Body plans and development

Question 1

what are the major event/time chunks of from when the solar system formed-now?

Answer 1

• 4.6 bya= solar system + earth formed
• 4 bya = first prokaryotes
• 1.8 bya first eukaryotes
• 800 mya first multicellular organisms

Question 2

Why was the fossil record so poor from the origin of life up until the cambrian explosion?

Answer 2

• up until the Cambrian, most organisms were soft-bodied life, and also unicellular.
• these either did not make fossils, or these fossils were too small to see

Question 3

What when was the cambrian explosion?

Answer 3

• ~542 million years ago
• was the origin and diversification of predator-prey relationships, which lead to a huge range of body plans developing during this time

Question 4

What are body plans?

Answer 4

• a suite of morphological and developmental traits that are shared by a group of phylogenetically related organisms, where phylum refers to “body plan”

Question 5

What are the three types of body symmetry?

Answer 5

• asymmetry (absence of symmetry)
• bilateral symmetry
• radial symmetry

Question 6

Body symmetry had correlations with three specific features of an organism, which are….

Answer 6

• locomotion
• feeding mode
• degree of cephalization

Question 7

Describe the asymmetrical body plans and the associated features with it

Answer 7

• lack any ‘head’ (no cephalization)- (and thus no part of the body is critical to survival over another)
• most are completely sessile - (defend themselves via chemicals and general tolerance to damage)
• suspension feeders
• ex. sponges and placozoans

Question 8

Describe the bilateral symmetry body plan and the associated features with it

Answer 8

• tend to be highly cephalized
• highly mobile
• ## forage feeders

Question 9

Describe the radial symmetry body plan and the associated features with it

Answer 9

• tend to have weak or no cephalization (have an oral and aboral axis)
• many are sessile, some are capable of locomotion
• ex. Cnidarians

Question 10

What is a germ layer? the 3 types of layers?

Answer 10

• embyronic cells that give rise to tissues and organs
• endoderm (gut lining), ectoderm (skin), mesoderm( muscle)

Question 11

What are diploblastic organisms?

Answer 11

• organisms with two germ layers
• endoderm and ectoderm
• tend to have simpler body plans

Question 12

What are triploblastic organisms?

Answer 12

• organisms with 3 germ layers (endoderm, ectoderm, and mesoderm)
• tend to be more complex organisms

Question 13

What are the three types of body cavities organisms can have?

Answer 13

• pseudocoelomate and coelomate (have a fluid filled body cavity present)
• acoelomate (lacking a fluid filled body cavity)

Question 14

what are some of the functions of a coelom/psudocoelomate?

Answer 14

1. fluid filled space means organs aren’t attached to anything, internal organs can process independently of each other, and this also allows for specialization of organs
2. fluid acts as protection for internal organs
3. fluid also acts as a circulatory system for nutrients, hormones,
4. can act a hydrostatic skeleton
5. can act as a water reserve

Question 15

What is the difference between protosomes and deuterosomes?

Answer 15

Protosomes: The first opening in the embryo becomes the mouth. Cells are also spiral and determinate
Deuterosomes: The first opening in the embryo becomes the anus, and the mouth develops later. cells are also radial and indeterminate