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Diversity and Classification of Living Organisms PYQs – Biology, SSC & Railway

68 Diversity and Classification of Living Organisms (Biology) questions asked in recent SSC and Railway exams, newest first, with exam, date & shift, answers and solutions.

📚 68 questionsSSC 8 · Railway 60
SSC Stenographer 2026 – 10 September 2026 Shift 3 · Plant kingdom groups (Thallophyta to Angiosperms)

Q1. Which plant family is most important for pulses and protein-rich crops in Indian agriculture?

  1. (a) Poaceae
  2. (b) Fabaceae
  3. (c) Solanaceae
  4. (d) Brassicaceae
Answer & solution

Answer: (b) Fabaceae

Answer: Option 2 — Fabaceae
Fabaceae, also called Leguminosae, is the pea or legume family, and it supplies almost every pulse grown in India — gram, tur, urad, moong, masoor, pea and soybean.
These seeds are the country's chief source of plant protein.
Revision note — Fabaceae and the major crop families
• Fabaceae (Leguminosae) is the third largest family of flowering plants; its fruit is a legume (pod) and its flower is typically papilionaceous, shaped like a butterfly.
• Legume roots bear root nodules containing Rhizobium bacteria, which fix atmospheric nitrogen — this is why pulses are sown in rotation with cereals to restore soil fertility.
• Examples: gram (Cicer arietinum), pigeon pea or tur (Cajanus cajan), groundnut (Arachis hypogaea), soybean (Glycine max), fenugreek or methi (Trigonella foenum-graecum).
• Poaceae (Gramineae) is the grass family — rice, wheat, maize, bajra, jowar, sugarcane, bamboo; its fruit is a caryopsis.
• Solanaceae is the potato or nightshade family — potato, tomato, brinjal, chilli, tobacco.
• Brassicaceae (Cruciferae) is the mustard family — mustard, cabbage, cauliflower, radish, turnip.
• India is the world's largest producer and consumer of pulses; Madhya Pradesh and Rajasthan lead in output.
Do not mix these up
• Fabaceae vs Poaceae — pulses and plant protein come from Fabaceae; cereals and grains come from Poaceae.
• Pulses vs cereals — pulses are the dried edible seeds of legumes and are protein-rich; cereals are grass grains and are carbohydrate-rich.
Also asked from this topic: the nutrient legumes replenish before a wheat crop (nitrogen); the bacterium of legume root nodules (Rhizobium); the family of fenugreek (Fabaceae).

Q2. What characteristic is shared by both bacteria and cyanobacteria?

  1. (a) Both reproduce by forming seeds
  2. (b) Both are single-celled prokaryotes
  3. (c) Both possess well defined nucleus
  4. (d) Both live in the gut of ruminants
Answer & solution

Answer: (b) Both are single-celled prokaryotes

Correct Answer:
Correct Answer: Option 2 – Both are single-celled prokaryotes
Explanation:
Bacteria and cyanobacteria (blue-green algae) are both prokaryotic, single-celled organisms lacking a membrane-bound nucleus and other membrane-bound organelles.
Important Facts:
• Cyanobacteria are photosynthetic prokaryotes, sometimes called blue-green algae.
• Prokaryotic cells lack a well-defined (membrane-bound) nucleus, unlike eukaryotic cells.
• Neither bacteria nor cyanobacteria reproduce by seeds; that is a feature of some plants.
RRB Group D 2025-26 – 21 August 2026 Shift 1 · Plant kingdom groups (Thallophyta to Angiosperms)

Q3. A researcher finds a plant group that does not need water for fertilisation and has seeds which are not enclosed in fruits. Which plant group is being described?

  1. (a) Bryophytes
  2. (b) Pteridophytes
  3. (c) Gymnosperms
  4. (d) Angiosperms
Answer & solution

Answer: (c) Gymnosperms

Explanation:
Gymnosperms (e.g., pines, cycads) are seed-bearing plants whose seeds are 'naked', i.e., not enclosed within a fruit, and their fertilisation (via pollen tubes) does not require external water, unlike bryophytes and pteridophytes which need water for the motile male gametes to reach the egg.
Correct Answer: Option 3 – Gymnosperms
RRB Group D 2025-26 – 21 August 2026 Shift 2 · Five-kingdom classification (Whittaker) and other systems

Q4. During a field study, a student finds an organism that is multicellular, lacks cell walls, and depends on others for food. According to the five kingdom classification, to which kingdom should this organism belong?

  1. (a) Plantae
  2. (b) Fungi
  3. (c) Animalia
  4. (d) Monera
Answer & solution

Answer: (c) Animalia

Correct Answer:
Correct Answer: Option 3 – Animalia
Explanation:
Organisms in Kingdom Animalia are multicellular, lack a cell wall, and are heterotrophic (depend on other organisms for food) — matching all the given features exactly.

Q5. A clinical investigation identifies a unicellular, motile, eukaryotic organism that ingests bacteria for food. Which is the best position for this organism in the five kingdom system?

  1. (a) Fungi
  2. (b) Protista
  3. (c) Animalia
  4. (d) Monera
Answer & solution

Answer: (b) Protista

Correct Answer:
Correct Answer: Option 2 – Protista
Explanation:
A unicellular, motile, eukaryotic organism that ingests bacteria (e.g., Amoeba, Paramecium) belongs to the kingdomProtistain the five-kingdom classification system.
Important Facts:
• Monera comprises unicellular prokaryotes (bacteria), which lack a true nucleus — ruling that option out.
• Fungi and Animalia typically contain multicellular organisms (with some unicellular fungal exceptions like yeast, which don't ingest food this way).

Q6. In a comparative study, some unicellular organisms from a hay infusion display flexible shapes and engulf food particles, while others have a rigid outer covering and are green in color. Which conclusion best explains the observed differences?

  1. (a) Monera have similar cell walls
  2. (b) Protists vary in structure and nutrition
  3. (c) Chlorophyll is absent in all
  4. (d) All protists are prokaryotic
Answer & solution

Answer: (b) Protists vary in structure and nutrition

Correct Answer:
Correct Answer: Option 2 – Protists vary in structure and nutrition
Explanation:
A hay infusion typically contains a variety of unicellular protists. Organisms with flexible shapes that engulf food particles (like Amoeba) showheterotrophicnutrition, while others with a rigid pellicle and green pigmentation (like Euglena/algae) showautotrophic (photosynthetic)nutrition. This diversity within a single kingdom (Protista) shows that protists vary widely in structure and mode of nutrition.
Important Facts:
• Protists are eukaryotic, not prokaryotic (Monera are prokaryotic).
• Not all protists lack chlorophyll — some (e.g., Euglena, algae) are photosynthetic.
• Monera (bacteria) have cell walls of peptidoglycan, distinct from protist cell coverings.
RRB Group D 2025-26 – 20 August 2026 Shift 2 · Animal kingdom - non-chordates

Q7. A zoologist observes a fixed aquatic animal with no tissue differentiation but efficient water filtration. Which of the following is most likely to happen if this animal was placed in a terrestrial environment?

  1. (a) It would close its pores to prevent drying
  2. (b) It would desiccate due to inability to retain water
  3. (c) It would move to moist areas for survival
  4. (d) It would use tentacles to trap moisture
Answer & solution

Answer: (b) It would desiccate due to inability to retain water

Correct Answer:
Correct Answer: Option 2 – It would desiccate due to inability to retain water
Explanation:
A fixed (sessile) aquatic animal with no tissue differentiation and efficient water filtration describes a sponge (phylum Porifera), which has cellular-level organisation and relies on a continuous flow of water (through pores/canals) for feeding, gas exchange, and support. On land, it would lose water rapidly and desiccate, as it has no adaptations to retain moisture or exchange gases in air.

Q8. A taxonomist is classifying a microscopic organism that is unicellular, has a true nucleus, and moves using cilia. Which kingdom is most appropriate for its classification?

  1. (a) Plantae
  2. (b) Fungi
  3. (c) Protista
  4. (d) Monera
Answer & solution

Answer: (c) Protista

Correct Answer:
Option 3 – Protista
Explanation:
Kingdom Protista includes unicellular eukaryotic organisms (having a true, membrane-bound nucleus) that often move using structures like cilia, flagella, or pseudopodia — e.g., Paramecium (ciliate protist).
Important Facts:
• Monera: unicellular, prokaryotic (no true nucleus) — e.g., bacteria.
• Fungi: mostly multicellular, eukaryotic, non-motile, absorptive nutrition.
• Plantae: multicellular, eukaryotic, autotrophic.
RRB Group D 2025-26 – 19 August 2026 Shift 3 · Characteristics of living organisms and life processes

Q9. Why do single-celled organisms not require specialized organs for taking in food and exchanging gases?

  1. (a) Because they have a transportation system
  2. (b) Because they do not need food or oxygen
  3. (c) Because they have complex body designs
  4. (d) Because their entire surface is in contact with the environment
Answer & solution

Answer: (d) Because their entire surface is in contact with the environment

Correct Answer:
Option 4 – Because their entire surface is in contact with the environment
Explanation:
Single-celled (unicellular) organisms are very small, so theirsurface area to volume ratiois large. Their entire body surface is in direct contact with the surrounding environment, which allows food, oxygen and waste to move in and out simply bydiffusionacross the cell membrane. Hence they do not need specialized organs like lungs or intestines.
Important Facts:
• As organisms become larger and multicellular, surface area to volume ratio decreases, requiring specialized organs for exchange and transport.
• Examples of unicellular organisms: Amoeba, Paramecium, bacteria.
Correct Answer: Option 4 – Because their entire surface is in contact with the environment
RRB Group D 2025-26 – 19 August 2026 Shift 3 · Plant kingdom groups (Thallophyta to Angiosperms)

Q10. In an experiment, a group of plants fail to reproduce when water is withheld, even though they have vascular tissues. Which plant group do they most closely resemble?

  1. (a) Pteridophyta
  2. (b) Angiosperm
  3. (c) Gymnosperm
  4. (d) Bryophyta
Answer & solution

Answer: (a) Pteridophyta

Correct Answer:
Option 1 – Pteridophyta
Explanation:
Pteridophytes (e.g., ferns) have well-developed vascular tissue (xylem and phloem) but are seedless plants that still depend onwater for fertilization, since their motile male gametes must swim through a film of water to reach the egg. Without water, they cannot reproduce, matching the scenario described.
Important Facts:
• Bryophytes (mosses, liverworts) lack vascular tissue entirely and also need water for reproduction.
• Gymnosperms and Angiosperms are seed-bearing plants and do not require external water for fertilization (they use pollen tubes).
Correct Answer: Option 1 – Pteridophyta
RRB Group D 2025-26 – 18 August 2026 Shift 1 · Basis and hierarchy of classification

Q11. A clinical botanist is required to identify a plant to its family. Which of the following taxonomic ranks is immediately higher than family in the classification hierarchy?

  1. (a) Genus
  2. (b) Order
  3. (c) Cultivar
  4. (d) Species
Answer & solution

Answer: (b) Order

Taxonomic hierarchy
The standard taxonomic hierarchy (from broad to specific) is: Kingdom > Phylum/Division > Class >Order> Family > Genus > Species.
The rank immediately above Family is Order. Genus and Species are ranks below Family, and Cultivar is not a formal rank in this hierarchy (it applies to cultivated plant varieties).
Correct Answer: Order
RRB Group D 2025-26 – 18 August 2026 Shift 2 · Basis and hierarchy of classification

Q12. In the biological taxonomic hierarchy, which taxonomic rank is determined last when classifying a newly discovered plant?

  1. (a) Genus
  2. (b) Family
  3. (c) Species
  4. (d) Order
Answer & solution

Answer: (c) Species

Taxonomic Hierarchy
The taxonomic hierarchy proceeds from broad to specific: Kingdom → Phylum/Division → Class → Order → Family → Genus → Species.
When classifying a newly discovered organism, broader categories (like Order, Family, Genus) can often be assigned based on general similarities early on, butSpecies— being the most specific and precise rank — is determined last, after detailed study.
Correct Answer: Species
RRB Group D 2025-26 – 18 August 2026 Shift 3 · Plant kingdom groups (Thallophyta to Angiosperms)

Q13. A researcher attempts to cultivate plants with true roots, stems, and leaves but finds that reproduction only occurs when water is present. Which feature limits these plants’ distribution?

  1. (a) Absence of true roots
  2. (b) Seeds encased in fruits
  3. (c) Water-dependent reproduction
  4. (d) Lack of vascular tissue
Answer & solution

Answer: (c) Water-dependent reproduction

Concept: Pteridophytes (Ferns)
Plants with true roots, stems, and leaves but reproducing via spores (not seeds) and requiring water for fertilization describe thePteridophytes(e.g., ferns). Their male gametes (antherozoids) are flagellated and must swim through a film of water to reach and fertilize the female gamete. This dependence on water for reproduction restricts pteridophytes to damp, moist habitats and limits their wider distribution — unlike seed plants which are not dependent on external water for fertilization.
Correct Answer: Water-dependent reproduction

Q14. A science teacher asks students to identify an organism under the microscope. The organism is single-celled, has a rigid cell wall, and produces oxygen through photosynthesis. Which organism is most likely being observed?

  1. (a) Amoeba
  2. (b) Euglena
  3. (c) Paramecium
  4. (d) Cyanobacterium
Answer & solution

Answer: (d) Cyanobacterium

Identifying a Photosynthetic Organism with a Rigid Cell Wall
A single-celled organism with a rigid cell wall that carries out oxygenic photosynthesis is acyanobacterium(blue-green algae) — a prokaryote possessing a peptidoglycan-containing rigid cell wall and chlorophyll-based photosynthesis producing oxygen.
• Amoeba has no cell wall and is heterotrophic.
• Euglena has a flexible pellicle (not a rigid cell wall), though it is photosynthetic.
• Paramecium has no cell wall and is heterotrophic (feeds via cilia).
Correct Answer: Cyanobacterium
RRB Group D 2025-26 – 17 August 2026 Shift 3 · Plant kingdom groups (Thallophyta to Angiosperms)

Q15. Two specimens: one has undifferentiated body living in water, the other has true roots, stems, and leaves. Which of the following correctly matches them with their classes?

  1. (a) Bryophyta and Angiosperm
  2. (b) Bryophyta and Thallophyta
  3. (c) Pteridophyta and Gymnosperm
  4. (d) Thallophyta and Pteridophyta
Answer & solution

Answer: (d) Thallophyta and Pteridophyta

Plant Classification
Matching the two described specimens to plant groups:
• An organism with an undifferentiated body living in water fitsThallophyta(e.g., algae) — body not differentiated into root, stem, leaf.
• An organism with true roots, stems, and leaves fitsPteridophyta(e.g., ferns) — the first group to show true differentiation into these organs (though still without seeds/flowers).
• Bryophyta (amphibians of plant kingdom) have rhizoids, not true roots, ruling out the other combinations.
Correct Answer: Thallophyta and Pteridophyta
RRB Group D 2025-26 – 14 August 2026 Shift 1 · Plant kingdom groups (Thallophyta to Angiosperms)

Q16. A student observes green mats growing on rocks in a damp forest. They have rhizoid-like structures but lack true roots. Which class do these plants most likely represent?

  1. (a) Thallophyta
  2. (b) Gymnosperm
  3. (c) Bryophyta
  4. (d) Pteridophyta
Answer & solution

Answer: (c) Bryophyta

Answer: Option 3 – Bryophyta.
• Green mats with rhizoid-like structures but no true roots arebryophytes(e.g. mosses).
RRB Group D 2025-26 – 14 August 2026 Shift 1 · Basis and hierarchy of classification

Q17. A student classifies animals in a diagram by both activity time (day/night) and visible characteristics. Which statement best shows what combining these criteria demonstrates about scientific classification?

  1. (a) It creates unique groups
  2. (b) It eliminates overlaps
  3. (c) It allows for multiple perspectives
  4. (d) It always focuses on genetics
Answer & solution

Answer: (c) It allows for multiple perspectives

Answer: Option 3 – It allows for multiple perspectives.
• Using more than one criterion shows classification can reflectmultiple perspectives.
RRB Group D 2025-26 – 14 August 2026 Shift 3 · Plant kingdom groups (Thallophyta to Angiosperms)

Q18. Two vascular plants: one produces seeds in cones, the other has seeds in fruits. Which statement accurately distinguishes these groups?

  1. (a) First is gymnosperm, second is angiosperm
  2. (b) First is bryophyte, second is gymnosperm
  3. (c) First is pteridophyte, second is bryophyte
  4. (d) First is angiosperm, second is pteridophyte
Answer & solution

Answer: (a) First is gymnosperm, second is angiosperm

Answer: Option 1 – First is gymnosperm, second is angiosperm.
• Seeds in cones =gymnosperm; seeds in fruits =angiosperm.
RRB Group D 2025-26 – 14 August 2026 Shift 3 · Animal kingdom - chordates and vertebrate classes

Q19. During rehabilitation, a patient with vertebral damage has impaired organ coordination. Which vertebrate feature underlies this complication?

  1. (a) Simple external limb appendages
  2. (b) Protective single-layered skin
  3. (c) Basic independent cell clusters
  4. (d) Complex organ system integration
Answer & solution

Answer: (d) Complex organ system integration

Answer: Option 4 – Complex organ system integration.
• Vertebrates havecomplex, integrated organ systemscoordinated via the spinal cord, so vertebral damage disrupts coordination.
RRB Group D 2025-26 – 13 August 2026 Shift 1 · Basis and hierarchy of classification

Q20. A zoologist finds two organisms with the same order but different families.Which conclusion about their classification does this indicate?

  1. (a) They share species but not order
  2. (b) They share genus but not family
  3. (c) They share family but not class
  4. (d) They share all higher levels up to order
Answer & solution

Answer: (d) They share all higher levels up to order

Answer: Option 4 – They share all higher levels up to order.
• Same order but different families means they match at order, class, phylum, kingdom (all levels above family) but diverge at family and below.
RRB Group D 2025-26 – 13 August 2026 Shift 1 · Plant kingdom groups (Thallophyta to Angiosperms)

Q21. In a comparative study, angiosperms might be more diverse than gymnosperms in various environments as:

  1. (a) Angiosperms utilize flowers and fruits for reproduction
  2. (b) Gymnosperms rely on efficient water transport
  3. (c) Aquatic fertilisation events increases variation
  4. (d) Needle-like leaves helps enhance species diversity
Answer & solution

Answer: (a) Angiosperms utilize flowers and fruits for reproduction

Answer: Option 1 – Angiosperms utilise flowers and fruits for reproduction.
• Flowers and fruits give angiosperms better pollination and seed dispersal, making them more diverse.

Q22. During an algal bloom, dominant species are single-celled organisms with a nucleus that can photosynthesize and ingest food. Which organism is most likely responsible?

  1. (a) Bacteria
  2. (b) Amoeba
  3. (c) Cyanobacteria
  4. (d) Euglena-like protists
Answer & solution

Answer: (d) Euglena-like protists

Answer: Option 4 – Euglena-like protists.
• Single-celled organisms with a nucleus that both photosynthesise and ingest food areEuglena-like protists.
RRB Group D 2025-26 – 13 August 2026 Shift 2 · Basis and hierarchy of classification

Q23. Three microbes were classified together, but DNA sequencing shows two have closer genetic material. Which classification change could this finding suggest?

  1. (a) Reassignment based on DNA similarities
  2. (b) Grouping by habitat similarities
  3. (c) Ignoring genetic information
  4. (d) Maintaining previous grouping
Answer & solution

Answer: (a) Reassignment based on DNA similarities

Answer: Option 1 – Reassignment based on DNA similarities.
• Closer DNA between two microbes suggestsregrouping by genetic (DNA) similarity.
RRB Group D 2025-26 – 13 August 2026 Shift 3 · Basis and hierarchy of classification

Q24. A taxonomist examines DNA sequences of two bacteria and finds high similarity. Based on current classification principles, which relationship does this suggest between them?

  1. (a) They are unrelated
  2. (b) They occupy same ecological niche
  3. (c) They belong to different domains
  4. (d) They likely share a common ancestry
Answer & solution

Answer: (d) They likely share a common ancestry

Answer: Option 4 – They likely share a common ancestry.
• High DNA similarity indicates acommon ancestor(close evolutionary relationship).

Q25. A waterborne outbreak reveals that causative agent is single-celled, nucleus-lacking organisms thriving in sewage and animal intestines. Which group do these organisms most likely belong to?

  1. (a) Kingdom Monera
  2. (b) Kingdom Fungi
  3. (c) Kingdom Plantae
  4. (d) Kingdom Protista
Answer & solution

Answer: (a) Kingdom Monera

Answer: Option 1 – Kingdom Monera.
• Single-celled organismslacking a true nucleus(prokaryotes, e.g. bacteria) belong toKingdom Monera.
RRB Group D 2025-26 – 12 August 2026 Shift 2 · Animal kingdom - chordates and vertebrate classes

Q26. A wildlife veterinarian observes that a certain animal can maintain a large body size and perform complex behaviors. Which structural attribute is most vital for these traits?

  1. (a) External tentacles for movement
  2. (b) Vertebral column for support
  3. (c) Protective rigid outer covering
  4. (d) Simple single-celled structure
Answer & solution

Answer: (b) Vertebral column for support

Answer: Option 2 – Vertebral column for support.
• Avertebral column (backbone)supports a large body and complex behaviour in vertebrates.
RRB Group D 2025-26 – 12 August 2026 Shift 3 · Basis and hierarchy of classification

Q27. A scientist groups forest animals first by their feeding habits and then by habitat. Which is the main advantage of this multi-criteria classification approach?

  1. (a) It reduces the number of groups
  2. (b) It focuses on genetic similarity
  3. (c) It reveals functional relationships
  4. (d) It simplifies taxonomy
Answer & solution

Answer: (c) It reveals functional relationships

Answer: Option 3 – It reveals functional relationships.
• Classifying by feeding habits and habitat highlights how organisms interact – i.e.functional relationships.
RRB Group D 2025-26 – 12 August 2026 Shift 3 · Plant kingdom groups (Thallophyta to Angiosperms)

Q28. A new land plant has vascular tissues but no flowers or seeds. Which group does it belong to, and which significant challenge does this group face?

  1. (a) Bryophyta; lack of vascular tissues for transport
  2. (b) Pteridophyta; absence of seeds limits reproductive success
  3. (c) Gymnosperm; reliance on water for fertilisation
  4. (d) Angiosperm; seeds exposed to environment
Answer & solution

Answer: (b) Pteridophyta; absence of seeds limits reproductive success

Answer: Option 2 – Pteridophyta; absence of seeds limits reproductive success.
• Plants with vascular tissue but no seeds/flowers arepteridophytes; lacking seeds limits their reproductive spread.
RRB Group D 2025-26 – 11 August 2026 Shift 2 · Five-kingdom classification (Whittaker) and other systems

Q29. While reviewing classification systems, a biologist notes confusion in placing amoeba in the two-kingdom system. Which key feature caused this confusion?

  1. (a) Amoeba is photosynthetic and multicellular
  2. (b) Amoeba has a true nucleus and is autotrophic
  3. (c) Amoeba lacks a cell wall and is stationary
  4. (d) Amoeba is unicellular, moves and is heterotrophic
Answer & solution

Answer: (d) Amoeba is unicellular, moves and is heterotrophic

Answer: Option 4 – Amoeba is unicellular, moves and is heterotrophic.
• Amoeba's mix of animal-like traits (motile, heterotrophic) in a single cell caused confusion in the two-kingdom system.
RRB Group D 2025-26 – 11 August 2026 Shift 3 · Animal kingdom - chordates and vertebrate classes

Q30. A researcher observes an animal with three-chambered heart and some mixing of oxygenated and deoxygenated blood. What energy adaptation does this animal likely exhibit according to the context?

  1. (a) It has a highly efficient oxygen supply
  2. (b) It maintains body temperature using constant energy
  3. (c) It does not maintain its body temperature using constant energy
  4. (d) It possesses double circulation with no mixing
Answer & solution

Answer: (c) It does not maintain its body temperature using constant energy

Answer: Option 3 – It does not maintain its body temperature using constant energy.
• A 3-chambered heart with mixed blood is typical ofcold-blooded (poikilothermic)animals, which do not spend energy to keep a constant body temperature.
RRB Group D 2025-26 – 10 August 2026 Shift 2 · Plant kingdom groups (Thallophyta to Angiosperms)

Q31. A plant sample, when tested, has vascular tissues (xylem and phloem) but no seeds. Which group does it belong to?

  1. (a) Pteridophyta
  2. (b) Gymnosperm
  3. (c) Bryophyta
  4. (d) Thallophyta
Answer & solution

Answer: (a) Pteridophyta

Answer: Option 1 – Pteridophyta.
• Plants withvascular tissue (xylem & phloem) but no seedsbelong toPteridophyta(e.g. ferns).
• Gymnosperms and angiosperms bear seeds; Bryophyta and Thallophyta lack true vascular tissue.
RRB Group D 2025-26 – 9 August 2026 Shift 1 · Five-kingdom classification (Whittaker) and other systems

Q32. A medical laboratory detects bacteria in a patient’s sample. According to the historical development of classification systems, in which kingdom would bacteria have been placed immediately after the three kingdom system was introduced?

  1. (a) Animalia
  2. (b) Plantae
  3. (c) Monera
  4. (d) Protista
Answer & solution

Answer: (d) Protista

Answer: Option 4 — Protista
Right after the three-kingdom system, bacteria were placed with other microbes inProtista(before Monera was created in the five-kingdom system) → Option 4.
RRB Group D 2025-26 – 9 August 2026 Shift 2 · Characteristics of living organisms and life processes

Q33. Which of the following statements best describes why visible movement alone cannot define whether a plant is alive?

  1. (a) Only animals can be alive without visible movement.
  2. (b) Visible movement is always present in living organisms.
  3. (c) All living things must show visible movement to be alive.
  4. (d) Plants may be alive even without visible growth or movement.
Answer & solution

Answer: (d) Plants may be alive even without visible growth or movement.

Answer: Option 4 — Plants may be alive even without visible growth or movement
Life is defined by metabolism, soplants can be alive without visible movement→ Option 4.
RRB Group D 2025-26 – 6 August 2026 Shift 1 · Basis and hierarchy of classification

Q34. Researchers studying genetic similarity in hornbill species are most likely to use which characteristic for classification?

  1. (a) DNA sequence comparison
  2. (b) Nesting site location
  3. (c) Diet composition
  4. (d) Beak shape and size
Answer & solution

Answer: (a) DNA sequence comparison

Answer: Option 1 — DNA sequence comparison
Genetic similarity is best assessed byDNA sequence comparison→ Option 1.
RRB Group D 2025-26 – 6 August 2026 Shift 2 · Characteristics of living organisms and life processes

Q35. Which of the following correctly explains why life processes such as nutrition, respiration, transport and excretion are essential for living organisms?

  1. (a) They are required only for growth and reproduction.
  2. (b) They occur only in plants to sustain photosynthesis.
  3. (c) They are independent processes that do not affect each other.
  4. (d) They maintain homeostasis and provide energy.
Answer & solution

Answer: (d) They maintain homeostasis and provide energy.

Answer: Option 4 — They maintain homeostasis and provide energy
Life processes togethermaintain homeostasis and supply energyfor survival → Option 4.
RRB Group D 2025-26 – 6 August 2026 Shift 2 · Plant kingdom groups (Thallophyta to Angiosperms)

Q36. A green, thread-like plant in freshwater pond lacks roots, stems, and leaves but photosynthesizes. Based on this information, which group does it belong to?

  1. (a) Thallophyta
  2. (b) Gymnosperm
  3. (c) Bryophyta
  4. (d) Pteridophyta
Answer & solution

Answer: (a) Thallophyta

Answer: Option 1 — Thallophyta
A plant lacking roots/stems/leaves but photosynthesising (like algae) belongs toThallophyta→ Option 1.
RRB Group D 2025-26 – 6 August 2026 Shift 2 · Basis and hierarchy of classification

Q37. After a genetic study, two bacteria previously grouped together are found to have highly divergent DNA. According to modern classification, which of the following is the most likely consequence?

  1. (a) They may be reclassified into separate domains or groups
  2. (b) Their similarity is confirmed by traditional traits
  3. (c) They remain in the same traditional group
  4. (d) They are merged as one species
Answer & solution

Answer: (a) They may be reclassified into separate domains or groups

Answer: Option 1 — They may be reclassified into separate domains or groups
Highly divergent DNA leads toreclassification into separate groups/domains→ Option 1.
RRB Group D 2025-26 – 6 August 2026 Shift 3 · Basis and hierarchy of classification

Q38. A student is analyzing digestive systems in different invertebrates. Which structural change allows efficient, one-way food processing and waste elimination?

  1. (a) Acquisition of bilateral symmetry
  2. (b) Development of two body openings
  3. (c) Presence of body segmentation
  4. (d) Evolution of feeding tentacles
Answer & solution

Answer: (b) Development of two body openings

Answer: Option 2 — Development of two body openings
Atwo-opening (complete) gut(mouth and anus) allows efficient one-way food processing → Option 2.
RRB Group D 2025-26 – 6 August 2026 Shift 3 · Binomial nomenclature and scientific names

Q39. A botanist names a new flowering plant growing in a remote region using binomial system. Which of the following is the correct format?

  1. (a) Species capitalized, genus in lowercase
  2. (b) Genus capitalized, species in lowercase
  3. (c) Both words in lowercase
  4. (d) Both words in uppercase
Answer & solution

Answer: (b) Genus capitalized, species in lowercase

Answer: Option 2 — Genus capitalized, species in lowercase
Binomial nomenclature:Genus capitalised, species lowercase(both italicised) → Option 2.
RRB Group D 2025-26 – 5 August 2026 Shift 3 · Animal kingdom - chordates and vertebrate classes

Q40. After severe trauma, a bird develops difficulty in body support and movement. Which vertebrate system is primarily affected?

  1. (a) Internal skeletal framework
  2. (b) Simple digestive sac
  3. (c) Basic muscle bands
  4. (d) External gill arches
Answer & solution

Answer: (a) Internal skeletal framework

Answer: Option 1 — Internal skeletal framework
Body support/movement in a bird is provided by itsinternal skeleton (endoskeleton)→ Option 1.
RRB Group D 2025-26 – 5 August 2026 Shift 3 · Monera, Protista and Fungi

Q41. A patient has a chronic infection from a eukaryotic organism that reproduces via spores and has a chitin cell wall. Which type of organism is most likely responsible for this infection?

  1. (a) Algae
  2. (b) Fungus
  3. (c) Protozoa
  4. (d) Bacteria
Answer & solution

Answer: (b) Fungus

Answer: Option 2 — Fungus
A eukaryote reproducing bysporeswith achitin cell wallis afungus→ Option 2.
RRB Group D 2025-26 – 4 August 2026 Shift 2 · Monera, Protista and Fungi

Q42. A tribal community identifies wild mushrooms for food and medicine. Which property is most relevant to their nutritional and medicinal value?

  1. (a) High content of bioactive compounds
  2. (b) Rapid spore production capability
  3. (c) Structural similarity to plants
  4. (d) Colorful cap pattern presence
Answer & solution

Answer: (a) High content of bioactive compounds

Answer: Option 1 — High content of bioactive compounds
The nutritional/medicinal value of mushrooms comes from theirbioactive compounds→ Option 1.
RRB Group D 2025-26 – 4 August 2026 Shift 2 · Monera, Protista and Fungi

Q43. A fungal culture in a laboratory is observed to grow best when kept in a warm and moist incubator. Which aspect of its biology is directly influenced by these conditions?

  1. (a) Maximum rate of cell division
  2. (b) High energy storage in vacuoles
  3. (c) Optimal spore germination and growth
  4. (d) Increased pigment production
Answer & solution

Answer: (c) Optimal spore germination and growth

Answer: Option 3 — Optimal spore germination and growth
Warmth and moisture promotespore germination and growthin fungi → Option 3.
RRB Group D 2025-26 – 4 August 2026 Shift 3 · Animal kingdom - non-chordates

Q44. Two aquatic animals: one has pores for water flow, the other uses tentacles to capture prey. Which key structural difference explains their feeding strategies?

  1. (a) Segmentation in both animals
  2. (b) Bilateral symmetry in the pore-bearing animal
  3. (c) Presence of a hard skeleton in the tentacled animal
  4. (d) Presence of tissues in the tentacled animal
Answer & solution

Answer: (d) Presence of tissues in the tentacled animal

Answer: Option 4 — Presence of tissues in the tentacled animal
The pore-bearing animal (sponge) lacks true tissues; the tentacled animal (e.g., Hydra/Cnidaria) hastrue tissues, enabling coordinated prey capture → Option 4.
RRB Group D 2025-26 – 4 August 2026 Shift 3 · Plant kingdom groups (Thallophyta to Angiosperms)

Q45. In a habitat recently affected by drought, which feature would most likely allow gymnosperms to persist when other plants fail?

  1. (a) Flowers attract diverse pollinators
  2. (b) Aquatic fertilisation ensures survival
  3. (c) Needle-like leaves prevent water loss
  4. (d) Fruits improve seed dispersal in water
Answer & solution

Answer: (c) Needle-like leaves prevent water loss

Answer: Option 3 — Needle-like leaves prevent water loss
Gymnosperms'needle-like leavesreduce transpiration, helping them survive drought → Option 3.
RRB Group D 2025-26 – 3 August 2026 Shift 1 · Characteristics of living organisms and life processes

Q46. A botanist observes a dormant seed with no visible growth or movement. How can the botanist determine whether the seed is alive?

  1. (a) Conclude it is not alive if it shows no movement
  2. (b) Wait only for visible growth before deciding
  3. (c) Test whether the seed can move independently
  4. (d) Monitor its internal metabolic activity
Answer & solution

Answer: (d) Monitor its internal metabolic activity

Answer: Option 4 — Monitor its internal metabolic activity
Concept:Life is defined bymetabolic activity, not visible movement. A dormant seed is alive if internal chemical (metabolic) processes — like slow respiration — are occurring. So the botanist should check for metabolic activity → Option 4.
RRB Group D 2025-26 – 3 August 2026 Shift 2 · Monera, Protista and Fungi

Q47. A new microorganism is found that is unicellular, prokaryotic, and lacks a membrane-bound nucleus but can perform photosynthesis. According to the five kingdom classification, which kingdom is it placed in?

  1. (a) Fungi
  2. (b) Protista
  3. (c) Monera
  4. (d) Plantae
Answer & solution

Answer: (c) Monera

Answer: Option 3 — Monera
Unicellular +prokaryotic(no membrane-bound nucleus) places it inKingdom Monera(e.g., cyanobacteria, which also photosynthesise) → Option 3.
RRB Group D 2025-26 – 3 August 2026 Shift 2 · Characteristics of living organisms and life processes

Q48. Why do multicellular organisms need specialized systems for the intake of energy and exchange of materials, unlike unicellular organisms?

  1. (a) They are much heavier than single-celled organisms
  2. (b) Most internal cells lack direct contact with the external environment
  3. (c) Single-celled organisms do not require cellular energy to survive
  4. (d) They are completely unable to move from one place to another
Answer & solution

Answer: (b) Most internal cells lack direct contact with the external environment

Answer: Option 2 — Most internal cells lack direct contact with the external environment
In large multicellular bodies, inner cells cannot exchange gases/nutrients directly with the surroundings, sospecialised systems(respiratory, circulatory, digestive) are needed → Option 2.
RRB Group D 2025-26 – 3 August 2026 Shift 3 · Animal kingdom - non-chordates

Q49. An earthworm and crab both have segmented bodies, but only one has a hard outer covering. Which benefit does this outer covering provide in terrestrial environments?

  1. (a) Facilitates single opening for digestion
  2. (b) Prevents water loss and offers protection
  3. (c) Allows more flexible movement
  4. (d) Provides tentacles for prey capture
Answer & solution

Answer: (b) Prevents water loss and offers protection

Answer: Option 2 — Prevents water loss and offers protection
The crab's hardexoskeleton (cuticle)preventswater lossand givesprotection, an advantage on land → Option 2.
SSC GD 2026 – 21 May 2026 Shift 1 · Animal kingdom - chordates and vertebrate classes

Q50. Animals that live both in water and on land are called ___.

  1. (a) Mammals
  2. (b) Terrestrial
  3. (c) Aquatic
  4. (d) Amphibians
Answer & solution

Answer: (d) Amphibians

Correct Answer: Amphibians — Option (d)
Animals that live both in water and on land are called Amphibians. Etymology: The word 'Amphibia' comes from the Greek words ' amphi ' (meaning 'both' or 'double') and 'bios' (meaning 'life') — literally meaning 'double life'; Characteristics of Amphibians: Can live both in water and on land; Cold-blooded (ectothermic) vertebrates; Undergo metamorphosis (larval stage in water, adult stage on land); Breathe through gills as larvae and through lungs and moist skin as adults; Examples: Frogs (Rana species), toads (Bufo species), salamanders (Ambystoma species), newts (Triturus species), caecilians (limbless amphibians); Life cycle: Eggs laid in water → tadpoles (aquatic, gill-breathing) → metamorphosis → adult frogs (terrestrial/semi-aquatic, lung-breathing); Ecological role: Act as bioindicators of environmental health; important in food chains (eat insects, are eaten by snakes and birds); Threats: Amphibians are among the most threatened vertebrate groups globally due to habitat destruction, climate change, and chytrid fungus disease.
Option (a) Mammals — Incorrect: Mammals are a class of vertebrates characterized by mammary glands (that produce milk), hair/fur, and warm-bloodedness; while some mammals (like whales, dolphins, seals) live in water, mammals are not the category specifically defined as living 'both in water AND on land' — that is Amphibians.
Option (b) Terrestrial — Incorrect: Terrestrial animals live exclusively on land (not in water); the term 'terrestrial' means 'of the land' and does not include animals adapted for aquatic life.
Option (c) Aquatic — Incorrect: Aquatic animals live exclusively in water (fish, aquatic insects, etc.); the question asks about animals that live BOTH in water AND on land — these are specifically called Amphibians.
RRB NTPC UG CBT-1 2025-26 – 9 May 2026 Shift 3 · Plant kingdom groups (Thallophyta to Angiosperms)

Q51. In dicotyledonous plants, which type of root system consists of a main primary root that gives rise to lateral branches?

  1. (a) Prop root system
  2. (b) Fibrous root system
  3. (c) Tap root system
  4. (d) Adventitious root system
Answer & solution

Answer: (c) Tap root system

Topic: Root Systems in Plants
Dicotyledonous plantshave atap root system.
Characteristics:
• Primary root develops from radicle
• Main central root grows vertically downward
• Lateral roots (secondary/tertiary) branch from primary root
Other root types:
• Fibrous root: Found in monocots (no main root)
• Prop root: Aerial supporting roots (e.g., banyan)
• Adventitious root: Arise from stem/leaves
Answer: Option 3 → Tap root system
RRB NTPC UG CBT-1 2025-26 – 8 May 2026 Shift 2 · Plant kingdom groups (Thallophyta to Angiosperms)

Q52. The fibrous root system, in which the primary root is short-lived and replaced by numerous adventitious roots, is a characteristic feature of which group of plants?

  1. (a) Monocotyledonous
  2. (b) Dicotyledonous
  3. (c) Gymnosperms
  4. (d) Pteridophytes
Answer & solution

Answer: (a) Monocotyledonous

Root Systems in Plants
Fibrous Root System:
Primary root (radicle) is short-lived
Replaced by numerous thin adventitious roots from stem base
No dominant central root
Characteristic of Monocots:
Examples: Wheat, Rice, Maize, Grass
Roots form dense network near soil surface
Dicots have:Tap root system with persistent primary root
Answer: Option 1 → Monocotyledonous
RRB NTPC GL CBT-1 2025-26 – 27 March 2026 Shift 1 · Animal kingdom - chordates and vertebrate classes

Q53. Which class of vertebrates possesses cold-blooded characteristics and scaly skin?

  1. (a) Mammalia
  2. (b) Amphibia
  3. (c) Aves
  4. (d) Reptilia
Answer & solution

Answer: (d) Reptilia

Topic:Vertebrate Classification
Cold-blooded (Ectothermic)animals cannot regulate body temperature internally.
Scaly skinis a protective covering made of keratin.
Reptiliacharacteristics: Cold-blooded, scaly skin, lay eggs on land.
Examples: Snakes, lizards, crocodiles, turtles.
Answer: Option 4 → Reptilia

Q54. Which of the following groups of organisms exhibit the phenomenon of haploid-dominant life cycle?

  1. (a) The amphibians
  2. (b) The fungi
  3. (c) The angiosperms
  4. (d) The mammals
Answer & solution

Answer: (b) The fungi

Topic: Life Cycle Patterns in Organisms
Haploid-dominant life cycle:Haploid stage is multicellular and dominant; diploid stage is brief (only zygote).
Analysis of options:
Amphibians & Mammals → Diploid-dominant (multicellular diploid body)
Angiosperms → Diploid-dominant (sporophyte is main plant body)
Fungi → Haploid-dominant (hyphae are haploid; only zygote is diploid)
Key fact:Most fungi spend majority of life as haploid mycelium.
Answer: Option 2 → The fungi
RRB NTPC GL CBT-1 2025-26 – 19 March 2026 Shift 1 · Plant kingdom groups (Thallophyta to Angiosperms)

Q55. Bamboo exhibits a specific type of leaf venation and root structure. What are the characteristics of these features?

  1. (a) Parallel Venation and Fibrous Root
  2. (b) Reticulate Venation and Fibrous Root
  3. (c) Reticulate Venation and Tap Root
  4. (d) Parallel Venation and Tap Root
Answer & solution

Answer: (a) Parallel Venation and Fibrous Root

Topic: Plant Morphology - Bamboo
Bamboo Classification:Monocotyledonous plant (grass family)
Monocot Characteristics:
• Leaf Venation:Parallel(veins run parallel to each other)
• Root System:Fibrous(no main root, many thin roots)
Key Point:All monocots show parallel venation + fibrous roots
Answer: Option 1 → Parallel Venation and Fibrous Root
RRB NTPC GL CBT-1 2025-26 – 19 March 2026 Shift 2 · Plant kingdom groups (Thallophyta to Angiosperms)

Q56. Which of the following statements differentiates bryophytes from algae?

  1. (a) Bryophytes possess chlorophyll
  2. (b) Bryophytes are cryptogams
  3. (c) Bryophytes exhibit the formation of an embryo from the zygote
  4. (d) Bryophytes can prepare their own food
Answer & solution

Answer: (c) Bryophytes exhibit the formation of an embryo from the zygote

Topic:Bryophytes vs Algae
Common features:
Both possess chlorophyll (photosynthetic)
Both are cryptogams (non-flowering plants)
Both can prepare their own food (autotrophic)
Key difference:
Bryophytes form a multicellular embryo from zygote
Algae do NOT form embryo (zygote develops directly)
Bryophytes = Embryophyta (embryo-forming plants)
Answer: Option 3 → Bryophytes exhibit the formation of an embryo from the zygote
RRB NTPC GL CBT-1 2025-26 – 16 March 2026 Shift 1 · Animal kingdom - non-chordates

Q57. What is the primary function of the water vascular system in echinoderms, such as starfish?

  1. (a) Reproduction
  2. (b) Locomotion and feeding
  3. (c) Sensory perception
  4. (d) Gas exchange
Answer & solution

Answer: (b) Locomotion and feeding

Unique hydraulic system filled with seawater.
Powers tube feet for movement across surfaces.
Tube feet also grab and manipulate food items.
Answer: Option 2 → Locomotion and feeding
RRB JE CBT-1 2025-26 – 20 February 2026 Shift 2 · Characteristics of living organisms and life processes

Q58. Which combination best represents essential life processes for maintaining an individual organism?

  1. (a) Growth, movement, reproduction and response
  2. (b) Locomotion, feeding, communication and defence
  3. (c) Reproduction, variation, heredity and adaptation
  4. (d) Nutrition, respiration, transportation and excretion
Answer & solution

Answer: (d) Nutrition, respiration, transportation and excretion

The essential life processes for maintaining an individual organism include Nutrition, Respiration, Transportation, and Excretion.
These processes are fundamental to sustain life and ensure proper functioning of the organism.
Growth, movement, reproduction and response are important but not all are essential for maintaining the organism itself.
Reproduction, variation, heredity and adaptation relate more to species survival, not individual maintenance.
Hence, option 4 best represents essential life processes for maintaining an individual organism.
Final answer: Option 4
RRB JE CBT-1 2025-26 – 19 February 2026 Shift 2 · Characteristics of living organisms and life processes

Q59. A scientist is designing an artificial multi-cellular organism. What must they include to ensure all cells receive nutrients and remove wastes effectively?

  1. (a) Only specialised tissues for nutrition
  2. (b) Direct contact of every cell with the environment
  3. (c) A transportation system for food, oxygen, and waste
  4. (d) Simple diffusion through the entire surface
Answer & solution

Answer: (c) A transportation system for food, oxygen, and waste

Correct option is 3.
Multicellular organisms need a system to transport nutrients, oxygen, and waste efficiently.
This is because not all cells can be in direct contact with the environment.
Specialised tissues alone cannot ensure complete transport.
Simple diffusion is not effective for large, complex organisms.
Therefore, a transportation system like blood vessels or vascular tissues is necessary.
This system ensures all cells receive what they need and wastes are removed properly.
Hence, a transportation system for food, oxygen, and waste must be included.
Final answer: Option 3
SSC MTS 2025 – 6 February 2026 Shift 3 · Animal kingdom - chordates and vertebrate classes

Q60. How many chambers are there in the heart of amphibians?

  1. (a) 2
  2. (b) 3
  3. (c) 4
  4. (d) 5
Answer & solution

Answer: (b) 3

Correct Answer: 2 (3)
Amphibians (frogs, toads, salamanders) have a 3-chambered heart consisting of 2 atria (right and left) and 1 ventricle. The single ventricle receives oxygenated blood from the left atrium and deoxygenated blood from the right atrium, and pumps mixed blood to the body.
Heart chambers by organism type:
- Fish: 2 chambers (1 atrium + 1 ventricle)
- Amphibians & most reptiles: 3 chambers (2 atria + 1 ventricle)
- Crocodiles, birds, mammals: 4 chambers (2 atria + 2 ventricles)
Option 1 (2) is incorrect - fish have 2-chambered hearts.
Option 3 (4) is incorrect - mammals and birds have 4-chambered hearts.
Option 4 (5) is incorrect - no vertebrate has a 5-chambered heart.
Delhi Police Constable (Exe) 2025-26 – 23 December 2025 Shift 3 · Animal kingdom - chordates and vertebrate classes

Q61. Which of the following pairs is correctly matched?

  1. (a) Mammals - 4-chambered heart
  2. (b) Amphibians - 4-chambered heart
  3. (c) Reptiles - 1-chambered heart
  4. (d) Birds - 2-chambered heart
Answer & solution

Answer: (a) Mammals - 4-chambered heart

The correct answer is Mammals - 4-chambered heart (Option 1).
Mammals (including humans) have a 4-chambered heart consisting of two atria and two ventricles. This completely separates oxygenated and deoxygenated blood, enabling efficient circulation to support high metabolic rates.
Option 2 - Amphibians - 4-chambered heart: Amphibians (frogs, toads, salamanders) have a 3-chambered heart (two atria and one ventricle), not 4-chambered.
Option 3 - Reptiles - 1-chambered heart: Most reptiles have a 3-chambered heart (two atria and one partially divided ventricle). Crocodilians are an exception with 4 chambers. No vertebrate has a 1-chambered heart.
Option 4 - Birds - 2-chambered heart: Birds, like mammals, have a 4-chambered heart. Fish have a 2-chambered heart (one atrium and one ventricle).
SSC Stenographer 2025 – 6 December 2025 Shift 3 · Animal kingdom - non-chordates

Q62. Which of the following is a unique characteristic of sponges (Phylum Porifera)?

  1. (a) Presence of cnidoblasts for defense
  2. (b) Radial symmetry and presence of tentacles
  3. (c) Water canal system and choanocytes
  4. (d) Jointed appendages and chitinous exoskeleton
Answer & solution

Answer: (c) Water canal system and choanocytes

The correct answer is Water canal system and choanocytes . Sponges, belonging to Phylum Porifera, are the simplest multicellular animals. Their most unique feature is the water canal system , which helps in food capture, respiration, and excretion. Water enters through tiny pores (ostia), passes through a system of canals, and exits via a large opening (osculum). The movement of water is facilitated by special cells called choanocytes (collar cells) , which have flagella to create water currents and trap food particles. Unlike cnidarians, they do not possess cnidoblasts ; unlike echinoderms, they do not have radial symmetry; and unlike arthropods, they lack jointed appendages or a chitinous exoskeleton. Thus, the water canal system and choanocytes are the defining characteristics of sponges.
SSC CHSL Tier-1 2025 – 20 November 2025 Shift 2 · Characteristics of living organisms and life processes

Q63. Why do single-celled organisms do not need specific organs for taking in food, exchanging gases, or removing wastes?

  1. (a) They have complex body structures
  2. (b) Their entire surface is in contact with the environment
  3. (c) They have a protective wall around them
  4. (d) They do not perform these functions
Answer & solution

Answer: (b) Their entire surface is in contact with the environment

Correct Answer: Their entire surface is in contact with the environment (Option 2)
Single-celled organisms (such as Amoeba and Paramecium) do not need special organs because their entire body surface is directly in contact with the surrounding environment. This allows them to directly absorb nutrients, exchange gases, and excrete wastes through simple diffusion across the cell membrane.
Why others are wrong:
Option 1 - They have complex body structures: This is incorrect; single-celled organisms have simple, not complex, body structures.
Option 3 - They have a protective wall around them: A cell wall does not explain the lack of need for organs; it is for protection, not nutrient exchange.
Option 4 - They do not perform these functions: Incorrect; they do perform these life functions like food intake, gas exchange, and waste removal.

Q64. What type of symmetry do humans exhibit?

  1. (a) Radial symmetry
  2. (b) Bilateral symmetry
  3. (c) Asymmetry
  4. (d) Spherical symmetry
Answer & solution

Answer: (b) Bilateral symmetry

Correct Answer: Option 2 – Bilateral symmetry
Humans exhibit bilateral symmetry, meaning the body can be divided into two mirror-image halves (left and right) along a single plane (the sagittal plane). This symmetry is characteristic of most animals including vertebrates, arthropods, and molluscs .
Option 1 (Radial symmetry): Found in organisms like starfish, sea anemones, and jellyfish, which can be divided into equal halves along multiple planes through a central axis.
Option 3 (Asymmetry): Characteristic of sponges (Porifera), which have no regular plane of symmetry.
Option 4 (Spherical symmetry): Found in very simple organisms like some radiolarians; any plane through the center produces equal halves — humans do not have this.
SSC Selection Post 2025 (Phase XIII) – 28 July 2025 Shift 2 · Animal kingdom - chordates and vertebrate classes

Q65. What term describes animals that regulate their body temperature internally?

  1. (a) Ectotherms
  2. (b) Endotherms
  3. (c) Amphibians
  4. (d) Invertebrates
Answer & solution

Answer: (b) Endotherms

Correct Answer: Option 2 – Endotherms
Endotherms (warm-blooded animals) are animals that generate and regulate their own body temperature internally through metabolic processes, regardless of external environmental temperature. Birds and mammals are endotherms. They maintain a constant internal temperature (homeothermy) through mechanisms like sweating, shivering, panting, and adjusting metabolic rate.
Option 1 (Ectotherms): Ectotherms (cold-blooded animals — reptiles, fish, amphibians, insects) rely on external heat sources to regulate body temperature.
Option 3 (Amphibians): Amphibians are ectotherms, not endotherms; they are a taxonomic class, not a temperature-regulation category.
Option 4 (Invertebrates): Invertebrates are animals without a vertebral column — a structural classification, not related to temperature regulation. Most invertebrates are ectotherms.

Q66. Which of the following is a unicellular ciliary organism?

  1. (a) Paramecium
  2. (b) Leeches
  3. (c) Amoeba
  4. (d) Ticks
Answer & solution

Answer: (a) Paramecium

Correct Answer: Option 1 — Paramecium
Paramecium is a unicellular (single-celled) organism whose entire body is covered with thousands of short, hair-like structures called cilia. That is why it is described as a ciliated or ciliary organism. The rhythmic beating of the cilia moves the animal through water and also sweeps food particles into the oral groove, where a food vacuole is formed.
Being unicellular, one single cell carries out every life process — nutrition, respiration, excretion, movement and reproduction. Because of its slipper-like outline it is often called the slipper animalcule.
❌ Why the other options are incorrect
✗ Leeches — multicellular blood-sucking annelid worms; they have suckers, not cilia, and belong to the phylum Annelida.
✗ Amoeba — it is indeed unicellular, but it moves and feeds by pseudopodia (false feet) of flowing cytoplasm; it has no cilia.
✗ Ticks — multicellular arachnids (eight-legged arthropods) that are external parasites of animals; they have jointed legs, not cilia.
📌 SSC & Railway Exam Facts
• Cilia — short and numerous (Paramecium); flagella — long and few (Euglena, sperm).
• Pseudopodia — Amoeba; parapodia — Nereis.
• Paramecium has two nuclei — a large macronucleus and a small micronucleus.
• Unicellular examples: Amoeba, Paramecium, Euglena, Chlamydomonas, yeast, bacteria.
• In humans, ciliated epithelium lines the trachea and pushes out dust and mucus.

Q67. Which of the following is an example of a unicellular organism?

  1. (a) Lizard
  2. (b) House fly
  3. (c) Amoeba
  4. (d) Hydra
Answer & solution

Answer: (c) Amoeba

Correct Answer: Option 3 — Amoeba
A unicellular (single-celled) organism is one whose entire body is made of only one cell, and that single cell carries out all the life processes — nutrition, respiration, excretion, movement and reproduction. Amoeba is the classic example: it belongs to the kingdom Protista, has an irregular, ever-changing shape, and moves and captures food using finger-like pseudopodia (false feet).
Inside the one cell, food is digested in a food vacuole, extra water is thrown out by the contractile vacuole, and reproduction takes place by binary fission.
❌ Why the other options are incorrect
✗ Lizard — a multicellular vertebrate reptile with a backbone, lungs, a four-chambered heart (partly divided) and a well-developed nervous system.
✗ House fly — a multicellular insect of the phylum Arthropoda, with a jointed body, compound eyes and a complete life cycle.
✗ Hydra — though simple and capable of budding and regeneration, it is a multicellular animal of the phylum Cnidaria (Coelenterata) with tentacles and stinging cells.
📌 SSC & Railway Exam Facts
• Other unicellular organisms: Paramecium, Euglena, Chlamydomonas, yeast and all bacteria.
• Amoeba shows holozoic nutrition and engulfs food by phagocytosis.
• Euglena has both plant and animal characters, so it is called a connecting link; it moves by a flagellum.
• Paramecium moves with cilia and is slipper-shaped.
• Kingdom Protista was added by R. H. Whittaker in his five-kingdom classification (1969).

Q68. Which of the following organisms is commonly referred to as bread mould?

  1. (a) Rhizopus
  2. (b) Yeast
  3. (c) Spirogyra
  4. (d) Planaria
Answer & solution

Answer: (a) Rhizopus

Correct Answer: Option 1 — Rhizopus
Rhizopus stolonifer is commonly called bread mould because it is the whitish, cottony fungus that grows on moist bread kept in the open for a few days. Its body is made of thread-like hyphae that together form a network called the mycelium.
Rhizopus is a saprophyte — it secretes digestive enzymes onto the bread, breaks the food down outside its body and then absorbs the dissolved nutrients. This is called saprophytic nutrition. It reproduces asexually by spore formation inside sporangia borne on upright hyphae, and the black colour of stale bread comes from these sporangia.
❌ Why the other options are incorrect
✗ Yeast — a unicellular fungus used in baking and brewing; it causes fermentation, but it is not called bread mould.
✗ Spirogyra — a green, filamentous freshwater alga (pond silk) that reproduces by fragmentation; it is not a fungus.
✗ Planaria — a flatworm (phylum Platyhelminthes) famous for regeneration; it is an animal, not a mould.
📌 SSC & Railway Exam Facts
• Fungi have chitin in their cell walls and store food as glycogen.
• Saprophytes — Rhizopus, mushroom, bread mould; Parasites — Cuscuta (amarbel), *Plasmodium*, tapeworm.
• Penicillium gave the first antibiotic Penicillin, discovered by Alexander Fleming (1928).
• Yeast (*Saccharomyces cerevisiae*) converts sugar into alcohol and CO₂, which makes bread rise.
• Lichen is a symbiotic association of a fungus and an alga; mycorrhiza is that of a fungus and plant roots.

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