15.1 diversity of animals

Question 1

when did animals originate?

Answer 1

approximately 600-800 million years ago

Question 2

how many animal species have we discovered so far?

Answer 2

more than one million

Question 3

are animals heterotrophs or autotrophs?

Answer 3

all animals are heterotrophs

Question 4

what are hox genes?

Answer 4

they are highly conserved genes that code for transcription factors that determine the course of embryonic development in animals and humans

Question 5

in vertebrates, the hox genes have been made into four divisions. What are they?

Answer 5

Hox a, hox b, hox c, and hox d

Question 6

what is segmentation?

Answer 6

a repeating series of body segments

Question 7

what are tissues?

Answer 7

they are groups of similar cells integrated into a functional unit

Question 8

do all animals have tissues?

Answer 8

all animals except sponges

Question 9

what is radial symmetry?

Answer 9

a form of symmetry where there are many lines of symmetry

Question 10

what is bilateral symmetry?

Answer 10

a form of symmetry where there is only one line of symmetry, referred to as the sagittal plane

Question 11

what are radial symmetric animals called?

Answer 11

they are called diploblasts

Question 12

what are bilateral symmetric animals called?

Answer 12

they are called triploblasts

Question 13

diploblasts have two embryonic layers, what are they?

Answer 13

endoderm and ectoderm

Question 14

triploblasts have three embryonic layers, what are they?

Answer 14

endoderm, ectoderm, and mesoderm

Question 15

endoderm forms tissues of what?

Answer 15

hollow organs such as intestines, livers, and lungs

Question 16

ectoderm forms tissues of what?

Answer 16

nerve tissue, skin

Question 17

mesoderm forms tissues of what?

Answer 17

muscles, circulatory and skeletal systems

Question 18

what is embryogenesis?

Answer 18

forming of the embryo

Question 19

where is the mesoderm?

Answer 19

between the endoderm and the ectoderm

Question 20

what is a coelom?

Answer 20

a fluid-filled space between the digestive tract and the body wall

Question 21

what are the two types of body cavities?

Answer 21

coelom and pseudocoelom

Question 22

do all animals have coeloms?

Answer 22

no, just the majority of bilateral symmetrical animals

Question 23

what are animals without coeloms called?

Answer 23

aceolomate

Question 24

tell us about the body cavity of eucelomates…

Answer 24

it is found within the mesoderm and lined with the mesoderm, it is called the coelom

Question 25

tell us about the body cavity of pseudocoelomates…

Answer 25

it is found between the endoderm and the mesoderm

Question 26

what is the function of the body cavity?

Answer 26

it makes the animal more flexible
helps internal organs move independently
helps fluid serve as a skeleton and distribute nutrients

Question 27

animals with a coelom are divided into two groups, what are they?

Answer 27

protostomes and deuterostomes.

Question 28

where is the first opening in embryonic development in protostomes vs. deuterostomes

Answer 28

in protostomes, mouth and in deuterostomes, anus

Question 29

what is the cleavage of protostomes and that of deuterostomes?

Answer 29

spiral cleavage vs. radial cleavage

Question 30

what are some protostomes?

Answer 30

Flatworms
Roundworm
Mollusks
Annelids
Arthropods

Question 31

what are some deuterostomes?

Answer 31

echinoderms and chordates

Question 32

when was the cambrian period?

Answer 32

540-510 mya

Question 33

what happened at the beginning of the cambrian period?

Answer 33

explosive radiation of marine organisms

Question 34

what happened near the end of the cambrian period?

Answer 34

mass extinction

Question 35

what was the first discovered site that represented the cambrian explosion? how old was it?

Answer 35

the burgess shale in canada, it was about 540 million years old