Biology MCQs
Topic Notes: Biology
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
141
Match the following plant products with their respective botanical sources: a. Opium, b. Hing, c. Rubber, d. Quinine.
Answer:
a-3, b-2, c-4, d-1
The correct matches are: Opium is derived from the fruit (capsule) of the poppy plant; Hing (asafoetida) is obtained from the root/rhizome; Rubber is extracted from the stem (latex); and Quinine is harvested from the bark of the Cinchona tree. This matching reflects the traditional botanical sources for these commercially and medicinally important plant-derived substances.
142
According to Hanstein's histogen theory, what is the name of the outermost layer of the apical meristem?
Answer:
Dermatogen
Hanstein's histogen theory proposes that the root and shoot apices consist of three distinct meristematic zones: the dermatogen (outermost layer forming the epidermis), the periblem (middle layer forming the cortex), and the plerome (innermost core forming the stele).
143
Match the following grafting techniques with their corresponding procedural descriptions.
Answer:
a-3, b-2, c-4, d-1
Grafting techniques vary based on the cut geometry. Tongue grafting involves oblique cuts on both stock and scion. Wedge grafting uses a V-shaped notch on the stock and a wedge on the scion. Side grafting involves inserting a scion into a lateral slit. Crown grafting is used for top-working where scions are inserted into slits at the top of a stock.
144
What term describes localized necrosis that manifests as sunken open wounds on plant stems, typically bordered by healthy living tissue?
Answer:
Cankers
Cankers are specific types of plant disease symptoms characterized by localized death of the bark or stem tissue. These areas often appear sunken or depressed because the surrounding healthy tissue continues to grow while the necrotic area remains static. This distinction separates them from general rots or blights, which often affect larger or different types of plant tissues.
145
According to the classification by Plant (1965), which type of stomata features subsidiary cells that originate from cells surrounding the guard cell mother cell?
Answer:
Perigenous type
In the perigenous type of stomatal development, the subsidiary cells are derived from the surrounding cells of the epidermis rather than from the same mother cell that produces the guard cells. This classification helps in understanding the ontogeny of stomatal complexes in various plant species.
146
In seed plants and ferns, what are the parenchymatous regions within the vascular cylinder that lack vascular elements called?
Answer:
Both A and B
In the vascular anatomy of plants, a leaf gap is a parenchymatous region in the vascular cylinder located above the point where a leaf trace departs. These gaps are essentially breaks in the vascular tissue filled with parenchyma cells. These spaces are also referred to as lacunae, which is a general botanical term for a cavity or gap within a tissue structure.
147
What is the primary adaptive function of the 'drip tips' observed on the leaves of Ficus religiosa?
Answer:
Draining off excess of water from the leaf surface
Drip tips are elongated, pointed leaf apices that allow water to shed rapidly from the leaf surface. This adaptation is common in plants from high-rainfall environments, as it prevents the accumulation of water, which could otherwise promote the growth of fungi, bacteria, or algae on the leaf surface and potentially hinder gas exchange or photosynthesis.
148
What are the typical morphological characteristics observed in total phanerogamic parasites?
Answer:
All of the above
Total phanerogamic parasites, such as Cuscuta, rely entirely on their host for nutrients. Consequently, they have lost the need for photosynthesis, resulting in the loss of chlorophyll, reduction of leaves to scales, and a simplified vascular system, as they do not need to transport water from the soil.
149
Which term describes the central group of cells derived from central mother cells that eventually differentiate into the pith?
Answer:
All of the above
In plant anatomy, the central mother cells in the shoot apical meristem give rise to the pith. Depending on the specific growth pattern and terminology used in different botanical contexts, these cells may be referred to as rib meristem, file meristem, or specifically pith meristem, as they all contribute to the formation of the central ground tissue.
150
What is the primary chemical composition of the middle lamella that connects adjacent plant cells?
Answer:
Calcium pectate
The middle lamella is the outermost layer of the plant cell wall, acting as a cementing material that binds the primary walls of adjacent cells together. It is primarily composed of pectin, specifically calcium and magnesium pectates. These pectic substances provide the necessary adhesion to maintain tissue integrity in plants.