Single-cell protein (SCP) and tissue culture are two biotechnology applications that appear in NEET as recall-heavy questions — and the common trap is mixing up the organisms, substrates, and techniques associated with each.
Single-cell protein (SCP) refers to the dried microbial biomass or total protein extracted from pure or mixed cultures of microorganisms used as food or animal feed. The key organism NCERT highlights is Spirulina — a cyanobacterium grown on waste water from potato processing, starch factories, or molasses. Other SCP organisms include Methylophilus methylotrophus (grown on methanol) and yeasts like Candida utilis. SCP addresses the problem of protein deficiency in developing nations by converting industrial waste into edible biomass — a dual benefit of nutrition and waste management (NCERT Class 12 Biology, Chapter 9, page 192).
The NEET-relevant facts to lock in: Spirulina is the textbook-cited SCP organism, it grows on industrial effluent (not soil or seawater), and SCP is whole microbial biomass — not a purified enzyme or antibiotic extract.
Tissue culture (plant tissue culture / micropropagation) exploits totipotency — the ability of any living plant cell to regenerate a complete organism. A small tissue piece (explant) is grown on a nutrient medium containing growth regulators to produce a callus, which differentiates into plantlets. The resulting plants are somaclones. This technique enables rapid clonal propagation of disease-free plants and is the basis for producing virus-free varieties (meristem culture).
Common NEET confusions: somaclones vs somatic hybrids (somaclones come from tissue culture of one parent; somatic hybrids come from protoplast fusion of two species). Totipotency is the underlying principle — not pluripotency (an animal-biology term rarely used in NCERT botany context).
Select an option to see the explanation. Wrong answers show why your choice was tempting — and name the exact trap it exploits.
Which microorganism is commonly cited in NCERT as a source of single-cell protein grown on industrial waste water?
The property of plant cells that allows tissue culture to regenerate a complete organism from a single cell is called:
Plants obtained through tissue culture of a single parent are genetically identical and are called:
A plant breeder wants to produce virus-free plants of a commercially important variety. Which tissue culture technique should be employed?
SCP production addresses two problems simultaneously. Which pair correctly identifies both?
In plant tissue culture, an undifferentiated mass of cells produced from an explant on nutrient medium is called:
A student claims that somaclones and somatic hybrids are the same because both are produced in vitro. What is the key distinction that makes this claim incorrect?
A researcher cultures *Spirulina* on potato processing waste water and harvests 250 kg of dried biomass. If *Spirulina* biomass contains approximately 60% protein by dry weight, and this protein is to supplement the diet of a community where each person requires 10 g of additional protein per day, how many people can be served for one day?
Given
A tissue culture lab receives an explant from a high-yielding tomato variety. The explant is placed on a nutrient medium with auxin and cytokinin. After several weeks, an undifferentiated cell mass forms. The lab then transfers portions to a differentiation medium, producing 500 identical plantlets.
Required
(a) Name the undifferentiated cell mass. (b) What property of plant cells makes this technique possible? (c) What are the 500 identical plantlets called? (d) If the lab instead fused protoplasts from this tomato with protoplasts from a wild potato species, what would the resulting hybrid be called?
Concept
Plant tissue culture relies on totipotency. An explant dedifferentiates into callus (undifferentiated mass), which redifferentiates into plantlets. Clonal plants from tissue culture are somaclones. Protoplast fusion produces somatic hybrids — a fundamentally different product.
Formula
No mathematical formula applies. The reasoning chain is: explant → callus → plantlets (somaclones) via totipotency. Protoplast fusion → somatic hybrid via a separate technique.
Substitution
(a) Undifferentiated mass on nutrient medium = callus. (b) Underlying property = totipotency. (c) 500 identical plants from one parent via tissue culture = somaclones. (d) Fusion of protoplasts from two species = somatic hybrid.
Calculation
No numerical calculation. This is a terminology-application problem typical of NEET biology.
Final answer
(a) Callus (b) Totipotency (c) Somaclones (d) Somatic hybrid
Common trap
Confusing somaclones with somatic hybrids is a high-frequency NEET distractor. The distinguishing criterion is the number of parents: somaclones = one parent (clonal), somatic hybrids = two parents (interspecific fusion). Another trap: confusing totipotency (plant cells, full organism regeneration) with pluripotency (animal stem cells, limited differentiation).
Similar NEET-style question
"Somatic hybridization involves: (A) grafting of two plants, (B) fusion of protoplasts from two different species, (C) tissue culture from a single explant, (D) cross-pollination followed by embryo rescue." The answer is B — protoplast fusion is the defining step for somatic hybridization. ---
In the NEET syllabus; removed from current NCERT.
Single-cell protein: Spirulina, Methylophilus methylotrophus — protein source. Tissue culture: totipotency (Haberlandt). Explant → callus → plantlet on hormone media (auxin/cytokinin ratio). Somatic embryos, somaclonal variation, micropropagation.
-- NCERT Class 12 Biology, Ch. 8, p. 192These are the exact patterns that cause wrong answers in NEET. Each trap includes when it triggers and how to avoid it.
Category: Similar Terms
ELISA = screening (cheap, sensitive); Western blot = confirmation. CD4+ T cell count tracks disease progression.
Question on which test confirms HIV vs which monitors progression.
ELISA first (screening); Western blot confirms; CD4+ count = monitoring marker (<200/µL = AIDS).
Category: Similar Terms
Active: own immune response (vaccination, infection). Passive: pre-formed antibodies received (colostrum, antiserum injection).
Question on immunity type from vaccination, antiserum, mother's milk.
Active = body produces; passive = body receives. Vaccination → active. Mother's milk → passive (IgA).
Root cause: term confusion
Vaccination = ACTIVE (body produces antibodies in response to antigen). Antiserum = passive. Maternal IgA in milk = passive.
Root cause: term confusion
Anopheles = vector (transmits). Plasmodium = causative agent (causes disease). Female Anopheles bite is the transmission route.
29 questions from NEET 2020, 2021, 2022, 2023, 2024, 2025. Answers verified against NTA official keys.
Streptokinase produced by bacterium Streptococcus is used for
The capacity to generate a whole plant from any cell of the plant is called:
Which one of the following is NOT an advantage of inbreeding?
Identify the asexual reproductive structure associated with Penicillium :
Select the incorrect statement with respect to acquired immunity.
Which of the following plants is monoecious? (b) Plant tissue culture (ii) Pomato
Recurring question shapes from past papers. Each pattern shows why wrong options look tempting.
active vs passive immunity confusion
Vaccination triggers the body to produce its own antibodies (active immunity), but students interpret 'given externally' as passive. Passive immunity (antiserum, colostrum IgA from mother's milk) provides preformed antibodies with no immune response from the recipient. Questions that pair vaccination, antiserum, and colostrum expose students who cannot classify by mechanism rather than by route of administration.
vector vs causative agent confusion
Questions name both the vector (organism that transmits) and the causative agent (organism that causes disease) as answer options. Students who associate 'Anopheles = malaria' select Anopheles as the causative agent rather than recognising it as the vector; Plasmodium is the causative agent. The distinction -- vector transmits, causative agent infects -- is lost when both options are plausible from partial recall.
microbe product pair swap
Match-list questions pair 10 or more microbe names with industrial or household products. Students confuse Lactobacillus (lactic acid fermentation, curd) with Saccharomyces cerevisiae (ethanol, bread), or Aspergillus niger (citric acid) with Clostridium butylicum (butyric acid). Partial recall of one-to-one mappings produces swapped pairs, especially when two products share the same chemical class.
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