Exams › NEET › Biology › Biological Classification
230 questions with worked solutions.
Q1. The smallest unit of classification is known as
Answer: species
Species is the smallest basic unit of biological classification. It groups organisms that are most closely related and can usually interbreed to produce fertile offspring.
Q2. Taxonomically, what is species?
Answer: A group of evolutionary related populations
A species is best understood taxonomically as a set of evolutionarily related populations sharing a common lineage. This is broader and more precise than only asking whether individuals can interbreed.
Q3. The system of giving one name to the individual is called
Answer: Uninomial system
A system that gives each individual only one name is called a uninomial system. The prefix “uni-” means one, which fits a single-name convention.
Q4. Genus is a group of similar and related
Answer: species
A genus is a taxonomic category made up of one or more closely related species. So the group of similar and related units within a genus are species.
Q5. The main difference in Gram (+ve and Gram (–)ve bacteria resides in their
Answer: cell wall
Gram-positive and Gram-negative bacteria differ mainly in their cell wall structure. Gram-positive bacteria have a thick peptidoglycan layer, while Gram-negative bacteria have a thinner peptidoglycan layer plus an outer membrane.
Q6. Photosynthetic bacteria have pigments in
Answer: chromatophores
Photosynthetic bacteria do not have chloroplasts or other plant plastids. Their photosynthetic pigments are located in chromatophores, which are membrane structures that contain the light-harvesting machinery.
Q7. A few organisms are known to grow and multiply at temperatures of 100–105°C. They belong to
Answer: marine archaebacteria
Organisms that grow at 100–105°C are hyperthermophiles, and many such organisms are archaea rather than true bacteria, algae, or fungi. Marine archaebacteria are known for thriving in extreme environments, including very high temperatures.
Q8. What is common about Trypanosoma, Noctiluca, Monocystis and Giardia?
Answer: These are all unicellular protists
Trypanosoma, Noctiluca, Monocystis, and Giardia are all protists, and each is unicellular. They do not all share the same mode of movement or parasitic habit, so the common feature is their being single-celled protists.
Q9. Which of the following statements is incorrect?
Answer: Yeasts have filamentous bodies with long thread-like hyphae.
Yeasts are generally unicellular and do not form long thread-like hyphae, so that statement is incorrect. The other options are correct facts about fungi and fungal products.
Q10. One of the major components of cell wall of most fungi is:
Answer: Chitin
Fungal cell walls are primarily built from chitin, a tough structural polysaccharide. Peptidoglycan is characteristic of bacteria, while cellulose and hemicellulose are typical plant wall components.
Answer: 32 × 10⁵ cells
A division every 35 minutes means 175 minutes gives 5 doublings. Starting from 10^5 cells/ml, doubling 5 times multiplies the count by 2^5 = 32, giving 32 × 10^5 cells/ml.
Answer: Anabaena
Anabaena is a nitrogen-fixing cyanobacterium that can live freely and also form a symbiotic association with Azolla. In this partnership, it helps supply fixed nitrogen to the fern.
Q13. Which aquatic fern performs nitrogen fixation?
Answer: Azolla
Azolla is an aquatic fern that hosts nitrogen-fixing cyanobacteria in its leaves, allowing it to fix atmospheric nitrogen. The other options are either not ferns or do not perform nitrogen fixation.
Q14. Which of the following can fix atmospheric nitrogen?
Answer: Anabaena
Anabaena is a cyanobacterium that can fix atmospheric nitrogen using specialized cells called heterocysts. The other options are water molds or parasitic fungi-like organisms and do not fix nitrogen.
Q15. Which of the following pairs is not correctly matched? Mode of reproduction - Example
Answer: Binary fission - Sargassum
Sargassum is a brown alga that reproduces mainly by fragmentation and other algal reproductive methods, not binary fission. Binary fission is typical of unicellular organisms like bacteria and Amoeba.
Q16. Infectious proteins are present in:
Answer: Prions
Prions are infectious proteins that lack both DNA and RNA. The other options are nucleic-acid-based agents, so they do not fit the definition of an infectious protein.
Q17. Chromosomes in a bacterial cell can be 1 – 3 in number and:
Answer: can be circular as well as linear within the same cell
Bacterial cells are not restricted to a single chromosome form. Some species can have multiple chromosomes, and in certain bacteria those chromosomes may include both circular and linear DNA within the same cell.
Q18. Which part of the tobacco plant is infected by Meloidogyne incognita?
Answer: Root
Meloidogyne incognita is a root-knot nematode, and it infects the roots of tobacco plants, where it induces characteristic galls. The above-ground parts listed are not its primary infection site.
Q19. A location with luxuriant growth of lichens on the trees indicates that the:
Answer: Location is not polluted
Lichens absorb water and nutrients directly from the air, so they are easily damaged by pollutants. Abundant lichen growth usually means the air is clean, so the location is not polluted.
Q20. Organisms which obtain energy by the oxidation of reduced inorganic compounds are called
Answer: chemoautotrophs
Chemoautotrophs obtain energy from chemical reactions involving inorganic substances and use that energy to fix carbon. The other options rely on light or organic matter instead.