BIOL 215 Modern Diversity II

Question 1

What are the main characteristics of animals ? [5]

Answer 1

Have the biggest number of species
2M described species over 8 to 64M unknown
Choanoflagellates descendant
Get their energy by ingestion
Cells without cell walls and secrete an extracellular matrix that consists of collagen, integrins, lycoproteins, proteoglycans

Question 2

What are the two main groups that evolves from choanoflagellates ?

Answer 2

Parazoa (no true tissue, marine choanocytes like sponges)

Eumetazoa (true tissues)

Question 3

What are the groups included in eumetazoa [2]?

Answer 3

Radiata (radially symetrical, 2 tissues, cnidarians, marine)

Bilateria (bilatery symetrical)

Question 4

What are the two groups included in bilateria ?

Answer 4

Protostomes (blastopore form first to be the mouth)

Deuterostomes (blastopore form first to be the anus)

Question 5

What are the two groups included in protostomes ?

Answer 5

Lophotrochzoa (lophophore → tentacules)

Ecdysozoa (shed their skin to form another skin)

Question 6

What are the two groups included in deuterostomes ?

Answer 6

Vertebrates

Echinodermata (radially symmetrical but share more similarities with bilateria)

Question 7

Are we closer to fungi or plants ?

Answer 7

Fungi

Question 8

What remains a mystery about plant ?

Answer 8

Their rapid on land evolution, especially the appear of angiosperms.

Question 9

What are the main characteristics of plants ?

Answer 9

Evolved from green algae
Multicellular eukaryotes
Cellulose rich cell walls
Photoautotrophic
Alternation of generations

Question 10

What are the four main categories of plants ?

Answer 10

Seedless non-vascular (bryophytes) [430mya]
Seedless vascular (ferns) [390 mya]
Gymnosperms (pines, etc.) [360mya)
Angiosperms (flowers) [130 mya]

Question 11

How did the green algae became a plant ?

Answer 11

Unicellular green algae that had incorporated
new genes through horizontal gene transfer
and gained organelles by endosymbiosis,
transformed into multicellular photosynthetic
organisms.

Question 12

What are the evidences for green algae to be the ancestor of plants ?

Answer 12

Both create starch to do their carbohydrates reserves
Rigid cellulose cell walls
Use the same pigments (chlorophyll (a and b) and yellow-orange carotenoids (α and β)).

Question 13

What are the major steps between gametophyte and sporophyte ?

Answer 13

Gametophyte (n) + sperm or egg = SYNGAMY → Zygote (2n) → sporophyte (2n) → Sporangia (2n) → MEIOSIS → Spores (n) → gametophyte

Question 14

What are the main characteristics of bryophytes ?

Answer 14

Earliest land plants
Have no roots so there is no or limited transport of water and nutrients
Live close to the ground in moist area
Imporatant in 2 transitions : water → land and haploid → diploid
ex: moss, liverworts

Question 15

What are the main characteristics of ferns ?

Answer 15

Have conductive tissues (xylem for water and phloem for nutrients)
Can live in dryer habitats compared to bryophytes
Have well developped cuticle and stomata to minimize water loss and maximize gaz exchanges
ex: ferns, horsetail, club moss

Question 16

What are the three major evolutions that permits plants such as gymnospems and angiosperms to move away from water and avoid dessication?

Answer 16

Reduction of the size of the gametophyte
Pollen
Spore in seeds

Question 17

What are the main characteristics of gymnosperms?

Answer 17

The haploid form is within a cone
The diploid form is the tree
Invented the seeds and the pollen
ex: conifers

Question 18

What are the main characteristics of angiosperms?

Answer 18

Show their sexual organs, advertise them
95% of plants are angiosperms
Their major evolutionary invention is the flower with the petals containing both male and female organs

Question 19

Given their origin remains a mystery, why are they so successfull ?

Answer 19

Because insects and birds can travel their seeds on long distances: they have a large range of different pollinators.

Question 20

What are the main characteristics of fungi ?

Answer 20

Appeared 440mya
Obtain nutrition by parasitism or digestion of dead organic matter
Cell walls made of chitin
They do not do photosynthesis nor have chlophyl
Have a choanoflagellates ancestor