Topic 12-13:Animals

Question 1

animals cell structure and specialization (its unique features)

Answer 1

animals are multicellular eukaryotes
-they lack a cell wall (unlike plants and fungi)
-their bodies are held together by an extracellular matrix called collagen (a protein molecule)
-nervous tissue and muscle tissue are unique, defining characteristic of animals (it gives them the ability to move)

Question 2

tissues

Answer 2

are a group of cells that have a common structure, function or both
-true tissue is separated by a membranous layer

Question 3

animals way of obtaining nutrients

Answer 3

they are chemoeteroptohic : they can’t make own carbon-based food sources, they consumer other organism

Question 4

Hox genes

Answer 4

they control anterior(front, or closest to head) to posterior(back side) developmental sequenced of embryo (pattern formation during development)
-the order of Hox genes along chromosomes similar among different groups of animals
-but the number of repetitions can differ

Question 5

Homeobox genes and Hox genes-gene regulation

Answer 5

Homeobox genes are a group of genes that encode for transcription factors that regulate the anatomical( cells, tissue and organs )development of organisms- they Regulate morphogenesis
Hox genes are a subset of homeobox genes that specifically, regulate the development of body axes and structures during embryonic development, their function is to Regulate body segmentation and development of appendages(legs, arm, the parts that are attached to the main body)

Question 6

reproduction and embryonic development

Answer 6

-most animals share a similar pattern of early embryonic development
-have haploid games of different sizes (small motile sperm and large non-motile egg)
-the diploid zygote undergoes a number of mitotic cell divisions (cleavage)
-the cleavage leads to the formation of a multicellular, callow blastula
-the blastula undergoes gastrulation, forming a gastrula with different layers of embryonic tissue

Question 7

embryonic development: first invagination and seconde (the action or process of being turned itself to folded back on itself)

Answer 7

protostomia: first invagination gastrula (blastopore ) becomes the mouth
deuterostomes: the second invagination becomes the mouth (first opening becomes the anus, or closes up )

Question 8

animal devloepment is…

Answer 8

directional devleopment )embyro contiues gradually on twowards adult form

Question 9

germ layers

Answer 9

endo -digestive tract (gut)
ecto -> outer covering (skin, nerves)
meso->muscle and other organs

Question 10

difference between diploblastic and triploblastic

Answer 10

diploblastic endo and ectoderm
triploblastic -endo, ecto and mesoderm

Question 11

body plans : the two symmetries

Answer 11

-radial symmetry is: no front or back or left or right (they are often sessile (fixed in one place ) or platonic (floats or weak swimmer )
-bilateral symmetry : tow sided symmetry (often move actively and have a central nervous system )

Question 12

bilateral symmetric animals have…

Answer 12

-a right and left side
- a dorsal (top ) side and a ventral (bottom side )
-an anterior (head) and posterior (tail ) ends

Question 13

cephalization is

Answer 13

the development of a head

Question 14

association between body symmetry and the nervous system

Answer 14

-radical symmetry =nerve network
-bilateral symmetry=central nervous system

Question 15

bilateral symmetry and cephalization

Answer 15

-concentration of sensory organs in the head (brain)
-adapted for forward and directional movement
-quicker reasons to stimuli in the environment
-better able to search for food
-better defense capabilities

Question 16

coelom

Answer 16

most triploblastic animals possess a fluid-filled body cavity, it’s deprived of mesoderm
-it cushions internal organs from blow to outside body
-allow internal organs to shift within deforming outside of body
-fluid filled cavity can be used as a hydrostatic skeleton

Question 17

pseudocoelomate

Answer 17

animals lack complete mesodermal lining

Question 18

the key shared derived characteristics of animals

Answer 18

-multicellularity -collagen
-Diploblastic Hox genes Tissues
-Bilateral symmetry
-Triploblastic
-Cephalization

Question 19

the common ancestor of animals is a ….

Answer 19

heterotrophic protist

Question 20

animals common ancestor resembles what…

Answer 20

Choanoflagellates
-which are heterotrophic protists
-single flagellum surrounded by collar of microvilli (fingerlike
projections of cell membrane)
-cell morphology very similar to that of sponges (Porifera)

Question 21

Evolution of Multicellularity

Answer 21

ball-shaped colony of choanoflagellates may
have evolved into a simple animals with endo- and ectodermal
layers
If cooperative aggregations of cells are able to survive better and produce
more offspring than their unicellular counterparts (higher relative
fitness), then these various evolutionary pathways could all be possible.

Question 22

the advantage of muticcllularity

Answer 22

-coordination among cells
-specialized cells for different functions
– protective skin
– enzyme secretion for trapping food
– coordinated movement
(or movement of water across food traps)
– specialized cells for reproduction

Question 23

Palaeozoic Era

Answer 23

Cambrian explosion : marks
the earliest fossil appearance
of many major groups of living
animals
* Suddenly complex life -
including many forms with
skeletons
* Most major phyla appeared

Question 24

why is animal diversification so late

Answer 24

• [O2] in oceans and
  atmosphere was low
  until Cambrian
  -need O2 to support the metabolism of large, active animals

Question 25

What caused such a rapid increase in diversity
during the Cambrian Period?

Answer 25

• Intrinsic causes:
  – Rapid change in genes regulating
• Body plan organization
• Exoskeletons/locomotion  “predator-prey arms race”
  – Genetic causes
• evolution of Hox gene complex
  – provided developmental flexibility
• Extrinsic causes:
  -Higher oxygen levels
  May have enabled the evolution of big, mobile animals due
  to the efficiency of aerobic respiration
  -New niches beget more new niches
  Animal diversification in and of itself created new niches

Question 26

Mesozoic Era(251–65.5 mya)

Answer 26

Dinosaurs were the dominant
terrestrial vertebrates
* The first mammals emerged
* Flowering plants and insects
diversified

Question 27

Cenozoic Era (65.5 mya - present)

Answer 27

• The beginning of the era
  followed by mass extinctions of
  both terrestrial and marine
  animals
• Extinctions included the large,
  nonflying dinosaurs and the
  marine reptiles
• Mammals increased in size and
  exploited vacated ecological
  niches
• The global climate cooled

Question 28

Phylum Porifera

Answer 28

sponges
-they lack hox genes
-they are sessile
No symmetry

Question 29

spicules

Answer 29

-tiny, hard needles or rods
– calcium carbonate or silica

Question 30

choanocytes

Answer 30

– flagellated for creating a stream
of water for feeding

Question 31

filter feeding

Answer 31

pass water through bodies and filter the nutrients they want

Question 32

Porifera and Cnidaria characteristics

Answer 32

• Phylum Porifera
  – lack true tissues
  – similar cell morphology as choanoflagellates
• Phylum Cnidaria
  – true tissues
  – diploblastic
  – cnidocytes

Question 33

Phylum Cnidaria

Answer 33

Eumetazoa: have true, differentiated tissues
– Diploblastic = two layers (ecto- and endoderm)
– Organs: collections of tissues specialized for
different tasks
* Most have radial symmetry & simple body plan

-Polyp (sessile form)
-Medusa (motile form)

Question 34

locomotion

Answer 34

the various movements of organisms (single-celled or multicellular organisms) to propel themselves from one place to another

Question 35

ecological role of anima groups

Answer 35

filter feeders, predators, and scavengers