12 - Protists*

Question 1

Common features of protists

Answer 1

• All are eukaryotic, have well defined organelles
• Membrane bound nucleus and mitochondria for cellular respiration
• Most are unicellular, Some multicellular forms
• Lack tissue organisation present in higher eukaryotes
• Undergo both sexual (Adverse conditions) and asexual reproduction.

Question 2

Different ways of nutrition

Answer 2

• Photosynthetic: autotrophic
• Ingest their food like animals: heterotrophic
• Absorb food like bacteria: heterotrophic by absorption
• Photosynthesis and ingest: mixotrophic (Euglena)

Question 3

What are the three domains (in domain system)

Answer 3

Bacteria, Archaea and Eurkarya

Question 4

What is the kingdom system based on

Answer 4

Phenotype (phenetic)

Question 5

What are the taxonomic groups within domain system based on

Answer 5

sequenced rRNA, present in all organisms

Question 6

Eukaryotic supergroups

Answer 6

• Excavata
• Chromalveolata
• Rhizaria
• Archaeplastida
• Amoebozoa
• Opisthokonta N/A

Question 7

Asexual reproduction

Answer 7

Mature cells (haploid, N) undergo mitosis and divide to produce identical daughter cells that are released to repeat the cycle

Question 8

Sexual reproduction

Answer 8

Conditions trigger gamete formation. Gametes (N) mate and their nuclei fuse (2N) to form a zygote, which divides by meiosis to produce haploid sexually recombined individuals

Question 9

Autotrophic

Answer 9

• Have photosynthetic pigments
• Use sunlight for energy, fix CO2 as a source of carbon, need only simple inorganic nutrients (N, P, S)
• Plant-like ‘primary producers’ (microalgae, phytoplankton)

Question 10

Heterotrophic

Answer 10

• ‘eat’ other organisms or organic matter to obtain carbon and energy
• phagocytosis, pinocytosis
• animal-like ‘protozoans’

Question 11

Mixotrophic

Answer 11

Capable of both autotrophic and heterotrophic nutrition. Balance determined by environmental coniditions

Question 12

Holozoic

Answer 12

Ingest whole cells or organisms for food

Question 13

Structures used for food gathering

Answer 13

• Cytosome: region on surface of cell where endocytosis can occur.
• Lysosomes: Vesicles that contain digestive enzymes needed to break down food taken in via endocytosis
• Cilia and flagella: can be used to sweep food towards cytosome
• Pseudopodia: extensions of amoeba that are used to engulf food and form vesicles

Question 14

Protist motility

Answer 14

• Non motile
  OR
• Motile by flagella (’flagellates’), cilia (’ciliates’) and pseudopodia (amoeba)
• Some species exhibit more than one during life cycle

Question 15

Trichomonas vaginalis life cycle

Answer 15

A very common human pathogen that is transmitted directly from one person to another.

Only 1 life stage and no sexual recombination

Question 16

Nosema bombysis life cycle

Answer 16

Relatively simple life cycle of the silk worm pathogen (spore and amoebae stages).
Has environmental and host stage = greater complexity

Question 17

Plasmodium vivax life cycle

Answer 17

Two hosts, multiple sites within the body and multiple life stages. Asexual - human and sexual recombination in mosquitoes. (malaria). learn diagram

Question 18

Pfiesteria piscicida life cycle - don’t need to know

Answer 18

At least 24 flagellated, amoeboid, and encysted stages or forms. Fish and human pathogen (toxins). Toxins incapacitate fish & cause lesions, which the protozoan invades

Question 19

Roles of protists affecting human life and nature

Answer 19

• primary production
• food chains
• mutualistic symbiosis
• nutrient recycling
• shaping our world
• medically important protists