lecture 2

Question 1

who are the protists

Answer 1

polyphyletic

usually unicellular but not simple

cytosome (mouth)

pellicle (micro tubules/ cytoskeleton that provides ridgity)

contractile vacuole ( tend to be aquatic features, early adaptation to control salt and water conc)

cytopyge/cytoproct (gets rid of waste)

asexual reproduction (binary fission, budding and schizogony)

Question 2

explain why protists are so diverse

Answer 2

first fossil from 1.5 billion years ago

heterotrophics and euglenoids

Question 3

four supergroups of animal like protists and features of each

Answer 3

excavata
- feeding groove
- phytoflagellated/ zooflagellated
- simplified mitochondria
- several are pathogenic
- important marine primary producers

amoebozoa
- feed and move using pseudopodia (throw something out)
- lack supporting structures
- consume via phagocytosis
- reproduction is unknown

Rhizaria
- amoeboid but not a sister group
- some have fliopodia or axopodia

Alveolata
- highly variable
- all have plastids
- all have stacked vesicles (alveoli) below plasma membrane

e.g.
dinoflagellates
ciliates
- fresh water and marine, mostly free living, cilia, fixed morphology, distinct cytosome, asexual reproduction by transverse fissio, sexual reproduction by conjugation, dimorphic nuclei

apicomplexans
- intracellularr parasites (PLASMODIUM), ring shaped apical complex, no cilia

Question 4

describe the life history of Plasmodium

Answer 4

PHASE 1: sporogony phase
- mosquito ingests gametocytes
- cooks in the mosquito
- ruptured oocyst releases sporozoites
- mosquito feasts again and injects sporozoites
PHASE 2: Schizogony phase
- human liver cell becomes infected forming a shizont which then ruptures ( end of Exoerythrocytic cycle A)

human blood phase (Erythrocytic cycle B)

immature trophozoite cycle
- schizont ruptures
- protozoa infects a new blood cell and repeats the cycle

PHASE 3: Gametogony phase

Mature trophozoite cycle
- immature trop matures becoming a gametocyte
- mosquito bites host and repeats the cycle, spreading the disease

Question 5

Cambrian explosion

Answer 5

during the Paleozoic period (300mya, old animal)

all protists present at this point

enormous diversification

Question 6

biggest mass extinction event

Answer 6

right before the mesozoic era (middle animal)

not dinos

Question 7

cenozoic

Answer 7

65 mya - now ish

Question 8

protozoa

Answer 8

proto= first
zoa = animal

Question 9

Forminifera

Answer 9

rhizaria

marine

calcareous test

abundant in fissil record since cambrian

responsible for limestone and chalk