Questions & explanations
1. Which of the following statements best distinguishes growth in living organisms from growth in non-living objects?
- Growth in living organisms is always external and visible.
- Growth in living organisms occurs by accumulation of material from outside.
- Growth in living organisms involves cell division, while non-living growth is by accretion.
- Growth in non-living objects is irreversible.
Answer: Growth in living organisms involves cell division, while non-living growth is by accretion.
Living organisms grow by cell division, increasing cell number, whereas non-living things grow by accumulation of material (accretion) on their surface. The other options are incorrect because growth in living organisms can be internal, and non-living growth is often reversible (e.g., crystal dissolution).
2. Which property is considered the defining feature of living organisms that distinguishes them from non-living matter?
- Growth
- Reproduction
- Consciousness
- Metabolism
Answer: Consciousness
Consciousness, the ability to sense and respond to environmental stimuli, is considered the defining property of living organisms. While growth, reproduction, and metabolism are important, they are not unique to life (e.g., crystals grow, fire has metabolism-like reactions).
3. Which of the following statements about metabolism is correct?
- Metabolism refers only to catabolic reactions.
- Metabolic reactions can occur in vitro and are considered living.
- Metabolism is the sum total of all chemical reactions occurring in a living organism.
- Isolated metabolic reactions in a test tube are considered living.
Answer: Metabolism is the sum total of all chemical reactions occurring in a living organism.
Metabolism includes both anabolic and catabolic reactions. Isolated metabolic reactions in vitro are not living because they lack the integrated cellular environment. Only when these reactions occur within a living system do they constitute life.
4. Which of the following is NOT considered a defining characteristic of living organisms?
- Metabolism
- Growth
- Reproduction
- Cellular organisation
Answer: Reproduction
Reproduction is not a defining characteristic because there are exceptions like sterile organisms (e.g., mules) that do not reproduce but are still considered living. The other options are universally present in all living organisms.
5. Why is classification of organisms necessary?
- To increase the number of species
- To study the diversity of organisms in a systematic manner
- To create new species
- To eliminate unwanted organisms
Answer: To study the diversity of organisms in a systematic manner
Classification helps in organizing the vast diversity of organisms into groups based on similarities and differences, making it easier to study, identify, and understand relationships. It does not create or eliminate species.
6. Which of the following best defines a species in taxonomy?
- A group of organisms that can interbreed and produce fertile offspring
- A group of organisms with similar morphology only
- A group of organisms living in the same habitat
- A group of organisms that share the same diet
Answer: A group of organisms that can interbreed and produce fertile offspring
The biological species concept defines a species as a group of organisms capable of interbreeding and producing fertile offspring. Morphological similarity, habitat, or diet alone are not sufficient to define a species.
7. Approximately how many species have been described and documented on Earth?
- 1.0-1.2 million
- 1.7-1.8 million
- 2.5-3.0 million
- 5.0-6.0 million
Answer: 1.7-1.8 million
Current estimates indicate that about 1.7-1.8 million species have been described. The actual number of species on Earth is much higher, but only this many have been formally identified and catalogued.
8. Which of the following is an exception to reproduction being a defining property of life?
- Bacteria
- Fungi
- Mule
- Flowering plants
Answer: Mule
Mules are sterile hybrids and cannot reproduce, yet they are considered living. This shows reproduction is not a defining property of life. Bacteria, fungi, and flowering plants all reproduce.
9. Which of the following correctly follows universal rules of nomenclature?
- Homo sapiens
- homo Sapiens
- Homo Sapiens
- homo sapiens
Answer: Homo sapiens
In binomial nomenclature, the genus name is capitalised and the species name is lowercase; both are italicised or underlined. Homo sapiens follows this rule.
10. In the complete classification of mango (Mangifera indica), which is the correct order from kingdom to species?
- Plantae → Angiospermae → Dicotyledonae → Sapindales → Anacardiaceae → Mangifera → indica
- Plantae → Dicotyledonae → Angiospermae → Sapindales → Anacardiaceae → Mangifera → indica
- Plantae → Angiospermae → Dicotyledonae → Anacardiaceae → Sapindales → Mangifera → indica
- Plantae → Dicotyledonae → Angiospermae → Anacardiaceae → Sapindales → Mangifera → indica
Answer: Plantae → Angiospermae → Dicotyledonae → Sapindales → Anacardiaceae → Mangifera → indica
Mango classification: Kingdom Plantae, Division Angiospermae, Class Dicotyledonae, Order Sapindales, Family Anacardiaceae, Genus Mangifera, Species indica.
11. A group of related genera is called a:
- Species
- Family
- Order
- Class
Answer: Family
A family is a taxonomic category that groups together related genera. For example, the family Felidae includes genera like Felis and Panthera.
12. Who proposed the system of binomial nomenclature?
- Charles Darwin
- Carolus Linnaeus
- Aristotle
- Theophrastus
Answer: Carolus Linnaeus
Carolus Linnaeus, the Swedish botanist, developed binomial nomenclature, giving each species a two-word Latinised name (genus + species).