Lecture 18 Algae

Question 1

What does polyphyletic mean?

Answer 1

Group that is characterized by one or more homoplasies.

Question 2

Are the algae a formal taxon?

Answer 2

NOOOOOOOO

Question 3

Please explain what makes an algae…an algae.

Answer 3

They are eukaryotes that have chlorophyll and other pigments for carrying out oxygenic photosynthesis.

They also lack a well-organized vascular conducting system.

They have simple reproducitve structures (teehee)

Question 4

What is phycology????

Answer 4

THE STUDY OF ALGAE!!!!

Question 5

Where do MOST algae live?

Answer 5

• Primarily aquatic
  
  • Planktonic
    
    • Suspended in aqueous environment
    • Phytoplankton: algae and small aquatic plants
    • Zooplankton: aninmals and nonphotosynthetic protists
  • Benthic
    
    • Attached and living on the bottom of a body of water
  • Neustonic
    
    • Live at water-atmosphere interface

Question 6

Ok, Ok… we all know algae are water lovers. But can they survive on land??

Answer 6

• Some are terrestrial
  
  • On moist surfaces
  • Endosymbionts in protozoa, mollusks, worms, and corals
  • Endosymbionts, ephiphytes, and parasites of plants
  • Associate with fungi to form lichens

Some algae can be found in desert or on the cliffs as well.

Question 7

How are the algae classified taxonomically?

Answer 7

Based on their cellular properties

Question 8

Describe the ultrastructure of the algal cell!

Answer 8

• Some have extensive outer matrixes
• May have pyrenoids: molecules associated with the synthesis and storage of starch.
• They have a very very simply body plan. Extensive cytoskeleton present.
• Many algae also have extensive cell walls. Lots of chloroplasts present.

Question 9

What are pyrenoids?

Answer 9

Molecules associated with the synthesis and storage of starch.

Question 10

How do algaes obtain their food/nutrition??

Answer 10

They can be either autotrophic or heterotrophic (or both).

Most are photoautotrophic. Some are chemoorganoheterotrophic.

A vast majority of algae are autotrophs.

Question 11

What is the thallus of algae?

Answer 11

It is the body of an alga. May be colonial, filamentous, uniecellular, tubular, etc.

Algae are the first organisms that can have true body plans and provide habitats for other organisms.

Question 12

Describe the various mechanisms of asexual reproduction in algae.

Answer 12

• Fragmentation
  
  • Thallus breaks up and each fragment forms a new thallus.
• Spores
  
  • Zoospores - flagellated motile
  • Aplanospores - nonmotile
• Binary fission
  
  • Mitotic nuclear division followed by cytoplasmic division

Volvox is the first time we’ve seen haploid and diploid cells in the organism. Gives rise to much more elaborate organisms.

Question 13

Describe the various mechanisms of sexual reproduction in algae.

Answer 13

• Oogonia (s., oogonium)
  
  • Relatively unmodified vegetative cells in which eggs are formed
• Antheridia (s., antheridium)
  
  • Specialized structures in which sperm are formed
• Zygote
  
  • Product of fusion of sperm and egg.

Question 14

Overall, how do most of the divisions of algae differ?

Answer 14

They tend to vary in the kind of chlorophylls (therefore giving them a different color pigment).

They can also vary in the type of carotenoids they have.