innovation through ectopic expression of genes for an already-existing structure” might describe which of the following landmark events in the history of animals?
```
A) the origin of fish-like chordates
B) the origin of jaws
C) the origin of bilaterians
D) the origin of the heart
E) the origin of antennae and mouth parts in arthropods
```
B) the origin of jaws
27
The physoclistous swim bladder of the Pacific mackerel (Scomber japonicus) and the human lung are both...
A) used principally in gas exchange and acquisition of oxygen for the animal
B) derived from physostomous swim bladders of Devonian fish
C) highly complex structures with expansive overall surface areas
D) able to assist in the down-regulation of body temperature during torpor
E) significant factors in each animal's osmoregulation
B) derived from physostomous swim bladders of Devonian fish
28
In which of the following ways is a marine osmoconformer at an advantage relative to a marine osmoregulator?
A) the osmoconformer does not expend energy to compensate for osmotic loss of water
B) the osmoregulator poisons its own water supply with its urine
C) osmoconformers have greater access to oxygen than osmoregulators
D) osmoconformers have a much greater surface area/volume ratio
E) osmoregulators are vertebrates, while osmoconformers are just lowly inverts (cool factor)
A) the osmoconformer does not expend energy to compensate for osmotic loss of water
29
Osmoconformers
- marine organisms that maintain an internal environment which is osmotic to their external environment
- the osmotic pressure of the organism's cells is equal to the osmotic pressure of their surrounding environment.
30
Osmoregulators
- tightly regulate their body osmolarity, maintaining constant internal conditions.
- more common in the animal kingdom
- actively control salt concentrations despite the salt concentrations in the environment
31
The fact that the tin man gene in fruit flies is practically identical in both sequence and function with the Nkx gene in mice and humans suggests that...
A) these genes assist animals in finding food, specifically ripe fruit
B) the most recent common ancestor of fruit flies and mice had radial symmetry
C) fruit flies are probably deuterostomes and not protostomes, as was previously thought
D) the protostome/deuterostome ancestor had some type of heart
E) the mice used in that study were genetically engineered with fruit fly genes
D) the protostome/deuterostome ancestor had some type of heart
32
The tracheal system of insects...
A) uses a countercurrent exchange system to minimize heat loss
B) allows insects to have high metabolic rates and open circulation
C) requires that the animal excrete nitrogenous waste in the form of ammonia
D) can be used to generate heat to warm the flight muscles on a cold morning
E) pumps blood through a dorsal system of hearts towards the insect's head
B) allows insects to have high metabolic rates and open circulation
33
The negative slopes in the graph at the right are consistent with the fact that...
A) ptarmigans are endotherms
B) ptarmigans are ectotherms
C) ptarmigans are bilaterians
D) ptarmigans are native to cold climates
E) ptarmigans are sessile and do not need bilateral symmetry
A) ptarmigans are endotherms
34
Why do bilaterians generally need their mesoderm, whereas radially symmetrical animals tend to do just fine without mesoderm?
A) bilaterians move more, and mesoderm provides the tissues that are good for movement
B) bilaterians make use of extracellular digestion, and mesoderm is important for this
C) bilaterians lack the stinging cells used by cnidarians, and mesoderm is used to immobilize prey
D) bilaterians are metabolically more active, and mesoderm draws oxygen because of myoglobin
E) bilaterians use the mesoderm for producing a protective outer layer, e.g. shells or exoskeletons
A) bilaterians move more, and mesoderm provides the tissues that are good for movement
35
Thermogenic fat ("brown fat") generates heat by...
A) consuming many food calories and making a lot of ATP
B) consuming many food calories and producing practically no ATP
C) consuming many food calories and creating heat through shivering
D) insulating the animal with a thick layer of a poor heat conductor
E) not insulating the animal very well, particularly around the vital organs
B) consuming many food calories and producing practically no ATP
36
Birds are classified as ________ , and their origin took place during the ________ .
```
A) ornithischian dinosaurs/Triassic
B) pteranodons/Permian
C) therapsids/Cretaceous
D) therapod dinosaurs/Jurassic
E) lepidosaurs/Carboniferous
```
C) therapsids/Cretaceous
37
Which of the following is not in the Vertebrata?
```
A) dinosaur
B) the MRCA of turtles and birds
C) Robert S. Mueller
D) the MRCA of all chordates
E) hagfish
```
E) hagfish
38
Which pair is the most closely related, from the standpoint of recency of common ancestry?
```
A) sponge and choanoflagellate
B) turkey and jellyfish
C) flatfish and starfish
D) sea cucumber and squid
E) spider and human
```
A) sponge and choanoflagellate
39
Which of the following gnathostomes has/had open circulation?
A) salamanders (Amphibia)
B) largemouth bass (Micropterus salmoides)
C) Alligator missisipiensis (Crocodilia)
D) Stegosaurus (Ornithischia)
E) All of the above have closed circulation
E) All of the above have closed circulation
40
What happens during gastrulation? (3)
- the embryo is called a gastrula
- cells undergo dramatic rearrangement, forming the embryonic germ layers and other structures, such as the blastopore
- once complete, the major body axes of the embryo (anterior-posterior and dorsal-ventral) are visible
41
What happens during organogenesis? (3)
- the three embryonic germ layers develop into the rudiments of organs
- structures such as the notochord, the neural tube, and somites form
- Somite cells undergo differentiation, giving rise to different body tissues and organs, including the skeleton, muscles, and skin.
42
How is the kidney of a kangaroo rat different anatomically and why?
They have renal medulla that not only contain a greater proportion or juxtamedullary nephroi, but also longer loops of Genie, which push the deepest part of the renal medulla part way down the ureter
43
Porifera (4)
- commonly called sponges
- organisms which are sessile/sedentary in nature
- most of them are marine while a few are fresh water forms
- body is cylindrical, asymmetrical or has radial symmetry
44
Ecdysozoa
The most notable characteristic shared by ecdysozoans is a three-layered cuticle (four in Tardigrada) composed of organic material, which is periodically molted as the animal grows. This process of molting is called ecdysis, and gives the group its name.
45
Similarities between Ecdysozoa and Lophotrochozoa (5)
- bilateral symmetry
- triploblastic embryo develops ectoderm, endoderm, and mesoderm
- protostome characteristics
- may be either coelomate or pseudocoelomate (depending on phylum)
- true tissues, true organs and true organ systems: integumentary system and digestive system
46
Protostomes (3)
- have true tissues,
- being bilaterally symmetric
- developing the mouth before the anus during embryonic development
47
Deuterostomes
Their blastopore (the opening at the bottom of the forming gastrula) becomes the anus, whereas in protostomes the blastopore becomes the mouth.
48
What does “tinman” gene do and where is it found? What did the products of this gene evolve into? (3)
- Tinman, or tin is an Nk2-homeobox containing transcription factor first isolated in Drosophila files
- The human homolog is the Nkx2-5 gene
- expressed in the precardiac mesoderm and is responsible for the differentiation, proliferation, and specification of cardiac progenitor cells
49
Insect respiratory system (3)
- composed of a system of tracheals and in some insects air sacs as well
- Tracheals are a series of air filled tubes that run from the edge of the exoskeleton to the tissues deep within the body that often go close to cells or right into cells to deliver O2 very close to the mitochondria
- there is usually fluid between the ends of the tracheoles and the cells, but as the insect becomes more active the fluid is replaced by air so gas exchange is increased
Biology 202
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