Biology Chapter 17
Which evidence supports the hypothesis that four-limbed animals came from fish?
-DNA analysis shows that fish are tetrapods' closest relatives. -The fossil record shows more and more tetrapod-like fish before the appearance of tetrapods about 365 million years ago. -Both fish and four-limbed animals are vertebrates. -Fish and four-limbed animals have very similar embryos.
Why have we NOT found examples in the fossil record of every animal that ever lived on Earth?
-To become a fossil, an animal must remain buried for thousands or millions of years until it (and the layer around it) turns to rock. -Many fossils remain buried. We can only find them when they are exposed by erosion or excavation. -To become a fossil, an animal must be quickly and completely buried in ash or sediment before it has a chance to decompose.
The evolutionary tree indicates that humans and orangutans shared a common ancestor approximately ________.
12 million years ago
About how many years ago did the lineages leading to chimpanzees and modern humans become separated?
5 million years
Where did humans first appear?
Africa
Most members of which class of chordates exhibit a mixture of aquatic and terrestrial adaptations?
Amphibia
Which of the following statements supports the conclusion that the common ancestor of modern chimps and modern humans lived around 7 million years ago?
Analysis of modern human and modern chimpanzee protein and DNA sequences suggests that their lineages diverged about 7 million years ago.
How are animals different from fungi?
Animals obtain food by ingestion, and fungi obtain food by absorption.
Which mode of nutrition characteristic distinguishes animals from other eukaryotes?
Animals obtain nutrients by eating.
What did scientists learn from other fossils found in the same sediment layer as Ardi?
Ardi lived in a woodland habitat
While on a biological expedition, you discover a new species with the following characteristics: it has an exoskeleton, exhibits bilateral symmetry, and has jointed appendages. What phylum does this newly discovered organism belong to?
Arthropoda
The __________ explosion occurred approximately 535 million years ago.
Cambrian
Which phylum includes animals that have the following characteristics: a dorsal, hollow nerve cord; a notochord; pharyngeal gill slits; and a post-anal tail?
Chordata
________ are characterized body tissues, radial symmetry, and tentacles with stinging cells.
Cnidarians
What evidence supports the hypothesis of interbreeding between Neanderthals and Homo sapiens?
DNA analysis shows that about 2% of the genome of most modern humans came from Neanderthals.
The first hominid species to spread beyond Africa was ________.
Homo erectus
Humans are _______.
Homo sapiens
Scientists contend that humans and modern apes are related. What specifically does that mean?
If you traced the ancestry of humans and apes, you would at some point arrive at a shared ancestor that was neither a modern ape nor a human.
All animals can trace their lineage to a common ancestor that lived in the __________.
Precambrian
Which of the following is an accurate statement regarding human evolution?
The fossil record contains creatures with features that are intermediate between those of modern humans and quadrupedal apes The first humans evolved in Africa In the latest phase of human evolution, there as been a greater reliance on culture
Louis and Mary Leakey found two different fossil hominid skulls at Olduvai. Which of the following statements about the skulls is true?
The second skull represented a species more closely related to modern humans than the first skull's species.
How did the great transition from fish to tetrapod occur?
The transition occurred gradually over time, so there are many intermediate forms.
Which characteristic is common to all chordates?
They all have a notochord sometime during their life cycle.
Why did Shubin and Daeschler search in the Canadian arctic for fossil evidence of the transition from fish to tetrapods?
They hypothesized that the transitional fossils were in sedimentary rocks older than 365 million years ago, when the first tetrapods appear in the fossil record.
What kind of habitat did tiktaalik live in?
Tiktaalik lived in a warm, freshwater swamp.
What is a transitional fossil?
Transitional fossils have features that are intermediate between ancestors and descendants.
Which of the following is a reptile?
a bird
One body plan, called bilateral symmetry, represents a major branch point in animal evolution and can be described as __________.
a body plan with only one way to split it into two equal halves—right down the midline
All chordates have ________.
a dorsal, hollow nerve cord and a notochord
Which of these is an anthropoid?
a gibbon
Which of the following anatomical features of the 3.2-million-year-old Australopithecus fossil known as "Lucy" suggest she was a bipedal hominid?
a much shorter hip bone that is broader from front to back and wraps around the side
Which of the following is a tetrapod?
a reptile a bird a mammal an amphibian
Insects, such as the grasshopper in the image, have ________.
a three-part body: head, thorax, and abdomen
Among vertebrates, the unique feature of lampreys and hagfish is the ________.
absence of jaws
The __________, is key adaptation for reptiles, has a waterproof shell that encloses the embryo and its life-support system.
amniotic egg
You discover an organism that has scaly skin and is aquatic but returns to the land to reproduce. What else would you expect to find in this organism?
amniotic egg
A group of animals called _____________ have several adaptions for living on land but must return to the water to breed.
amphibians
In the image, the segmented body of the worm suggests that it is a(n) ________.
annelid
segmented worms, have a closed circulatory system
annelids
Members of the phylum Mollusca __________.
are soft-bodied and often covered by a shell
The phylogenetic tree indicates that ________ demonstrate the most advanced body plan in reference to the presence of tissues and bilateral symmetry.
arthropods
There are more species of ________ than of any other type of animal.
arthropods
have jointed appendages and an exoskeleton that must be shed to permit growth
arthropods
Which clade includes all of these phyla: molluscs, arthropods, and echinoderms?
bilaterians
What was the first key hominid trait to appear in the fossil record?
bipedalism, as indicated by skeletal structure
What traits were present in early Homo habilis, the first representatives of the genus Homo?
bipedalism, moderate brain size, and tool use
Which of the following traits can be used to differentiate humans from our closest living primate relatives?
bipedality (the ability to walk exclusively on two legs) large brain size extensive tool use
One key adaptation of animals was the evolution of a(n) _ a fluid-filled gap between the outer wall of the body and the outer wall of the digestive system.
body cavity
What is a way in which scientists can test hypotheses about events that occurred in the distant past?
by analyzing fossils recovered from the Earth
How do scientists know that the hominid called "Ardi" is about 4.4 million years old?
by using radiometric dating techniques on the volcanic deposits found above and below the layer containing Ardi
Rays are a type of ________.
cartilaginous fish
The arthropod skeleton is composed of ________.
chitin
What name is given to the food-trapping cells of sponges?
choanocytes
Imagine that you are a paleontologist. In a recent dig, you unearthed the following bones: jaw bone, vertebral column, and femur (thigh bone). Which phylum does the organism you unearthed belong to?
chordata
The phylum _____________ contains animals that share four specific anatomical features, including a hollow nerve cord and a tail.
chordate
Tunicates are examples of ________.
chordates
exhibit 2 radial body forms, the polyp and the medusa, and use stinging cells to capture prey
cnidarians
The common ancestor of all animals is likely to have been a ________.
colonial, flagellated protist
All ________ exhibit the arthropod characteristic of multiple pairs of specialized appendages.
crustaceans
"spiny skin", have a water vascular system that functions in locomotion, feeding, and gas exchange
echinoderms
Sea stars and sand dollars belong to a group of spiny marine animals called __________.
echinoderms
A(n) ____________ is an organism that must obtain heat from the environment.
ectotherm
All vertebrates have a(n) ________________, and internal system of bones (in your case, 206 bones)
endoskeleton
A(n) ____________ is an organism that generates heat within its body
endotherm
Which human characteristic was hypothesized to have evolved first but was later found NOT to have evolved first?
erect posture Submit
All animals are __ organisms with cells that are relatively large, complex, and contain membrane-enclosed organelles such as the nucleus.
eukaryotes
Placental mammals are called ________.
eutherians
Which clade includes only nematodes and arthropods?
exdysozoans
The figure shows a simple worm. Bilateral symmetry and a highly branched gastrovascular cavity all suggest that the worm is a(n) ________.
flatworm
Which group of animals includes the simplest animals with bilateral symmetry?
flatworms
simplest bilaterian animals, lack a body cavity; live in marine, freshwater, and damp terrestrial habitats
flatworms
Almost every element of bird anatomy is modified for what?
flying
What are the two defining features of the class Mammalia?
hair and mammary glands
The phylogenetic tree indicates that flatworms are similar to cnidarians in that both ________.
have true tissues
What does the term "tetrapod" mean?
having four feet
Swim bladders ________.
help bony fish maintain buoyancy
All animals eat other organisms in order to gain building materials for the body. This makes them __ since they obtain necessary energy and chemical building blocks from the environment.
heterotrophs
________ are the most diverse group of arthropods.
insects
Tiktaalik had a combination of fishlike and tetrapod-like characteristics. Which were the tetrapod-like characteristics?
interlocking ribs flat head with eyes on top a neck
Currently, we humans are the only hominid species on Earth. This situation _____.
is relatively recent. For most of hominid history there were multiple coexisting hominid species.
A(n) ___________ is and example of an animals that is a chordate but not a vertebrate.
lancelet
A(n) ________ is an example of a chordate that is not a vertebrate.
lancelot
A row of organs that are sensitive to changes in water pressure is called a _____________.
lateral line system
A fish that has muscular pectoral and pelvic fins supported by rod-shaped bones is known as a _______.
lobe fine
Which group of fishes includes a lineage that migrated out of fresh water and adapted to life on land?
lobe-finned fishes
The phylogenetic tree indicates that annelids are most closely related to ________.
molluscs
have a body plan with 3 main parts: a visceral mass, a mantle, and a foot
molluscs
________ are the mammalian group that lays eggs.
monotremes
What do the yellow labels (Eumetazoans, Bilaterians, etc.) represent?
names of clades
have a pseudocoelom and are the simplest animals that have a complete digestive tract
nematodes
Is this statement supported or not supported by the phylogenetic tree? Annelids and nematodes are more closely related to each other than either group is to flatworms.
not supported
One of the features shared by all chordates is a(n) _____________, a flexible rod that run along the top side of the back.
notochord
Movement of the _________ allows some fish to breathe without swimming.
operculum
The stationary stage of the cnidarian life cycle is the ________ stage.
polyp
Annelids, such as leeches, __________, a characteristic shared by all other bilateral animals except flatworms.
possess a complete digestive tract
You are given the task of confirming the categorization of a newly discovered marine animal that has been tagged as a species of echinoderm. What evidence would convince you that it is an echinoderm and not different marine animal such as a sponge or sea anemone?
presence of a water vascular system
What type of symmetry does this organism exhibit?
radial
Cnidarians are the only animal phylum to display _ meaning that their bodies can be divided any way through the center point to yield two even halves.All other adult animals display _ meaning that their bodies can only be sliced lengthwise through the midline to produce two even halves.
radial symmetry, bilateral symmetry
A fish that has a bony skeleton and thin, flexible supports in its fins is known as a ____________
ray-finned fish
Adaptations that evolved in the group of animals called the __________ have allowed them to complete their life cycles entirely on land.
reptiles
Which animals have a cylindrical body that is tapered at both ends?
roundworms
Which of the following are nematodes?
roundworms
Which diagnostic feature is specific to cartilaginous fish?
skeleton of cartilage
Unique features of vertebrates include the presence of a(n) ________.
skull and a backbone
Radial symmetry is seen in a ________.
snowflake
A characteristic of arthropods that has allowed for their great success is the presence of ________.
specialized segments
Which of the following is an invertebrate?
sponge
sessile animals that have specialized cells called amoebocytes and choanocytes
sponges
Is this statement supported or not supported by the phylogenetic tree? Chordates and echinoderms are more closely related to each other than either group is to arthropods.
supported
Is this statement supported or not supported by the phylogenetic tree? The two lineages of eumetazoans are the bilaterians and the cnidarians.
supported
Sponges are examples of ________.
suspension feeders
The gas-filled sac found in many fishes is called a ________.
swim bladder
Cnidarians have __________.
tentacles with stinging cells
A four-limbed, land-dwelling vertebrate is generally known as a(n).
tetrapod
The process of biological evolution often allows humans to survive consistent environmental stresses that occur across multiple generations. As humans colonized Earth's diverse environments, they encountered hot, dry areas and decided to settle. What trait likely offered an advantage in this environment?
the ability to produce sweat to cool their bodies
A characteristic that is shared by snakes and birds is ________.
the amniotic egg
A feature that freed reptiles from dependence on water for reproduction is ________.
the amniotic egg
A feature unique to mammals includes ________.
the presence of hair
All animals except sponges have __ groups of cells that work together to perform a specific function.
tissues
Which derived character is shared by all eumetazoans?
true tissues
A(n) ____________ is an animals that has a backbone in addition to displaying the four feature of all chordates.
vertebrate