Protists

Question 1

Define protists

Answer 1

All eukaryotic organisms that are not animals, plants or fungi

Question 2

Basic information about protists

Answer 2

• Mostly unicellular
• Diverse in form and function (more than other eukaryotic organisms)
• Very complex
• Important primary producers
• Some are pathogens in some organisms

Question 3

Classification of protists

Answer 3

• Used to be a kingdom but genetic analysis has placed them with other eukaryotic organisms
• They are polyphyletic (classified within same group but different ancestors)
  Current Hypothesis: 6 Supergroups (vs. 4)
  1. Excavata - unicellular, flagella, hetero
  2. Chromalveolata - both uni and multi cellular, auto, hetro and mixotrophs
  3. Rhizaria - same as above
  4. Archaeplastida - Red and green algae, other land plants (descended from green algae)
  5. Ameobozoa - slime molds, etc…
  6. Opisothokonta - animals, fungi and related protists

Question 4

Protist nutrition

Answer 4

1. Phototrophs / autotrophs
   - Plant-like protists
2. Heterotrophs
   - Animal-like protists
3. Mixotrophs
   - Combination of auto and hetero

Question 5

Protist reproduction

Answer 5

1. Asexually
   - Binary Fission
2. Sexually
   - Two organisms go through meiosis and create gametes (half amount of chromosomes) which fertilize = zygote
   - Genetic variation can increase chance at survival

Question 6

Protist complexity

Answer 6

EXAMPLE:
- Stentor roeseli: single-celled, uses hair-like cilia to attach itself to floating algae, has complex evasive behaviours

Question 7

Protists and primary producers

Answer 7

• Protists use the energy from sunlight to create organic molecules which other organisms consume and gain carbon and energy
• They are the base of the ecological food web - all rely on them for food
• ~30% of all world’s photosynthesis are performed by protists = diatoms, dinoflagellates, multicellular algae and other protists
• Growth of primary producers relies on the nutrients uplifted through upwelling on the ocean floors. But heated waters is decreasing this meaning that there is a decrease in protists

Question 8

Diatoms

Answer 8

• Unicellular with unique two part, glass-like wall of silicon dioxide
• Major component of phytoplankton
• Diatomaceous earth (fossilized diatom walls)

Question 9

Dinoflagellates

Answer 9

• Unicellular with two flagella
• Abundant component of phytoplankton
• Can trigger toxic ‘red tides’

Question 10

Protists and pathogens

Answer 10

Example:
- Plasmodium: genus of parasite (protist) that causes Malaria
- Transmitted by female mosquitoes who feed from red blood cells
- Causes fever, fatigue, vomiting and in extreme causes seizures, coma and death
*Affects liver and red blood cells