practical activity: lichens
find out: what is a lichen? what organisms are working together to create lichen?
what kind of symbiosis does the make-up of lichen represent?
do lichens have roots?
why not? (hint: find out if either algae or fungus has roots)

Question

Accepted Answer

### 1. What is a lichen? What organisms work together to create lichen?
# Brief Explanations:
A lichen is a composite organism resulting from a symbiotic relationship. A fungus (usually an ascomycete or basidiomycete) and a photosynthetic partner (either a green alga or a cyanobacterium, or sometimes both) work together. The fungus provides a protective structure and absorbs water and minerals, while the photosynthetic partner produces food via photosynthesis.
# Answer:
A lichen is a composite organism from a fungus - photosynthetic partner (alga/cyanobacterium) symbiosis. A fungus (ascomycete/basidiomycete) and a photosynthetic partner (green alga/cyanobacterium) work together to create lichen.

### 2. What kind of symbiosis does the make - up of lichen represent?
# Brief Explanations:
The symbiosis in lichen is mutualism. In mutualism, both organisms benefit. The fungus gets organic carbon (food) from the photosynthetic partner (alga/cyanobacterium) which does photosynthesis. The photosynthetic partner gets a protected environment, water, and minerals from the fungus.
# Answer:
The make - up of lichen represents mutualism (a type of symbiosis where both the fungus and the photosynthetic partner benefit).

### 3. Do Lichens have roots?
# Brief Explanations:
Lichens do not have true roots. True roots are structures found in vascular plants that absorb water and nutrients from the soil. Lichens attach to surfaces (like rocks, bark) using structures called rhizines (in some lichens) or holdfasts, which are not roots as they don't have the same function or structure as plant roots. Also, the fungal and algal components of lichen (fungus and alga/cyanobacterium) do not have roots (algae are simple and lack roots, fungi have hyphae not roots).
# Answer:
Lichens do not have roots.

### 4. Why not? (hint: find out if either algae or fungus has roots)
# Brief Explanations:
Algae are simple photosynthetic organisms. Most algae (like the green algae in lichens) are aquatic or live in moist environments and do not have roots. They absorb water and nutrients directly through their cell surfaces. Fungi, the other component of lichen, have hyphae for absorption and growth, not roots. Since neither the algal nor the fungal component of lichen has roots, lichens do not have roots. Also, lichens are not vascular plants, and roots are a characteristic structure of vascular plants for water and nutrient uptake from soil. Lichens attach to surfaces with rhizines/holdfasts which are not roots.
# Answer:
Algae (in lichen) lack roots (absorb via cell surfaces), fungi (in lichen) have hyphae not roots. Lichens are not vascular plants (roots are a vascular plant structure), and use rhizines/holdfasts (not roots) to attach, so they have no roots.

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Question

Explanation:

1. What is a lichen? What organisms work together to create lichen?

Answer:

2. What kind of symbiosis does the make - up of lichen represent?