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
21
What is the term for the fungal tissue formed by the loose interweaving of hyphae?
Answer:
prosenchyma
Fungal hyphae can aggregate to form organized tissues known as plectenchyma. When the hyphae are loosely interwoven and retain their individual identity, the tissue is specifically referred to as prosenchyma.
22
What term describes hyphae that contain two genetically distinct nuclei per cell, resulting from a conjugation division?
Answer:
dikaryotic hyphae
Dikaryotic hyphae are a hallmark of the Basidiomycota and Ascomycota life cycles. Following plasmogamy, where two compatible haploid cells fuse, the nuclei do not immediately fuse. Instead, they remain paired within the same cell, forming a dikaryon. This state is maintained through conjugate division, where both nuclei divide simultaneously to ensure each daughter cell receives a pair of compatible nuclei.
23
What does the term 'aseptate' refer to in the context of fungal hyphae?
Answer:
without cross wall
In mycology, 'aseptate' or coenocytic hyphae are those that lack internal cross-walls (septa). This results in a continuous cytoplasmic mass containing multiple nuclei, which is a characteristic feature of certain fungal groups like the Zygomycota.
24
How do the flagella of prokaryotic organisms compare structurally to those found in eukaryotic organisms?
Answer:
different
Prokaryotic and eukaryotic flagella are fundamentally different in structure and mechanism. Prokaryotic flagella are rigid, rotating protein filaments made of flagellin, powered by a proton motive force. In contrast, eukaryotic flagella are flexible, whip-like structures composed of microtubules arranged in a 9+2 pattern, powered by ATP hydrolysis. They represent an example of convergent evolution rather than common ancestry.
25
What is the term for the long, stiff, pointed appendages found on the surface of certain fungal structures?
Answer:
crown
In the context of fungal morphology, particularly regarding the cleistothecia of certain powdery mildews like Phyllactinia, the appendages are often described as having a crown-like appearance. These specialized structures are stiff and pointed, serving as diagnostic features for identifying specific genera within the Erysiphaceae family. The term 'crown' refers to the arrangement of these appendages at the apex of the fruiting body.
26
Approximately how many body lengths per second can highly motile bacteria achieve during movement?
Answer:
100
Bacteria are remarkably efficient swimmers relative to their size. Studies on motile bacteria, such as those using flagellar propulsion, have shown that they can reach speeds of approximately 100 body lengths per second. This high-speed motility allows them to navigate effectively through liquid environments to reach nutrient sources or escape unfavorable conditions.
27
Which term describes fungi that obtain nutrients by absorbing organic matter directly from their environment?
Answer:
Absortive heterotrophs
Fungi are heterotrophic organisms that secrete extracellular enzymes into their surroundings to break down complex organic matter. The resulting simple nutrients are then absorbed through the fungal cell walls and membranes. This mode of nutrition is specifically defined as absorptive heterotrophy, which is a hallmark characteristic of the kingdom Fungi.
28
What is the term for the multinucleate protoplast formed by the repeated division of myxamoeba nuclei?
Answer:
plasmodium
In the life cycle of slime molds (Myxomycetes), the myxamoebae or swarm cells fuse to form a large, multinucleate, naked mass of protoplasm known as a plasmodium. This structure is capable of amoeboid movement and feeding.
29
What is the term for the complex tissue structures formed by tertiary mycelium in fungi?
Answer:
tertiary mycelium
Tertiary mycelium is the highly organized, differentiated tissue that forms the complex fruiting bodies (sporophores) in higher fungi, such as mushrooms. It develops from the secondary mycelium and is essential for spore production.
30
Which cellular structure is associated with the initiation of DNA replication in bacterial cells?
Answer:
mesosome
Mesosomes are invaginations of the plasma membrane in bacteria. Historically, they were thought to be involved in DNA replication and cell division by anchoring the bacterial chromosome to the membrane. While modern research suggests some mesosomes might be artifacts of electron microscopy preparation, they are traditionally taught in biological curricula as sites for DNA replication and respiratory enzyme activity.