Exam 4

Question 1

Identify synapomorphies of the Echinodermata

Answer 1

2nd Pentaradial Symmetry
Ambulacral zone: where tube feet pass through body
Loss of cerebral ganglia
CaCO3 endoskeleton
Hydrostatic system with madreporite and tube feet

Question 2

Describe the transition in symmetry that Echinoderms undergo. Explain the adaptive significance of each kind of symmetry.

Answer 2

All Echinoderms have a pentaradial symmetry but they started out as bilateral larvae. Their larvae actually swim in the water to avoid predators, but as they grow they become slow/stationary and have to be able to see/feel from all directions.

Question 3

Describe the unique connective tissues of echinoderms and how they can be adaptive.

Answer 3

Echinoderms have smart connective tissue that allows them to voluntarily separate their appendages (which they can regrow back). This allows them to escape their predators or hopefully satisfy their hunger enough to not eat the rest of the echinoderm.

Question 4

Explain how Echinoderms deal with the major challenges that your skeleton deals with.

Answer 4

Essentially Echinoderms have all three skeletal types: Hydrostatic( they use water to move around), Exoskeleton (they have CaCO3 armour that protects), and an Endoskeleton plate (that gives them structure)

Question 5

Describe the characteristics (synapomorphies) of each class of echinoderms.

Answer 5

Crinoidea (sea lillies)

• lack tube feet
• No Madreporite
• tube feet with suckers
• oral side down

Ophithuroidea (Brittle Star)

• no anus
• articulating appendages
• madreporite
• loss of suckers

Asteroidea (the common starfish)

• gonads and guts in arms
• pedicellirae

Echinoidea (sea urchins)

• Test
• Moveable spikes
• pedicellirae
• no arms

Question 6

List the defining characteristics of chordates. Identify the subphyla.

Answer 6

All Chordates have: post-anal tail, notochord, dorsal hollow nerve chord

Urochordata: Sea Squirts, Salp, Tunicate

Cephalochordata: Lancelet

Craniata: hagfishes and vertebrates

Question 7

Identify the traits that show how the hemichordates are related to echinoderms, and to chordates.

Answer 7

Echinoderms: They have similar larvae states and DNA sequences

Chordates: branchial openings, or “gill slits,” that open into the pharynx; there is a rudimentary structure in the collar region, the stomochord, that is similar to a notochord; and there is a dorsal nerve cord, in addition to a smaller ventral nerve cord

Question 8

Explain the function of a lateral line system.

Answer 8

The lateral line system is a sense organ in fishes that allows them to detect movement and vibration via water pressure. This allows them to react quickly to predators and move as a group.

Question 9

Explain the evolution of jaws.

Answer 9

During development, the 1st and 2nd-gill slits disappear, and the 3rd gill slit develops into the jaw while the 4th develops into jaw supports

Question 10

Explain why shark scales are called denticulate.

Answer 10

Shark scales are made of dentine, so basically shark scales are little teeth.

Question 11

Determine the sex of a shark or ray from a picture or specimen.

Answer 11

A male shark/ray have two reproductive organ call claspers that they use to inject sperm into the female reproductive opening called a cloaca

Question 12

Explain the distribution and function of ampullae of Lorenzini.

Answer 12

The ampullae of Lorenzini are found on Elasmobranchii (such as shark, rays, and chimaeras). They are sensory canals and receptors that respond to weak electric fields, and possibly to temperature, water pressure, and salinity.

Question 13

Compare and contrast the cartilaginous fishes and the ray-finned fishes.

Answer 13

cartilaginous fish: swim bladder absent, cartilaginous endoskeleton, internal fertilization, placciod scale

ray-finned fishes: swim bladder present, bony endoskeleton, external fertilization, cycloid scales

Question 14

List characteristics that Tiktaalik has that are like tetrapods. List tetrapod traits that Tiktaalik lacks or is not known to have. Explain why Tiktaalik is such an important fossil.

Answer 14

Similarities: neck, wrist, flat head, eyes on top of head, snaps food
It is important because it’s the first species to have a pictorial girdle that allows it to crawl on land

Question 15

Explain how amphibians are suited to life on land. Explain how they are still dependent on water.

Answer 15

Land: Doesn’t have scales, poison glands in skin for protection, powerful legs, claws, moist skin for gas exchange.
Dependent on Water: Eggs need water and larval stage requires aquatic environment.

Question 16

Draw a diagram of the amniotic egg and explain the functions of each membrane.

Answer 16

Allantois: Waste disposal sac for metabolic waste produced by embryo; membrane functions with the chorion as respiratory organ.
Amnion protects the embryo in a fluid-filled cavity that cushions against shock. Chorion and allantois exchange gas between the embryo and the air; O2 and CO2 diffuse freely across shell. Yolk sac: Contains nutrients (yolk); blood vessels in this membrane transports nutrients into the embryo.

Question 17

Explain the significance of the evolution of the amniotic egg.

Answer 17

The amniotic egg was an evolutionary invention that allowed the first reptiles to colonize dry land more than 300 million years ago. Fishes and amphibians must lay their eggs in water and therefore cannot live far from water. But thanks to the amniotic egg, reptiles can lay their eggs nearly anywhere on dry land.

Question 18

List some defining characteristics of mammals.

Answer 18

Mammary glands, Hair, Three inner ear bones (malleus[hammer], incus[anvil], and stapes[stiruup]), sweat glands

Question 19

Compare how many bones are present in the lower jaw of reptiles vs. the lower jaw of mammals.

Answer 19

Reptiles: larger angular, quadrate, and articular
Mammals: dentary is the only real part of the lower jaw

Question 20

Explain the evolution of middle ear bones in mammals.

Answer 20

In mammals, a new joint formed beneath the dentary and quadrate and articular bones became incorporated into the middle ear as 2 of 3 bones that transmit sound from the ear drum to the inner ear.

Question 21

Identify a feature of a mammalian skull that is evidence of high body temperature

Answer 21

Scroll-shaped bone in naval cavity. Brain case size, multiple holes in skull.

Question 22

Identify two unique features of turtle skeletons.

Answer 22

Box-like shell with upper and lower shields fused to vertebrae, clavicles and ribs with horned beak, head retractable into skeletal system.

Question 23

List characteristics of modern birds that suit them for flight.

Answer 23

1. hand bones with attached feathers provides propulsion
2. wing is streamlined with a concave lower surface
3. The leading edge of the wing has small tight-fitting feathers.

Question 24

Distinguish between saurischian and ornithischian dinosaurs by examining the pelvic bones. Identify which group was the most recent ancestor of birds.

Answer 24

Saurischian: Pelvic bone (pubis) points forward
Ornithischian: Pelvic bone points backwards
Saurischians are most related to birds, birds derived the trait later.

Question 25

List traits that Archaeopteryx shares with modern birds, and traits of modern birds it lacks. Explain why Archaeopteryx is such an important species for understanding the evolution of birds.

Answer 25

Wings with feathers, but has clawed digits in wings, teeth, long tails, shows that birds are related to dinosaurs and what traits derived first.

Question 26

Explain the difference between population size and density

Answer 26

Population size is the number of species present, while population density is the number of individuals per unit area.

Question 27

Describe 4 basic changes to population size

Answer 27

Birth, Death, Immigration (coming in), Emigration (going out)

Question 28

Describe exponential and logistic population growth.

Answer 28

exponential growth: population grows rapidly and eventually over carrying capacity
logistic growth: populations grows then slows down and eventually plateaus

Question 29

Define biome, give some examples, and explain what factors determine where different biomes are found.

Answer 29

a large naturally occurring community of flora and fauna occupying a major habitat, e.g., forest or tundra.

Question 30

Explain the difference between climate & weather.

Answer 30

Weather is what conditions of the atmosphere are over a short period of time, and climate is how the atmosphere “behaves” over relatively long periods of time.

Question 31

Explain why temperatures are colder at the poles than at the equator.

Answer 31

Sunlight hits both the equator and the poles. However, it’s more concentrated at the equator. Due to the Earth having a tilt the sunlight is less concentrated at the poles. Also light bounces off snow

Question 32

Explain what causes seasons.

Answer 32

seasons are caused by the tilt of the Earth’s rotational axis away or toward the sun as it travels through its year-long path around the sun

Question 33

Define “greenhouse effect”

Answer 33

greenhouse effect is the process by which radiation from a planet’s atmosphere warms the planet’s surface to a temperature above what it would be without its atmosphere

Question 34

Identify the most common greenhouse gasses.

Answer 34

water vapor, carbon dioxide, methane, nitrous oxide, and ozone