Fungi And Protozoa

Question 1

Characteristics of fungi

Answer 1

• Eukaryotic - has a nucleus and mitochondria
• Heterotrophs - depends on others for food
• Multicellular
• Non-motile

Can reproduce sexually and asexually

Question 2

More facts about fungi

Answer 2

• Has no chlorophyll
• Not photosynthetic
• Doesn’t reproduce by seeds
• Have a cell wall but contains chitin instead of cellulose

Question 3

How is fungi distinguished from other kingdoms ?

Answer 3

By:

• Nutrition
• Structural organisation
• Growth
• Reproduction

Question 4

Nutrition of fungi

Answer 4

• Heterotrophic - lacks chlorophyll
• Obtains nutrients by enzyme secretion and absorption of resulting byproducts
• Cell wall has chitin and beta-glucans
• Glycogen is its primary food storage

Question 5

What is the difference between yeast and mould ?

Answer 5

Yeast is unicellular whereas moulds have hyphae (mat of fibers) as the main body of the organism

Question 6

Characteristics of yeast

Answer 6

• Unicellular
• Can reproduce sexually by asci/basidia or asexually by budding
• Can cause issues e.g, thrush and rhodotorula (found on shower curtains)

-Can be used for baking and brewing with ‘saccharomyces cerevisiae’

Question 7

Structure of a mould

Answer 7

• Basic structural unit of mycelium ( fungal vegetative body) is the hypha
• Hyphae are composed of tubular walls containing chitin… they provide large surface areas e.g, 10cm^2 of soil can contain 1km of hyphae with 314cm^2 surface area

Question 8

What is mycelia ?

Answer 8

The mass of hyphae that makes up one individual fungus

Question 9

How does a spore become mycelium ?

Answer 9

1. A spore lands on the food source
2. It uses the food supply and grows radially to utilise more food sources (24hrs)
3. The radial growth continues to eventually form a mycelial mat (48 hrs)
4. If the food source is endless the mycelium can continue to grow

Question 10

Reproduction

Answer 10

• Sporangiophores - upright stalk with an enclosed sac e.g, bread mold
• Conidia - upright stalk with no enclosed sac (penicillin)
• Fragmentation - hyphae dry out and shatter = individual cells that act like spores are realised (athlete’s foot)
• Budding - small offspring

Question 11

Separate vs aseptate hyphae

Answer 11

• Hyphae of septate fungi are divided into cells by cross walls = septa. Each cell has 1 or 2 nuclei.
• Hyphae of aseptate fungi lack cross walls = coenocytic
• Haustoria = modified hyphae that penetrates the host tissue but remain outside the cell membrane

Question 12

Spread of fungal spores

Answer 12

1. Shooting of the spores into the air
2. Use of animals, water or wind

Once caught by something, the spores can be carried long distances

Question 13

Ascomycota

Answer 13

• One of the two largest phyla
• Approx 2000 genera and 30,000 species identified
• Constituted of filamentous fungi and yeasts
• Some used in commercial and medical processes
• Characterised by the production of spores in an ascus (asci)
• Example is truffles

Question 14

Basidiomycota

Answer 14

• One of the two largest fungal phyla
• Approx 1600 genera and 32,000 species
• Mainly uses sexual reproduction through the production of basidiocarp and basidispores

Question 15

Chytridiomycota

Answer 15

• Approx 700 species
• Aseptate mycelium
• Sexual spores are flagellate - also known as protists
• Predominately haploid, short dikaryotic and diploid phases in sexual cycles
• Cell wall is composed by chitin
• Moist terrestrial habitats such as forest litter layer or in freshwater

Question 16

Examples of pathogenic fungi

Answer 16

• Humans - Aspergillus fumigatus & Candida albicans
• Frogs - Batrachochytrium dendrobatidis
• Insects - Ophiocordyceps unilateralis
• Plants - Puccinia graminis, Ustilago maydis

Question 17

Characteristics of Protozoa

Answer 17

• Majority and non-pathogenic and free-living (water)
• Complex life cycles
• Unicellular
• Locomotive structures - flagella, cilia, pseudopods
• Varies in shape
• Inhabits water and soil
• Zoonotic when pathogenic
• Has 65,000 species

Question 18

Life cycle of Protozoa

Answer 18

1. Trophoziote - motile feeding stage
2. Cyst - a dormant resistant stage
3. Asexual and sexual reproduction - most propagate by asexual cell division of the trophozoite
   / undergo formation of a cyst
   / have a complex life cycle that contains both types of reproduction

Question 19

Main example of Protozoa - Malaria

Answer 19

• Caused by Plasmodium species
• Transmitted by female Anopheles mosquitos
• Infects 300 million - 1 million die
• Intacellular & extracellular stages
• Complex life cycle

Question 20

Symptoms of malaria

Answer 20

• Feeling cold and experiencing hot dry sweat and then drenching sweat
• Headache, muscle pain and vomiting
• Similar to influenza symptoms
• Anaemia in later stages
• Cerebral malaria, liver damage