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Biology 101 > origin and diversity of life (PP20) > Flashcards

origin and diversity of life (PP20) Flashcards

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1
Q

The first part on life was hetero or auto trophic and what does that mean?

A

The first life on earth was probably heterotrophic

i.e. Used organic carbon for energy

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2
Q

Why is it unlikely that autotrophs were the first organisms

A

Because Photosynthesis is complicated & requires fairly complex machinery
So autotrophs were probably not the first thing to come about
and Breaking down external sources is a much easier of gaining energy
e.g. Biomolecules from chance electrical events (such as in the Miller and Urey experiment)

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3
Q

Did earliest types of photosynthesis produce oxygen?

If no, did it eventually aCCUMULATE?

A

no

yes. Oxygen began to accumulate in the atmosphere to a significant degree ~2.7 billion years ago

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4
Q

One benefit of early oxygen.

One disadvantage of early oxygen

A

-Offered up new opportunities & provided selective pressure (eukaryotes may have had an advantage)

–Oxygen posed a challenge for life (toxic to obligate anaerobes)

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5
Q

explain theory of endosymbiosis

A

Theory: mitochondria & plastids were formerly small prokaryotes living in larger host cells

Chloroplasts resemble cyanobacteria (photosynthetic bacteria)

Prokaryotic ancestors probably entered host cell as undigested prey or internal parasites

Became more interdependent; host & endosymbionts became a single organism

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6
Q

were first eukaryotes multicellular or unicellular

A

unicellular

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7
Q

explain what it means when we say “First multicellular organisms were colonies”

A

it means they were Collections of autonomously replicating cells

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8
Q

What did the specializing of cells for different functions lead to?

A

Specialization enabled emergence of more complex multicellular organisms
e.g. Animals

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9
Q

what 4 common features does every animal have

A

1) Multicellularity
2) Heterotrophy
3) Lack of rigid cell walls
4) Motility throughout at least some portion of their life

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10
Q

What are the 3 general features of morphology/development can animals be characterized by

A

-Body symmetry (or lack thereof)
Asymmetry vs. Radial Symmetry vs. Bilateral Symmetry

-Tissue organization
Acoelomate vs. Pseudocoelom vs. Coelom

-Developmental strategies
Protostomes vs. Deuterostomes

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11
Q

what are the 3 types of symmetry and give an example of an organism that has that.

A 
Bilateral symmetry (1 plain of symmetry)
ex:beetle
Radial symmetry (multiple plains of symmetry)
ex:starfish

Asymmetry (no symmetry)
ex: sponge

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12
Q

explain bilateral symmtetry

A

Bilateral animals have a left side & right side: only 1 imaginary cut divides the animal into mirror-image halves
Anterior (head), posterior (rear), dorsal (back), ventral (‘stomach’)
e.g. Lobster (phylum Arthropoda

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13
Q

explain radial symmetry

A

Parts of a radial animal radiate from the center: any imaginary slice through the central axis divides the animal into mirror images
e.g. Sea anemone (phylum Cnidaria)

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14
Q

what are tissues

A

Tissues = collections of specialized cells isolated from other tissues by membranous layers

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15
Q

What are the 3 germ layers(embryonic tissues)

A

ectoderm, endoderm, & mesoderm

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16
Q

diploblasts have two many germ layers? and which tissues does it entail

A

2

Ecto and Endo derm

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17
Q

explain triploblasts

A

all 3 germ layers present

Body cavity may or may not be present

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18
Q

explain endoderm

A

after several cell divisions, cells differentiate into endoderm (inner layer)
Endoderm gives rise to digestive tract

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19
Q

explain ectoderm

A

ectoderm (outer layer),

Ectoderm gives rise to skin & neural system

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20
Q

explain mesoderm

A

mesoderm (intermediate layer)

Mesoderm gives rise to muscles & skeleton

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21
Q

DIAGRAM OF CROSS SECTION FOR DIPLE AND TRIPLO AND COELEM

A

DIAGRAM IN NOTES

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22
Q

What are the 2 tissue organization and explain them

A

Pseudocoelom: body cavity derived from the blastocoel (only partially lined by mesoderm)

Coelom: body cavity derived from the mesoderm

DIAGRAM IN NOTES

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23
Q

WHAT IS a blastopore

A

Blastopore: opening of the central cavity in early embryo

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24
Q

if your blastopore becomes a mouth you are…

A

Protostome:

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25
Q

if your blastopore becomes the anus you are…

A

Deuterostome:

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26
Q

MEMORIZE TABLE OR PROTO VS DEUTERO

A

IN NOTES

27
Q

explain segmentation and its importance

A

Allows for differentiation of different tissues

Important for locomotion, reproductive structures, nervous system
includes Metameres
Genes repeated for each segment: probably more economical & less error prone than 1 giant set of genes for whole body.
Evolved separately in different phyla

28
Q

what is a metemere

A

Metameres = repeating units which forms the animals body

29
Q

explain cephalization

A

Formation of an area with large concentration of nervous tissue
In some animals, this appears as a brain
Certain animals have cephalization without a specific brain area

30
Q

CHECK NOTES FOR PHYLOGENETIC TREES

A

NOTES

31
Q

what does the Sub-Kingdom Parazoa include

A

Includes phylum Porifera (i.e. sponges)

32
Q

explain phylum porifera

A

Most “primitive” animals (i.e. fewest derived characteristics)

  • No symmetry
  • Limited cell specialization
  • Do not have distinct organs
  • Do not have nervous or muscular tissue

Sessile (don’t get out much)
Suspension feeders
Hermaphroditic

33
Q

what does the Sub-Kingdom Eumetazoa include?

A

everything that is not a sponge

34
Q

explain phylum cnidaria

A
  • Both sessile & motile forms
  • Diploblastic
  • Radial symmetry
  • No cephalization (since radial)
  • No segmentation
  • Carnivorous: tentacles armed with cnidocytes – cells with harpoon threads (nematocysts)
35
Q

what are cnidocytes

A

cells with harpoon threads (nematocysts)

36
Q

creatures with radial symmetry are part of what clade?

A

clade radiata

37
Q

What is the body plan of cnidarians

A

Body plan = sac with central digestive compartment (gastrovascular cavity)
Single opening functions as both mouth and anus

38
Q

what are the 4 classes of cnidarians and examples

A

Hydrozoa (man of war, hydras),
Scyphozoa (jellies, sea nettles)
, Cubozoa (box jellies, sea wasps),
Anthozoa (sea anemones, corals).

39
Q

know the difference because poly/hydra and medusa

A

PICS ON SLIDES

40
Q

if you have bilateral symmetry you are part of which clade?

A

clade Bilateria

41
Q

Explain phylum Platyhelminthes

A

-Triploblastic
-Acoelomate
No circulatory system
Digestive cavity = single area that uses same opening as mouth & anus

Bilateral symmetry
-Left/right, anterior/posterior, dorsal/vemtral

Cephalization
-Anterior ganglia (simple brain)

-No segmentation
Includes flatworms, flukes, tape worms

42
Q

explain phylum nematoda

A
  • Triploblastic
  • Pseudocoelomate

-Crude circulatory system
Digestive cavity has 2 ends (anterior & posterior)

  • Bilateral symmetry
  • Cephalization

No segmentation
Includes roundworms

43
Q

explain phylum mollusca

A
  • Triploblastic
  • Coelomate
  • Tissue-covered body cavity

-Bilateral symmetry
Varying levels of nervous tissue development
Some are highly cephalized (octopi, squid, cuttlefish) with large brains & complex sensory machinery (lensed eyes)

-No segmentation
-Not considered to have proper appendages (like arms or legs)
Have muscular regions that can help with movement
Includes snails, slugs, oysters, clams, squids, octopi

44
Q

explain phylum annelida

A

Triploblastic
Coelomate
Tissue-covered body cavity

Bilateral symmetry
Cephalization

-Segmented
Repeated regions of the body structure (similar internal components)
Allows for localized specialization of different tissues

Non-jointed appendages
Small legs (cetae) help with the movement
Includes earthworms, sandworms, leeches
45
Q

explain phylum anthropda

A

triploblastic
-Coelomate
Open circulatory system

Bilateral symmetry
-Cephalization
More complex sensory apparatuses (compound eyes, olfaction)

-Segmented
Localized specialization of different tissues

Jointed appendages
Specialized for eating, capturing prey, walking, swimming
Exoskeleton derived from cuticle
Includes insects, crustaceans, spiders, scorpions, centipedes

46
Q

explain phylum echinodermata

A 
Triploblastic
Coelomate
-Bilateral + radial symmetry
(Larvae are bilatera)l
Adults show pentaradial symmetry

No cephalization
No segmentation
Deuterostome
(Blastopore develops into the anus)

Many are sessile as adults
Differ from cnidarians by having a fully closed internal cavity, digestive system, nervous tissue.
Includes sea stars, sea cucumbers

47
Q

explain phylum chordata

A 
Triploblastic
Coelomate
Bilateral 
Cephalization
(Highly cephalized)

Segmented
Localized specialization of different tissues
Deuterostome
A bunch of novel characteristics: e.g. Notochord
Includes some invertebrates & all vertebrates

48
Q

which phylums are part of clade radiata?

A

phylum cnidaria

49
Q

which phylums are part of clade bilateria

A
  • platyhelimnthes
  • annelida
  • nematoda
  • mollusca
  • anthropoda
  • echinodermata
  • chordata
50
Q

which phylums are part of prostostomia

A
  • platyhelimnthes
  • annelida
  • nematoda
  • mollusca
  • anthropoda
51
Q

which phylums are part of deuterostomia.

A
  • chordata

- echinodermata

52
Q

what are the 4 traits that all chordates display at some point in their lives

A
  • Presence of a flexible notochord
  • Presence of a hollow dorsal nerve cord
  • Presence of pharyngeal slits
  • Presence of a muscular post-anal tail
53
Q

Do all chordates show all traits during their whole life?

A

no
All chordates share this set of 4 derived characters, ALTHOUGH some species possess some of these traits only during embryonic development

54
Q

explain the notochord and its function

A
  • Flexible longitudinal rod located between the digestive tube & nerve cord
  • Provides structural support

In most vertebrates, a more complex, jointed skeleton develops → adult retains only remnant of embryonic notochord

55
Q

explain the dorsal hollow nerve chord

A

Also called a “spinal cord”
Develops from a plate of ectoderm that rolls into a tube dorsal to the notochord
Develops into the central nervous system (CNS = brain & spinal cord)

56
Q

explain pharyngeal slits

A
  • Allow for movement of gases in aquatic environments & filter-feeding
  • Grooves in the pharynx develop into slits that open to the outside of the body
  • Develop into parts of the ear, head, & neck in terrestrial vertebrates
57
Q

explain post anal tail and its function

A
  • Tail extending posterior to the anus
  • In many species (e.g. humans) it is lost during embryonic development
  • Used for movement / balance
  • Provides much of the propelling force in many aquatic species
  • Contains skeletal elements & muscles
58
Q

do all chordates keep their post anal tail?

A

In many species (e.g. humans) it is lost during embryonic development

59
Q

what is a craniate?

A

chordates with heads

60
Q

what did development of a head lead to for chordates

A

Development of a head opened up a new way of feeding for chordates: active predation

61
Q

what common characteristics do craniates share?

A

Craniates share some common characteristics:

skull, brain, eyes, & other sensory organs

62
Q

what is a neural crest and where is it found

A

collection of cells that appears near the dorsal margins of the closing neural tube in an embryo
found in choradates

63
Q

what do neural crest cells lead to ?

A

These cells give rise to a variety of structures: e.g. some of the bones & cartilage of the skull

Biology 101 (15 decks)

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