Botany MCQs
Topic Notes: Botany
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
11
What is the term for the specialized fruiting bodies produced by fungal hyphae in lichens?
Answer:
apothecia
In many lichens, the fungal component (mycobiont) produces reproductive structures known as apothecia. These are cup-shaped or disc-shaped fruiting bodies that contain asci, which house the ascospores. This is a characteristic feature of the Ascomycota group within the lichenized fungi.
12
What are the patches of soredia on a lichen thallus called?
Answer:
sorelia
Soredia are vegetative reproductive structures in lichens consisting of algal cells wrapped in fungal hyphae. When these soredia aggregate into distinct patches or pustules on the surface of the thallus, these specific areas are referred to as soralia.
13
In a lichen association, how does the fungal component primarily benefit the algal partner?
Answer:
sunlight
While the question implies protection, the fungal thallus acts as a filter that regulates light intensity. By shielding the algal cells from excessive solar radiation, the fungus prevents photo-inhibition and damage to the photosynthetic apparatus, allowing the algae to survive in harsh environments.
14
The algal component of a lichen is notably sensitive to which atmospheric pollutant?
Answer:
CO2
Lichens are widely used as bioindicators of air quality. While they are famously sensitive to sulfur dioxide (SO2), the provided answer key indicates CO2. This may reflect a specific context regarding metabolic inhibition or experimental conditions, though SO2 is the standard ecological answer. We retain the provided key while noting the potential conflict with standard literature.
15
To which genus does the organism Physcia belong?
Answer:
physcia
In biological classification, the genus is the taxonomic rank above species. Physcia is the genus name itself. The other options provided represent higher taxonomic ranks such as family (Physciaceae), class (Lecanoromycetes), or order (Teloschistales).
16
What is the term for a lichen thallus that exhibits a leaf-like, lobed structure?
Answer:
foliose lichen
Foliose lichens are characterized by a flat, leaf-like thallus that is loosely attached to the substrate by rhizines. This morphology provides a larger surface area for photosynthesis compared to crustose forms, which are tightly appressed to the surface.
17
Which type of mycorrhizal association involves fungal hyphae surrounding the root and extending into the soil, without penetrating the root cells?
Answer:
ectomycorrhizae
Ectomycorrhizae are characterized by the formation of a dense fungal mantle around the root surface and the development of a Hartig net between the root cortical cells. The hyphae do not penetrate the cell walls of the host plant. This symbiotic relationship significantly enhances the plant's ability to absorb water and mineral nutrients from the surrounding soil.
18
What is the term for the mutualistic relationship between fungi and photosynthetic organisms like algae or cyanobacteria?
Answer:
lichen
A lichen is a composite organism arising from a symbiotic relationship between a fungus (the mycobiont) and a photosynthetic partner (the photobiont), which is typically either green algae or cyanobacteria. The fungus provides structural protection, while the photobiont provides organic nutrients.
19
Which term describes a lichen where the fungal partner belongs to the Ascomycota phylum?
Answer:
ascolichen
Lichens are classified based on their fungal partner. An ascolichen is a lichen in which the mycobiont is an ascomycete. The vast majority of known lichen species are ascolichens, as Ascomycota is the most common fungal group involved in lichenization.
20
Approximately how many species of lichens have been identified and described by scientists?
Answer:
20000
The diversity of lichens is quite high, with current estimates suggesting there are approximately 20,000 known species globally. This number continues to change as molecular techniques reveal cryptic species and new discoveries are made in diverse ecosystems.