Algae Flashcards
What proportion of global O2 production is due to algae?
50-90%
What are the 2 types of microalagae?
- Diatoms
- Dinoflagellates
What are kelp forrests mainly composed of?
Brown algae
Name 3 unusual environments algae can inhabit
- cryptobiotic crusts on desert soil
- endocriptoliths in rocks
- symbionts inside other animals or plants
Why is Gonyaulax deadly?
It secretes a neurotoxin called saxotoxin which blocks Na+ transport and hence all action potentials
What do algae include?
- photosynthetic organisms which are not mosses, bryophytes or vascular plants
- However evolved at different times from different ancestors => not monophyletic
What is Van den Hoek’s 5 classifications of algae?
- Rhodophyta: include red algae, no flagella and chloroplasts with phycobilisomes
- heterokontophyta: heterokont flagella, diatoms and brown algae
- Haptophyta: small unicellular
- Dinophyta: unicellular flagellates. armored cellulose plates
- Chloropyta: evolutionary pathway to land plants
What is involved in sexual reproduction?
A diploid phase, nuclear fusion (syngamy) and reduction division (meiosis)
What are the 2 ways a sexual cycle could have evolved?
- A fusion of haploid unicells followed by meiosis
2. Meiosis of diploid unicells to form a free-living haploid state
Describe the 3 types of sexual life cycles
- Haplonic (mostly haploid)
- Diplontic (mostly diploid)
- Diplo-haplontic (two or more multicellular phases)
What are the advantages and disadvantages of sexual reproduction:
Advantages:
- Offspring with varied genotypes which allows adaptation to the environment
- Selection can remove deleterious mutations
- Recessive mutations are masked
Disadvantages:
- Asexual reproduction is faster
- In asexual reproduction an individual passes on all of its genes and a ‘successful’ genome is retained
