Q2777. Which of the following statements is correct?
Year: 2021
✅ Correct Answer: Fusion of protoplasm between two motile or non-motile gametes is called plasmogamy
🧠 Solution:
Plasmogamy is the fusion of two protoplasts (contents of two cells), bringing together two compatible haploid nuclei in the same cell. Incorrect statements can be corrected as: organisms that fix atmospheric nitrogen have heterocysts; karyogamy is fusion of two nuclei forming diploid cells; organisms that depend on living plants are called heterotrophs.
Q2779. Which of the following is incorrect about cyanobacteria?
Year: 2020
✅ Correct Answer: They lack heterocysts
🧠 Solution:
Cyanobacteria or blue-green algae are photosynthetic organisms performing oxygenic photosynthesis. They fix nitrogen using heterocysts—large pale cells with thick walls impermeable to oxygen.
Q2778. The size of Pleuropneumonia Like Organism (PPLO) is:
Year: 2020
✅ Correct Answer: 0.1 µm
🧠 Solution:
PPLO size is about 0.1 µm. Viruses are 0.02–0.2 µm, bacterial cells are 1–2 µm, and eukaryotic cells are 10–20 µm.
Q2864. Select the wrong statement.
Year: 2018
✅ Correct Answer: Pseudopodia are locomotory and feeding structures in sporozoans
🧠 Solution:
Sporozoans are endoparasites. They lack locomotory organelles like cilia, flagella, pseudopodia, etc., e.g. Plasmodium. Pseudopodia are found in amoeboid protozoans, e.g., Amoeba, Entamoeba, etc. Therefore, statement (a) is wrong while rest of the statements are correct.
Q2849. Select the wrong statement.
Year: 2018
✅ Correct Answer: Pseudopodia are locomotory and feeding structures in sporozoans
🧠 Solution:
Sporozoans are endoparasites. They lack locomotory organelles like cilia, flagella, pseudopodia, etc., e.g. Plasmodium. Pseudopodia are found in amoeboid protozoans, e.g., Amoeba, Entamoeba, etc. Therefore, statement (a) is wrong while rest of the statements are correct.
Q2781. Which of the following organisms are known as chief producers in the oceans?
Year: 2018
✅ Correct Answer: Diatoms
🧠 Solution:
Diatoms are chief producers in the oceans contributing about 40% of marine primary productivity. They are unicellular microalgae and major phytoplankton members.
Q2780. Oxygen is not produced during photosynthesis by:
Year: 2018
✅ Correct Answer: Green sulphur bacteria
🧠 Solution:
Green sulphur bacteria are anaerobic and do not evolve oxygen during photosynthesis (anoxygenic photosynthesis). They use hydrogen sulphide as a reducing agent instead of water.
Q2783. Which among the following are the smallest living cells, without a definite cell wall, pathogenic to plants as well as animals, and can survive without oxygen?
Year: 2017
✅ Correct Answer: Mycoplasma
🧠 Solution:
Mycoplasma are the smallest living cells lacking a definite cell wall. They are anaerobic and cause diseases in plants (little leaf of brinjal) and animals (pleuropneumonia in humans).
Q2782. Which of the following are found in extreme saline conditions?
Year: 2017
✅ Correct Answer: Archaebacteria
🧠 Solution:
Archaebacteria are the most primitive bacteria living in extreme environments. Halophiles (e.g., Halobacterium, Halococcus) live in highly saline conditions due to branched lipid chains reducing membrane fluidity.
Q2867. Which one of the following is wrong for fungi?
Year: 2016
✅ Correct Answer: All fungi possess a purely cellulosic cell wall
🧠 Solution:
In fungi, cell wall contains chitin or cellulose along with other polysaccharides, proteins and lipids. Only in some fungi, e.g. Phytophthora or other oomycetes a purely cellulosic cell wall is present. Hence, only option (b) is wrong, rest of the options are correct.
Q2866. One of the major components of cell wall of most fungi is
Year: 2016
✅ Correct Answer: chitin
🧠 Solution:
Cell wall of most fungi is made up of chitin. Chemically it is N-acetyl glucosamine. It is also found in the exoskeleton of insects.
Q2865. Which of the following would appear as the pioneer organisms on bare rocks?
Year: 2016
✅ Correct Answer: Lichens
🧠 Solution:
In primary succession on rocks, lichens secrete acids to dissolve rock, helps in weathering and soil formation. So, lichens are pioneer species to colonise the bare rock.
Q2852. Which one of the following is wrong for fungi?
Year: 2016
✅ Correct Answer: All fungi possess a purely cellulosic cell wall
🧠 Solution:
In fungi, cell wall contains chitin or cellulose along with other polysaccharides, proteins and lipids. Only in some fungi, e.g. Phytophthora or other oomycetes a purely cellulosic cell wall is present. Hence, only option (b) is wrong, rest of the options are correct.
Q2851. One of the major components of cell wall of most fungi is
Year: 2016
✅ Correct Answer: chitin
🧠 Solution:
Cell wall of most fungi is made up of chitin. Chemically it is N-acetyl glucosamine. It is also found in the exoskeleton of insects.
Q2850. Which of the following would appear as the pioneer organisms on bare rocks?
Year: 2016
✅ Correct Answer: Lichens
🧠 Solution:
In primary succession on rocks, lichens secrete acids to dissolve rock, helps in weathering and soil formation. So, lichens are pioneer species to colonise the bare rock.
Q2825. Select the wrong statement.
Year: 2016
✅ Correct Answer: The walls of diatoms are easily destructible
🧠 Solution:
Diatoms are single celled plant like protists that produce intricately structured cell walls made of nano–silica (SiO2). Thus, the walls are indestructible. Hence, only option (a) is wrong and rest of the options are correct.
Q2824. Chrysophytes, euglenoids, dinoflagellates and slime moulds are included in the kingdom
Year: 2016
✅ Correct Answer: Protista
🧠 Solution:
All single celled eukaryotic organisms like chrysophytes [diatoms and desmids], euglenoids [Euglena], dinoflagellates and slime moulds are included in kingdom–Protista.
Q2786. Methanogens belong to:
Year: 2016
✅ Correct Answer: Archaebacteria
🧠 Solution:
Methanogens belong to the archaebacteria group, including methanogens, halophiles, and thermoacidophiles. They are strict anaerobes found in ruminant guts and produce methane gas.
Q2785. Which one of the following statements is wrong?
Year: 2016
✅ Correct Answer: Eubacteria are also called false bacteria
🧠 Solution:
Eubacteria are true bacteria showing all typical characteristics of bacteria. Hence, calling them false bacteria is incorrect.
Q2784. The primitive prokaryotes responsible for the production of biogas from the dung of ruminant animals include:
Year: 2016
✅ Correct Answer: Methanogens
🧠 Solution:
Methanogens are obligate anaerobic archaebacteria involved in methanogenesis and produce methane gas in the gut of ruminant animals.
Q2869. The imperfect fungi which are decomposers of litter and help in mineral cycling belong to
Year: 2015
✅ Correct Answer: Deuteromycetes
🧠 Solution:
The imperfect fungi which are decomposers of litter and help in mineral cycling belong to Deuteromycetes. They are fungi which do not fit into the commonly established taxonomic classification of fungi. They include all those fungi in which the perfect stage (sexual stage) is not reported.
Q2868. Choose the wrong statement.
Year: 2015
✅ Correct Answer: Morels and truffles are poisonous mushrooms
🧠 Solution:
All statements are correct, except statement (c), which can be corrected as Morels and truffles are edible and members of Ascomycetes in fungi.
Q2854. The imperfect fungi which are decomposers of litter and help in mineral cycling belong to
Year: 2015
✅ Correct Answer: Deuteromycetes
🧠 Solution:
The imperfect fungi which are decomposers of litter and help in mineral cycling belong to Deuteromycetes. They are fungi which do not fit into the commonly established taxonomic classification of fungi. They include all those fungi in which the perfect stage (sexual stage) is not reported.
Q2853. Choose the wrong statement.
Year: 2015
✅ Correct Answer: Morels and truffles are poisonous mushrooms
🧠 Solution:
All statements are correct, except statement (c), which can be corrected as Morels and truffles are edible and members of Ascomycetes in fungi.
Q2827. In which group of organisms the cell walls form two thin overlapping shells which fit together?
Year: 2015
✅ Correct Answer: Chrysophytes
🧠 Solution:
Chrysophytes are placed under the kingdom–Protista. This group includes diatoms and golden algae (desmids). Most of them are photosynthetic. In diatoms, the cell walls form two thin overlapping shells, which fit together as in a soap box.
Q2826. Pick up the wrong statement.
Year: 2015
✅ Correct Answer: Nuclear membrane is present in Monera
🧠 Solution:
In Protista kingdom members exhibit both autotrophic as well as heterotrophic nutrition. Animal cells lack cell wall and there are a few fungi that are edible. Monera is the kingdom that contains unicellular organisms with a prokaryotic cell organisation, i.e. which lacks nuclear membrane and other membrane bound organelles.
Q2787. Chromatophores take part in:
Year: 2015
✅ Correct Answer: Photosynthesis
🧠 Solution:
Chromatophores are found in phototrophic bacteria. They contain bacteriochlorophyll pigments and carotenoids and participate in photosynthesis. In purple bacteria like Rhodospirillum rubrum, the light-harvesting proteins are present in chromatophore membranes, while in green sulphur bacteria, they are arranged in antenna complexes called chlorosomes.
Q2788. Archaebacteria differ from eubacteria in:
Year: 2014
✅ Correct Answer: Cell membrane structure
🧠 Solution:
Archaebacteria differ from eubacteria in membrane structure. Eubacteria have membranes made of glycerol-ester lipids, while archaebacteria have glycerol-ether lipids, which are more stable, allowing them to survive in high temperature and extreme pH environments.
Q2790. Pigment-containing membranous extensions in some cyanobacteria are:
Year: 2013
✅ Correct Answer: Chromatophores
🧠 Solution:
In cyanobacteria, chlorophyll is not located in chloroplasts but in chromatophores—infoldings of the plasma membrane where photosynthesis occurs. Heterocysts are nitrogen-fixing cells, basal bodies form cilia or flagella, and pneumatophores are roots for oxygen intake in mangroves.
Q2789. Besides paddy fields, cyanobacteria are also found inside vegetative part of:
Year: 2013
✅ Correct Answer: Cycas
🧠 Solution:
Cyanobacteria are found in the coralloid roots of Cycas in a symbiotic relationship. They are chemoheterotrophic and adapted for life inside the roots. Pinus is a gymnosperm; Equisetum is a vascular plant (horsetail); Psilotum is a fern-like pteridophyte.
Q2870. The highest number of species in the world is represented by
Year: 2012
✅ Correct Answer: fungi
🧠 Solution:
Fungi represent the highest number of species in the world. Around 100000 species of fungi have been formally described by taxonomists but the global biodiversity of kingdom—Fungi is not fully understood.
Q2855. The highest number of species in the world is represented by
Year: 2012
✅ Correct Answer: fungi
🧠 Solution:
Fungi represent the highest number of species in the world. Around 100000 species of fungi have been formally described by taxonomists but the global biodiversity of kingdom—Fungi is not fully understood.
Q2793. Nuclear membrane is absent in:
Year: 2012
✅ Correct Answer: Nostoc
🧠 Solution:
Nostoc is a prokaryote. Prokaryotic cells lack membrane-bound organelles and a nuclear envelope. Penicillium, Agaricus, and Volvox are eukaryotic and possess a true nucleus.
Q2792. The cyanobacteria are also referred to as:
Year: 2012
✅ Correct Answer: Blue-green algae
🧠 Solution:
Cyanobacteria, also known as blue-green algae, are primitive prokaryotic organisms and the most ancient chlorophyll-bearing organisms on Earth.
Q2791. Which of the following are likely to be present in deep sea water?
Year: 2012
✅ Correct Answer: Archaebacteria
🧠 Solution:
Archaebacteria thrive in extreme environments such as hot springs and deep-sea hydrothermal vents. Their unique membrane structure allows survival under extreme conditions. Eubacteria are true bacteria, fungi are heterotrophs, and cyanobacteria are photosynthetic autotrophs.
Q2796. A prokaryotic autotrophic nitrogen-fixing symbiont is found in:
Year: 2011
✅ Correct Answer: Cycas
🧠 Solution:
The coralloid roots of Cycas have symbiotic associations with nitrogen-fixing cyanobacteria like Anabaena cycadae and Nostoc punctiforme, which are prokaryotic, photosynthetic, and autotrophic.
Q2795. Organisms called methanogens are most abundant in:
Year: 2011
✅ Correct Answer: Cattle yard
🧠 Solution:
Methanogens are found in the guts of ruminant animals like cows and buffaloes and produce methane (biogas) from dung. Hence, they are most abundant in cattle yards.
Q2794. In eubacteria, a cellular component that resembles eukaryotic cells is:
Year: 2011
✅ Correct Answer: Plasma membrane
🧠 Solution:
The plasma membrane of eubacteria resembles that of eukaryotic cells. It is made of phospholipids and proteins but lacks sterols. Instead, hopanoids serve a similar structural function.
Q2798. Some hyperthermophilic organisms that grow in highly acidic habitats belong to the two groups called:
Year: 2010
✅ Correct Answer: Eubacteria and Archaea
🧠 Solution:
Thermophiles live at very high temperatures (60°–80°C). Many thermophiles, including some eubacteria and archaebacteria, are autotrophs and metabolize sulfur. Some archaebacteria thrive in extremely acidic or basic environments and around deep-sea thermal vents.
Q2797. Maximum nutritional diversity is found in the group:
Year: 2010
✅ Correct Answer: Monera
🧠 Solution:
Members of kingdom Monera show maximum nutritional diversity. Some are autotrophic (photosynthetic or chemosynthetic), while most are heterotrophic (saprotrophic or parasitic). Ecologically, they act as producers or decomposers.
Q2800. Bacterial leaf blight of rice is caused by a species of:
Year: 2008
✅ Correct Answer: Xanthomonas
🧠 Solution:
Leaf blight of rice is caused by Xanthomonas oryzae. Other examples: Red stripe of sugarcane – Pseudomonas rubrilineans; Fire blight of apple – Erwinia amylovora; Early blight of potato – Alternaria solani.
Q2799. Thermococcus, Methanococcus and Methanobacterium exemplify:
Year: 2008
✅ Correct Answer: Archaebacteria that contain protein homologous to eukaryotic core histones
🧠 Solution:
Archaebacteria like Methanobacterium, Methanococcus, and Thermococcus belong to the Euryarchaeota group. They possess histone-like proteins homologous to eukaryotic core histones.
Q2801. Which one of the following statements about Mycoplasma is wrong?
Year: 2007
✅ Correct Answer: They are sensitive to penicillin
🧠 Solution:
Mycoplasma lacks a cell wall, so it is not sensitive to penicillin which acts on cell wall synthesis. It is inhibited by antibiotics like chloramphenicol and tetracycline.
Q2828. What is common about Trypanosoma, Noctiluca, Monocystis and Giardia?
Year: 2006
✅ Correct Answer: These are all unicellular protists
🧠 Solution:
Trypanosoma, Noctiluca, Monocystis and Giardia are all unicellular protists. Trypanosoma gambiense causes sleeping sickness, Giardia causes giardiasis, Noctiluca is a marine dinoflagellate, and Monocystis is an endoparasite in earthworms.
Q2830. Which of the following unicellular organism has a macro-nucleus for trophic function and one or more micro-nuclei for reproduction?
Year: 2005
✅ Correct Answer: Paramecium and Vorticella
🧠 Solution:
Paramecium and Vorticella have dimorphic nuclei (heterokaryotic). Macronucleus controls daily synthetic activities or metabolic functions and asexual reproduction, while micronucleus is involved in genetic control during cell division.
Q2829. Auxospores and hormocysts are formed respectively by
Year: 2005
✅ Correct Answer: several diatoms and a few cyanobacteria
🧠 Solution:
Auxospores and hormocysts are formed by several diatoms and a few cyanobacteria respectively. Diatoms reproduce sexually by forming auxospores, while cyanobacteria form hormocysts for perennation.
Q2802. Barophillic prokaryotes:
Year: 2005
✅ Correct Answer: Grow and multiply in very deep marine sediments
🧠 Solution:
Barophilic prokaryotes are organisms that grow and multiply in very deep marine sediments under extreme pressure conditions.
Q2871. Lichens are well known combination of an alga and a fungus where fungus has
Year: 2004
✅ Correct Answer: a symbiotic relationship with the alga
🧠 Solution:
Lichen is a symbiotic association between a fungus and an alga. The fungal part is called mycobiont while the algal part is called phycobiont. The fungi absorb mineral and water to algae and the algae synthesise food by photosynthesis.
Q2837. When a freshwater protozoan possessing a contractile vacuole is placed in a glass containing marine water, the vacuole will
Year: 2004
✅ Correct Answer: disappear
🧠 Solution:
Freshwater protozoans live in hypotonic solution so, for regulation of excess of water which comes in the protoplasm through the process of endosmosis, contractile vacuoles have developed. When these protozoans are placed in marine (hypertonic) water, the contractile vacuoles disappear because the process of endosmosis does not occur and thus, water does not enter the protoplasm.
Q2835. When a freshwater protozoan possessing a contractile vacuole is placed in a glass containing marine water, the vacuole will
Year: 2004
✅ Correct Answer: disappear
🧠 Solution:
Freshwater protozoans live in hypotonic environment so, for regulation of excess water which comes in the protoplasm through the process of endosmosis, contractile vacuoles have developed. When these protozoans are placed in marine water (hypertonic water), the contractile vacuoles disappear because the process of endosmosis does not occur and thus, water does not enter into the protoplasm.
Q2803. A free-living nitrogen-fixing cyanobacterium which can also form symbiotic association with the water fern Azolla is:
Year: 2004
✅ Correct Answer: Anabaena
🧠 Solution:
Anabaena is a free-living nitrogen-fixing cyanobacterium that forms a symbiotic relationship with the water fern Azolla, helping in nitrogen enrichment of soil.
Q2886. Tobacco mosaic virus is a tubular filament of size
Year: 2003
✅ Correct Answer: 300 × 18 nm
🧠 Solution:
TMV is elongated rod-like, 3000Å (300 nm) long and 180Å (18 nm) in diameter.
Q2885. Which one of the following statements about viruses is correct?
Year: 2003
✅ Correct Answer: Viruses are obligate parasites
🧠 Solution:
Viruses are non-cellular, obligate parasites. They have DNA or RNA as genetic material (never both). Genetic material is covered in a protein coat, known as capsid. Viruses do not contain their own metabolic system.
Q2884. Viruses are no more ‘alive’ than isolated chromosomes because
Year: 2003
✅ Correct Answer: both require the environment of a cell to replicate
🧠 Solution:
Viruses are non-cellular obligate parasites. In the free state they are just like particles. They do not have their own metabolic machinery and use host’s machinery for multiplication.
Q2831. The chief advantage of encystment to an Amoeba is
Year: 2003
✅ Correct Answer: the ability to survive during adverse physical conditions
🧠 Solution:
Encystment of Amoeba occurs during unfavourable conditions like drought or extreme temperature. The Amoeba forms a protective cyst wall around itself to survive adverse conditions.
Q2804. Chromosomes in a bacterial cell can be 1–3 in number and:
Year: 2003
✅ Correct Answer: Are always circular
🧠 Solution:
Bacterial chromosomes are typically circular DNA molecules that carry the genetic material of the cell.
Q2873. Which fungal disease spreads by seed and flowers?
Year: 2002
✅ Correct Answer: Loose smut of wheat
🧠 Solution:
Fungal disease, loose smut of wheat spreads by seed and flowers. The causal organism of this disease is Ustilago fungus. It is an internal parasite. It infects the ovary of the host flower resulting in masses of teliospores in place of grains.
Q2872. During the formation of bread it becomes porous due to the release of CO2 by the action of
Year: 2002
✅ Correct Answer: yeast
🧠 Solution:
Strains of Saccharomyces cerevisiae are extensively used for leavening of bread. During fermentation, the yeasts produce alcohol and CO2 which leaves the bread porous.
Q2838. In Protozoa like Amoeba and Paramecium, an organelle is found for osmoregulation which is
Year: 2002
✅ Correct Answer: contractile vacuole
🧠 Solution:
Unicellular organisms such as Amoeba and Paramecium have organelles called contractile vacuoles for excretion and osmoregulation. These freshwater animals live in hypotonic solution; therefore, water flows from outside to inside of the organism. The contractile vacuoles collect excess water and gradually increase in size, then contract to expel contents by diffusion.
Q2834. In which animal, dimorphic nucleus is found?
Year: 2002
✅ Correct Answer: Paramecium caudatum
🧠 Solution:
Paramecium is heterokaryotic and possesses a dimorphic nuclear apparatus — a macronucleus for metabolism and micronuclei for reproduction.
Q2806. In bacteria, plasmid is:
Year: 2002
✅ Correct Answer: Extra-chromosomal material
🧠 Solution:
Plasmid is an extra-chromosomal, circular DNA molecule capable of independent replication. It often carries antibiotic resistance genes.
Q2805. Organisms which obtain energy by the oxidation of reduced inorganic compounds are called:
Year: 2002
✅ Correct Answer: Chemoautotrophs
🧠 Solution:
Chemoautotrophs obtain energy through chemical oxidation of inorganic compounds such as ammonia, nitrites, or hydrogen sulfide, independent of light.
Q2888. Cauliflower mosaic virus contains
Year: 2001
✅ Correct Answer: dsDNA
🧠 Solution:
Caulimovirus (Cauliflower Mosaic Virus) contains double stranded (ds) DNA. Influenza virus contains single stranded RNA (ssRNA). Parvovirus contains single stranded DNA (ssDNA).
Q2887. Interferons are synthesised in response to
Year: 2001
✅ Correct Answer: viruses
🧠 Solution:
Cells infected by virus produce interferon which is an antiviral protein. It spreads to neighbouring cells and makes them resistant to virus infections by inhibiting viral growth.
Q2875. Adhesive pad of fungi penetrates the host with the help of
Year: 2001
✅ Correct Answer: mechanical pressure and enzymes
🧠 Solution:
Cell wall degrading enzymes (cellulolytic, pectolytic) as well as mechanical pressure of adhesive pad (appressorium) help the fungus in penetrating the host.
Q2874. Plant decomposers are
Year: 2001
✅ Correct Answer: Monera and Fungi
🧠 Solution:
Decomposers are living components chiefly the bacteria and fungi that break down complex compounds of dead protoplasm of producers and consumers, absorb some products and release others.
Q2836. Extranuclear inheritance occurs in
Year: 2001
✅ Correct Answer: killer strain in Paramecium
🧠 Solution:
Paramecium exhibits cytoplasmic inheritance due to the presence of Kappa particles (self-replicating bodies that produce toxin called paramecin). Besides binary fission and conjugation, other reproductive processes that occur in Paramecium are autogamy, endomixis and cytogamy. Tay Sachs disease is a rare autosomal recessive genetic disorder. Colour blindness is X-chromosome linked disease and hence, a sex-linked disorder.
Q2809. What is true for photolithotrophs?
Year: 2001
✅ Correct Answer: Obtain energy from radiations and hydrogen from inorganic compounds
🧠 Solution:
Photolithotrophs obtain energy from light and use inorganic electron donors like H₂ or H₂S as the hydrogen source. Examples include purple and green sulphur bacteria.
Q2808. What is true for cyanobacteria?
Year: 2001
✅ Correct Answer: Oxygenic with nitrogenase
🧠 Solution:
Cyanobacteria, also known as blue-green algae, perform oxygenic photosynthesis and fix atmospheric nitrogen with the help of the enzyme nitrogenase.
Q2807. What is true for archaebacteria?
Year: 2001
✅ Correct Answer: Oldest living beings
🧠 Solution:
Archaebacteria can survive in extreme environments that resemble those of early Earth. They are believed to represent the earliest forms of life, hence called the 'oldest living beings'.
Q2877. Black rust of wheat is caused by
Year: 2000
✅ Correct Answer: Puccinia
🧠 Solution:
Black rust of wheat is caused by Puccinia graminis tritici. It causes major economic loss in wheat-growing regions. The fungus passes its life cycle on two hosts, wheat and barbery.
Q2876. In fungi stored food material is
Year: 2000
✅ Correct Answer: glycogen
🧠 Solution:
Glycogen, also known as ‘animal starch’, is the chief storage polysaccharide of animal cells and most of the fungi. Food is also stored as oil globules in some fungi.
Q2878. Which of the following is the use of lichens in case of pollution?
Year: 1999
✅ Correct Answer: They act as bioindicators of pollution
🧠 Solution:
Growth of lichens on trees is inhibited by air pollution. Hence, atmospheric pollution decreases their population, making lichens biological indicators of pollution.
Q2810. Photosynthetic bacteria have pigments in:
Year: 1999
✅ Correct Answer: Chromatophores
🧠 Solution:
Photosynthetic bacteria have small vesicles called chromatophores attached to the inner surface of the cell membrane. They contain bacteriochlorophyll pigments for photosynthesis.
Q2880. Columella is a specialised structure found in the sporangium of
Year: 1998
✅ Correct Answer: Rhizopus
🧠 Solution:
In Rhizopus, the central non-sporiferous region of sporangium is called columella.
Q2879. Puccinia forms
Year: 1998
✅ Correct Answer: uredia and telia on wheat leaves
🧠 Solution:
Puccinia graminis tritici (fungus) causes black rust of wheat. It forms Urediospores (uredia) and teleutospores (telia) on wheat leaves.
Q2814. The site of respiration in bacteria is:
Year: 1998
✅ Correct Answer: Mesosome
🧠 Solution:
Mesosomes are infoldings of the bacterial plasma membrane that contain enzymes for respiration and perform functions similar to mitochondria.
Q2813. A bacterium divides every 35 minutes. If a culture containing 10⁵ cells/mL is grown for 175 minutes, what will be the cell concentration after 175 minutes?
Year: 1998
✅ Correct Answer: 32 × 10⁵ cells
🧠 Solution:
The bacterium divides every 35 minutes. In 175 minutes, it divides 5 times (2⁵ = 32). Therefore, the final cell concentration is 32 × 10⁵ cells/mL.
Q2811. A few organisms are known to grow and multiply at temperatures of 100–105°C. They belong to:
Year: 1998
✅ Correct Answer: Marine archaebacteria
🧠 Solution:
Archaebacteria have membranes made of branched-chain lipids and ether-linked glycerol, enabling them to survive in extreme heat and other harsh conditions.
Q2889. Which one of the following statements about viruses is correct?
Year: 1997
✅ Correct Answer: Viruses contain either DNA or RNA
🧠 Solution:
Viruses contain only one type of nucleic acid DNA or RNA. These are obligate parasites; do not possess metabolic machinery and are not readily killed by antibiotics.
Q2881. Most of the lichens consist of
Year: 1997
✅ Correct Answer: blue-green algae and Ascomycetes
🧠 Solution:
Lichens consist of the fungal component mycobiont, mainly Ascomycotina, and the algal component phycobiont which are mostly blue-green algae (Nostoc, Scytonema) or green algae (Trebouxia, Trentophila, etc.).
Q2812. The hereditary material present in the bacterium Escherichia coli is:
Year: 1997
✅ Correct Answer: Double-stranded DNA
🧠 Solution:
Bacterial chromosomes consist of a single circular, double-stranded DNA molecule that carries the genetic information.
Q2890. Influenza virus has
Year: 1996
✅ Correct Answer: RNA
🧠 Solution:
Influenza virus is single (–) stranded RNA virus, which cannot serve directly as mRNA but rather as templates for mRNA synthesis via a viral transcriptase. Influenza virus (orthomyxovirus) infects the respiratory tract and causes influenza.
Q2882. Which one of the following is not true about lichens?
Year: 1996
✅ Correct Answer: These grow very fast at the rate of about 2 cm per year
🧠 Solution:
Statement (d) is incorrect because lichens show very slow growth. Their slow rate of growth suggests that some lichens in the Arctic are about 4000 years old.
Q2816. Sex factor in bacteria is:
Year: 1996
✅ Correct Answer: F-replicon
🧠 Solution:
The F-factor (fertility factor) is a small circular DNA molecule that acts as a self-replicating plasmid. It codes for the sex pilus, enabling conjugation between bacterial cells.
Q2815. In bacterial chromosomes, the nucleic acid polymers are:
Year: 1996
✅ Correct Answer: Circular DNA molecule
🧠 Solution:
The bacterial nucleoid consists of a single, circular DNA molecule lacking histone proteins and occupying 10–20% of the cell’s volume.
Q2883. Which of the following is not correctly matched?
Year: 1995
✅ Correct Answer: Covered smut of barley — Ustilago nuda
🧠 Solution:
Option ‘c’ is mismatched because covered smuts are caused by Ustilago hordei, where the sorus or smut ball is covered by a peridium of host cells. Ustilago nuda is responsible for causing loose smut of barley.
Q2833. Macro and micronucleus are the characteristic feature of
Year: 1995
✅ Correct Answer: Paramecium
🧠 Solution:
Paramecium is a heterokaryotic organism with two nuclei near the cytostome. The macronucleus controls vegetative functions, while the micronucleus is responsible for reproduction.
Q2832. Which of the following organisms possesses characteristics of both a plant and an animal?
Year: 1995
✅ Correct Answer: Euglena
🧠 Solution:
Euglena is a connecting link between plants and animals. It contains chlorophyll and can photosynthesize like plants, but in absence of sunlight, it behaves like an animal and ingests food.
Q2817. The plasmid
Year: 1995
✅ Correct Answer: is the genetic part in addition to DNA in microorganisms
🧠 Solution:
Plasmids are small, self-replicating, extrachromosomal, non-essential genetic elements in bacteria. Each plasmid has a ring of circular, supercoiled, double stranded DNA. They carry genes for replication and for one or more cellular non-essential functions. These are also called minichromosomes or dispensable autonomous elements.
Q2891. Tobacco Mosaic Virus (TMV) genes are
Year: 1994
✅ Correct Answer: single stranded RNA
🧠 Solution:
Tobacco Mosaic Virus (TMV) is elongated, rod shaped, with 95% protein and 5% RNA by weight. RNA is genomic, i.e. genetic material which is single stranded, linear, helically coiled, 5mµ in length with 6500 nucleotides.
Q2857. Protists obtain food as
Year: 1994
✅ Correct Answer: photosynthesisers, symbionts and holotrophs
🧠 Solution:
Protistans have variable modes of nutrition. They are photosynthetic heterotrophic, i.e. saprophytic, parasitic and ingestive.
Q2856. Entamoeba coli causes
Year: 1994
✅ Correct Answer: None of these
🧠 Solution:
Entamoeba coli is the common parasitic genera of phylum—Protozoa. It harbours the upper part of large intestine (colon) and very often in the liver, brain and testes and causes constipation.
Q2842. Protists obtain food as
Year: 1994
✅ Correct Answer: photosynthesisers, symbionts and holotrophs
🧠 Solution:
Protistans have variable modes of nutrition. They are photosynthetic heterotrophic, i.e. saprophytic, parasitic and ingestive.
Q2841. Entamoeba coli causes
Year: 1994
✅ Correct Answer: None of these
🧠 Solution:
Entamoeba coli is the common parasitic genera of phylum—Protozoa. It harbours the upper part of large intestine (colon) and very often in the liver, brain and testes and causes constipation.
Q2840. Protistan genome has
Year: 1994
✅ Correct Answer: membrane bound nucleoproteins embedded in cytoplasm
🧠 Solution:
Eukaryotic (e.g. protistan) genome is organised in the form of a nucleus. It is differentiated into nuclear envelope, chromatin, one or more nucleoli, and nucleoplasm. Nuclear DNA is linear and associated with histone proteins. A small quantity of DNA is also found in plastids and mitochondria. In contrast, prokaryotic (bacterial) DNA is circular and lies freely in the cytoplasm.
Q2818. Temperature tolerance of thermal blue-green algae is due to
Year: 1994
✅ Correct Answer: cell wall structure
🧠 Solution:
Cyanobacteria provide a good example of the adaptability of life to extremes of environment (high temperature of hot springs and low temperature of polar regions). It is due to their gelatinous sheath, that can withstand long periods of desiccation. The compactness of protein molecules and their bonds in the protoplasm also help the cells to face the extremes.
Q2820. Genophore bacterial genome or nucleoid is made of
Year: 1993
✅ Correct Answer: a single double stranded DNA
🧠 Solution:
In bacteria nucleoid or genophore is haploid and consists of single, naked, double stranded, circular ring like highly folded supercoiled DNA with no free ends, no histone proteins. The nucleoid of E. coli has a central core of RNA surrounded by about 50 super coilings of DNA which is then associated with some basic proteins but never histones. Some proteins like polyamines rich in alanine are also found associated with DNA.
Q2819. ESCHERICHIA COLI is used extensively in biological research as it is
Year: 1993
✅ Correct Answer: easily cultured
🧠 Solution:
Escherichia coli, a commensal bacterium is most studied bacterium and widely used in research because it is easily cultured on minimal medium and has fast rate of multiplication and short generation time.
Q2821. Bacteria lack alternation of generation because there is
Year: 1992
✅ Correct Answer: neither syngamy nor reduction division
🧠 Solution:
Bacteria reproduces asexually by transverse binary fission, conidia, budding, cyst and sporulation. No true sexual reproduction (involving formation of gametes, their fusion and meiosis) is known to occur in bacteria. However, in bacteria the transfer of genetic material from donor to recipient cell to bring genetic recombinations/variations is reported that occurs not through gametes/sex cells, but by other methods like conjugation, transduction and transformation. It does not result in any multiplication of cells.
Q2859. In Amoeba and Paramecium osmoregulation occurs through
Year: 1991
✅ Correct Answer: contractile vacuole
🧠 Solution:
Amoeba and Paramecium contain two contractile vacuoles (anterior and posterior, the latter being faster) for osmoregulation, i.e. maintaining water balance in the body.
Q2858. African sleeping sickness is due to
Year: 1991
✅ Correct Answer: Trypanosoma gambiense transmitted by Glossina palpalis
🧠 Solution:
The disease African sleeping sickness is caused by Trypanosoma gambiense and this is transmitted by tse-tse fly (Glossina palpalis).
Q2844. In Amoeba and Paramecium osmoregulation occurs through
Year: 1991
✅ Correct Answer: contractile vacuole
🧠 Solution:
Amoeba and Paramecium contain two contractile vacuoles (anterior and posterior, the latter being faster) for osmoregulation, i.e. maintaining water balance in the body.
Q2843. African sleeping sickness is due to
Year: 1991
✅ Correct Answer: Trypanosoma gambiense transmitted by Glossina palpalis
🧠 Solution:
The disease African sleeping sickness is caused by Trypanosoma gambiense and this is transmitted by tse-tse fly (Glossina palpalis).
Q2862. What is true about Trypanosoma?
Year: 1990
✅ Correct Answer: Polymorphic
🧠 Solution:
Trypanosoma is an obligate parasite, it is digenetic polymorphic (Trypanosoma is adult form in human, whereas crithidal and leptomonal are developmental forms in tse-tse fly).
Q2861. Plasmodium, the malarial parasite, belongs to class
Year: 1990
✅ Correct Answer: Sporozoa
🧠 Solution:
Plasmodium, the malarial parasite belongs to class—Sporozoa. Sporozoans are intracellular parasites, reproduce by multiple fission and life cycle may include two different hosts.
Q2860. Genetic information in Paramecium is contained in
Year: 1990
✅ Correct Answer: micronucleus
🧠 Solution:
Ciliates (Paramecium) show nuclear dimorphism, large macronucleus controls metabolic activities and growth. It is called vegetative nucleus. Micronucleus contains genetic information and thus, takes part in reproduction.
Q2847. What is true about Trypanosoma?
Year: 1990
✅ Correct Answer: Polymorphic
🧠 Solution:
Trypanosoma is an obligate parasite, it is digenetic polymorphic (Trypanosoma is adult form in human, whereas crithidal and leptomonal are developmental forms in tse-tse fly).
Q2846. Plasmodium, the malarial parasite, belongs to class
Year: 1990
✅ Correct Answer: Sporozoa
🧠 Solution:
Plasmodium, the malarial parasite belongs to class—Sporozoa. Sporozoans are intracellular parasites, reproduce by multiple fission and life cycle may include two different hosts.
Q2845. Genetic information in Paramecium is contained in
Year: 1990
✅ Correct Answer: micronucleus
🧠 Solution:
Ciliates (Paramecium) show nuclear dimorphism, large macronucleus controls metabolic activities and growth. It is called vegetative nucleus. Micronucleus contains genetic information and thus, takes part in reproduction.
Q2822. Which one belongs to the Monera?
Year: 1990
✅ Correct Answer: Escherichia
🧠 Solution:
The kingdom–Monera (Gr. monera = simple) includes simple, prokaryotic primitive organisms. It includes bacteria, archaebacteria, Actinomycetes, Mycoplasma, spirochaetes, rickettsiae, chlamydiae and cyanobacteria. Escherichia coli is the most studied bacterium. E. coli is an enteric bacteria, found in entire colon, secretes vitamin-K, B3 , B6 , B12 and folic acid.
Q2863. Trypanosoma belongs to class
Year: 1989
✅ Correct Answer: Zooflagellata
🧠 Solution:
Zooflagellates are protozoan parasites which possess one to several flagella for locomotion. They are generally uninucleate (occasionally multinucleate), body is covered by a firm pellicle, e.g. Trypanosoma, Leishmania, Trichomonas, etc.
Q2848. Trypanosoma belongs to class
Year: 1989
✅ Correct Answer: Zooflagellata
🧠 Solution:
Zooflagellates are protozoan parasites which possess one to several flagella for locomotion. They are generally uninucleate (occasionally multinucleate), body is covered by a firm pellicle, e.g. Trypanosoma, Leishmania, Trichomonas, etc.
Q2839. Excretion in Amoeba occurs through
Year: 0
✅ Correct Answer: contractile vacuole
🧠 Solution:
Endoplasm of Amoeba in the posterior part contains a single, clear, rounded, and pulsating contractile vacuole. The contractile vacuole is analogous to uriniferous tubules of frog. It functions in excretion and osmoregulation.
Q2823. Ciliates differ from all other protozoans in
Year: 0
✅ Correct Answer: having two types of nuclei
🧠 Solution:
Ciliates differ from all other protozoans in having two types of nuclei. These two nuclei are usually of different size, i.e. one is meganucleus and the other is micronucleus. The former controls metabolism whereas the latter is concerned with reproduction, e.g. Paramecium. In other protozoans, like Amoeba, single nucleus is present which is involved in metabolism and reproduction.