Bio 1200 exam 3

What is the Cambrian Explosion?

The --------------- was a period of rapid diversification of life forms that occurred approximately 541 million years ago, during the-------- period. It marked the appearance of most major groups of animals in the fossil record and is considered a key event in the history of life on Earth.

Why is the Cambrian Explosion considered important in the evolution of animal life?

The Cambrian Explosion is considered important in the evolution of animal life because it marks the sudden appearance of a diverse array of complex animal forms in the fossil record.

Why do we think the Cambrian Explosion occurred?

The Cambrian Explosion is believed to have occurred due to a combination of factors, including the evolution of new genetic and developmental mechanisms, changes in the environment, and the emergence of new ecological niches. Fossil evidence also suggests that the explosion may have been triggered by a sudden increase in atmospheric oxygen levels, which allowed for the evolution of more complex and energy-intensive organisms.

What is a mass extinction?

A mass extinction is an event in which a significant proportion of Earth's biodiversity is lost in a relatively short period of time, usually due to a catastrophic event such as a meteor impact or volcanic activity. There have been five major mass extinctions in Earth's history, with the most recent occurring approximately 66 million years ago and resulting in the extinction of the dinosaurs.

How many mass extinctions have occurred that we are aware of?

1. Ordovician-Silurian extinction event (about 443 million years ago) - caused by glaciation and a drop in sea level, possibly triggered by a supernova.
2. Late Devonian extinction event (about 359 million years ago) - caused by several factors, including climate change, sea level fluctuations, and possibly a comet impact.
3. Permian-Triassic extinction event (about 252 million years ago) - the most severe extinction event in the history of life on Earth, caused by massive volcanic activity that led to global warming, acid rain, and ocean anoxia.
4. Triassic-Jurassic extinction event (about 201 million years ago) - caused by a combination of climate change, volcanic activity, and possibly an asteroid impact.
5. Cretaceous-Paleogene extinction event (about 66 million years ago) - caused by an asteroid impact that led to global cooling and widespread environmental disruption, including wildfires and acid rain.

\

Who or what are the closest relatives of the animals?

Choanoflagellates

What is a hydrostatic skeleton?

cavities that are fluid-filled, and that fluid is primarily water. Water is non-compressible, so these cavities function as a ------- (water pressure) --------. This allows them a greater degree of control over their movement and provided support for the body, allowing them to grow larger than organisms that don’t have a -----------.

Understand the differences in embryonic development between protostomes and \n deuterostomes.

Protostomes – undergo spiral cleavage = cells orient at angles to the main axis, results in a spiral. They also have determinate cell development which means cells have predetermined fate.

Deuterostomes – undergo radial cleavage = cells orient parallel to main axis resulting in stacking and they have indeterminate development, any cell can develop into complete organism.



In Protostomes, the first pore (blastopore) formed becomes the mouth (second opening later becomes anus).

In Deuterostome, the first pore becomes the anus (second opening later becomes mouth).



In protostomes, cells split off from the mesoderm and expand into blocks inside which the coelomic cavities form, whereas in deuterostomes, the coelomic cavities form from evaginations of the mesoderm while still associated with the endoderm.

Be familiar with diploblasty, triploblasty

Organisms which only have the ectoderm and endoderm are known as diploblastic – Cnidarians (jellyfish, anenomes) and Ctenophores (comb jellies) are only diploblasts.

Organisms which have all three tissue layers are known as triploblastic. This is a derived condition relative to diploblastic organisms

know the three tissues types.

Ectoderm – which give rise to skin and nervous system

Mesoderm - which give rise to circulatory system, muscles, bone, and most organs

Endoderm - which give rise to the lining of gut, or digestive tract

Know the difference between an acoelomate, pseudocoelomate and coelomate \n organism.

The body cavity in animals is known as the coelom (pronounced \[*see-luh m*\]).

These animals without a coelom are known as acoelomate.



The next group of organisms are the pseudocoelomates like nematodes. These critters do have a fluid-filled body cavity, but it’s lined on the outer side by mesodermal tissue and on the inside by endodermal tissue.



Finally we have the coelomate animals, where the fluid filled body cavity is completely lined with mesodermal tissue.

What is symmetry, and what types of symmetry exist in animals?

Asymmetry - sponges (porifera) - no symmetry

Radial symmetry = multiple planes of symmetry, mirror image when divided at angles - sessile filter feeders

Bilateral - single plane of symmetry  (left and right halves, posterior and anterior)- more efficient for movement

Bilateral symmetry also allows for cephalization to occur - evolution of a head with a concentration of sense organs and nerve tissue and ganglia (thinking end). What is the benefit of this?

Understand the benefit/s of bilateral symmetry

Bilateral symmetry refers to the arrangement of body parts in a way that can be divided into two mirror-image halves. This type of symmetry is beneficial for many organisms as it allows for efficient movement and coordination. It also allows for specialization of body parts, such as the development of different types of limbs for different functions. Additionally, bilateral symmetry can aid in predator avoidance and prey capture by providing a streamlined body shape and improved sensory perception. Overall, bilateral symmetry is an important adaptation that has evolved in many different types of organisms.

What organisms are considered to be representative of the likely ancestor of animals?

Choanoflagellates

Understand the requirements for the water to land transition.

•New habitats and new resources to exploit

•To make the transition to land, new adaptations must allow protostomes to

1\. Exchange gases

2\. Avoid drying out

3\. Hold up their bodies under their own weight

4\.Reproduction



•Insects evolved a waxy layer to minimize water loss from the body surface

–If the environment dries, openings to respiratory passages can be closed

•Desiccation-resistant eggs evolved repeatedly in populations that made the transition to life on land

–Insect eggs have a thick membrane that keeps in moisture

–Snail and slug eggs have a thick shell that retains water

Why are most lophotrochozoans aquatic and/or restricted to damp environments?

soft bodies and rely on water or moist environments to support their internal organs and protect them from desiccation.

What are the synapomorphies of the lophotrochozoans and ecdysozoans?

Lophotrochozoans

* no coelom
* segmentation
* reduced coelom
* coelom

Ecdysozoa

* Coelom
* growth by molting
* limbs
* pseudocoelom
* reduced coelom
* segmentation
* jointed limbs

\
\

What are the key differences between lophotrochozoans and ecdysozoans?

Lophotrochozoans and ecdysozoans are two groups of animals that have some similarities, but also some important differences. Ecdysozoans grow by molting their outer layer, while lophotrochozoans grow continuously. Ecdysozoans have a segmented body plan, while lophotrochozoans do not. Ecdysozoans undergo spiral cleavage during embryonic development, while lophotrochozoans can undergo either spiral or radial cleavage. Lophotrochozoans often have a special larval stage called a lophophore or trochophore, while ecdysozoans have different types of larvae.

Understand metamorphosis and growth in ecdysozoans.

Ecdysozoans grow by molting their outer covering or cuticle. This process happens in stages, where the animal grows before shedding its old cuticle and emerging with a larger body size and new cuticle. Some ecdysozoans also undergo metamorphosis, which is a dramatic change in body form as they transition from one life stage to another. For example, insects undergo a complete metamorphosis, which includes four stages: egg, larva, pupa, and adult. Other ecdysozoans have incomplete metamorphosis, where they gradually change in body form as they grow and mature.

Be familiar with the arthropod body plan.

Synapomorphies for the arthropods are segmentation, a hard chitonous exoskeleton, and jointed limbs.

\
Arthro = joint

Pod = limb or foot

Why arthropods have been so successful?

Arthropods are very successful because of their adaptable body plan, which allows them to evolve specialized structures and behaviors for different environments. They can reproduce quickly and in large numbers, and their hard exoskeleton provides protection and conserves water. Arthropods also have specialized sensory structures and defense mechanisms, which help them detect stimuli and avoid predators.

Review the key innovations of the vertebrates (jaws, lungs, limbs, feathers, flight, \n amniotic egg, placenta).

1. Jaws - Vertebrates were the first animals to evolve jaws, which allowed them to grasp and manipulate food more efficiently.
2. Lungs - Vertebrates also evolved lungs, which allowed them to breathe air and live in environments with lower oxygen concentrations, such as on land.
3. Limbs - The evolution of limbs allowed vertebrates to move efficiently on land, in water, and in the air.
4. Feathers and flight - The evolution of feathers and flight was a key innovation for birds, allowing them to fly and access new food sources and habitats.
5. Amniotic egg - The amniotic egg, which evolved in reptiles and birds, allowed vertebrates to reproduce on land and avoid the need for a water-based environment for reproduction.
6. Placenta - The evolution of the placenta in mammals allowed for more efficient nutrient transfer between the mother and developing embryo, enabling longer gestation periods and more complex social behaviors.

\

What are jawless fishes?

Jawless fishes are primitive fish that don't have true jaws or paired fins. There are two types of jawless fishes: hagfish and lampreys. Hagfish are scavengers with slimy bodies and no backbone. Lampreys are parasitic or non-parasitic fish that have sharp teeth and feed on other fish. Jawless fishes are important for studying vertebrate evolution.

\

What are cartilaginous fishes?

Cartilaginous fishes, such as sharks, rays, and chimaeras, are fish that have a skeleton made of cartilage instead of bones. They don't have a swim bladder to control their buoyancy. Cartilaginous fishes live in the ocean and some in freshwater, and they have many different shapes and sizes. Sharks are predators with sharp teeth, rays have flat bodies and live on the bottom, and chimaeras have a unique body shape with a long, thin tail and a broad head. Cartilaginous fishes are important for understanding vertebrate evolution and are successful in different environments.

What are bony fishes?

Bony fishes, also known as Osteichthyes, are a diverse group of fish that have a bony skeleton and a swim bladder to control their buoyancy. They are found in different aquatic environments and come in many shapes and sizes, with a wide range of adaptations to thrive in their environment. Some bony fishes are predators, while others are herbivores or detritivores. They are important for both ecological and economic reasons, playing important roles in aquatic food webs and being a source of food and income for humans.

What are lobe-finned fishes?

Lobe-finned fishes are a group of fish that have fleshy, lobed fins similar to limbs of four-legged animals. This group includes lungfishes, coelacanths, and tetrapods (four-legged animals). They can be found in freshwater and marine environments and have a range of ecological roles, such as being able to breathe air or being a rare living fossil. The evolution of lobe-finned fishes provides insights into the origin of tetrapods and the evolution of vertebrates from fish to land-dwelling animals. The development of lobed fins is thought to have helped the transition from water to land.

What fish group is thought to have given rise to terrestrial vertebrates?

The fish group that is thought to have given rise to terrestrial vertebrates is the lobe-finned fishes, also known as Sarcopterygii. This group includes lungfishes, coelacanths, and several extinct groups of fish, as well as all tetrapods (four-legged animals). The development of the lobed fins in lobe-finned fish is thought to have been a key adaptation that allowed for the transition from water to land. This transition is considered to be a major event in the history of life on Earth, as it gave rise to the diversity of terrestrial vertebrates that exist today.

What is the prevailing hypothesis regarding jaw evolution?

The prevailing hypothesis is that jaws evolved from the first pair of gill arches in primitive fishes. The gill arches became more specialized over time, eventually evolving into jaws. Jaws allowed for a wider range of feeding strategies and predatory behavior, leading to the diversity of jawed vertebrates we see today. This hypothesis is supported by similarities between the development of gill arches in primitive fishes and the development of jaws in modern jawed vertebrates.

What is a swim bladder; why is it important?

A swim bladder is a gas-filled organ found in some fish that helps them control their buoyancy in water. By regulating the amount of gas in the swim bladder, fish can stay at a particular depth without having to constantly swim. This helps fish conserve energy, find food, avoid predators, and migrate. The swim bladder is an important adaptation that has evolved independently in different fish groups and is used to classify fish species.

What is an amniotic egg? Why is it an important step in vertebrate evolution?

An amniotic egg is a special type of egg that allows reptiles, birds, and some mammals to reproduce on land by protecting the embryo from drying out and predators. This adaptation freed vertebrates from the dependence on water for reproduction and allowed them to live on land, leading to the evolution of a wide variety of terrestrial animals. The amniotic egg is considered one of the most significant evolutionary innovations in the history of life on Earth.

What features define the group Mammalia?

§Mammary glands that produce milk

§Hair

§A fat layer under the skin

§The kidney, which conserves water during waste removal

§A high metabolic rate, due to endothermy

§A relatively large brain

Differentiated teeth

What are the reproductive differences between Monotremes, Marsupials, and true \n Mammals?

Monotremes: Monotremes, such as platypuses and echidnas, lay eggs instead of giving birth to live young. The eggs are incubated outside of the mother's body and hatch into relatively undeveloped young, which then must be cared for by the mother until they are able to survive on their own.

Marsupials: Marsupials, such as kangaroos and opossums, give birth to relatively undeveloped young, which then complete their development while attached to their mother's nipples inside a pouch called the marsupium. The young receive nutrients and protection from the mother's milk and body heat, and eventually leave the pouch when they are able to survive on their own.

True Mammals: True mammals, such as humans and most other familiar mammals, give birth to well-developed young that are nourished by the mother's milk. The young receive nutrients and protection from the mother's milk and body heat until they are able to survive on their own.

\

Why are the tropics warm, and the poles cold?

The tropics are warm and the poles are cold due to differences in the amount of sunlight that they receive and how that sunlight is distributed across the Earth's surface.

The sun's rays hit the Earth most directly at the equator, which is located in the tropical region. This means that the tropics receive more direct sunlight than any other part of the Earth. The angle of the sun's rays also creates a more concentrated area of solar energy, which causes the air to warm up and rise, creating a low-pressure zone. The warm, moist air rises and expands, eventually cooling and condensing into clouds, which produce the heavy rainfall that is characteristic of tropical regions.

In contrast, the poles are located at a much higher angle from the sun, so the sun's rays are spread over a larger area. This means that the poles receive much less direct sunlight and solar energy than the tropics. Additionally, the atmosphere at the poles is thicker, so the sunlight that does reach the surface is spread out even further. As a result, the poles are much colder than the tropics.

\

Why are the tropics wet?

The tropics are wet because they receive a lot of direct sunlight, which heats up the air and causes it to rise. As the warm, moist air rises, it cools and water vapor condenses into clouds, which produce heavy rainfall. Additionally, the tropics are home to large bodies of water, like oceans and rainforests, which create a lot of moisture in the air through evaporation and transpiration. These factors combine to make the tropics a very humid and wet region.

What causes seasonality in weather?

The seasonality in weather is caused by the tilt of the Earth's axis and its orbit around the sun. As the Earth revolves around the sun, its axis remains tilted at an angle of 23.5 degrees relative to its plane of orbit. This means that at different times of the year, different parts of the Earth receive more direct sunlight than others.

\

Understand the circulation patterns of air in the atmosphere.

Air circulates in the atmosphere in a pattern known as atmospheric circulation. This pattern is driven by differences in temperature and pressure between different parts of the Earth's surface, caused by the unequal distribution of solar radiation.

At the equator, the sun's rays are most concentrated, causing the air to heat up and rise. As this warm air rises, it creates an area of low pressure at the surface. This rising air then moves away from the equator towards the poles, where it cools and sinks, creating an area of high pressure at the surface.

This movement of air creates three distinct circulation cells in each hemisphere, known as Hadley cells, Ferrel cells, and Polar cells. Hadley cells are located near the equator and are responsible for the trade winds that blow from east to west. Ferrel cells are located between 30 and 60 degrees latitude and are responsible for the prevailing westerlies that blow from west to east. Polar cells are located near the poles and are responsible for the polar easterlies that blow from east to west.

These circulation cells create global wind patterns that affect weather and climate patterns around the world. They also play a role in the movement of heat and moisture around the globe, as well as in the distribution of nutrients and other important substances.

\

Know what biogeography is, and how abiotic and biotic factors can impact the range of \n species.

Biogeography is the study of the distribution of living organisms on Earth and the processes that have led to their current geographic ranges. The distribution of species is influenced by both abiotic (non-living) and biotic (living) factors.

Abiotic factors that can impact the range of species include climate, geology, topography, and ocean currents. For example, species may be restricted to certain latitudes or elevations based on temperature or precipitation patterns. Other species may be limited to specific types of soil or geological formations. Ocean currents can also play a major role in determining the distribution of marine species, such as the movement of warm water currents creating tropical habitats for coral reefs.

Biotic factors can also impact the range of species. For example, competition with other species can limit the range of a particular species. Additionally, predation pressure can limit a species' range, as some species may not be able to survive in areas where they are vulnerable to predation. Other biotic factors that can impact range include mutualistic relationships, such as pollination, and disease.

The interaction between abiotic and biotic factors can lead to complex patterns of distribution for different species. Some species may have wider ranges due to their ability to adapt to a variety of environmental conditions, while others may be restricted to very specific habitats. Human activities, such as habitat destruction and climate change, can also have a significant impact on the range of species, leading to range contractions, expansions, or even extinction. Understanding the factors that influence species ranges is important for conservation efforts and managing biodiversity in a changing world.

\

What is the Wallace Line?

The Wallace Line is a biogeographic boundary that separates the ecozones of Asia and Australia. It was named after the British naturalist Alfred Russel Wallace, who first noted the distinctive differences in the flora and fauna of the two regions during his travels in Southeast Asia in the mid-19th century.

The Wallace Line is located between the islands of Bali and Lombok, and it extends northward through the Makassar Strait between Borneo and Sulawesi. West of the line, the animal and plant species are mostly of Asian origin, while to the east, they are mostly of Australian origin. This is due to the fact that during the Pleistocene era, when sea levels were lower, the landmass of Asia and Australia were connected by a land bridge. However, as the sea level rose, the land bridge was submerged, and the two regions were separated, leading to the development of distinct flora and fauna on each side of the line.

\

What is a biome?

A biome is a large, distinctive ecological community characterized by its particular climate, soil type, and the types of plants and animals that live there. Biomes are typically defined by their dominant vegetation, which is adapted to the specific climate and soil conditions of the area.

There are several different types of biomes found on Earth, including tropical rainforests, savannas, deserts, tundras, and temperate forests. Each biome has its own unique set of characteristics, such as temperature range, precipitation levels, and vegetation types.

Biomes play a critical role in the Earth's ecosystems, as they provide habitat and resources for a wide variety of plant and animal species. They also play a key role in regulating the Earth's climate and carbon cycle, and they provide important ecosystem services such as carbon sequestration, water filtration, and soil erosion control.

\

What two physical factors are key in identifying different terrestrial biome types?

The two key physical factors that are used to identify different terrestrial biome types are temperature and precipitation. These factors, along with soil type and other abiotic factors, determine the types of vegetation that can grow in a particular biome and the types of animals that can live there.

Temperature and precipitation are closely linked, as temperature affects the rate of evaporation and the amount of moisture that can be held in the atmosphere. In general, biomes with high average temperatures and high precipitation levels tend to have lush vegetation, while biomes with low temperatures and low precipitation tend to have sparse vegetation or no vegetation at all. The combination of temperature and precipitation also determines whether a biome is forested, grassy, or desert-like.

\

What physical factor delineates the two major aquatic biomes?

The physical factor that delineates the two major aquatic biomes is salinity. The two major aquatic biomes are freshwater and marine biomes. Freshwater biomes have low salinity, typically less than 1%, while marine biomes have high salinity, typically around 3.5%. This difference in salinity affects the types of organisms that can survive in each biome. Freshwater biomes are home to a wide range of aquatic life, including fish, amphibians, and invertebrates, while marine biomes are dominated by a diverse array of marine organisms, such as fish, marine mammals, and invertebrates like coral and krill.

What is ocean upwelling, and how does it affect nutrient availability? \n \n

Ocean upwelling is a process where deep, nutrient-rich water rises to the surface, replacing warmer surface water. This occurs when winds blow surface water away from a coastline, allowing colder, deeper water to rise and take its place. This deep water is typically rich in nutrients like nitrogen and phosphorus, which are essential for the growth of phytoplankton and other organisms at the base of the marine food web.

Upwelling is important because it brings nutrients to the surface, which fuels the growth of phytoplankton and other primary producers. These organisms form the base of the marine food web and are a crucial source of food for larger organisms like fish and marine mammals. Upwelling is particularly important in areas where there is typically low nutrient availability, such as in tropical regions where warm surface water prevents the mixing of nutrient-rich deep water.

Upwelling can also have negative effects, such as causing harmful algal blooms that can be toxic to marine life and humans. However, overall, upwelling is an important process that supports the productivity and biodiversity of marine ecosystems.

\

Why is water depth a key physical factor in aquatic ecosystems?

\n

\

Water depth is a key physical factor in aquatic ecosystems because it determines the amount of sunlight that reaches the organisms living within the water column. Sunlight is essential for photosynthesis, the process by which plants and algae produce energy-rich organic compounds from carbon dioxide and water. In shallow water, light can penetrate to the bottom, allowing photosynthesis to occur over a larger area. As water depth increases, less light is able to penetrate the water column, reducing the amount of photosynthesis that can occur.

Water depth can also affect temperature and pressure, which can impact the distribution and abundance of aquatic organisms. For example, many species of fish are adapted to specific temperature ranges and may not be able to survive in waters that are too warm or too cold. Similarly, some organisms are adapted to living at specific depths and may not be able to survive if they are exposed to the high pressures found at deeper depths.

Overall, water depth is a critical physical factor that influences the structure and function of aquatic ecosystems and the distribution of aquatic organisms.

\

How old are plants?

450-480 million years old

Why are plants also called embryophytes?

Because the plants nurture young embryo sporophytes within the plant itself during its developmental stages

What are the derived traits of plants?

Green algae, terrestrial plants, vascular plants, seed plants, respectfully

Why are plants important for ecosystem services?

Produce oxygen, build soil, hold water, moderate climate, base of the terrestrial food chain

What are the synapomorphies for green plants?

Beta carotene (pigment for green plants)

What are the major groups of land plants? Are they monophyletic?

Non-vascular plants, seedless vascular plants, gymnosperms, angiosperms. All land plants are monophyletic

What is the most diverse and derived group of land plants? What is their key innovation?

Seed plants are the most diverse and evolved group of land plants; consisting of angiosperms and gymnosperms. The key innovation is the use of vessels (vascular tissue to transport water)

What are the key innovations that allow green plants to diversify on land?

Cuticles allowed green plants to diversify on land, since they act as a protective layer to prevent desiccation and other environmental stressor

What adaptation allowed seeded plants to be able to reproduce in the absence of water?

Flowering in seeded plants, allowing for plant sperm to be spread by pollinators

What was required for plants to transition from a aquatic to terrestrial habitat?

The reproductive organ of a flower. Allows for the plant to be pollinated by birds, bees, insects etc.

Review the basics of plant phylogeny.

Plant phylogeny is the study of the evolutionary relationships among plants. It is based on molecular, morphological, and anatomical data, which are used to construct phylogenetic trees that represent the evolutionary history of plant groups.

Plants are divided into two main groups: the non-vascular plants and the vascular plants. Non-vascular plants, such as mosses and liverworts, do not have specialized tissues for conducting water and nutrients throughout the plant body. In contrast, vascular plants, which include ferns, gymnosperms, and angiosperms, have specialized tissues called xylem and phloem that transport water and nutrients throughout the plant.

Vascular plants are further divided into two groups based on the presence or absence of seeds. Seedless vascular plants, such as ferns and horsetails, reproduce by spores. Seed plants, which include gymnosperms and angiosperms, have seeds that contain an embryo and a food source, which allows them to survive and germinate under favorable conditions.

Gymnosperms, which include conifers, cycads, and ginkgoes, have seeds that are not enclosed in a protective fruit. Angiosperms, which make up the majority of all plant species, have seeds that are enclosed in a fruit. They are further divided into two groups based on the number of cotyledons, or seed leaves, that their embryos have. Monocots, such as grasses and lilies, have one cotyledon, while dicots, such as most trees, shrubs, and flowering plants, have two cotyledons.

\

The most direct ancestors of land plants were probably _____.

green algae

Molecular phylogenies show all land plants are a monophyletic group. This suggests that _____.

there was a single transition from aquatic to terrestrial habitats

What evidence do paleobotanists look for that indicates the movement of plants from water to land?

 waxy cuticle to decrease evaporation from leaves

You find a green organism in a pond near your house and believe it is a plant, not an alga. The mystery organism is most likely a plant and not an alga if it _____.

is surrounded by a cuticle

In the process of alternation of generations, the _____.

 sporophyte is diploid and produces spores

Which of the following was a challenge to the survival of the first land plants?

  desiccation

Archegonia _____.

may contain sporophyte embryos

Which of the following features of how seedless land plants get sperm to egg are the same as for some of their algal ancestors?

Flagellated sperm swim to the eggs in a water drop.

Angiosperms are the most successful terrestrial plants. Which of the following features is unique to them and helps account for their success?

 fruits enclosing seeds

The fruit of the mistletoe, a parasitic angiosperm, is a one-seeded berry. In members of the genus *Viscum*, the outside of the seed is viscous (sticky), which permits the seed to adhere to surfaces such as the branches of host plants or the beaks of birds. What should be expected of the fruit if the viscosity of *Viscum* seeds is primarily an adaptation for dispersal rather than an adaptation for infecting host plant tissues? It should ______.

 be nutritious to the dispersing organisms 

Among protostomes, which morphological trait has shown the most variation?

type of body cavity (coelom vs. pseudocoelom vs. acoelom)

Cnidarians and Ctenophores differ from all other eumetazoans by having

radial symmetry and a diploblastic tissue organization

\
\

In a tube-within-a-tube body plan, what is the interior tube?

The gut

 

\

Limbs–especially jointed limbs, are an important evolutionary development because they allow animals to ________.

move quickly and precisely.

 

\

Of the major groups of Animals listed below, which one lacks symmetry and has no true tissues or organs?

Porifera

 

\

The protostome developmental sequence arose just once in evolutionary history, resulting in two main subgroups - Lophotrochozoa and Ecdysozoa. What does this finding suggest?

Division of these two groups occurred after the protostome developmental sequence appeared.

A cephalopod's tentacles are modified from its _____.

foot

Which adaptation is unique to insects among all protostomes?

 the ability to move by flying 

Which of the following attributes is true for both arthropod exoskeletons and mollusk shells?

They help retain moisture in terrestrial habitats.

 

\

Which one of these groups does not molt?

Mollusks

 

\

Which of the following is a characteristic of all chordates at some point during their life cycle?

post-anal tail

 

\

In order to successfully colonize terrestrial habitats, an animal must be able to

Bear its own body weight

 

  

Resist dessication (drying out)

 

\

The fish group that is most closely related to the organisms that first invaded terrestrial habits were

Lungfish

 

\

It is believed that the coelacanths and lungfish represent a crucial link between other fishes and tetrapods. What is the major feature in these fish in support of this hypothesis?

Their fins have skeletal and muscular structures similar to amphibian limbs

Vertebrate jaws are hypothesized to have evolved from

Cartilaginous gill arches

A certain species of pine tree survives only in scattered locations at elevations above 2800 meters in the western United States. To understand why this tree grows only in these specific places, an ecologist should _____.

investigate the various biotic and abiotic factors that are unique to high altitude

 

\

For a species to be called "invasive," it must _____.

be introduced to a new area, spread rapidly in this area, and eliminate native species

 

\

In deep water, which of the following abiotic factors would most limit productivity?

light availability

 

\

The main reason polar regions are cooler than the equator is that _____.

sunlight strikes the poles at a lower angle

 

\

Theoretically, which would be the most effective way to disrupt a Hadley cell?

Remove all equatorial moisture and convection.

What happens to animal and plant diversity as latitude decreases?

Animal and plant diversity increases.

What is the main difference between climate and weather?

 Climate typically describes longer-term conditions. 

What would happen to the seasons if the Earth were tilted 35 degrees off its orbital plane instead of the usual 23.5 degrees?

Winters and summers would be more severe.

 

\

Which abiotic factor would have the most significant physiological effect on migrating salmon?

 water solute content 

Which of the following are important biotic factors that can affect the structure and organization of biological communities?

 predation, competition 

Which of the following organisms is likely to have the widest geographic distribution?

bacteria