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
Assess the following statements: 1. ATP is the energy currency of the cell. 2. Oxidation of fat yields the maximum amount of energy. 3. Alcohol is a byproduct of anaerobic respiration. Which of these are correct?
Answer:
1, 2 and 3
ATP is the primary energy carrier in cells. Fats contain more energy per gram than carbohydrates due to their highly reduced state, yielding more ATP upon oxidation. Anaerobic respiration (fermentation) in yeast produces ethanol and carbon dioxide as metabolic byproducts.
2
Which of the following is a naturally occurring radioactive isotope produced in the Earth's atmosphere?
Answer:
Radioactive carbon
Carbon-14 (radiocarbon) is a naturally occurring radioactive isotope produced in the upper atmosphere. It is formed when cosmic rays interact with nitrogen-14 atoms. This isotope is then incorporated into living organisms through carbon dioxide fixation during photosynthesis and subsequent ingestion, making it the basis for radiocarbon dating of organic materials.
3
Which law of thermodynamics states that every energy transformation results in an increase in entropy and a reduction in the availability of useful energy?
Answer:
Second law
The second law of thermodynamics dictates that in any closed system, the total entropy must increase over time. In biological systems, this means that energy transfers are never 100% efficient; some energy is always lost as heat, which increases the disorder (entropy) of the universe and decreases the energy available to perform work.
4
What is the term for the thermochemical decomposition of organic material at elevated temperatures in the absence of oxygen?
Answer:
Pyrolysis
Pyrolysis is a thermochemical process that involves the decomposition of organic materials at high temperatures in an inert atmosphere, specifically in the absence of oxygen. Unlike combustion, which requires oxygen, pyrolysis breaks down complex molecules into smaller components like char, bio-oil, and syngas. It is a fundamental process in industrial chemistry and biomass conversion.
5
What is the primary form of chemical energy produced during the process of cellular respiration?
Answer:
ATP
Cellular respiration is the metabolic process that converts biochemical energy from nutrients into adenosine triphosphate (ATP). ATP serves as the universal energy currency for cells, powering various biological functions including muscle contraction, active transport, and biosynthesis.
6
In what units is redox potential typically measured?
Answer:
Volts or milivolts
Redox potential, also known as reduction potential, measures the tendency of a chemical species to acquire electrons and thereby be reduced. It is expressed in volts (V) or millivolts (mV), representing the electrical potential difference relative to a standard hydrogen electrode.
7
All electrons possess the same intrinsic spin, which is characterized by a spin quantum number S, the magnitude of which is always
Answer:
$$\frac{1}{2}$$ (half)
Source answer preserved: option A ($$\frac{1}{2}$$ (half)). AI attempted to change protected answer data (option_a), so this item is flagged for manual review before study use.
8
What term describes the portion of total energy in a system that is available to perform thermodynamic work?
Answer:
Gibbs free energy
Gibbs free energy (G) is a thermodynamic potential that measures the maximum amount of reversible work that can be performed by a system at constant temperature and pressure. In biological systems, the change in Gibbs free energy (ΔG) determines whether a chemical reaction will occur spontaneously. If ΔG is negative, the reaction is exergonic and can release energy to do work.
9
What term describes the quantitative measure of a chemical species' tendency to acquire electrons and thereby be reduced?
Answer:
Redox potential
Redox potential, also known as reduction potential or oxidation-reduction potential, measures the affinity of a substance for electrons. It is expressed in volts or millivolts. A higher positive redox potential indicates a stronger tendency to gain electrons (act as an oxidizing agent), while a lower or negative potential indicates a stronger tendency to lose electrons (act as a reducing agent).
10
At temperatures above absolute zero, what form of energy do all components of matter possess due to their constant motion?
Answer:
Translational kinetic energy
According to the kinetic molecular theory, particles of matter are in constant, random motion at any temperature above absolute zero. This motion is characterized by translational kinetic energy, which is directly proportional to the absolute temperature of the substance, reflecting the average speed of the particles.