Bio 2 Exam 2 Practice (2)

Root hairs are important to a plant because they \_____.
a.) help the root slide between soil particles
b.) protect the plant from freezing
c.) protect the plant from soil microbes
d.) increase the surface area for absorption
e.) develop into lateral roots

d.) increase the surface area for absorption (root hairs are extensions of individual epidermal cells on the root surface, which increase the absorptive surface area of the root tremendously)

Secondary growth NEVER occurs in \_____.
a.) stems
b.) leaves
c.) roots and leaves
d.) roots
e.) stems and leaves

b.) leaves (secondary growth never occurs in leaves)

\_____ provides cells for secondary growth.
a.) apical meristem
b.) vascular cambium
c.) secondary phloem
d.) the root
e.) secondary xylem

b.) vascular cambium (vascular cambium is later meristem that provides cells for secondary growth)

Vascular cambium forms wood toward the stem's \_____ and secondary phloem towards the stem's \_____.
a.) surface...center
b.) top...bottom
c.) center...center
d.) center...surface
e.) surface...surface

d.) center...surface (wood, or secondary xylem, is formed toward the stem's center, and secondary phloem is formed toward the stem's surface)

What is the function of cork?
a.) providing cells for secondary growth
b.) providing a site for photosynthesis
c.) providing cells for primary growth
d.) regulating the opening and closing of stomata
e.) insulation and waterproofing

e.) insulation and waterproofing (cork insulates and waterproofs roots and stems)

How is the supply of vascular cambium maintained?
a.) by the differentiation of secondary xylem
b.) by the differentiation of cork
c.) by the differentiation of secondary phloem
d.) by the differentiation of apical meristem
e.) by the division of its cells

e.) by the division of its cells (when a vascular cambium cell divides, one cell differentiates and the other cell remains meristematic)

A water molecules consists of one oxygen atom joined to each of two hydrogen atoms by a(n) \_____, a type of bond in which the electrons do not spend equal time with the two atoms involved.

polar covalent bond (the chemical bonds between the oxygen and hydrogen atoms in a water molecules are polar covalent bonds)

Because \_____ is more electronegative than hydrogen, the electrons in a water molecules spend more time closer to \_____.

oxygen

The unequal distribution of electrons means that each of the three atoms in a water molecules has a \_____. This makes water a polar molecule.

partial charge (because of their polar covalent bonds, each of the three atoms in a water molecule has a partial charge, the oxygen has a partial negative charge, and each hydrogen has a partial positive charge, these partial charges make water a polar molecule)

The oxygen of a water molecule has a partial \_____ charge.

negative

Each hydrogen in a water molecules has a partial \_____ charge.

positive

A weak bond called a(n) \_____ forms as a result of the attraction between the slightly positive hydrogen of one water molecule and the slightly negative oxygen of a nearby water molecule.

hydrogen bond (a hydrogen bond binds the slightly positive hydrogen of one water molecule to the slightly negative oxygen of a nearby water molecules, hydrogen bonds are weak, only about 1/20 as strong as a covalent bond, so they form, break, and re-form with great frequency, however, at any instant, a substantial percentage of all water molecules are hydrogen-bonded to their neighbors)

Put these events in order:
1.) Water enters the xylem after it is absorbed by a plant's roots.
2.) Water evaporates from the cell walls of leaf mesophyll cells, increasing the surface tension of water in the leaves.
3.) Water vapor moves from leaf air spaces to the atmosphere through stomata.
4.) Water molecules pull on adjacent water molecules all the way down the xylem. They also adhere to the walls of xylem cells.

3, 2, 4, 1 (In the transpiration-cohesion-tension mechanism: transpiration describes the loss of water from the stomata of leaves, as water vapor is lost through transpiration, more water evaporates from the cell walls of leaf mesophyll cells, the evaporation of water from leaf mesophyll cells creates a surface tension that pulls water up the xylem, water molecules pull on adjacent water molecules all the way down the xylem, water molecules also adhere to the walls of xylem cells, which helps to counteract the force of gravity, water enters the xylem after it is absorbed by a plant's roots)

Hydrogen bonds are broken when water molecules \_____ from cell walls in leaves.

evaporate

\_____ helps pull water up the xylem. \_____ is the result of hydrogen bonds between water molecules at the surface of a layer of water.

surface tension in leaves

Water molecules pull on adjacent water molecules all the way down the xylem. This is possible because of the \_____, which is the result of hydrogen bonds between water molecules.

cohesion of water molecules to each other

\_____ (along with cohesion) helps to counteract the downward force of gravity. The \_____ to the walls of the xylem results from hydrogen bonds between water molecules and the cell walls of xylem cells.

adhesion of water molecules

Secondary xylem is produced from \_____.

vascular cambium

Water and ions can pass from cell to cell via these channels. Also, recall that \_____ are a type of cell junction.

plasmodesmata

Which of these are symbiotic associations?
a.) apoplasts
b.) root hairs
c.) mycorrhizae
d.) Casparian strips
e.) symplast

c.) mycorrhizae (mycorrhizae are mutualistic associations of roots and fungi)

Water and ions move through the root via the \_____ route if they are moving along a cell wall continuum.

apoplastic

In roots the \_____ forces water and solutes to pass through the plasma membranes of \_____ cells before entering the \_____.
a.) Casparian strip...endodermis...xylem
b.) Casparian strip...endodermis...phloem
c.) transpiration...endodermis...xylem
d.) xylem...endodermis...Casparian strip
e.) Casparian strip...ectoderm...xylem

a.) Casparian strip...endodermis...xylem (the Casparian strip is a waterproof barrier that forces water and solutes to pass through the plasma membranes of endodermis cells)

\_____ provide(s) the major force for the movement of water and solutes from roots to leaves.
a.) transpiration
b.) root pressure
c.) transfer cells
d.) translocation
e.) bulk flow

a.) transpiration (transpiration, the evaporation of water from leaves, exerts a pull that bears the primary responsibility for the movement of water and solutes from roots to leaves)

\_____ bonds are responsible for the cohesion of water molecules.
a.) ionic
b.) hydrogen
c.) peptide
d.) polar covalent
e.) nonpolar covalent

b.) hydrogen (hydrogen bonds among water molecules are responsible for the tendency of those molecules to stick together)

\_____ cells are the cells that regulate the opening and closing of stomata, thus playing a role in regulating transpiration.
a.) companion
b.) tracheid
c.) Casparian strip
d.) guard
e.) sieve-tube member

d.) guard (guard cells regulate the opening and closing of stomata)

The solute most abundant in phloem sap is \_____.
a.) minerals
b.) amino acids
c.) water
d.) hormones
e.) sugar

e.) sugar (phloem transports sugar from a sugar source to a sugar sink)

Which of the following is a correct statement about a difference between xylem and phloem transport?
a.) xylem sap moves from sugar source to sink, but phloem sap does not
b.) active transport moves xylem sap but not phloem sap
c.) transpiration moves phloem sap but not xylem sap
d.) phloem carries water and minerals; xylem carries organic molecules
e.) xylem sap moves up; phloem sap moves up or down

e.) xylem sap moves up; phloem sap moves up or down (the direction of movement in xylem is from roots to leaves, phloem sap is transported throughout the plant from source to sink)

Which tissue acts as a filter on the water absorbed by root hairs?
a.) epidermis
b.) vascular tissue
c.) endodermis
d.) cortex

c.) endodermis (endodermal cells filter solutes from water and allow them to pass through to the vascular tissue)

True of false? Root pressure can move water a long distance up the xylem because of the higher water potential of the xylem in comparison to the water potential in the surrounding cells.

false (root pressure can move water a short distance up the xylem because of the lower water potential of the xylem in comparison to the water potential in the surrounding cells)

Which of the following statements about the distribution of sap throughout a plant is true?
a.) the main component of phloem sap is glucose
b.) the mechanism that explains the movement of sugars throughout a plant is called the pressure-flow hypothesis
c.) the driving force for sugar movement is transpiration
d.) companion cells form the conducting tissue for sap

b.) the mechanism that explains the movement of sugars throughout a plant is called the pressure-flow hypothesis

Which term describes an area where sugars are used or stored?
a.) sink
b.) leaves
c.) source
d.) stomata

a.) sink (a sink is an area where sugars are used or stores, typically, these are the roots and fruits of a plant)

Which of the following statements about xylem transport is true?
a.) all water transported by the xylem is used for photosynthesis in the leaves
b.) the xylem cells that conduct water and minerals are alive
c.) water and minerals move through the root cortex into the xylem and upward through the stem and into leaves
d.) water and minerals enter the xylem by diffusion

c.) water and minerals move through the root cortex into the xylem and upward through the stem and into leaves (water and minerals that are taken up in the soil are transported from roots to leaves by the xylem)

What characterizes the rates of photosynthesis and transport in a plant on a dry cloudy day?
a.) the photosynthesis rate is high and phloem transport rates are low
b.) both the photosynthesis and transpiration rates are high
c.) the photosynthesis rate is low and stomata are open
d.) both the photosynthesis and transpiration rates are low

d.) both the photosynthesis and transpiration rates are low (on a cloudy day with low soil moisture, the photosynthesis rate is low and stomata are closed, so the transpiration rate is low)

True of false? The rate of sugar transport in a plant depends on the rate of photosynthesis, the rate of transpiration, and the differences in turgor pressure between the source and the sink.

false (while the rate of photosynthesis and the difference in turgor pressure between the source and the sink do influence the rate of sugar transport in the phloem, the rate of transpiration does not; transpiration mainly influences the rate of water transport through the xylem

Which of the following is not a type of primary meristematic cell found in apical meristems?
a.) ground meristem
b.) vascular cambium
c.) protoderm
d.) procambium

b.) vascular cambium (the vascular cambium is a type of cell found in lateral, not apical, meristems and is involved in secondary, not primary, growth)

Which structure determines the direction of root growth by sensing gravity?
a.) root hairs
b.) root cap
c.) mucigel
d.) pith

b.) root cap (the root cap is a layer of protective cells that determines the direction of root growth by sensing gravity)

True or false? Plant growth involves both the production of new cells by mitosis and the expansion of cell volume.

True

Which of the following statements about the vascular cambium is true?
a.) it is located between the primary xylem and cortex
b.) it is a type of apical meristem
c.) it develops into cork cells on the outside of the cortex
d.) it is a layer of undifferentiated cells that develops into secondary xylem and phloem

d.) it is a layer of undifferentiated cells that develops into secondary xylem and phloem (vascular cambium is a type of lateral meristem that produces secondary xylem and phloem in a plant)

Why do plants need secondary growth?
a.) to produce new leaves
b.) to grow taller
c.) to provide structural support for the plant
d.) to produce a more extensive root system

c.) to provide structural support for the plant (structural support in the form of widening stems and roots is achieved through secondary growth)

Which of the following parts of a plant remains on the plant even after several years of growth?
a.) cortex
b.) epidermis
c.) primary phloem
d.) primary xylem

d.) primary xylem (the primary xylem is located close to the pith of the plant and remains a part of the plant even after several years of growth)

True or false? Primary growth can occur at both the apical and lateral meristems at the tips of the roots and stems in a plant.

False (primary growth results in increased length and occurs only at the apical meristems at the tips of the roots and stems in a plant)

Select the accurate statement about water potential.
a.) free water moves from a region of lower water potential to a region of higher water potential
b.) adding solutes to water increases water potential
c.) water in a turgid cell has positive pressure potential

c.) water in a turgid cell has positive pressure potential (the pressure potential of a cell increases as water enters the cell and it becomes more turgid)

Why do fleshy fruits often have seeds with very tough seed coats?
a.) so the seeds can survive the mechanical forces and conditions in an animal's gut
b.) so the seeds can be dispersed by propulsion
c.) so the seeds can adhere to passing animals
d.) so the seeds can extend the distance they travel by catching breezes

a.) so the seeds can survive the mechanical forces and conditions in an animal's gut (animals are the most common dispersal agents for fleshy fruits, and seeds must survive the passage through an animal's digestive tract)

What characterizes the fruit of seeds that are dispersed by the wind?
a.) they are very fleshy
b.) they are large
c.) they have structures to extend the distance they travel on the wind
d.) they contain a large amount of sugar

c.) they have structures to extend the distance they travel on the wind (the fruits of seeds that are dispersed by the wind often have external structures that allow them to extend the distance they travel on the wind)

True or false? Fruits provide food to the developing plant.

False (fruits protect seeds and aid in their dispersal; the endosperm provides food to the developing plant)

Which part of a flower develops into the seed?
a.) endosperm cell
b.) pericarp
c.) ovule
d.) carpel

c.) ovule (once pollination has occurred, the fertilized ovule develops into the seed)

Which term describes the portion of a peach that can be eaten by humans?
a.) pericarp
b.) seed coat
c.) endosperm
d.) zygote

a.) pericarp (the edible portion of a peach is the pericarp, or fruit wall, which is a protective structure that encloses the seed and aids in its dispersal)

True or false? The endosperm tissue that nourishes the developing plant has the same nutritional characteristics regardless of the plant species.

False (the characteristics of the endosperm tissues vary by plant species; some tissues contain large amounts of starch, corn, while others contain large amounts of protein, beans)

Which part of a plant attracts pollinators?
a.) stamen
b.) petals
c.) sepal
d.) carpel

b.) petals (the petals of a plant serve to attract pollinators)

Which process involves the transfer of pollen grains from an anther to a stigma?
a.) pollination
b.) gametogenesis
c.) germination
d.) fertilization

a.) pollination

True or false? The endosperm in a seed develops into the embryo.

False (the endosperm in a seed is not the embryo, but the food supply for the embryo)

Which term describes the male gametophytes of flowering plants?
a.) microsporocytes
b.) pollen grains
c.) megaspores
d.) micropyle

b.) pollen grains (pollen grains are the male gametophytes of flowering plants; they contain a generative cell that develops into sperm)

Which structure formed by the male gametophyte allows sperm to reach the ovary of a flowering plant?
a.) micropyle
b.) stigma
c.) anther
d.) pollen tube

d.) pollen tube (the pollen tube is formed after a pollen grain is transferred to a receptive stigma and germinates, forming a tube that grows down through the style to the ovary of a flowering plant)

How is fertilization in flowering plants different from fertilization in other plant groups?
a.) two sperm nuclei fuse with a polar nuclei to form a diploid zygote
b.) one sperm nucleus fuses with the egg to form a diploid zygote, whereas the other sperm nucleus fuses with a polar nucleus to form a diploid cell that forms a nutrient-rich tissue
c.) one sperm nucleus fuses with the egg to form a diploid zygote
d.) one sperm nucleus fuses with the egg to form a diploid zygote, whereas the other sperm nucleus fuses with two polar nuclei to form a cell that develops into endosperm

d.) one sperm nucleus fuses with the egg to form a diploid zygote, whereas the other sperm nucleus fuses with two polar nuclei to form a cell that develops into endosperm (angiosperms are unusual in that one sperm nucleus fuses with the egg and one sperm nucleus fuses with two polar nuclei to form a triploid cell that develops into a nutrient-rich tissue that nourishes the growing embryo

Which of the following statements about seed formation in a flowering plant is true?
a.) the terminal cell formed from mitosis of the zygote divides to form a row of single cells that eventually forms the embryo
b.) the swellings that develop into cotyledons are located at the end of the embryo on top of the row of single cells
c.) the basal cell formed from mitosis of the zygote divides to form a globular mass that is the route for nutrient transfer to the developing embryo
d.) hypocotyls are the seed leaves of the embryonic plant

b.) the swellings that develop into cotyledons are located at the end of the embryo on top of the row of single cells (the swellings that develop into cotyledons do indeed grow on top of the row of single cells produced by the basal cell)

In angiosperms, each pollen grain produces two sperm. What do these sperm do?
a.) one fertilizes an egg, and the other fertilizes the fruit
b.) one fertilizes an egg, and the other combines with two polar nuclei, which develop into stored food cells (endosperm)
c.) both sperm fertilize a single egg cell
d.) each one fertilizes a separate egg cell
e.) one fertilizes an egg, and the other is kept in reserve

b.) one fertilizes an egg, and the other combines with two polar nuclei, which develop into stored food cells (endosperm) (fertilization of an egg produces a zygote, and the combination of the two polar nuclei produces a triploid cell that will develop into the endosperm)

Which of the following is an example of sexual reproduction?
a.) fragmentation
b.) cuttings
c.) stump sprouts
d.) apomixis
e.) fusion of sperm and egg nuclei in an ovule

e.) fusion of sperm and egg nuclei in an ovule

Which association below is correct?
a.) monoecious...bisexual flowers
b.) dioecious...separate female and male plants
c.) unisexual flowers...dioecious
d.) anther...egg production
e.) bisexual flowers...dioecious

b.) dioecious...separate female and male plants (the term "dioecious" means two houses, indicating that the males and females are on separate plants)

Which of the following is an advantage of asexual reproduction in plants?
a.) enhanced seed dispersal
b.) no need for a pollinator
c.) more robust offspring
d.) genetic variation
e.) enhanced survival of genetically favorable offspring

e.) enhanced survival of genetically favorable offspring (in constant environments, asexually produced offspring have higher survival rates)

Self-incompatibility \_____.
a.) does not have potential agricultural applications
b.) works the same way in all plants
c.) is based on the same mechanism of transplant rejection seen in animals
d.) is the rejection of a graft by a plant
e.) helps maintain genetic variability in a population

e.) helps maintain genetic variability in a population (by preventing self-pollination or pollination by closely related individuals, variability is maintained)

A graduate student finds an organism in a pond and thinks it is a freshwater sponge. A postdoctoral student thinks it looks more like an aquatic fungus. How can they decide whether it is an animal or a fungus?
a.) figure out whether it is autotrophic or heterotrophic
b.) see if it reproduces sexually
c.) determine whether it is unicellular or multicellular
d.) see if it is a eukaryote or prokaryote
e.) look for cell walls under a microscope

e.) look for cell walls under a microscope (fungal cells have cell walls, and animal cells do not)

An important trend in animal evolution was cephalization. An animal is said to show cephalization when it \_____.
a.) has bilateral symmetry
b.) is large
c.) has tissue specialization
d.) has an aggregation of sensory neurons at the anterior end
e.) has a hard, outer covering

d.) has an aggregation of sensory neurons at the anterior end (cephalization is an evolutionary trend toward the concentration of sensory equipment at the anterior end, it is associated with bilateral symmetry)

The animal phylum most like the protists that gave rise to the animal kingdom is \_____.
a.) echinodermata
b.) cnidaria
c.) ctenophora
d.) lycophyta
e.) porifera

e.) porifera (evidence that supports this includes the lack of true tissues in sponges and the close similarity between choanocytes and choanoflagellates)

Which of the following is a characteristic of cnidarians?
a.) bilateral symmetry
b.) an anus
c.) gastrovascular cavity
d.) mesoderm
e.) radula

c.) gastrovascular cavity (the gastrovascular cavity, characterized by a single opening, is the digestive compartment of cnidarians)

Which of the following is NOT a characteristic of all animals?
a.) they are all multicellular
b.) they are eukaryotes
c.) they have tissues, organs, and organ systems
d.) they are heterotrophic
e.) they ingest their food

c.) they have tissues, organs, and organ systems (sponges are considered animals, and they lack these levels of organization)

Which of the following statements about deuterostomes is false?
a.) all deuterostomes have a similar pattern of early embryonic development
b.) all deuterostomes exhibit radial symmetry in their bodies
c.) all deuterostomes are triploblastic and have three tissue layers
d.) all deuterostomes have a coelom

b.) all deuterostomes exhibit radial symmetry in their bodies (this statement is false, in the deuterostome lineage, only adult echinoderms exhibit radial symmetry)

Which structure is not an innovation that occurred during vertebrate diversification?
a.) amniotic egg
b.) bone
c.) jaws
d.) exoskeleton

d.) exoskeleton (exoskeletons are present in groups other than the vertebrates, including some in the protostome lineage)

True or false? An organism that is radially symmetric has many well-developed head regions.

false (an organism that is radially symmetric does not have a well-developed head region)

Which characteristic distinguishes echinoderms from the other two deuterostome lineages?
a.) their body plan
b.) the presence of an endoskeleton
c.) their ability to move
d.) their habitat

a.) their body plan (echinoderms exhibit a unique body plan characterized by an endoskeleton and a water vascular system)

Which of the following statements about vertebrates is true?
a.) the development of more efficient surfaces for gas exchange in reptiles stimulated expansion into terrestrial habitats
b.) birds are more related to mammals than to dinosaurs
c.) all vertebrates have jaws with which to catch their prey
d.) the development of an amniotic egg and internal fertilization allowed vertebrates to reproduce away from water

d.) the development of an amniotic egg and internal fertilization allowed vertebrates to reproduce away from water (reptiles and their descendants reproduce on land via an amniotic egg, which prevents the embryo from drying out)

Which characteristics define a chordate?
a.) the ability to live on land
b.) the presence of a well-developed circulatory system
c.) the development of an anus from the blastopore
d.) the presence of four specific morphological traits

d.) the presence of four specific morphological traits (chordates are defined by the presence of four morphological traits: a notochord, a dorsal nerve cord, pharyngeal gill slits, and a tail behind the anus)

Which structure can be used for feeding and gas exchange?
a.) notochord
b.) pharyngeal gill slit
c.) endoskeleton
d.) dorsal nerve cord

b.) pharyngeal gill slit (a pharyngeal gill slit is an opening into the throat that can be used for feeding and gas exchange)

Which of the following are most closely related to mammals?
a.) sharks, rays, and chimaeras
b.) ray-finned fishes
c.) tunicates
d.) reptiles
e.) amphibians

d.) reptiles

Which of the following are most closely related to reptiles and mammals?
a.) sharks, rays, and chimaeras
b.) amphibians
c.) lampreys
d.) ray-finned fishes
e.) lancelets

b.) amphibians

Which one of these chordate groups lacks a post-anal tail and a notochord as adults?
a.) lancelets
b.) tunicates
c.) amphibians
d.) mammals
e.) reptiles

b.) tunicates (while larval tunicates have a post-anal tail and a notochord, adult tunicates do not)

The common ancestor of all these chordate groups EXCEPT the \_____ probably had paired appendages.
a.) mammals
b.) amphibians
c.) lampreys
d.) ray-finned fishes
e.) reptiles

c.) lampreys (lampreys lack paired appendages)

Which of these is the only chordate group that has hair?
a.) tunicates
b.) ray-finned fishes
c.) mammals
d.) amphibians
e.) sharks, rays, and chimaeras

c.) mammals (hair is one of the defining characteristics of mammals)

Which vertebrate groups would you expect to have lungs or lung derivatives? Select all that apply.
a.) Myxini
b.) Petromyzontida
c.) Chondrichthyes
d.) Actinopterygii
e.) Actinistia
f.) Dipnoi
g.) Amphibia
h.) Reptilia
i.) Mammalia

d, e, f, g, h, i

In animal development, which of the following best describes the process of cleavage?
a.) meiosis
b.) fertilization
c.) differentiation
d.) mitosis

d.) mitosis (cleavage refers to the rapid cell division that takes place in animals after fertilization, cleavage partitions the egg cytoplasm without additional cell growth taking place)

What are the cells created by cleavage called?
a.) blastulas
b.) blastomeres
c.) blastopores
d.) blastocoels

b.) blastomeres (a blastomere is a cell created by cleavage division)

Which of the following are the three germ layers contained in the gastrula?
a.) ectotherm, mesoderm, endoderm
b.) ectoderm, mesoderm, epidermis
c.) ectoderm, mesoderm, endoderm
d.) ectoderm, mesoderm, echinoderm

c.) ectoderm, mesoderm, endoderm (these are the three basic embryonic cell layers of all vertebrate embryos)

Which of the following stages of development is defined by the three embryonic tissue layers (ectoderm, mesoderm, and endoderm)?
a.) blastula
b.) yolk
c.) zygote
d.) gastrula

d.) gastrula (gastrulation is the process that leads to the formation of the gastrula, which contains the three embryonic tissue layers)

What happens to a cell during the process of differentiation?
a.) it divides to produce a cell with one-half the number of original chromosomes
b.) it divides to produce a cell with the same number of chromosomes
c.) material moves across the cell membrane from a region of higher concentration to a region of lower concentration
d.) it undergoes a change toward a more specialized form or function

d.) it undergoes a change toward a more specialized form or function (during organogenesis, embryonic cells become progressively more specialized as they develop into their specific cell types, brain, muscle, etc.)

A child is born without a fully developed pancreas. He is normal in all other respects, and thus doctors believe that the problem most likely began early in development. During which of the following processes did the original error most likely occur?
a.) ectoderm formation
b.) mesoderm formation
c.) endoderm formation
d.) cleavage

c.) endoderm formation (the endoderm provides the cells that develop into the lining of the digestive and respiratory tracts, as well as the liver and pancreas, problems with its formation could result in an unformed pancreas)

True or false? Early animal development progresses through distinct stages: first the production of the zygote through fertilization, then cleavage, then the formation of the gastrula, and then the formation of the blastula.

false (the formation of a gastrula is the last stage in early animal development; the zygote undergoes cleavage to form a blastula, which eventually forms a gastrula)

In sea urchins, the process of fertilization produces a(n) \_____.
a.) archenteron
b.) morula
c.) gastrula
d.) gamete
e.) zygote

e.) zygote (fertilization, the combination of haploid sets of chromosomes, results in the formation of a diploid zygote)

What is the cortical reaction?
a.) the formation of a fertilization envelope that bars additional sperm from entry into the egg
b.) the release of hydrolytic enzymes from the sperm cell
c.) a depolarization of the eggs' plasma membrane so that only one sperm cell can fuse with it
d.) a series of rapid mitotic divisions that follow fertilization
e.) the process that form a three-layered embryo

a.) the formation of a fertilization envelope that bars additional sperm from entry into the egg

As cleavage continues, a zygote forms into a solid multicellular ball called a(n) \_____.
a.) endometrium
b.) morula
c.) trophoblast
d.) gastrula
e.) blastula

b.) morula (the morula is a solid ball of cells produced when the zygote undergoes cleavage)

Several hours after fertilization, cleavage results in the formation of a hollow ball of cells called a \_____.
a.) blastomere
b.) morula
c.) trophoblast
d.) gastrula
e.) blastula

e.) blastula (the blastula is a hollow ball of cells formed as the result of cleavage)

The three-layered embryo is the \_____.
a.) archenteron
b.) morula
c.) trophoblast
d.) gastrula
e.) blastula

d.) gastrula (the gastrula, formed when the blastula undergoes gastrulation, is a ball of cells that consists of the three primary germ layers)

The \_____ eventually develops into the sea urchin's digestive tract.
a.) blastocoel
b.) archenteron
c.) blastomere
d.) ectoderm
e.) blastopore

b.) archenteron (the archenteron is formed as a result of gastrulation)

During gastrulation, invagination occurs at the \_____.
a.) archenteron
b.) blastocoel
c.) endometrium
d.) blastopore
e.) trophoblast

d.) blastopore (during gastrulation, invagination occurs at the blastopore, which develops into the sea urchin's anus)

In vertebrates, the ectoderm gives rise to the \_____.
a.) skeleton
b.) circulatory system
c.) outer layer of skin
d.) lining of the digestive tract
e.) pancreas

c.) outer layer of skin (the ectoderm gives rise to the outer layer of skin and the nervous system)

During gastrulation in frogs, a rod of mesoderm under the dorsal surface forms the \_____.
a.) notochord
b.) ectoderm
c.) endoderm
d.) archenteron
e.) blastopore

a.) notochord (this rod of mesoderm forms the notochord, a physically supportive structure)

During gastrulation in frogs, cells from the animals pole spread over the embryo and form the \_____.
a.) endoderm
b.) ectoderm
c.) archenteron
d.) blastopore
e.) blastula

b.) ectoderm (cells from the animal pole form the ectoderm)

The notochord functions as a core around which mesodermal cells form the frog's \_____.
a.) backbone
b.) blastopore
c.) endometrium
d.) nervous system
e.) archenteron

a.) backbone

An ectodermal thickening above the frog's notochord forms a \_____.
a.) pancreas
b.) neural plate
c.) skeleton
d.) liver
e.) lining of the stomach

b.) neural plate

The \_____ is(are) formed when the neural folds join and a portion of the neural plate sinks beneath the embryo's surface.
a.) archenteron
b.) anus
c.) back muscles
d.) neural tube
e.) digestive system

d.) neural tube

The enlarged anterior portion of the neural tube will develop into a frog's \_____.
a.) spinal cord
b.) tongue
c.) reproductive system
d.) outer layer of skin
e.) brain

e.) brain

The posterior portion of the neural tube will develop into the frog's \_____.
a.) spinal cord
b.) brain
c.) blastocoel
d.) digestive tract
e.) anus

a.) spinal cord