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
1
What is the name of the specialized, single-cell thick layer that surrounds the starchy endosperm in a maize grain?
Answer:
Aleurone layer
The aleurone layer is a specialized peripheral layer of cells surrounding the endosperm in cereal grains like maize. It is rich in proteins and enzymes, such as alpha-amylase, which are synthesized and secreted during germination to break down the stored starch in the endosperm into sugars for the developing seedling.
2
Which of the following factors is not typically involved in the dispersal of plant seeds?
Answer:
Fungus
Seed dispersal is the movement or transport of seeds away from the parent plant. Common agents of dispersal include abiotic factors like wind and water, and biotic factors such as animals (zoochory). Fungi are decomposers or pathogens and do not function as primary agents for the mechanical transport and dispersal of plant seeds.
3
What is the botanical source of the alkaloid noscapine?
Answer:
Poppy
Noscapine is a benzylisoquinoline alkaloid found in the opium poppy, Papaver somniferum. It is used medically as a cough suppressant (antitussive) and has been studied for potential anti-cancer properties. It is one of the many alkaloids extracted from the latex of the poppy plant.
4
What is the botanical term for the phenomenon where plant structures like stems or fruit valves curl together when dry and open when moistened?
Answer:
Hygrochasy
Hygrochasy is a mechanism of seed dispersal or movement where plant parts respond to changes in humidity. When the environment is dry, the tissues shrink and curl, often closing the fruit or protecting the seeds. When moisture is present, the tissues absorb water and expand, causing the structures to open and release the seeds, facilitating dispersal under favorable conditions.
5
What is the specific term for a fruit that develops from an entire hypanthodium inflorescence?
Answer:
Syconus
A syconus is a type of multiple fruit that develops from a hypanthodium, which is a specialized, fleshy, cup-shaped inflorescence axis. The flowers are located inside the cavity of this receptacle. A classic example of a syconus is the fig (Ficus carica), where the internal flowers develop into tiny achenes after pollination, collectively forming the mature fruit structure.
6
Which fruit is characterized by an edible fleshy thalamus?
Answer:
apple
In an apple, the edible part is the fleshy thalamus, which develops into a false fruit (pome). The true fruit is the core containing the seeds, while the thalamus grows around the ovary to form the fleshy portion consumed.
7
Botanically, how is the fruit of the litchi plant classified?
Answer:
Nut
The litchi fruit is botanically classified as a nut or a drupaceous nut. It features a hard, leathery pericarp (the shell) surrounding a single seed, which is covered by a fleshy, edible aril. This classification aligns with the structural characteristics of a nut.
8
Which specific mango variety is most notably affected by the physiological disorder known as 'spongy tissue'?
Answer:
Alphonso
Spongy tissue is a serious physiological disorder characterized by the development of a soft, spongy, and acidic patch in the fruit pulp. It is a major problem specifically in the 'Alphonso' mango variety, significantly impacting its export quality and market value. The exact cause is complex, involving heat and metabolic factors during fruit ripening.
9
What is the term for the fleshy, whitish outgrowth found at one end of a castor seed?
Answer:
Caruncle
In castor seeds (Ricinus communis), the caruncle is a specialized, fleshy, whitish outgrowth that develops from the integuments near the micropyle. It is also known as a strophiole. It plays a role in water absorption during germination and is often involved in seed dispersal by ants (myrmecochory).
10
Which of the following fruits is classified as a multiple fruit, developing from an entire inflorescence?
Answer:
Pineapple
A pineapple is a classic example of a multiple fruit (or composite fruit). It develops from the fusion of ovaries from many individual flowers clustered together on a single inflorescence. As the flowers mature, their ovaries and associated floral parts fuse to form a single, fleshy, collective fruit structure, unlike simple fruits like apples or grapes which develop from a single ovary.