Ch34 Flashcards
1
Q
What is the defining characteristic of vertebrates?
A
Animals with a backbone
2
Q
Name the three groups of animals included in the phylum Chordata.
A
- Vertebrates
- Urochordates
- Cephalochordates
3
Q
What are the four key characters of chordates?
A
- Notochord
- Dorsal, hollow nerve cord
- Pharyngeal slits or clefts
- Muscular, post-anal tail
4
Q
What is the function of the notochord?
A
Provides flexible skeletal support during early development
5
Q
What does the dorsal, hollow nerve cord develop into?
A
The central nervous system: the brain and the spinal cord
6
Q
True or False: All chordate embryos have grooves along the outer surface of the pharynx.
A
True
7
Q
What are pharyngeal slits modified into in non-tetrapod vertebrates?
A
Gills for gas exchange
8
Q
What is the primary function of the muscular, post-anal tail in chordates?
A
Provides propelling force in many aquatic species
9
Q
Describe lancelets.
A
Marine suspension feeders that retain key characteristics of the chordate body plan
10
Q
What are tunicates also known as?
A
Sea squirts
11
Q
What happens during the larval stage of tunicates?
A
Larvae use tail muscles and notochord to swim until they settle for metamorphosis
12
Q
True or False: Adult tunicates retain all chordate characteristics.
A
False
13
Q
What do hagfishes and lampreys lack?
A
Jaws
14
Q
What clade do hagfishes and lampreys belong to?
A
Cyclostomes
15
Q
What is a characteristic of hagfishes?
A
They have a cartilaginous skull and retain the notochord as a flexible rod
16
Q
How do parasitic lampreys feed?
A
By clamping their mouths onto host fish and feeding on blood and tissue
17
Q
What is significant about the fossils of Haikouella?
A
They represent some of the most primitive vertebrates
18
Q
What did Myllokunmingia represent in vertebrate evolution?
A
The first chordate to have a head
19
Q
What are gnathostomes?
A
Jawed vertebrates
20
Q
List some groups included in gnathostomes.
A
- Sharks
- Ray-finned fishes
- Lobe-finned fishes
- Amphibians
- Reptiles
- Mammals
21
Q
What are two derived characters of gnathostomes?
A
- Jaws with teeth
- Genome duplication, including four sets of Hox genes
22
Q
What is a defining feature of chondrichthyans?
A
Skeleton composed primarily of cartilage
23
Q
How do sharks maintain buoyancy?
A
By storing oil in their liver
24
Q
What is the cloaca?
A
A common chamber with a single opening for the reproductive, excretory, and digestive systems
25
Fill in the blank: The largest sharks and rays are _______.
Suspension feeders
26
What type of fertilization do shark eggs undergo?
Internal fertilization
27
What is the term for organisms that give birth to live young after developing within the uterus?
Viviparous
## Footnote
Viviparous organisms are nourished by a yolk sac placenta or by absorbing nutrient-rich fluid.
28
What is the cloaca?
A common chamber with a single opening for the reproductive, excretory, and digestive systems
## Footnote
The cloaca is found in chondrichthyans.
29
What type of diet do most rays have?
They feed on molluscs and crustaceans
## Footnote
Most rays are bottom-dwellers with crushing jaws.
30
What is the current status of chondrichthyans populations?
Severely threatened by overfishing
## Footnote
Shark populations in the Pacific have plummeted by up to 95%.
31
What are osteichthyans?
Vertebrates with a bony endoskeleton
## Footnote
Osteichthyans include bony fishes and tetrapods.
32
What structure protects the gills of fishes?
Operculum
## Footnote
The operculum is a bony flap that allows water to flow over the gills.
33
What is the function of the swim bladder in fish?
To maintain buoyancy
## Footnote
The swim bladder is an air sac found in most fishes.
34
What are lobe-fins?
Fishes with pectoral and pelvic fins that have rod-shaped bones
## Footnote
Lobe-fins include coelacanths and lungfishes.
35
What is Tiktaalik?
A fossil species with characteristics of both fish and tetrapods
## Footnote
Tiktaalik is significant for understanding the evolution of limbs.
36
What term describes the retention of larval features in sexually mature salamanders?
Paedomorphosis
## Footnote
This phenomenon is common in aquatic salamander species.
37
What is the main characteristic of amphibians?
They have a life stage that is both aquatic and terrestrial
## Footnote
The term 'amphibian' means 'both ways of life.'
38
What happens during the metamorphosis of frog larvae (tadpoles)?
They develop legs, lungs, and external eardrums
## Footnote
Tadpoles transition from an aquatic herbivorous diet to a carnivorous diet.
39
What is the main cause of the decline in amphibian populations?
Chytrid fungus, habitat loss, climate change, and pollution
## Footnote
Over the past 30 years, amphibian populations have declined rapidly.
40
What are amniotes?
Tetrapods with a terrestrially adapted egg
## Footnote
Amniotes include reptiles and mammals.
41
What is the function of the amniotic egg?
Reduces dependence on water for reproduction
## Footnote
It contains four membranes that protect the embryo.
42
What are the four extraembryonic membranes of the amniotic egg?
* Amnion
* Chorion
* Yolk sac
* Allantois
## Footnote
These membranes serve various functions including gas exchange and nutrient transfer.
43
What adaptations do reptiles have for life on land?
* Scales to prevent desiccation
* Shelled eggs
* Internal fertilization
## Footnote
These adaptations help reptiles thrive in terrestrial environments.
44
What are diapsids?
Reptiles with a pair of holes on either side of the skull
## Footnote
Diapsids include turtles, lepidosaurs, and archosaurs.
45
What is a key characteristic of pterosaurs?
They were the first tetrapods to exhibit flapping flight
## Footnote
Pterosaurs had a membrane stretched between a long digit on the foreleg and the trunk.
46
What is the relationship between turtles and crocodilians?
Turtles are most closely related to crocodilians and birds
## Footnote
Turtles have unique evolutionary adaptations including a boxlike shell.
47
What adaptations allow some turtles to thrive in deserts?
Loss of the ability to retract the head into the shell
## Footnote
Some turtles have developed mechanisms to fold their necks for protection.
48
What is the ecological role of many dinosaurs?
They were agile and social, some building nests and protecting eggs
## Footnote
Some dinosaur species were endothermic.
49
What major event is believed to have caused the extinction of many dinosaurs?
An asteroid or comet impact
## Footnote
However, declines in dinosaur populations began millions of years before this event.
50
What is the main characteristic of ectothermic reptiles?
They absorb external heat as their main source of body heat
## Footnote
Ectotherms regulate body temperature through behavioral adaptations.
51
What is a characteristic of the earliest turtles?
They could not retract their head into their shell
52
How do side-necked turtles fold their neck?
Horizontally
53
How do vertical-necked turtles fold their neck?
Vertically
54
What are some habitats where turtles have adapted?
* Deserts
* Ponds
* Rivers
* The sea
55
What is a major threat to sea turtles?
Accidental capture in fishing nets and development of beaches where they lay eggs
56
What is the tuatara?
A single lizard-like species representing a lineage of lepidosaurs
57
Where are living tuataras restricted to?
30 islands off the coast of New Zealand
58
What is the evolutionary origin of snakes?
Descended from lizards with legs
59
What adaptations do snakes have for capturing prey?
* Chemical sensors
* Sensitivity to ground vibrations
* Heat-detecting organs
* Tongue flicking
* Toxic venom
* Loosely articulated jawbones and elastic skin
60
What lineage do crocodilians belong to?
A lineage that dates back to the late Triassic
61
What adaptations have birds developed for flight?
* No urinary bladder
* Only one ovary (females)
* Small gonads (both sexes)
* Toothless mouths
* Air-filled bones
62
What are the benefits of flight for birds?
* Hunting and scavenging
* Escape from terrestrial predators
* Long-distance migration
63
What is the earliest known bird?
Archaeopteryx
64
What are monotremes?
A small group of egg-laying mammals found only in Australia and New Guinea
65
What distinguishes marsupials from monotremes?
* Higher metabolic rates
* Nipples to provide milk
* Birth of live young
* Embryonic development in the uterus
* A placenta for nutrient transfer
66
What is paleoanthropology?
The study of human origins
67
What are hominins?
Extinct species more closely related to humans than to chimpanzees
68
What are two misconceptions about human evolution?
* Early hominins were chimpanzees
* Human evolution is like a ladder leading directly to Homo sapiens
69
What adaptation do primates have for grasping?
Hands and feet adapted for grasping
70
What characterizes the brain of primates?
A relatively large brain and short jaws
71
What is a derived character of humans?
Upright posture and bipedal locomotion
72
What percentage of the human and chimpanzee genomes are identical?
99%
73
What is the significance of the foramen magnum placement in early hominins?
Indicates a more upright and bipedal posture
74
What are the two common misconceptions about human evolution?
Human evolution is like a ladder leading directly from an ancestral ape to Homo sapiens; there are many branches and some coexisting species in the human evolutionary tree.
75
What are Australopiths?
A paraphyletic assemblage of hominins that lived 4–2 million years ago.
76
Which is the earliest known australopith?
Australopithecus anamensis (4.2–3.9 million years ago).
77
What characteristics did A. africanus have?
Walked fully erect and had humanlike hands and teeth.
78
What are the characteristics of A. afarensis?
Bipedal, had a small brain and body, and a long lower jaw.
79
What are 'robust' australopiths?
Australopiths such as Paranthropus boisei that had sturdy skulls with powerful jaws and large teeth.
80
What distinguishes 'gracile' species?
They had lighter feeding structures adapted for softer foods (e.g., A. afarensis and A. africanus).
81
When did hominins begin to walk long distances on two legs?
About 1.9 million years ago.
82
Why was bipedal walking energy efficient for hominins?
In the arid environments inhabited by hominins at the time.
83
What is the oldest evidence of tool use?
Cut marks on animal bones, dated to 2.5 million years ago.
84
What does fossil evidence suggest about the origin of tool use?
It may have originated prior to the evolution of large brains.
85
What are the earliest Homo fossils?
Homo habilis (2.4–1.6 million years old).
86
Why was Homo habilis named 'handy man'?
For the tools found at its fossil sites.
87
What adaptations did Homo ergaster have?
Fully bipedal, large-brained, long, slender legs, and smaller teeth than australopiths.
88
What does reduced sexual dimorphism indicate?
It is associated with species that undergo more pair-bonding.
89
When did Homo erectus migrate out of Africa?
By at least 1.8 million years ago.
90
Where did Homo erectus migrate to?
As far as the Indonesian archipelago.
91
What is the time range during which Neanderthals lived?
From 350,000 to between 40,000 and 28,000 years ago.
92
What are some characteristics of Neanderthals?
Thick-boned, larger brain than modern humans, buried their dead, made tools from stone and wood.
93
Did humans descend directly from Neanderthals?
No, the human and Neanderthal lineages diverged from a common ancestor about 600,000 years ago.
94
What evidence indicates mating occurred between humans and Neanderthals?
DNA extracted from human fossils contained long stretches of Neanderthal DNA.
95
What does genomic analysis support regarding Denisovans and Neanderthals?
A history of gene flow between Denisovans and H. sapiens.
96
Where did the ancestors of living humans originate?
In Africa.
97
What is the age of the earliest Homo sapiens fossils from Ethiopia?
195,000 and 160,000 years old.
98
When did humans first arrive in the New World?
About 15,000 years ago.
99
What is significant about Homo naledi?
It was found in 2015 and indicates it was fully bipedal with fine motor skills.
100
What is unique about the dating of the original H. naledi fossils?
They could not be dated using radioactive isotopes.
101
What is the age of the newly found H. naledi skull teeth dated to?
300,000 years ago.
102
What is the significance of Homo floresiensis?
Individuals were much shorter and had smaller brains than Homo sapiens.
103
What evidence supports H. floresiensis being a new hominin species?
Wrist and foot bones support it being a new species that arose before H. sapiens.
104
What is credited for the rapid expansion of Homo sapiens?
Advances in cognition as humans evolved.
105
What evidence of symbolic thought did Homo sapiens show?
A 77,000-year-old artistic carving discovered in a cave in South Africa.
106
What was produced by humans by 30,000 years ago?
Spectacular cave paintings.
