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
1
Approximately how many spores are typically contained within a single sporangium of Polypodium?
Answer:
64
In the genus Polypodium, the sporangium typically undergoes a series of meiotic divisions resulting in the production of 64 spores. This is a characteristic feature of many leptosporangiate ferns where the spore mother cell divides to form a tetrad, followed by further divisions.
2
By what mechanism are the antherozoids of Adiantum attracted to the archegonia?
Answer:
Chemotactically
In Adiantum and many other ferns, the archegonia secrete specific chemical substances, such as malic acid, into the surrounding water. The motile, flagellated antherozoids detect these chemical gradients and swim toward the archegonia, a process known as chemotaxis.
3
What is the outermost layer of a mature fern spore called?
Answer:
Perenium
In many ferns, the mature spore is protected by several layers. The outermost layer, often referred to as the perispore or perenium, provides additional protection against environmental stress, while the exine and endosporium form the inner wall layers.
4
In which region of Pakistan is the fern Adiantum commonly found in the plains?
Answer:
Punjab
Adiantum, commonly known as the maidenhair fern, is widely distributed across various ecological zones in Pakistan. It is frequently observed in the plains and sub-mountainous regions of Punjab, where it thrives in moist, shaded environments such as near water channels, walls, and damp soil. Its distribution is often limited by the availability of sufficient moisture and appropriate microclimates.
5
Which taxonomic family does the genus Adiantum belong to?
Answer:
Polypodiaceae
The genus Adiantum, commonly known as maidenhair ferns, is classified under the family Polypodiaceae within the order Filicales. This family is characterized by specific sporangial development patterns and leaf morphology typical of true ferns.
6
In the genus Marsilea, when is the large placenta typically produced within the sporocarp?
Answer:
Young sporocarp
In Marsilea, the sporocarp is a specialized structure that houses the sori. The placenta is a gelatinous structure that develops within the young sporocarp. As the sporocarp matures, the placenta expands, pushing the sori out through the gelatinous ring to facilitate spore release. The development of this structure is a critical phase in the reproductive cycle of this aquatic fern.
7
What is the characteristic shape of the Adiantum prothallus?
Answer:
Heart
The gametophyte of Adiantum, known as the prothallus, is typically a small, green, photosynthetic, and heart-shaped structure. It is monoecious, bearing both male (antheridia) and female (archegonia) reproductive organs on its ventral surface. This heart-shaped morphology is a classic diagnostic feature of the gametophyte generation in many homosporous leptosporangiate ferns, facilitating the process of fertilization in moist environments.
8
What is the common name for the fern genus Adiantum?
Answer:
Maiden hair ferns
The genus Adiantum is popularly known as the maidenhair fern. This name is derived from the delicate, dark, and slender stipes (stalks) of the fronds, which resemble human hair. These ferns are highly valued in horticulture for their aesthetic appeal and are characterized by their fan-shaped or wedge-shaped leaflets, which are often arranged in a graceful, drooping manner.
9
What are the characteristic color and shape of the spores in the genus Polypodium?
Answer:
A and b both
In the fern genus Polypodium, the spores are typically dark brown in color and possess an oval or ellipsoidal shape. These morphological characteristics are often used in the identification and classification of different species within the genus. The spores are produced in sori located on the underside of the fronds.
10
What is the term for leaves that bear sporangia in the genus Polypodium?
Answer:
Sporophylls
In pteridophytes, leaves that are specialized to bear sporangia are called sporophylls. In Polypodium, these leaves are often morphologically similar to vegetative leaves but contain sori on their abaxial surface where sporangia are produced.