Subdivisions of Biology: notes and MCQs for State PSC prelims

Subdivisions of Biology is part of Biology. Below are notes on 9 sub-topics, followed by practice MCQs from State PSC and UPSC papers.

Anatomy

Anatomy: Branch of biology dealing with the structure of organisms and their parts.
Osteology: The scientific study of bones.
Histology: The scientific study of tissues.
Craniology: The scientific study of the human skull, including its shape, size, and other features.

Botany

Janaki Ammal: First Indian woman to receive Ph.D./honorary D. Sc. in Botany (University of Michigan).
Bryology: Study of mosses and liverworts.
Valley of Flowers ('फूलों की घाटी'): Discovered by Frank S. Smythe.
Birbal Sahni: Paleobotany.
K.C. Mehta: Plant Pathology.
P. Maheshwari: Embryology.
M.S. Swaminathan: Green Revolution.

Cell Biology (Cytology)

In a compound microscope, the correct sequence of light passage is: Condenser → Objective lens → Body tube → Eyepiece.
When using centrifuges, tubes must be filled to the same level and placed at opposite locations to ensure proper balance.
Good laboratory ethics includes documenting mistakes, ensuring transparency, and reporting accurate information.

Ecology

Ecology: Study of interactions among organisms and between organisms and their physical environment.
Population: A group of organisms of one species, living in the same area at the same time.
Community: A group of different species living and interacting in the same area.
Food Chain: Shows the flow of energy, e.g., Grass (producer) → Goat (primary consumer) → Human (secondary consumer).
Decomposers: Heterotrophic organisms (chiefly bacteria and fungi) that break down complex organic compounds of dead matter into simple usable substances.
Aquatic Food Chain Example: Diatoms (producers) → Crustaceans (primary consumers) → Herrings (secondary consumers).
Primary Producers in Oceans: Cyanobacteria and Diatoms.
Necton: Swimming organisms in water.
Plankton: Organisms floating in water.
Upper Sea Aquatic Ecosystem: Contains both plankton and nekton.
Man in Food Chain: Can be a primary consumer (herbivore) and a secondary consumer (carnivore/omnivore).
Composting: Process of decomposing organic matter, primarily involves aerobic digestion.
Symbiosis:

Commensalism: One member benefits, the other is neither benefited nor harmed.
Parasitism: One member benefits (parasite) at the expense of the other (host).
Mutualism: Both members benefit from the interaction.

Population Growth with Unlimited Resources: Exhibits exponential growth (Jshaped curve).
10% Law: States that only about 10% of the energy is transferred from one trophic level to the next; proposed by Lindemann.
Competitive Exclusion Principle: States that two species competing for the same limited resources cannot coexist stably; proposed by Gause.
Biomagnification: Increase in concentration of non-metabolized, non-excreted toxicants (e.g., DDT, heavy metals) at successive trophic levels in a food chain.
BOD (Biological Oxygen Demand): The amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample at a certain temperature over a specific time.
Biophilia: Means an urge to affiliate with other forms of life.
Ozone Layer: Absorbs harmful Ultra-Violet (UV) rays from the sun.
Biodegradable Materials: Substances that can be decomposed by natural processes (e.g., woollen mat, leather bag, jute basket).
Non-biodegradable Materials: Substances that cannot be decomposed by natural processes (e.g., silver foil).

Evolutionary Biology

Palaeontology: Study of plant and animal fossils.
Gerontology: Study of ageing.
Relative Biological Effectiveness (RBE): Damage is a result of radiation exposure.
Effective Dose-50% (ED50): Dose resulting in a significant response in 50% of subjects.
Wilhelm Wundt: Established the first Psychology Laboratory at Leipzig University, Germany.
Crow & Crow: Defined Educational Psychology as the branch dealing with teaching and learning.
Functionalism (Psychology): Associated with William James, John Dewey, James R. Angell.
E.B. Titchener: Associated with Structuralism, not Functionalism.
Narcissism: Characteristic often more powerful during Late Adolescence stage of development.

Genetics

Genetics: Branch of biology studying heredity and variation in living organisms.
Heredity: Transmission of characteristics from parents to offspring.
Variation: Differences among individuals of the same species.
Coefficient of Variation (CV): A statistical measure of the relative dispersion of data points around the mean.
CV Calculation: (Standard Deviation / Mean) × 100%.
CV Purpose: Used to compare the relative variability or dispersion between two or more data sets, especially when they have different units of measurement (e.g., plant height in cm, seed weight in g) or vastly different means. It provides a unitless comparison.

Microbiology

Curd formation from milk is due to bacteria (e.g., Lactic Acid Bacteria).
Bacteria that feed on decaying organic matter are heterotrophic (specifically saprophytic).
E. coli is a common indicator organism for polluted water, particularly fecal contamination.
Denitrification (conversion of nitrates to nitrogen gas) is primarily carried out by bacteria.
The limiting water activity ($Aw$) for the growth of any microorganism is approximately 0.60 (e.g., for xerophilic molds). Most bacteria require $Aw > 0.91$.
Louis Pasteur discovered the process of fermentation.

Physiology

Physiology: Branch of biology that studies the normal functions of living organisms and their parts.
Living vs. Non-living Beings:

Living beings demonstrate growth, repair, and metabolic processes.
Non-living beings do not exhibit these characteristics.

Bionics: The study of functions, characteristics, and phenomena observed in the living world and the application of this knowledge to machines.
Adolescence:

Described as the "stage of stress and storm" by Stanley Hall.
At its terminal stage, muscle weight constitutes approximately 45% of the total body weight.

Svante Pääbo: Awarded the Nobel Prize in Physiology or Medicine in 2022.
Sound Waves:

In air, sound waves are longitudinal.
Speed of sound is maximum in solids (e.g., metals), followed by liquids, then gases; it cannot travel in a vacuum.

Liquid Volume Units: Common units include Litre (L) and millilitre (ml).
Candle Burning: Involves both physical changes (e.g., wax melting) and chemical reactions (e.g., combustion).
Formalin: An aqueous solution of formaldehyde.
Wastewater Treatment - Trickling Filters: Always provided between the primary sedimentation tank and the final settling tank to remove organic solids.
Wastewater Treatment - Grit Chambers:

Grit particles typically range from 0.1 to 1 mm in size.
Stokes' Law is applicable for settling particles with a diameter less than 1 mm.
The loss of head in a grit chamber

Sludge Index: The ratio of the volume of activated sludge typically varies from 150 to 300.
Imhoff Tank: Gas vent area is generally provided as 20 to 25% of the plan area.
High-Rate Trickling Filter: The depth of the

Zoology

Acarology: Study of Mites and Ticks.
Cetology: Study of Whales and Dolphins.
Geoponics: Study of Agriculture.
Ichthyology: Study of Fish.
Dr. Salim Ali: Renowned Ornithologist, known as 'Bird Man of India'.
Ornithology: Scientific study of Birds.
Entomology: Study of Insects.
Mycology: Study of Fungi.
Phycology: Study of Algae.
Desmology: Study of Ligaments.
Aristotle: Father of Biology.
Theophrastus: Father of Botany.
Hippocrates: Father of Medicine.
Gregor Johann Mendel: Father of Genetics.
Sericulture: Rearing of Silk worms for silk production.
Silk: An animal product.
Apiculture (Bee-keeping): Culture of Honey bees for honey production.
Horticulture: Cultivation and maintenance of gardens.
Aquaculture: Farming of aquatic organisms.
Pisciculture: Rearing of Fish.
Products obtained from insects: Silk, Honey, Lac.
Pearl: Obtained from molluscs, not insects.
Common Myna: A bird known to stalk alongside cattle for insects disturbed by their movement.
Zoology: Study of animals, encompassing both living and dead organisms.
National Research Centre on Pig: Located at Guwahati.
Naphthalene balls: Used as an Insect repellent.
Ethology: Science of animal behaviour.
NEET: Entrance examination for MBBS (Bachelor of Medicine, Bachelor of Surgery) and BDS (Bachelor of Dental Surgery) courses.

2. Evolution of Life

Practice MCQs: Subdivisions of Biology

Anatomy

The study of bones is done under the branch of science called
Asked in: BPSC Prelims Exam 65th
1. geology
2. serology
3. orology
4. osteology
Show answer
Answer: D. osteology
The scientific study of bones is called osteology.
‘Histology’ is associated with Study of tissues Study of heart diseases Study of finger prints Science of plant kingdom
Asked in: Assistant Engineer (AE) Exam 2012
1. Study of tissues
2. Study of finger prints
3. Study of heart diseases
4. Science of plant kingdom
Show answer
Answer: A. Study of tissues
Histology is a branch of biology that studies the microscopic anatomy of biological tissues.
What is Craniology?
Asked in: LAW OFFICER CUM JUNIOR DRAFTSMAN 2018
1. The scientific study of the human skull in terms of shape, size etc.
2. The scientific study of the internal organs of the human torso
3. The scientific study of a particular species of cranes
4. None of the above
Show answer
Answer: A. The scientific study of the human skull in terms of shape, size etc.
Craniology is a sub-discipline within physical anthropology that focuses on the study of skulls. It involves measuring and comparing skull features to understand human variation, evolution, and relationships.

Botany

Janaki Ammal was the first Indian woman to get a Ph.D. and an honorary D. Sc. from the University of Michigan in which subject ?
Asked in: HAS Prelims 2019
1. Physics
2. Mathematics
3. Chemistry
4. Botany
Show answer
Answer: D. Botany
- E. K. Janaki Ammal (1897–1984) was a renowned Indian botanist and cytogeneticist. - She obtained her Ph.D. in Botany from the University of Michigan in 1931. - The University of Michigan also awarded her an honorary D. Sc. later in her career (1956).
What is 'Bryology'?
Asked in: HOMOEOPATHIC MEDICAL OFFICER 1 2023
1. Study of ringworm
2. Study of food
3. Study of fruit
4. Study of mosses and liverworts
Show answer
Answer: D. Study of mosses and liverworts
The question is a direct definition of a scientific term. Understanding specialized branches of science is common in UPSC examinations.
‘फू लों की घाटी’ की खोज ͩकसने की ?
Asked in: Data Entry Operator 2023
1. जोसफ हुकर
2. lविlलियम मूरक्रॉफ्ट
3. फ्रैं क lÖमथ
4. नैनlसंह रावित
Show answer
Answer: A. जोसफ हुकर
Joseph Hooker is credited with the discovery and exploration of the Valley of Flowers.
Match list-I with list-II and select the correct answer from the code given below the lists – List-I (Name of Scientist) A Birbal Sahni B K.C. Mehta C P. Maheshwari D M.S. Swaminathan List-II (Area of work) 1 Green Revolution 2 Embryology 3 Paleobotany 4 Plant pathology Code - (a) A-1, B-2, C-3, D-4 (b) A-3, B-4, C-2, D-1 (c) A-2, B-1, C-3, D-4 (d) A-4, B-3, C-2, D-1
Asked in: RO ARO Mains 2021
1. A-1, B-2, C-3, D-4
2. A-3, B-4, C-2, D-1
3. A-2, B-1, C-3, D-4
4. A-4, B-3, C-2, D-1
Show answer
Answer: B. A-3, B-4, C-2, D-1
Birbal Sahni - Paleobotany, K.C. Mehta - Plant pathology, P. Maheshwari - Embryology, M.S. Swaminathan - Green Revolution.

Cell Biology (Cytology)

Which one of the following is the correct sequence of passage of light in a compound microscope?
Asked in: UPSC CDS 1 2019
1. Condenser—Objective lens—Eyepiece— Body tube
2. Objective lens—Condenser—Body tube— Eyepiece
3. Condenser—Objective lens—Body tube— Eyepiece
4. Eyepiece—Objective lens—Body tube—Mir‐ ror
Show answer
Answer: C. Condenser—Objective lens—Body tube— Eyepiece
The correct sequence for light passage in a compound microscope is typically Condenser -> Specimen -> Objective lens -> Body tube -> Eyepiece.
When using centrifuges, the contents of centrifuge tubes must be
Asked in: JUNIOR laboratory assistant 2025
1. Filled to the same level and placed at same locations
2. Filled to the same level and placed at opposite locations
3. Filled to the different level and placed ran‐ domly
4. All of the above
Show answer
Answer: B. Filled to the same level and placed at opposite locations
Centrifuges operate by spinning samples at high speeds. Proper balancing of the centrifuge rotor is essential for safe and effective operation.
Example of good laboratory ethics is
Asked in: JUNIOR laboratory assistant 2025
1. The Intentional recording or reporting incorrect information
2. The Intentional misrepresentation of laborat‐ ory data to hide known or potential problems
3. Documenting mistakes
4. All of the above
Show answer
Answer: C. Documenting mistakes
Good laboratory ethics involve principles of integrity, honesty, and responsibility in scientific research.

Ecology

While studying vegetation of an area, terms like 'population' and 'community' are often used. Which one of the following statements best describes a population ?
Asked in: UPSC CDS 2 2021
1. A group of organisms of one species, living in the same area at the same time.
2. A group of organisms of one species living in different areas during different seasons.
3. A unit consisting of biotic and abiotic compon‐ ents.
4. A group of organisms of more than one spe‐ cies, living in the same area at the same time.
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Answer: A. A group of organisms of one species, living in the same area at the same time.
The defining characteristics of a biological population are that the organisms must be of the same species, live in the same geographical area, and exist at the same time.
Which of the following constitute a food chain ?
Asked in: CGPSC Prelims Exam 2016
1. Grass Wheat Mango
2. Grass Goat Human
3. Goat Crow Elephant
4. Grass Fish Goat
Show answer
Answer: B. Grass Goat Human
Option B, "Grass Goat Human", represents a valid food chain where Grass is the producer, Goat is the primary consumer (herbivore) feeding on grass, and Human is a secondary or tertiary consumer feeding on the goat or products derived from it. This shows a clear sequence of who eats whom.
Heterotrophic organisms, chiefly bacteria and fungi that breakdown the complex compounds of dead protoplasm and release simple usable substances for other organisms are :
Asked in: MPSC CS Prelims 2014
1. Autotrophs
2. Decomposers
3. Consumers
4. Omnivorous
Show answer
Answer: B. Decomposers
In an ecosystem, organisms play different roles in the flow of energy and nutrients. Decomposers are crucial for nutrient cycling by breaking down dead organic matter.
Which one of the following is the correct sequence of a food chain?
Asked in: UPSC IAS 2014
1. Diatoms-Crustaceans-Herrings
2. Crustaceans-Diatoms-Herrings
3. Diatoms-Herrings-Crustaceans
4. Crustaceans-Herrings-Diatoms
Show answer
Answer: A. Diatoms-Crustaceans-Herrings
- Food chains illustrate the flow of energy through an ecosystem. - The sequence starts with producers, followed by consumers at different trophic levels. - Diatoms (phytoplankton) are producers. - Crustaceans (zooplankton) are primary consumers. - Herrings (fish) are secondary consumers.
Consider the following kinds of organisms : 1. Copepods 2. Cyanobacteria 3. Diatoms 4. Foraminifera Which of the above are primary producers in the food chains of oceans?
Asked in: UPSC IAS 2021
1. 1 and 2
2. 2 and 3
3. 3 and 4
4. 1 and 4
Show answer
Answer: B. 2 and 3
Primary producers in the ocean are photosynthetic organisms, primarily phytoplankton like cyanobacteria and diatoms, which form the base of the marine food web.
Which one of the following groups of organisms correctly makes a food chain ?
Asked in: UPSC CISF AC EXE 2023
1. Grass, Goat, Human
2. Elephant, Goat, Grass
3. Tiger, Snake, Grass
4. Insect, Frog, Grass
Show answer
Answer: A. Grass, Goat, Human
- A food chain starts with a producer (organism that makes its own food, usually plants). - The arrows in a food chain indicate the direction of energy flow (from the organism being eaten to the organism that eats it). - The sequence is typically Producer -> Primary Consumer (Herbivore) -> Secondary Consumer (Carnivore/Omnivore) -> Tertiary Consumer, etc.
Necton are
Asked in: WBPSC CS Prelims 2017
1. floating organisms in water.
2. swimming organisms in water.
3. animals associated with aquatic plants.
4. sub-merged plants in water.
Show answer
Answer: B. swimming organisms in water.
Aquatic organisms are broadly classified based on their mode of life and movement in water. - Plankton are organisms (plants - phytoplankton, and animals - zooplankton) that float or drift in the water, largely dependent on currents for movement. - Benthos are organisms that live on or in the bottom substrate of an aquatic environment. - Nekton (or Necton) are organisms that are active swimmers and can move independently of water currents. This includes fish, marine mammals, squid, etc. Options A, C, and D do not accurately describe Necton. Floating organisms are plankton. Animals associated with aquatic plants could be either plankton, benthos, or nekton depending on their mobility. Sub-merged plants are producers, not necessarily defined by their mobility in this classification.
In a food chain, man is
Asked in: UPPCS Prelims 2016
1. producer
2. only primary consumer
3. only secondary Consumer
4. primary as well as secondary consumer
Show answer
Answer: D. primary as well as secondary consumer
Humans are omnivores, consuming both plant and animal matter.
Composting of organic matter involves
Asked in: APPSC Panchayat secretary Prelims 2016
1. Anaerobic digestion
2. Aerobic digestion
3. Fermentation
4. Combustion
Show answer
Answer: B. Aerobic digestion
Composting relies on microorganisms that require oxygen to break down organic waste efficiently.
Which form of symbiosis benefits one member of the interaction, but neither benefits nor harms the other member?
Asked in: WBCS Main Paper 4 2022
1. Parasitism
2. Commensalism
3. Sequentialism
4. Mutualism
Show answer
Answer: B. Commensalism
Symbiosis refers to any type of a close and long- term biological interaction between two different biological organisms. The main types are mutualism (both benefit, +/+), commensalism (one benefits, other unaffected, +/0), and parasitism (one benefits, other is harmed, +/-). Predation and competition are other types of ecological interactions but not typically classified under symbiosis in this narrow sense.
A population has unlimited resources and exhibits rapid and sustained population growth.
Asked in: WBCS Main Paper 4 2022
1. Exponential
2. Logistic
3. Sigmoidal
4. Parabolic
Show answer
Answer: A. Exponential
This type of growth would be best described by which one of the following? Exponential population growth occurs when resources are unlimited, allowing the population to grow at a constant per capita rate. The growth rate accelerates as the population size increases, leading to a J-shaped growth curve.

Evolutionary Biology

Palaeontology is the study of:
Asked in: HAS Prelims 2019
1. Plant and animal fossils
2. Rocks
3. Volcanoes
4. Atmosphere
Show answer
Answer: A. Plant and animal fossils
- Palaeontology focuses on the life forms of past geological periods. - The primary evidence studied in palaeontology consists of fossils, which are the preserved remains or traces of organisms.
Fact 1 : All chickens are birds. Fact 2 : Some chickens are hens. Fact 3 : Female birds lay eggs. If the first three statements are facts, which of the following statement/(s) must also be a fact ? I. All birds lay eggs. II. Hens are birds. III. Some chickens are not hens. Choose the correct answer from the options given below :
Asked in: KPSC KAS Prelims 2017
1. Only II
2. Only II and III
3. I, II and III
4. None of the statements is a known fact
Show answer
Answer: A. Only II
Fact 1 states that all chickens are birds. Fact 2 states that some chickens are hens. The structure of Fact 2 implies that hens are a type of chicken. Therefore, if something is a hen, it is a chicken, and since all chickens are birds (Fact 1), it must also be a bird. Statement II ("Hens are birds") logically follows from Fact 1 and Fact 2. Statement I ("All birds lay eggs") does not follow, as Fact 3 states only female birds lay eggs, and not all birds are female. Statement III ("Some chickens are not hens") does not necessarily follow from Fact 2 ("Some chickens are hens") under a strict logical interpretation where "some" means "at least one". It is consistent with the facts that all chickens are hens, although common language might imply otherwise. In strict logic, Fact 2 does not guarantee the existence of chickens that are not hens. Therefore, only Statement II is a logical consequence of the given facts.
The study of ageing is known as
Asked in: UPPSC Upper Mains 2014
1. Gerontology
2. Ethnology
3. Anthropology
4. Thanatology
Show answer
Answer: A. Gerontology
Gerontology is the specific field dedicated to the study of the aging process.
Which is the result of damage to relative biological effectiveness?
Asked in: WBCS Main Paper 4 2022
1. High temperature
2. Pollution
3. Radiation
4. Low temperature
Show answer
Answer: C. Radiation
Relative Biological Effectiveness (RBE) is a concept used in radiobiology and health physics to compare the effectiveness of different types of ionizing radiation in causing biological damage. RBE is defined relative to a standard radiation (usually X-rays or gamma rays). Different types of radiation (e.g., alpha, beta, gamma, neutrons) have different RBE values, meaning they cause different amounts of biological damage for the same amount of absorbed energy.
"Effective dose-50%" describes which one of the following?
Asked in: WBCS Main Paper 4 2022
1. The dose that results in 50% mortality
2. The dose that results in 50% survival
3. The dose that is 50% less than the lethal dose
4. The dose that results in a significant response in 50% of subjects
Show answer
Answer: D. The dose that results in a significant response in 50% of subjects
ED50 (median effective dose) is a measure used in pharmacology and toxicology to indicate the effectiveness of a drug or toxic substance. It is defined as the dose of a medication or substance that produces a specific effect (e.g., therapeutic response, pain relief) in 50% of the test population.
Who established first Laboratory of Psychology in Leipzig University, Germany ?
Asked in: Sr. Teacher Gr II (Sanskrit Edu.) Exam 2018 1 2018
1. J.B. Watson
2. Francis Galton
3. Wilhelm Wundt
4. James Drever
Show answer
Answer: C. Wilhelm Wundt
Wilhelm Wundt is considered the "father of experimental psychology" for his pioneering work in establishing psychology as a scientific discipline through empirical research in a dedicated laboratory setting.
Who stated that "Educational Psychology is that branch of Psychology which deals with Teaching and Learning" ?
Asked in: Sr. Teacher Gr II (Sanskrit Edu.) Exam 2018 1 2018
1. B.F. Skinner
2. James Drever
3. E.L. Thorndike
4. Crow & Crow
Show answer
Answer: A. B.F. Skinner
This quote by B.F. Skinner defines the scope and focus of Educational Psychology, emphasizing its role in understanding and improving the processes of teaching and learning. Skinner was a prominent behaviorist psychologist.
Out of the following which Psycholo gist is not related with 'functionalism' ?
Asked in: Sr. Teacher Gr II (Sanskrit Edu.) Exam 2018 1 2018
1. William James
2. John Dewey
3. James R. Angell
4. E.B. Titchener
Show answer
Answer: D. E.B. Titchener
Functionalism was a school of psychology that emerged in the United States, focusing on the purpose and function of the mind and behavior in adapting to the environment. Structuralism, in contrast, focused on the basic elements of consciousness.
In which stage of Development "Narcissism" characteristics is more powerful ?
Asked in: Sr. Teacher Gr II (Sanskrit Edu.) Exam 2018 1 2018
1. Infancy
2. Childhood
3. Early adulthood
4. Late adolescence
Show answer
Answer: A. Infancy
In psychoanalytic theory, the concept of narcissism refers to a focus on oneself. Infancy is often characterized by a strong sense of self-absorption due to the developmental stage and dependency on primary caregivers.

Genetics

Variation between plant height and seed weight can be compared using
Asked in: Agri. Officer 2020
1. Range
2. Coefficient of variation
3. Standard deviation
4. All of these
Show answer
Answer: D. All of these
- Range The difference between the maximum and minimum values in a dataset. It gives a simple idea of the spread but is sensitive to outliers. - Standard Deviation A measure of the amount of variation or dispersion of a set of values. A low standard deviation indicates that the values tend to be close to the mean, while a high standard deviation indicates that the values are spread out over a wider range. - Coefficient of Variation (CV) The ratio of the standard deviation to the mean, expressed as a percentage. It is a useful measure for comparing variability between datasets with different means and units, making it ideal for comparing plant height and seed weight, which have different scales.

Microbiology

Making of Curd from Milk is because of:
Asked in: RPSC RAS Prelims 2010
1. Virus
2. Bacteria
3. Prozoa
4. Other
Show answer
Answer: B. Bacteria
Specific types of lactic acid bacteria (LAB), such as Lactobacillus bulgaricus and Streptococcus thermophilus, are added to milk. These bacteria consume the lactose sugar in milk and produce lactic acid as a byproduct. The increase in acidity causes the casein proteins in milk to coagulate and thicken, forming curd.
Bacteria that feed upon decaying organic matter in the soil would best be described as which one of the following?
Asked in: WBCS Main Paper 4 2022
1. Heterotrophic
2. Autotrophic
3. Fungi
4. Cyanobacteria
Show answer
Answer: A. Heterotrophic
Organisms that feed upon decaying organic matter are obtaining energy and nutrients from external organic compounds. This mode of nutrition, where an organism cannot produce its own food and relies on consuming other organisms or organic matter, is known as heterotrophic nutrition. Decomposers like many bacteria and fungi are heterotrophs that break down dead organic material.
The most common indicator organism that represents polluted water is
Asked in: WBCS Main Paper 4 2022
1. C.vibrio
2. Entamoeba histolytica
3. E.coli
4. P.typhi
Show answer
Answer: C. E.coli
E. coli is a bacterium that is normally found in the intestines of warm-blooded animals, including humans. Its presence in water indicates that the water has been contaminated with fecal matter, which may contain various disease-causing pathogens.
The following organism helps in denitrification:
Asked in: WBCS Main Paper 4 2023
1. Fungi
2. Bacteria
3. Algae
4. Protozoa
Show answer
Answer: B. Bacteria
Denitrification is a microbially-facilitated process where nitrate (NO₃⁻) is reduced and eventually produces molecular nitrogen (N₂) gas. This process is carried out by a diverse group of bacteria in anaerobic conditions.
What is the limiting value of water activity for the growth of any microorganism ?
Asked in: Food Safety Officer 2019
1. $A_w$ 0.75
2. $A_w$ 0.88
3. $A_w$ 0.60
4. $A_w$ greater than 0.91
Show answer
Answer: C. $A_w$ 0.60
- Water activity ($A_w$) is a measure of the unbound water available in a system, which is essential for microbial growth. - Lower $A_w$ values inhibit microbial growth by causing osmotic stress, drawing water out of the microbial cells. - Most bacteria require a high $A_w$ (around $A_w$ values, with some xerophilic molds growing down to $A_w$ 0.60.
Who discovered the process of fermentation ?
Asked in: ASO 2025
1. Robert Koch
2. Joseph Lister
3. Ernst Haeckel
4. Louis Pasteur
Show answer
Answer: D. Louis Pasteur
Louis Pasteur discovered that microorganisms cause fermentation.

Physiology

Sound wave in air is
Asked in: BPSC Prelims Exam 65th
1. transverse
2. longitudinal
3. electromagnetic
4. polarized
Show answer
Answer: B. longitudinal
Sound waves in air are longitudinal waves.
Which of the following statements about living and non-living being is/are correct? 1. While living being can demonstrate growth and repair, non-living being cannot. 2. While living being demonstrates metabolic processes, non-living being does not. Select the correct answer using the code given below.
Asked in: UPSC NDA 1 2022
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Show answer
Answer: C. Both 1 and 2
Growth in living organisms is an internal process, while growth in non-living matter is external accumulation. Metabolism is a unique feature of living organisms.
The study of Functions, Characteristics and phenomena observed in the living world and the application of this knowledge to the world of Machines is known as:
Asked in: RPSC RAS Prelims 1995
1. Bionics
2. Bionomics
3. Bionomy
4. Biometry
Show answer
Answer: A. Bionics
Bionics translates biological principles into engineering solutions.
द्रव का आयतन मात्रक है
Asked in: JUNIOR ACCOUNTANT AND TRA 2013
1. L
2. m.l.
3. ml.
4. ltr.
Show answer
Answer: A. L
The standard unit of volume in the International System of Units (SI) is the cubic meter (m³). However, for liquids, the liter (L) is widely used and accepted. A liter is defined as 1 cubic decimeter (1 dm³), which is equal to 1000 cubic centimeters (1000 cm³) or 1000 milliliters (1000 ml).
मोमबत्ती के जलने के प्रक्रम में शाͧमल हैं (1) के वल भौǓतक अͧभͩक्रयाएँ (2) के वल रासायǓनक अͧभͩक्रयाएँ (3) भौǓतक और रासायǓनक दोनों अͧभͩक्रयाएँ (4) के वल रासायǓनक पǐरवतर्तन
Asked in: JUNIOR ACCOUNTANT AND TRA 2013
1. के विलि भौlतक अlभlक्रयाएँ
2. के विलि रासायlनक अlभlक्रयाएँ
3. भौlतक और रासायlनक दोनों अlभlक्रयाएँ
4. के विलि रासायlनक पåरवितर्तन
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Answer: C. भौlतक और रासायlनक दोनों अlभlक्रयाएँ
The burning of a candle involves both physical and chemical processes. The heat from the flame melts the solid wax, which then rises up the wick as a liquid. This liquid wax vaporizes and then undergoes combustion, a chemical reaction with oxygen in the air, producing heat, light, carbon dioxide, and water vapor.
The trickling filters are always provided between ______ to remove organic solids produced in filtration.
Asked in: Local Self Government Dept. Exam 2022
1. intermittent filters and contact beds
2. intermittent filters and final settling tank
3. primary sedimentation tank and final settling tank
4. screening and primary sedimentation tank
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Answer: C. primary sedimentation tank and final settling tank
- Trickling Filter A secondary wastewater treatment process where wastewater is distributed over a bed of filter media, allowing biological organisms to break down organic matter. - Treatment Sequence In a typical wastewater treatment plant, the sequence of operations involving trickling filters is: Screening -> Primary Sedimentation Tank -> Trickling Filter -> Final Settling Tank. - Purpose Trickling filters are used to remove dissolved and suspended organic solids from wastewater. The organic solids produced during filtration are removed in the subsequent final settling tank.
Read the below given statements carefully and identify the correct statements : A. Generally grit particles lie between 0.1 to 1 mm in size. B. Stokes law holds good for settling of particles of diameter less than 1 mm. C. Usually the detention period of grit chambers is 60 min. D. The loss of head in a grit chamber varies from
Asked in: Local Self Government Dept. Exam 2022
1. A and D
2. B and C
3. A and C
4. B and D
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Answer: A. A and D
- Grit Chamber Design Grit chambers are designed to remove heavy inorganic solids (grit) from wastewater. - Particle Size Grit particles are typically in the size range of 0.1 mm to 1 mm. - Stokes' Law Applicability Stokes' Law is applicable for settling of particles generally up to 0.1 mm in diameter. - Detention Period Grit chambers have short detention periods (1-3 minutes) to allow grit settling without settling organic solids. - Head Loss The head loss in grit chambers is kept low (0.06 to 0.6 m) to facilitate grit removal without removing organic matter.
The sludge index is the ratio of the volume of activated sludge varies from
Asked in: Local Self Government Dept. Exam 2022
1. 0 to 100
2. 150 to 300
3. 350 to 500
4. 400 to 550
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Answer: A. 0 to 100
- Sludge Index (SI) / Sludge Volume Index (SVI) A parameter used to evaluate the settling properties of activated sludge. - Definition Volume (in ml) occupied by 1 gram of dry solids of activated sludge after settling for 30 minutes. - Desirable Range Typically, the SI is expected to be between 0 and 100 for good settling. Values higher than this indicate potential problems like sludge bulking. - Interpretation A low SI indicates that the sludge settles compactly, while a high SI means the sludge is dispersed and settles poorly.
The gas vent area for Imhoff tank is provided as
Asked in: Local Self Government Dept. Exam 2022
1. 5 to 8% of the plan area.
2. 30 to 35% of the plan area.
3. 10 to 15% of the plan area.
4. 20 to 25% of the plan area.
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Answer: A. 5 to 8% of the plan area.
- Imhoff Tank A two-story wastewater treatment tank designed for primary treatment and sludge digestion. - Gas Vent A space or opening designed to release gases produced during sludge digestion. - Area Requirement The gas vent area in an Imhoff tank is generally designed to be 5% to 8% of the tank's total plan area.
Identify the figure :
Asked in: Local Self Government Dept. Exam 2022
1. Single Stack System
2. One-Pipe System
3. Two-Pipe System
4. Single Stack Partially Ventilated System
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Answer: B. One-Pipe System
- One-Pipe System A plumbing system where a single pipe handles both wastewater discharge and ventilation. - Key Feature A single pipe receives waste from multiple fixtures and also carries away sewer gases through vent pipes connected to the system. - Alternative Systems - Single Stack System Similar to the one-pipe system, but often without extensive venting, relying more on the inherent trap seals. - Two-Pipe System Uses separate pipes for wastewater discharge and for venting. - Single Stack Partially Ventilated System A variation of the single stack system with limited or strategically placed vents.
The depth of tank for a high-rate trickling filter may vary from Ans: A High-rate trickling filters are designed with tional trickling filters to optimize aerobic conditions and performance. 59. Who stated adolescence is the "stage of stress and storm"?
Asked in: Local Self Government Dept. Exam 2022 · Sr. Teacher Gr II (Sanskrit Edu.) Exam 2018 1 2018
1. Ross
2. Valentine
3. Stanley Hall
4. Biggi and Hunt
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Answer: C. Stanley Hall
G. Stanley Hall described adolescence as a period of "storm and stress," characterized by heightened emotions, conflicts, and significant developmental changes.

Zoology

Match the names of the branches of the biological studies given in Column I with their areas of specialization in Column II and select the correct answer using the options given below the columns: Column I Column II 1. Acarology a. Study of Fish 2. Cetology b. Study of Agriculture 3. Geoponics c. Study of Mites 4. Ichthyology d. Study of Whales and Dolphins
Asked in: HAS Prelims 2019
1. 1-a, 2-b, 3-c, 4-d
2. 1-b, 2-c, 3-d, 4-a
3. 1-c, 2-d, 3-b, 4-a
4. 1-d, 2-a, 3-b, 4-c
Show answer
Answer: C. 1-c, 2-d, 3-b, 4-a
Matching the branches of biological studies with their areas of specialization: 1. Acarology: The study of mites and ticks. (1-c) 2. Cetology: The branch of marine mammal science that studies the approximately eighty species of whales, dolphins, and porpoises in the scientific order Cetacea. (2-d)
Geoponics: The art or science of cultivating the earth; farming or agriculture. (3-b) 4. Ichthyology: The branch of zoology devoted to the study of fish. (4-a) 65. Match the following branches of Biology given in List I with their areas of specialization given in List II and select the correct answer from the options given below: List I List II 1. Acrology a. Study of fish 2. Citology b. Study of agriculture 3. Geoponics c. Study of mites and ticks 4. Ichthyology d. Study of whales and dolphins
Asked in: HAS Prelims 2019
1. 1-a, 2-b, 3-c, 4-d
2. 1-b, 2-c, 3-d, 4-a
3. 1-c, 2-d, 3-b, 4-a
4. 1-d, 2-a, 3-b, 4-c
Show answer
Answer: C. 1-c, 2-d, 3-b, 4-a
This question is identical to ID 11417. Assuming the intended terms despite possible typos in the list:
Acrology (likely intended as Acarology): The study of mites and ticks. (1-c) 2. Citology (likely intended as Cetology): The study of whales and dolphins (Cetaceans). (2-d) (Note: Cytology is the study of cells, which is not an option in List II). 3. Geoponics: The study of cultivating plants in soil; agriculture. (3-b) 4. Ichthyology: The study of fish. (4-a) 66. "Dr. Salim Ali" is a well known
Asked in: KPSC KAS Prelims 2014
1. Ornithologist
2. Biologist
3. Environmentalist
4. Dermatologist
Show answer
Answer: A. Ornithologist
Dr. Salim Ali (Salim Moizuddin Abdul Ali) was a renowned Indian ornithologist and naturalist. He is often referred to as the "Birdman of India" for his extensive work on the study and conservation of birds.
Match the study disciplines (List I) with the subjects of study (List II) : List I List II (Study Discip‐ (Subject of line) Study)
Asked in: KPSC KAS Prelims 2015
1. Entomology I. Algae
2. Mycology II. Fungi
3. Phycology III. Insects Liga‐
4. Desmology IV. ments Select the code for the correct answer from the options given below : A. A-III, B-II, C-IV, D-I B. A-III, B-II, C-I, D-IV C. A-II, B-III, C-IV, D-I D. A-II, B-III, C-I, D-IV
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Answer: B. Mycology II. Fungi
- Entomology is the branch of zoology concerned with the study of insects. - Mycology is the branch of biology concerned with the study of fungi. - Phycology (or Algology) is the scientific study of algae. - Desmology is the branch of anatomy or biology concerned with the study of ligaments, particularly in the context of joints and skeletal structure.
Match the following (use correct codes) : Father of Medi‐ (a) Aristotle (i) cine (ii) Father of Genet‐ (b) Theophrastus ics (c) Hippocrates (iii) Father of Botany (d) Gregor Johann (iv) Father of Biology Mendel
Asked in: MPSC CS Prelims 2020
1. (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)
2. (a)-(iii), (b)-(ii), (c)-(iv), (d)-(i)
3. (a)-(iv), (b)-(iii), (c)-(i), (d)-(ii)
4. (a)-(i), (b)-(ii), (c)-(iv), (d)-(iii)
Show answer
Answer: C. (a)-(iv), (b)-(iii), (c)-(i), (d)-(ii)
- Aristotle: Founder of biological classification and extensive observations. - Theophrastus: Pioneer in the study and classification of plants. - Hippocrates: Laid foundations for rational medicine and medical ethics. - Gregor Johann Mendel: Discovered the basic principles of heredity.
Sericulture is a rearing practice of:
Asked in: OPSC CS Prelims 2018
1. Honey bee
2. Fishes
3. Spiders
4. Silk worm
Show answer
Answer: D. Silk worm
Sericulture specifically refers to the farming of silkworms for silk production.
Silk is a :
Asked in: OPSC CS Prelims 2019
1. Synthetic product
2. Animal product
3. Plant product
4. Man-made product
Show answer
Answer: B. Animal product
Silk is a natural protein fiber produced by certain insect larvae, most commonly the larvae of the mulberry silkworm (Bombyx mori). Because it is derived from an animal source (the silkworm), it is classified as an animal product.
Match the following : (a) Sericulture 1. Farming of aquatic organisms (b) Horticul‐ 2. Culture of honey bees ture (c) Aquacul‐ 3. Rearing of silk worms ture (d) Apiculture 4. Cultivation and maintaining gardens A. (a) (b) (c) (d) 3 4 1 2 B. (a) (b) (c) (d) 2 3 4 1 C. (a) (b) (c) (d) 1 2 3 4 D. (a) (b) (c) (d) 4 3 2 1 Ans: A - Sericulture: Silk production from silkworms. - Horticulture: Garden cultivation and management. - Aquaculture: Cultivation of aquatic organisms in controlled environments. - Apiculture: Beekeeping for honey and other products. 72. Which of the following is NOT obtained from insects?
Asked in: TNPSC CS Prelims 2015 · UPPCS Prelims 2018
1. Silk
2. Honey
3. Lac
4. Pearl
Show answer
Answer: D. Pearl
Silk is obtained from silkworms (larvae of silk moths), honey is produced by bees, and lac is a resin secreted by lac insects. All silkworms, bees, and lac insects belong to the class Insecta. Pearls, however, are produced by molluscs, primarily oysters and mussels, which belong to the phylum Mollusca and are not insects.
If you walk through countryside, you are likely to see some birds stalking alongside the cattle to seize the insects disturbed by their movement through grasses. Which of the following is/are such bird/birds? 1. Painted Stork 2. Common Myna 3. Black-necked Crane Select the correct answer using the code given below.
Asked in: UPSC IAS 2014
1. 1 and 2
2. 2 only
3. 2 and 3
4. 3 only
Show answer
Answer: B. 2 only
Common Mynas (Acridotheres tristis) are frequently observed foraging for insects in grasslands, often following grazing animals like cattle, sheep, or even lawnmowers, taking advantage of insects stirred up from the vegetation. This is a form of commensalism, where the bird benefits, and the cattle are largely unaffected.
An Ornithologist deals with:
Asked in: WBPSC CS Prelims 2018
1. Insects
2. Birds
3. Eyes
4. Heart
Show answer
Answer: B. Birds
Ornithology is the study of birds.
‘Ornithology’ is the science of
Asked in: WBPSC CS Prelims 2022
1. Bird
2. Reptile
3. Amphibia
4. Mammal
Show answer
Answer: A. Bird
The term "ornithology" comes from the Greek words "ornis" (ὄρνις) meaning "bird" and "logos" (λόγος) meaning "science" or "study".

Anatomy

Botany

Cell Biology (Cytology)

Ecology

Evolutionary Biology

Genetics

Microbiology

Physiology

Zoology

2. Evolution of Life

Practice MCQs: Subdivisions of Biology

Anatomy

Botany

Cell Biology (Cytology)

Ecology

Evolutionary Biology

Genetics

Microbiology

Physiology

Zoology

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