Q.A protoxin is:

Showing the 12 most recent of 59 on this concept.

1. TG EAPCET 2026Set ap-2026-05-04-AN1 markMCQ
   Q.Identify blank spaces A, B, C and D in the following table and select the correct option (A) A $\rightarrow$ Streptococcus, B $\rightarrow$ Fungus, C $\rightarrow$ Cyclosporin-A, D $\rightarrow$ Clostridium butylicum (B) A $\rightarrow$ Clostridium butylicum, B $\rightarrow$ Bacteria, C $\rightarrow$ Citric acid, D $\rightarrow$ Streptococcus (C) A $\rightarrow$ Streptococcus, B $\rightarrow$ Yeast, C $\rightarrow$ Cyclosporin-A, D $\rightarrow$ Lactobacillus (D) A $\rightarrow$ Streptococcus, B $\rightarrow$ Fungus, C $\rightarrow$ Statins, D $\rightarrow$ Clostridium butylicum

   ›Reveal solutionSolution

   This question tests your knowledge of which microbe produces which industrial product. The correct pairing is: Streptococcus produces Streptokinase (A), Fungus produces Cyclosporin-A (B and C), and Clostridium butylicum produces Butyric acid (D). The correct option is (A).

   The table is missing the names of microbes and products for four blanks. To fill them, you need to recall the specific microbe–product pairs from biotechnology and industrial microbiology. Each blank corresponds to a well-known association that appears frequently in exam questions.

   Let’s go through each blank one by one.

   1. Blank A — the microbe that produces Streptokinase.

      Streptokinase is a clot-busting enzyme used to dissolve blood clots in heart attack patients. It is produced by the bacterium Streptococcus (specifically, Streptococcus pyogenes). So A is Streptococcus.

   2. Blank B — the category of organism that produces Cyclosporin-A.

      Cyclosporin-A is an immunosuppressive drug used in organ transplants to prevent rejection. It is produced by a fungus — the fungus Trichoderma polysporum (now often called Tolypocladium inflatum). So B is Fungus.

   3. Blank C — the product made by the fungus Trichoderma polysporum.

      As just noted, that product is Cyclosporin-A. So C is Cyclosporin-A.

   4. Blank D — the microbe that produces Butyric acid.

      Butyric acid is a short-chain fatty acid used in food flavouring and chemical synthesis. It is produced by the bacterium Clostridium butylicum. So D is Clostridium butylicum. …

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2. TG EAPCET 2026Set ap-2026-05-04-AN1 markMCQ
   Q.Match of the following A Cell wall lacks pectin B Cell wall with polysulphate esters C Cell wall with chitin D Cell wall with murin (A) A-II, B-III, C-IV, D-I (B) A-II, B-V, C-IV, D-III (C) A-III, B-IV, C-V, D-II (D) A-II, B-III, C-IV, D-V

   ›Reveal solutionSolution

   Matching each cell-wall feature to its group by its characteristic wall polymer gives A-II, B-III, C-IV, D-I — option (A).

   Cell-wall chemistry is a reliable taxonomic marker, so each clue points to one group:

   • A – Cell wall lacks pectin: fungal walls are built of chitin and glucans and contain no pectin, so A maps to the fungal entry (II).
   • B – Cell wall with polysulphate esters: sulphated polysaccharides such as agar and carrageenan are the signature of the red algae, Rhodophyceae, so B maps to III.
   • C – Cell wall with chitin: chitin, a nitrogenous polysaccharide, is the defining wall material of fungi/fungal-type walls, giving C the value IV in this key. …

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3. TG EAPCET 2026Set ap-2026-05-04-AN1 markMCQ
   Q.Among the situations given below, choose the one that prevents both autogamy and geitonogamy. (A) Monoecious plant bearing unisexual flowers (B) Dioecious plant with bisexual flowers (C) Monoecious plant with bisexual flowers (D) Dioecious plant bearing only male or female flowers

   ›Reveal solutionSolution

   Autogamy (self-pollination within the same flower) and geitonogamy (pollination between different flowers on the same plant) are both prevented only when a plant has unisexual flowers and is dioecious — meaning male and female flowers occur on separate individuals. The correct choice is (D).

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   Concept & Intuition

   Pollination can be divided into three types:

   • Autogamy: pollen from a flower lands on its own stigma.
   • Geitonogamy: pollen from one flower lands on a stigma of a different flower on the same plant.
   • Xenogamy: pollen from a flower on one plant lands on a stigma of a flower on a different plant.

   To prevent both autogamy and geitonogamy, we need a mechanism that ensures no flower can receive its own pollen and no flower can receive pollen from another flower on the same individual. The only sure way is to have unisexual flowers (so autogamy is impossible) and to have male and female flowers on separate plants (dioecy), so geitonogamy is impossible because there is no second flower of the opposite sex on the same plant.

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   Step-by-step reasoning

   1. Autogamy requires bisexual flowers

      If a flower has both stamens and pistil, self-pollination is physically possible. Unisexual flowers (either male or female) cannot self-pollinate because they lack the opposite sex organ. So to block autogamy, flowers must be unisexual.

   2. Geitonogamy requires two flowers of opposite sex on the same plant

      Even if flowers are unisexual, if the plant is monoecious (male and female flowers on the same individual), pollen from a male flower can reach a female flower on the same plant — that’s geitonogamy. To block geitonogamy, the plant must be dioecious: male flowers on one plant, female flowers on another.

   3. Evaluate each option

      • (A) Monoecious plant bearing unisexual flowers → Autogamy is prevented (unisexual flowers), but geitonogamy is possible (male and female flowers on same plant). ✗
      • (B) Dioecious plant with bisexual flowers …

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4. TG EAPCET 2026Set ap-2026-05-04-AN1 markMCQ
   Q.Among the following identify Zwitterionic form of amino acid (A) $\begin{array}{c} \text{R} \\ | \\ \text{H}_3^+\text{N} - \text{CH} - \text{COOH} \end{array}$ (B) $\begin{array}{c} \text{R} \\ | \\ \text{H}_3^+\text{N} - \text{CH} - \text{COO}^- \end{array}$ (C) $\begin{array}{c} \text{R} \\ | \\ \text{H}_3^+\text{N} - \text{CH} - \text{CO}^- \end{array}$ (D) $\begin{array}{c} \text{R} \\ | \\ \text{H}_2\text{N} - \text{CH} - \text{COO}^- \end{array}$

   ›Reveal solutionSolution

   A zwitterion is a neutral molecule with equal positive and negative charges. For an amino acid, this means the amino group is protonated ($-\mathrm{NH_3^+}$) and the carboxyl group is deprotonated ($-\mathrm{COO^-}$). The correct option is (B).

   The concept here is simple but often confused: a zwitterion (from German "zwitter" meaning hybrid) is a molecule that carries both a positive and a negative charge, yet overall is electrically neutral. For amino acids in aqueous solution near their isoelectric point, this is their dominant form.

   Why does this happen? The amino group ($-\mathrm{NH_2}$) is basic and picks up a proton to become $-\mathrm{NH_3^+}$, while the carboxyl group ($-\mathrm{COOH}$) is acidic and loses a proton to become $-\mathrm{COO^-}$. The result is a dipolar ion — a zwitterion.

   Now let's examine each option carefully.

   1. Option (A): $\mathrm{H_3^+N - CH(R) - COOH}$

      Here the amino group is protonated (positive charge), but the carboxyl group is still in its acid form ($-\mathrm{COOH}$) — it has not lost a proton. So the molecule carries a net positive charge. This is not a zwitterion; it's the cationic form found in acidic solutions.

   2. Option (B): $\mathrm{H_3^+N - CH(R) - COO^-}$

      The amino group is protonated (positive) and the carboxyl group is deprotonated (negative). The molecule has equal and opposite charges, making it electrically neutral overall. This is the classic zwitterionic form of an amino acid.

   3. Option (C): $\mathrm{H_3^+N - CH(R) - CO^-}$

      This structure shows a carboxylate-like group with only a single negative charge on the carbon (a carbanion), which is chemically unrealistic. The carboxyl group normally exists as $-\mathrm{COO^-}$, not $-\mathrm{CO^-}$. This is not a valid representation of any stable amino acid form.

   4. Option (D): $\mathrm{H_2N - CH(R) - COO^-}$ …

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5. TG EAPCET 2026Set ap-2026-05-04-FN1 markMCQ
   Q.In a tripod of cockroach during locomotion the pivot is (A) Left front leg (B) Right front leg (C) Middle leg (D) Right last leg

   ›Reveal solutionSolution

   In cockroach locomotion, the tripod gait uses the middle leg of one side as the pivot while the other two legs on that side swing forward. The correct answer is (C) Middle leg.

   The cockroach moves using a tripod gait, a highly efficient pattern where at any given moment three legs are on the ground and three are in the air. The key is understanding which leg acts as the pivot — the fixed point that supports the body while the other two legs on that side advance.

   1. The tripod arrangement

      The six legs are divided into two alternating tripods:

      • Tripod 1: Left front, right middle, left hind
      • Tripod 2: Right front, left middle, right hind When one tripod is on the ground, the other is lifted and swung forward.

   2. Identifying the pivot on one side

      Consider the right side of the body. During a step, the right front and right hind legs lift and move forward. The right middle leg remains planted on the ground, acting as the stable support. This middle leg is the pivot because it bears the body’s weight and provides the fulcrum for the forward swing of the other two legs on that side.

   3. Why not the front or hind leg?

      • The front leg is lifted during the swing phase, so it cannot be a pivot. …

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6. TG EAPCET 2026Set ap-2026-05-04-FN1 markMCQ
   Q.Choose the mismatched pair (A) Carcinoma – Epithelial tissues (B) Sarcoma – Connective tissues (C) Leukemia – Bone marrow (D) Lymphoma – Nervous tissue

   ›Reveal solutionSolution

   The question asks which cancer–tissue pair is incorrect. Lymphoma is a cancer of the lymphatic system, not nervous tissue, so (D) is the mismatched pair.

   The key here is knowing the standard classification of cancers by their tissue of origin. Each cancer type gets its name from the tissue it arises in — that’s the whole logic behind the naming. Carcinoma comes from epithelial cells, sarcoma from connective tissue, leukemia from blood-forming cells in bone marrow, and lymphoma from lymphatic tissue. Nervous tissue cancers are called gliomas or neuroblastomas, not lymphomas.

   Let’s check each option:

   1. Carcinoma – Epithelial tissues

      Carcinomas are indeed cancers of epithelial cells, which line organs and surfaces. This is correct — think of lung carcinoma, breast carcinoma, etc.

   2. Sarcoma – Connective tissues

      Sarcomas arise in connective tissues like bone, cartilage, fat, or muscle. Osteosarcoma (bone) and liposarcoma (fat) are examples. This pair is correct.

   3. Leukemia – Bone marrow

      Leukemia is a cancer of white blood cells, which are produced in the bone marrow. So it’s correctly linked to bone marrow. This is accurate.

   4. Lymphoma – Nervous tissue …

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7. TG EAPCET 2026Set ap-2026-05-05-FN1 markMCQ
   Q.The biosynthesis of ribosomal RNA occurs in (A) Ribosomes (B) Golgi (C) Glyoxysomes (D) Nucleolus

   ›Reveal solutionSolution

   Ribosomal RNA (rRNA) is synthesized in the nucleolus, which is the specialized region of the nucleus where rRNA genes are transcribed and ribosome subunits begin to assemble. The correct option is (D).

   The question asks where the biosynthesis of ribosomal RNA takes place. This is a classic cell biology fact, but the real understanding comes from knowing why the nucleolus is the site, and why the other options are wrong.

   Ribosomal RNA (rRNA) is not just any RNA — it forms the structural and catalytic core of ribosomes. Ribosomes are the protein factories of the cell, and they are assembled in a specific order. The genes for rRNA are located on certain chromosomes, and they are clustered together in a region of the nucleus called the nucleolus. This is not a membrane-bound organelle but a dense, dynamic structure where rRNA is transcribed, processed, and combined with ribosomal proteins (which are imported from the cytoplasm) to form the large and small ribosomal subunits. Those subunits are then exported to the cytoplasm to become functional ribosomes.

   Now, let’s examine each option:

   1. Ribosomes (A) — Ribosomes are the site of protein synthesis, not RNA synthesis. They are made of rRNA and proteins, but they do not manufacture rRNA. So this is incorrect.

   2. Golgi apparatus (B) — The Golgi modifies, sorts, and packages proteins and lipids for transport. It has no role in nucleic acid synthesis. Incorrect.

   3. Glyoxysomes (C) — These are specialized peroxisomes found in plant seeds, involved in converting fats into carbohydrates during germination. They have nothing to do with RNA synthesis. Incorrect. …

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8. TG EAPCET 2026Set ap-2026-05-05-FN1 markMCQ
   Q.Nodules of Soyabean export the fixed nitrogen in the form of (A) Proteins (B) Organic acids (C) Ureides (D) Amines

   ›Reveal solutionSolution

   Soyabean nodules export fixed nitrogen as ureides — a transport form that efficiently carries nitrogen from the root nodules to the rest of the plant.

   The key here is understanding how leguminous plants handle the nitrogen fixed by their symbiotic bacteria. In root nodules, Rhizobium bacteria convert atmospheric nitrogen ($N_2$) into ammonia ($NH_3$), which is then quickly incorporated into organic compounds. But the plant doesn't just leave that nitrogen in the nodule — it needs to ship it to growing leaves, fruits, and seeds.

   Different legumes use different "shipping molecules" for this job. Temperate legumes (like peas and clovers) typically export nitrogen as amides (e.g., asparagine, glutamine). But tropical and subtropical legumes — and soyabean is a classic example — use ureides instead.

   Ureides are nitrogen-rich compounds (allantoin and allantoic acid are the main ones) that have a very high nitrogen-to-carbon ratio. That makes them incredibly efficient for transport: you can move more nitrogen per unit of carbon spent. For a fast-growing crop like soyabean, that efficiency matters a lot.

   Let's walk through the logic step by step.

   1. What happens in the nodule?

      Fixed ammonia is immediately converted into amino acids (like glutamine) inside the nodule cells. But these aren't the final export form — they're intermediates.

   2. The key metabolic pathway in soyabean

      In soyabean nodules, the nitrogen from these amino acids is further processed through the ureide pathway. Enzymes in the nodule convert purine derivatives (made from the amino acids) into allantoin and allantoic acid — both ureides.

   3. Why ureides and not the other options?

      • (A) Proteins — Too large and insoluble to be transported efficiently in the xylem sap. Proteins are storage forms, not transport forms.
      • (B) Organic acids — These carry carbon, not nitrogen. They're not involved in nitrogen export. …

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9. TG EAPCET 2026Set ap-2026-05-05-FN1 markMCQ
   Q.Consider the following statements Statement I: In protozoans, gliding locomotion is brought about by myonemes. Statement II: Generally, in protozoans, asexual reproduction takes place during unfavourable conditions (A) Both statement I and statement II are true (B) Both statement I and statement II are false (C) Statement I is true, but statement II is false (D) Statement I is false, but statement II is true

   ›Reveal solutionSolution

   Gliding by myonemes (I true); protozoan asexual reproduction occurs in favourable, not unfavourable, conditions (II false).

   Certain protozoans move by a smooth gliding produced by contractile myoneme fibrils. Regarding reproduction, protozoans multiply asexually (binary/multiple fission) rapidly when conditions are favourable and food is plentiful; adverse conditions instead induce cyst formation or a sexual phas …

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10. TG EAPCET 2026Set ap-2026-05-05-FN1 markMCQ
    Q.Drugs extracted from Papaver somniferum (A) Opioids (B) Cannabinoids (C) Cocaine (D) Dopamine

    ›Reveal solutionSolution

    The question asks which class of drugs is extracted from the opium poppy (Papaver somniferum). The correct answer is opioids, as the plant yields opium, which contains morphine, codeine, and other opioid compounds.

    The opium poppy, Papaver somniferum, is one of the most historically significant plants in medicine and pharmacology. Its latex — the milky fluid that oozes from unripe seed pods when scored — is dried to produce raw opium. This opium contains a rich cocktail of alkaloids, the most famous being morphine and codeine. These compounds are the natural origin of the entire class of drugs we call opioids.

    Why does this matter for the exam? You need to know the source plants for major drug categories. The opium poppy is the exclusive natural source of opioids. No other plant produces morphine or codeine in significant amounts. So when you see Papaver somniferum, your mind should immediately jump to opioids.

    Let’s walk through the options:

    1. Opioids — This is the correct class. Opium from Papaver somniferum contains morphine, codeine, thebaine, and papaverine. These are all opioid compounds, used medically as painkillers (morphine) and cough suppressants (codeine), but also abused as narcotics. The plant’s name literally means “sleep-bringing poppy,” hinting at its sedative, pain-relieving effects.

    2. Cannabinoids — These come from Cannabis sativa (marijuana/hemp plant). The active compounds are THC (tetrahydrocannabinol) and CBD. No connection to the opium poppy. A common confusion: both are “drug plants,” but they are completely different species with different active principles.

    3. Cocaine — This is extracted from the leaves of the coca plant (Erythroxylum coca), native to South America. Cocaine is a stimulant and local anesthetic, not an opioid. The opium poppy has nothing to do with cocaine. …

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11. TG EAPCET 2026Set ap-2026-05-05-FN1 markMCQ
    Q.Study the following and identify the correct statements I. In cockroach, sub-oesophageal ganglion is the principal sensory centre II. Ventral nerve cord of cockroach has only nine ganglia along its length III. The images formed by ommatidia in nocturnal insects are called superposition images IV. During expiration, thoracic spiracles are kept open and abdominal spiracles are kept closed in cockroach (A) II, IV (B) I, II (C) I, III (D) I, IV

    ›Reveal solutionSolution

    This question tests knowledge of cockroach anatomy and insect physiology. By evaluating each statement about the nervous system, vision, and respiration, we find that statements I and III are correct, making the answer (C).

    This question requires us to evaluate four statements about insect anatomy and physiology, particularly focusing on the cockroach. Let's examine each statement systematically using our knowledge of arthropod biology.

    Evaluating Each Statement

    1. Statement I: "In cockroach, sub-oesophageal ganglion is the principal sensory centre"

    The cockroach nervous system consists of a brain (supra-oesophageal ganglion) and a ventral nerve cord. The sub-oesophageal ganglion lies below the esophagus and receives sensory information from the antennae, maxillae, and labium (mouthparts). It serves as the primary sensory integration center for these important sensory organs. While the supra-oesophageal ganglion (brain) also processes information, the sub-oesophageal ganglion is indeed considered the principal sensory centre.

    Statement I is TRUE.

    2. Statement II: "Ventral nerve cord of cockroach has only nine ganglia along its length"

    The ventral nerve cord of a cockroach actually contains:

    • 3 thoracic ganglia (one per thoracic segment)
    • 6 abdominal ganglia (reduced from the original segmental pattern)

    This gives us a total of 9 ganglia in the ventral nerve cord (not counting the sub-oesophageal ganglion, which is in the head region).

    Statement II is TRUE.

    3. Statement III: "The images formed by ommatidia in nocturnal insects are called superposition images"

    Compound eyes work in two main ways:

    • Apposition images: Each ommatidium functions independently, forming a separate image. Common in diurnal (day-active) insects where light is abundant.
    • Superposition images: Light from multiple ommatidia converges to form a single, brighter image. This adaptation is found in nocturnal insects that need to maximize light capture in dim conditions.

    Statement III is TRUE.

    4. Statement IV: "During expiration, thoracic spiracles are kept open and abdominal spiracles are kept closed in cockroach"

    In cockroach respiration:

    • During inspiration: The first 4 pairs of spiracles (thoracic and anterior abdominal) open to allow air in …

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12. TG EAPCET 2026Set ap-2026-05-05-FN1 markMCQ
    Q.Zoological name of European honey bee (A) Apis indica (B) Apis cyranea (C) Apis dorsata (D) Apis mellifera

    ›Reveal solutionSolution

    The European honey bee is scientifically named Apis mellifera. This is the species commonly used in commercial beekeeping worldwide.

    The question asks for the zoological (scientific) name of the European honey bee. Scientific names follow binomial nomenclature — genus followed by species. The honey bee genus is Apis. The key is matching the species name to the geographic origin: "European" tells you it's not native to India or Asia.

    1. Option (A) Apis indica — indica means "from India." This is the Indian honey bee, found in the Indian subcontinent. Not European.

    2. Option (B) Apis cyranea — This is a misspelling or variant of Apis cerana, the Asian or Eastern honey bee. It is native to Asia, not Europe.

    3. Option (C) Apis dorsata — This is the giant honey bee, a large species found in South and Southeast Asia. It builds single-comb nests in the open and is not domesticated for commercial honey production. Definitely not European. …

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