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Biol 102 lab and lec > Lab 4: Dissection > Flashcards

Lab 4: Dissection Flashcards

1
Q

Why study worms/invertebrates?

A

Worms were the first group an animals to acquire a complete digestive tract and display sexual dimorphism

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2
Q
A
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3
Q

Define bilateral symmetry

A

body in which internal and external features are divided by a central longitudinal plane that are mirror images of each other

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4
Q

Describe characteristics of bilaterally symmetric animals

A

motile (move in direction of their heads)
bodies are streamlined

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5
Q

The back of an animal is referred to as the

A

dorsal surface

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6
Q

The belly of the animal is defined as the

A

ventral surface

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7
Q

Structures close to the midline are said to be ___

A

medial

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8
Q

Structures close the midline are known as

A

medial

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9
Q

Structures closer to the body are

A

proximity

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10
Q

Structures close to the sides are termed

A

lateral

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11
Q

Structures farther from the center of the body are

A

distal

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12
Q

A cut made through an organism is called a

A

section

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13
Q

Define sagittal and a mid-sagittal section

A

a longitudinal plane that divides the body of a bilaterally symmetric organism in to right and left sections
mid-sagittal section is cut down the midline and divides the animal into right and left halves

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14
Q

Define a frontal section

A

plane parallel to the long axis of the body. Perpendicular to sagittal plane and separates body into dorsal and ventral portions

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15
Q

Define transverse section

A

plan perpendicular to the long axis of the body. A cut through the body along this plane is commonly referred to as “cross section”
divides organism into posterior and anterior

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16
Q

Define radial symmetry

A

body that lacks a discernable sideness, often shaped like a pie or barrel. It is divided into two equal halves by any plane through its central axis

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17
Q

Describe some characteristics of radially symmetric animals

A

Their sensory organs are not concentrated in one particular region.
Tend to be either immobile or slow moving. Motile individuals move equally well in all directions

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18
Q

Where is the mouth of a radially symmetric animal located?

A

Located at or near the center of one surface, can be at the top or bottom

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19
Q

True or False: The terms dorsal and ventral are used for both radially and bilaterally symmetric animals

A

False, only for bilateral

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20
Q

The surface of a radially symmetric organism that contains the mouth is called the ___ while the opposite surface is called ___

A

oral
aboral

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21
Q

The axis of symmetry in radially symmetric organisms is the

A

imaginary line that connects the center of the oral and aboral surfaces

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22
Q

A plane that runs parallel and through the axis of symmetry in radially symmetric organisms is considered the plane of symmetry if___

A

it divides the body into two equal mirror image halves

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23
Q

Structures located close to the oral/aboral axis are said to be ___ while those farthest away are termed ___

A

central
peripheral

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24
Q

TorF: radially symmetric organisms have only one plane of symmetry

A

false, can have multiple that are often displayed in fives

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25
Q

Free swimming larval sea star demonstrate ____ symmetry. Adult sea star demonstrate ___ symmetry.

A

bilateral
radial

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26
Q

The direction of caudal is___ and opposite ___

A

toward or regarding the tail
cephalic

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27
Q

The direction of deep is ___ and opposite ___

A

toward the center
superficial (toward exterior)

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28
Q

Pectoral is in the direction __ and opposite ___

A

regarding the shoulders
pelvic regarding the hips

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29
Q

A tissue is

A

an integrated collection of cells that functions as a unit with a common purpose

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30
Q

A zygote divides mitotically in a process known as

A

cleavage

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31
Q

True or False: during cleavage, each mitotic division doubles the number of cells without an appreciable increase in the volume of the sphere due to lack of cell growth between division

A

true

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32
Q

A blastula is

A

a hollow ball of cells made after cleavage

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33
Q

Gastrulation can best be defined as

A

cells in the blastula move inward, a hollow tube is formed within the blastoceol with a single opening in the exterior

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34
Q

During gastrulation, the gastrula contains a single layer of kin tissue on the exterior ____ and a single layer if interior dermal tissue __. This will ultimately give rise to the __

A

ectoderm
endoderm
the digestive tract

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35
Q

Dipoblastic animals can be defined as

A

animals that have two germ (ectoderm and endoderm) layers
mouth/anus

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36
Q

Triploblastic animals can best be defined as

A

bilaterally symmetric animals that contain a third germ layer, the mesoderm (between ecto and endo)

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37
Q

In protostomes, the blastophere develops into the ___. In deuterostomes, the blastopore develops into the __

A

mouth of the organism protostomes
Blastopores develops into the anus and second opening into the mouth

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38
Q

True or False: Cnidaria are dipoblastic, bilaterally symmetric animals

A

False: They are dipoblastic, but they are radially symmetric

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39
Q

All Cnidaria possess _____, specialized cells which they use to immobilize their prey for protection

A

cnidocytes

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40
Q

The gastrovascular cavity in Hydra is __ cell layers thick and was developed by ___

A

two
the migration of cells into the blastocoel during gastrulation

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41
Q

The cells in the epidermis contain contractile ___ fibers, which enable the animal to contract into a ____. These cells are enidocytes that contain _____

A

contractile muscle fibers contract into a ball
contain nematocysts

42
Q

Nematocytes are

A

enidocytes on epidermal layer of hydra that discharge stinging barbed projectiles

43
Q

Nematocysts can be distinguished from cell nuclei with

A

their-dark staining nucleoli and appear as translucent vacuole-like spheres

44
Q

The epidermis of the Hydra’s basal disc is composed of ___ which anchors the animal to the substrate

A

a single layer of columnar epithelial cells

45
Q

The inner layer of Hydra cells is called _____. They are thicker than epidermal cells of the main column. They also contain ____ which secrete digestive enzymes into the body cavity

A

gastrodermis
epitheliomuscular cells

46
Q

How are hydra able to move?

A

Extend their bodies by contracting circular muscle fibers or retract their bodies by contracting longitudinal fibers

47
Q

As predators, Hydras hunt by

A

bending sideways and grabbing onto an adjacent structure with their tentacles

48
Q

Hydra capture ___ by using their outstretched tentacles.

A

plankton/Daphnia

49
Q

How do hydra acquire plankton?

A

prey cause the nematocyst to fire. A finger-like barbed projection penetrates and anchors the prey, a hollow thread delivers venomous chemicals.
Once the prey is immobilized, it is pulled to the mouth
The mouth then seals off the gastrovascular cavity. dissolved nutrients are circulated through the digestive cavity by water currents generated by cilia
Nutritive cells absorb the nutrients to meet the metabolic needs of the organism

50
Q

TorF: Hydras lack a true excretory system

A

True

51
Q

The main waste of Hydra’s excretory system is

A

ammonia

52
Q

Note the difference between excretion and defection in hydra

A

excretion: dissolved waste diffuse from the cell layers into the surrounding water and are carried away by the water current
defecation: feces are expelled through the same aperture as they were acquired (the mouth)

53
Q

How is oxygen and CO2 exchanged between layers in Hydra?

A

Diffusion

53
Q

Describe the Hydra nervous system

A

neurons innervate both tissue layers, neurons are interlaced through mesoglea

54
Q

Describe asexual reproduction in Hydra

A

Grow and regenerate through mitotic differentiation of interstitial/stem cells

55
Q

Describe sexual reproduction in hydra

A

Hydra are hermaphroditic
The sperm are released into a pore in a mound into the surrounding water

56
Q

Earthworms are part of the phylum..

A

annelida

57
Q

Annelida are phylum who

A

all possess a cylindrical body divided into segments

58
Q

why are annelida evolutionarily significant

A

a. one of the simplest groups to possess a true coelomic cavity with related organs grouped into definite regions (digestive, circulatory)
b. lays the groundwork for a more highly organized type of animal

59
Q

Septa in annelida are composed of

A

connective tissue sandwiched between esothelium

60
Q

The worm is divided into distinct anterior and posterior regions by the

A

clitellum

61
Q

The U shaped region in the earthworm gut is the___ the interior is referred to as

A

typhlosole
the intestinal lumen

62
Q

Earthworm move by

A

alternating serial contractions of the circular and longitudinal muscles in their body wall

63
Q

Earthworms are detritovores, which are…

A

heterotrophs that feed by consuming decomposing organic matter found in the soil

64
Q

The earthworm gizzard is

A

a chamber whose thick, muscular walls mechanically grind up the contents into small particles, increasing the surface area of the mixture

65
Q

Earthworms possess a __ circulatory system, where blood travels exclusively through well-defined vessels

A

closed

66
Q

There are two major earthworm longitudinal blood vessels, the

A

dorsal and ventral

67
Q

Surrounding the esophagus of the earthworm are the five pairs of ____

A

pseudo-hearts

68
Q

Describe the process of respiration for earthworms

A

blood vessels supplying the epidermis brings carbon dioxide where it diffuses across the moist layer. This requires a moist layer. Earthworms have no specialized tissue for gas exchange

69
Q

When the soil becomes too dry to maintain normal activity, worms can enter a dormant state known as

A

estivation

70
Q

Unlike a hydra whose nerve net is generalized, worms are among the first animals to

A

demonstrate cephalization, a concentration of sensory and neural structures toward the head of the organism

71
Q

The earthworm is a hermaphroditic, however it still requires

A

two individuals to create offspring since self fertilization is an anatomical impossibility

72
Q

The members of the echinodermata phylum are divided into six classes

A

asteroida, echinoidea, holothuroidea, crinodes, crinoided, ophiureda, and concentricycloidea

73
Q

The most striking feature of echinoderms is their

A

radial symmetry shown in the adult form of the organism, but bilateral symmetry in the larva

74
Q

The six characteristics of echinoderms include

A
  1. cylindrical, round, unsegmented, or star shaped bod with five or more radial divisions
  2. an endoskeleton of calcareous plates
  3. a unique water-vascular system
  4. a lack of cephalization
  5. an absence of excretory organs
  6. respiration through dermal branchiae
75
Q

Describe sea star locomotion

A

Internal skeletons serve as framework to anchor bundles of muscle and connective fibers
fluid filled compartments act as a hydrostatic skeleton, allowing muscle contractions

76
Q

Do sea stars have excretory structures?

A

no, nitrogeneous wastes diffuse across epidermal layers in the form of ammonia

77
Q

TorF: sea stars lack a circulatory system with defined vessels and a pumping organ. Fluids move through the coleomic cavities by the actions of ciliated epithelia along defined pathways

A

true

78
Q

Describe sea star respiration

A

dissolved gases are circulated by ciliary actions of the peritoneal linings

79
Q

Describe sea stars nervous system

A

lack a brain and no cephalization
with no head or anterior structures, they easily move laterally in any direction

80
Q

Describe asterias reproduction

A

separate male and female individuals, they are impossible to tell apart externally
gametes meet in a water column and divide mitotically

81
Q

The sea star spines are extensions of the ___, which underlies the ____

A

endoskeleton
epidermis

82
Q

The madreporite of the sea star is…. it can be found at

A

the small circular opening of the water vascular system
found at the periphery of the central disc, junction of arms 1 and 2

83
Q

Asterias pedicellariae are

A

specialized ossicles that form jaw-like pincers covered by a thin epidermal layer

83
Q

Describe the sea star digestive tract

A

short, complete
mouth opens to an indistinguishable esophagus, which connects to cardiac stomach chamber
Cardiac stomach attacks to a smaller pyloric stomach
pyloric connects to short intestine, and then anus

84
Q

Sea stars are able to evert the cardiac chamber of their stomach, meaning

A

they can force their stomach out through their mouth, into or around their food

85
Q

Nitrogeneous wastes generated from asterias digestive process are released into

A

the coeolomic fluid

86
Q

Although starfish have little solid waste, it is eliminated by

A

being carried from the pyloric stomach to the anus by the intestine

87
Q

When asterias meal is done, the stomach is retracted into the

A

coelomic cavity

88
Q

TorF: Asterias have no true excretory structures

A

true

89
Q

How does waste leave asterias?

A

leave water vascular system through the tube feet and coelom via dermal branchiae

90
Q

Asterias coelomocytes can

A

capture wastes released in the cavity and accumulate to the tips of the dermal branchiae, then the waste is ejected by exocytosis

91
Q

Describe sea star circulatory system

A

lack defined vessels and heart
fluids move through coelomic cavities by ciliated epithelia

92
Q

Describe sea star respiration

A

dissolved gases are circulated by ciliary actions of the peritoneal linings.
Gas exchanged between perivisceral coelom and exterior at the dermal branchiae

93
Q

Describe sea star nervous system

A

lack cephalization and brain
generalized nerve net that lies within epithelia and extends into the body wall, connects with many different types of sensory cells.
Chemo and mechanoreceptors distributed through epidermis
eyes consist of photoreceptors

94
Q

Unlike hydra, sea star nerve plexus is

A

interconnected to circumoral nerve ring from which five radial nerves extend, innervating the arms.

95
Q

TorF: asrterias is dioecious

A

true

96
Q

TorF: it is possible to distinguish male from female asterias post dissection

A

false, gonads are difficult to locate and absent in juveniles
additionally, they spawn seasonally

97
Q

Describe sea star reproduction

A

when ripe, testes or ovaries fill oral portion of each arm on either side of the amulacral bridge
external, release of gametes in one group triggers release of gametes in the other. clouds of sperm randomly fertilize in suspended water column

98
Q

Asterias zygotes divide via

A

mitosis

99
Q

because asterias blastopore gives rise to the anus in the developing gastrula, it is classified as

A

a deuterostome

Biol 102 lab and lec (17 decks)

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