Protista

Question 1

1) . Is mode of nutrition considered when organisms are to be placed in Protista? Term by?
2) . Comment wrt cellular differentiation. What position does it occupy in the evolutionary link?
3) . Describe structural nitty gritties.
4) . What kind of members does it hold?

Answer 1

1) . No, all unicellular eukaryotes, irrespective of their mode nutrition are placed in Protista in Whittaker’s system. Term by Ernst Haeckel.
2) . Tissue level organisation is absent and not much cellular differentiation is seen in some members. It is said to be the ancestor of all multicellular eukaryotes (fungi, plants, animals)

3). Cell wall: some may have cellulosic
Ribosomes: classic euk 80S CYTOPLASMIC ribosomes
Locomotary structures: membranous extensions Cilia and flagella (9+2) made of TUBULIN protein
(Movement also takes place by pseudopodia, and of course, above-mentioned cilia and flagella where ciliary movement is fastest)

4). Mostly aquatic members, some are colonial without much cellular differentiation.

Question 2

Intro, habitat, Reproduction in Protistan algae. Also comment on and ploidy and type of life cycle of members.

Answer 2

Palmelloid: non-motile phase which may occur in a generally motile species

Protistan algae reproduce by both asexual and sexual means.
Three types of members of following classes:

1).Chrysophytes (“Chryso” gold, includes diatoms and desmids)
Golden brown photosynthetic Protista, which are both {aquatic and terrestrial}. {Some are marine}. THEY SUPPORT MUCH OF MARINE LIFE.

2). Dinophyceae/Pyrrophyta (“Dinos” whirling)
Golden brown photosynthetic Protistans, motile, biflagellate (some are non-motile, amoeboid, palmelloid* or filamentous)
{Mainly marine}, though {few are fresh water forms}.

3). Euglenoids: group of both chlorophyllous and non chlorophyllous flagellate protists found in {water and damp soil}. {Majority of them are fresh water} forms found in {stagnant water}. Largest genera: Euglena

DIATOMS
-asexual (mainly): binary fission,
-sexual: generally diploid, hence gametic meiosis is involved which makes the life cycle diplontic
~ isogamy to oogamy

DINOFLAGELLATES

• asexual (commonly): cell division/binary fission
• sexual: some members (Ceratium and Gymnodinium) have zygotic meiosis while gametic meiosis occurs in some (Noctiluca)

Haplontic life cycle: Ceratium, Gymnodinium
Diplontic life cycle: Noctiluca

~isogamous and anisogamous (Eg Ceratium)

EUGLENOIDS
-Asexual: favourable conditions, LONGITUDINAL Binary fission
Unfavorable conditions: perennation (palmella stage and cysts are formed)
-Sexual: not known to occur in euglenoids

Question 3

A).Give an overview of the members of Protistan algae. Comment on the nutrition as well.

B).Discuss Mixotrophic nutrition along with the characteristics of the odd member in which it is seen

Answer 3

Protistans can be grouped into three categories somewhat (not strictly) based on their nutrition as some protistans may be
-holophytic (photosynthetic),
-holozoic (ingestive),
-absorbtive (saprobic or parasitic).
Some have MIXOTROPHIC nutrition as well (photosynthetic/holophytic and saprobic/absorptive like Euglena)
AUTOTROPHIC/PHOTOSYNTHETIC/HOLOPHYTIC

1).Chrysophytes: 
Diatoms and Desmids
Eg. -Triceratium
-Navicula: {bilateral sym}
-Melosira: {radial sym}
-Cymbella

2).Pyrrophytes/Dinophyceae:
Dinoflagellates like
- Ceratium: photosynthetic, isogamous and oogamous reproduction, zygotic meiosis, Haplontic life cycle, {some dinos can be saprobic or parasitic as well}
- Gymnodinium: Zygotic meiosis, haplontic life cycle, proliferates in large number and causes red tide of sea
- Noctiluca: Gametic meiosis, Diplontic life cycle, bioluminiscence
-Pyrodinium, Pyrocystis: bioluminiscence, sea glows at night because of them
-Gonyaulax: produces Saxitoxin which is extremely poisonous to vertebrates (ingested by shell fish, doesn’t harm the mussel by causes PARALYTIC SHELL FISH POISONING in man), proliferates in large number and causes red tide of sea

Overlapping/theme wise:
~autotrophic/photosynthetic Dino, zygotic meiosis, Iso and anisogamous sexual rep reported in Ceratium
~zygotic meiosis: Ceratium, Gymnodium
~Gametic meiosis: Noctiluca
~Bioluminiscence: Pyrocystis, Pyrodinium, Noctiluca
~Toxin Saxitocin, PSP: Gonyaulax
~Red tide of sea: Gonyaulax, Gymnodium

3). Euglenoids:
Most common genera is Euglena (plant animal, producer-decomposer Protist)
-Euglena viridis: holophytic/photosynthetic and absorptive/saprobic (mixotrophic), HOLOZOIC (ingestive) IS ABSENT
-Paranema: holozoic
-Rhabdomonas: saprobic

             MIXOTROPHIC NUTRITION Seen in: producer-decomposer protist Euglena 

Primarily an autotroph, (photosynthetic/holophytic), but obtains nutrition from dead and decaying organisms in absence of light (saprobic/absorptive)

Plant characters: chloroplast and holophytic nutrition
Animal characters: 
a). Absence of cell wall
presence of:
b). Contractile vacuole
c). proteinaceous pellicle
d). Stigma and paraflagellar body
e). Longitudinal binary fission

Question 4

1) . Name two euglenoids which are holozoic and saprobic, respectively.
2) . Mention animal characters of the producer-decomposer protist.

Answer 4

1). Holozoic: Paranema
Saprobic: Rhabdomonas

2). Animal characters:
a). Absence of cell wall
presence of-
b). Contractile vacuole
c). proteinaceous pellicle
d). Stigma and paraflagellar body
e). Longitudinal binary fission

Question 5

1) . Haplontic life cycle involves which type of meiosis?
2) . Name some diseases caused by protests and their causative organisms, vectors as well. What mode of nutrition is being exhibited?

Answer 5

1). Zygotic meiosis

2). Parasitic/Absorptive mode of nutrition
Diseases:
~Dysentery caused by Entamoeba (vector: housefly)
~Sleeping sickness by Trypanosoma (vector: Tse Tse fly/Glossina)
{Trypanosoma: flagellated Protist}
~Malaria by Plasmodium(vector: female Anopheles mosquito)
{Plasmodium: Sporozoan}

Question 6

1). Gametic meiosis implies which type of life cycle

Answer 6

1). DIPLONTIC