Origin of life + Porifera

Question 1

how did life originate?

Answer 1

From primordial soup (H2O,NH3,CH4) plus addition of energy organic molecules were created, oparine-heldane hypotesis

Question 2

When did life arise?

Answer 2

3.8 billion years ago proto cells. 3.5 BYA prokaryotes. 2.5BYA phot/chemosyntesys.
1.5, oldest eukaryote fossil.

Question 3

Explain endosymbiosis.

Answer 3

endosymbiosis is the process through which ancestral eukariotic cells assimilated different bacterias into their own functioning, hence leading to a more complex cell with chloroplasts and mithocondrion

Question 4

What are protists?

Answer 4

A vast heterogenous group of unicellular eukariotes

Question 5

what is the cambrian explosion?

Answer 5

A period of 10.000 milion years occurred 540 BYA, in which a vast amount of different phylums emerged.

Question 6

what are some major unicellular eukariotic taxa?

Answer 6

Ameba, Euglenozoa, Chlorophyta, Dinoflagellata, ciliophora.

Question 7

What are some charatteristics of Amebas?

Answer 7

They have chemical sensors to find food sources, and they have a unique way of locomotion through pseudopods

Question 8

what are unique charatteristics of euglenozoa?

Answer 8

they have a light receptor , chloroplasts, and the direction of their locomotion is in the same orientation of the flagellum, as opposed to using the flagellum for creating thrust

Question 9

What are some charatteristics of clorophyta?

Answer 9

they can form colonies

Question 10

What are some charatteristics of cilophora?

Answer 10

they have complex structures, they are multynucleates, and their body is covered in cilia

Question 11

what are the main charatteristichs of the phylum porifera?

Answer 11

They are multycellular organisms with no germ layer. they only function at a cellular level with no tissues or organs. they have a calcium or silicate skeleton and are composed by a large spongocoel cavity with an osculum used for waterflow

Question 12

what major cell types can be found in poriferae?

Answer 12

Cohanocytes for waterflow and food gathering.

pinacocytes form a protective external layer

archeocites, used for reproduction, digestion and transport of nutrients

Question 13

explain how does a cohanocyte works.

Answer 13

a cohanocyte creates a water flow through the fast beating of its flagella and gathers food particles in its collar. those are than transported to the archaeocytes or pinacocytes for further digestion through fagocytosis

Question 14

name the three type of poriferae.

Answer 14

Ascon type (lowest 3D complexity with cohanocytes in a single chamber)

Sycon type (cohanocytes lay in multiple radial canals)

Leucon type ( cohanocytes are found in many separate chambers)

Question 15

Describe the feeding steps for the Ascon type.

Answer 15

water is drawn in the spongocoel by the cohanocytes and enters through porocytes on the external layer of the sponge, the water is than expelled through the osculum.

Question 16

describe the water filtering process of the Sycon type.

Answer 16

Water enters incurrent canals through the dermal ostium. than through the prosopyles it enters into the radial canal. from there water is expelled in the spongocoel through internal pores called apopyles, and finally it is expelled through the osculum.

Question 17

describe the water filtering process of the Leucon type type.

Answer 17

Through the ostium water is drawn in the incurrent canals, through which it than slows down significantly once it reaches the flagellated chambers (where the cohanocytes are). after that water goes through excurent canals and it exit through the osculum at a much higher speed in order to not be reabsorbed by the sponge.

Question 18

what function do the spicules have in poriferae?

Answer 18

they form the skeleton of the sponges

Question 19

how do poriferae reproduce?

Answer 19

poriferae are monoecious (contain both male and female cells).
They are viviparous, wich means that the fertilization and embryo developement happens internally in the mesohyl untill a larvae is expelled and disperses to form a new colony elswhere.