NCERT Solutions Class 12 Biotechnology Chapter 8 Animal Cell Culture

Strategic angle. Read the term by splitting it into three parts: animal cells, a culture medium and an outside-body environment. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. Animal tissue is first taken under sterile conditions so that unwanted microbes do not enter the culture.
2. Cells are placed in a culture medium containing amino acids, glucose, salts, vitamins, serum or other supplements.
3. The culture vessel is kept under controlled conditions, commonly with proper temperature, humidity and carbon dioxide.
4. If the cells survive and divide outside the organism, the process is called animal cell culture.
5. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

Animal cell culture is the in vitro maintenance and multiplication of animal cells outside the body in a suitable nutrient medium and controlled laboratory conditions.

Strategic angle. Classify the media first, then list the examples inside each class. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. A typical animal cell culture medium contains amino acids, vitamins, glucose, inorganic salts, hormones and often serum.
2. Natural media contain biological fluids or extracts, such as plasma, serum, lymph, amniotic fluid and tissue extracts.
3. Synthetic media contain a basal medium with defined supplements, such as serum, growth factors or hormones.
4. Synthetic media include serum-containing, serum-free, xeno-free, protein-free, chemically defined and complex media such as EMEM, DMEM, RPMI-1640 and Ham F-12.
5. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

Animal cell culture media are nutrient mixtures that support survival, growth and functions of cultured animal cells. They are broadly natural media and artificial or synthetic media.

Strategic angle. Serum is useful because it is rich, but that same undefined richness creates control problems. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. Serum provides amino acids, proteins, vitamins, carbohydrates, lipids, hormones and growth factors.
2. It supplies binding proteins such as albumin and transferrin, which can carry molecules into cells.
3. It provides adhesion factors that help cells attach to the substratum before division.
4. Its disadvantages are batch variation, possible cytotoxic compounds, growth inhibitors and contamination by viruses, fungi or mycoplasma.
5. Serum can also interfere with purification of cell culture products, including pharmaceutical proteins.
6. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

Serum supplies nutrients, growth factors, binding proteins and adhesion factors, but it varies by batch and may carry inhibitors or contaminants.

Strategic angle. Choose examples listed in the chapter, then explain what makes them synthetic. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. Dulbecco Minimal Essential Medium, or DMEM, is a commonly used animal cell culture medium.
2. It contains balanced salts, amino acids, vitamins and a carbon source, and it can be supplemented according to the cell type.
3. Roswell Park Memorial Institute medium, or RPMI-1640, is another synthetic medium used for many animal cell culture systems.
4. RPMI-1640 also supplies salts, nutrients and buffering support, and it is often used with serum or defined supplements.
5. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

Two chemically synthesised media are DMEM and RPMI-1640. Both are artificial media used for animal cell culture.

Strategic angle. The word primary signals direct origin from tissue, before repeated passaging changes the cell population. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. A tissue sample is dissected under sterile conditions.
2. The tissue is chopped into small pieces or disaggregated by enzymes such as trypsin or collagenase.
3. In the explant method, tissue pieces are attached to a dish and cells grow out from them.
4. In the cell suspension method, dissociated cells are allowed to attach and spread on a substrate.
5. The resulting culture is called primary cell culture, and it may be adherent or in suspension.
6. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

Primary cell culture is obtained directly from host tissue. It is developed by sterile tissue removal, mechanical or enzymatic disaggregation, and growth of cells in suitable medium.

Strategic angle. Think of passaging as giving cells a new flask, new medium and fresh space. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. Cells in a culture vessel grow and may reach confluence, where the available surface is crowded.
2. Crowding reduces growth and can lead to cell death, so the culture needs passaging.
3. Adherent cells are detached by trypsin, trypsin with EDTA, scraping, shaking or pipetting.
4. The detached cells are collected, centrifuged if needed, mixed with fresh medium and transferred to new flasks.
5. Splitting one flask into two or more flasks is a common form of passaging.
6. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

Subculture or passaging is the transfer of cells from an old crowded culture to a fresh vessel with new medium so that growth can continue.

Strategic angle. Use life span as the first difference, then add origin and growth behaviour. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. Finite cell lines have a limited life span and limited number of cell divisions.
2. After several passages, finite cell lines lose the ability to proliferate. This is called senescence.
3. Normal primary cell cultures usually give finite cell lines.
4. Continuous cell lines arise when some cells undergo transformation spontaneously, chemically or virally.
5. Continuous cell lines are immortal, often tumorigenic, faster growing and less demanding for nutrients.
6. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

Finite cell lines divide for a limited number of passages and then senesce, while continuous cell lines divide indefinitely after transformation.

Strategic angle. Both methods ask the same question, but one reads membrane integrity and the other reads metabolism. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. In dye exclusion assays, stains such as trypan blue, propidium iodide, 7-AAD or acridine orange are added.
2. Live cells keep the dye out because their membrane integrity is intact.
3. Dead cells allow the dye to enter because their membrane integrity is lost.
4. In metabolic assays, living cells carry out a measurable biochemical reaction.
5. In MTT assay, live-cell mitochondrial dehydrogenases reduce yellow MTT to purple formazan crystals, and the colour formed is proportional to cell number.
6. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

Cell viability is measured by dye exclusion assays or metabolic viability assays such as the MTT assay.

Strategic angle. Group the applications into research, testing, vaccines and biopharmaceutical production. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. It is used as a model system to study interactions between cells, disease-causing agents and drugs.
2. It supports virus research and large-scale vaccine production.
3. It helps produce medically important proteins, including FSH, HGH, EPO, Factor VIII, Factor IX, interleukin-2, tPA and monoclonal antibodies.
4. CHO cells are used for several recombinant glycoproteins, such as EPO and clotting factors.
5. Hybridoma cells are used for monoclonal antibodies for cancer therapy and autoimmune diseases.
6. The technique also supports molecular genetics, immunological analysis, surgery, bioengineering and pharmaceutical research.
7. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

Animal cell culture is used for disease models, drug testing, virus research, vaccine production and manufacture of therapeutic proteins such as EPO, Factor VIII, Factor IX, tPA and monoclonal antibodies.

Strategic angle. Eliminate media from other systems first. The remaining option is the animal cell culture medium. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. DMEM is listed in the chapter as Dulbecco Minimal Essential Medium.
2. MS medium is associated with plant tissue culture, not animal cell culture.
3. LB medium is used mainly for bacterial culture.
4. Therefore the only animal cell culture medium among the options is DMEM.
5. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

(A) DMEM

Strategic angle. Direct tissue origin is the clue. Directly from tissue means primary. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. A culture made directly from host tissue is the first culture from that tissue.
2. The NCERT definition names this as primary cell culture.
3. Secondary culture forms only after a primary culture is passaged.
4. Transformed culture involves changed cells that can divide for long periods.
5. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

(A) Primary cell culture

Strategic angle. Link sodium bicarbonate with pH buffer, not with attachment or iron chemistry. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. Animal cell media often use the carbon dioxide and bicarbonate buffering system.
2. The concentrations of carbon dioxide, bicarbonate and pH are linked.
3. Changing carbon dioxide shifts the buffer balance and affects acidity.
4. So sodium bicarbonate is added to help maintain the correct pH when carbon dioxide is present.
5. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

(C) maintain the correct pH when carbon dioxide is present

Strategic angle. Compare the option with the textbook list of medium components. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. The chapter lists vitamins, amino acids, glucose, inorganic salts, serum and hormones in typical media.
2. Bicarbonate is part of the natural buffering system used with carbon dioxide.
3. Glucose acts as the common carbon source.
4. Starch is not a normal component of animal cell growth medium.
5. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

(D) Starch

Strategic angle. When every listed method is a known disaggregation method, choose the inclusive option. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. Primary culture preparation may use mechanical disaggregation.
2. It may use enzymes such as trypsin or collagenase.
3. Chelating agents help separate cells by weakening calcium-dependent attachments.
4. Since all three methods can disaggregate cells, the correct option is all of the above.
5. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

(D) All of the above

Strategic angle. The word pharming points to pharmaceutical production in a living organism. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. The question describes gene transfer into animals.
2. The goal is large-scale production of the encoded protein in milk, blood or other body products.
3. This production approach is called molecular pharming.
4. Gene therapy treats disease in a patient, and hybridoma technology produces monoclonal antibodies from fused cells.
5. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

(B) Molecular pharming

Strategic angle. Do not confuse a named basal medium with the category called protein-free medium. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. RPMI-1640 is listed as a complex animal cell culture medium.
2. MS medium is used mainly for plant tissue culture.
3. LB medium is used mainly for bacteria.
4. None of the listed options is specifically a protein-free animal cell culture medium.
5. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

(D) None of the above

Strategic angle. The colour change in MTT comes from living-cell metabolism. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. Live cells contain mitochondrial dehydrogenase enzymes.
2. These enzymes reduce yellow MTT to purple insoluble formazan.
3. More live cells form more formazan colour.
4. Therefore MTT assay is used to test cell viability.
5. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

(A) Cell viability test

Strategic angle. Passage number counts subcultures, so passaging means sub-culturing. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. Cells reach confluence and become crowded in the old vessel.
2. They are detached by enzyme or mechanical methods when needed.
3. They are transferred into fresh medium for further growth.
4. This process is called sub-culturing or passaging.
5. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

(A) Sub-culturing of the cells

Strategic angle. Reject the plant-specific option when the question is about animal cell culture serum. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. Serum provides adhesion factors that help cells attach to the substratum.
2. It contains growth factors and hormones that stimulate cell growth.
3. It contains proteins such as albumin and transferrin for transport.
4. Promotion of tuber and bulb formation is not a major function of serum in animal cell culture.
5. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

(C) Promotion of tuber and bulb formation

Strategic angle. For assertion-reason items, test truth first, then test whether the reason explains the assertion. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. Serum is described as one of the most important components of culture media.
2. The reason states that serum supplies nutrients and supports proliferation and cell-matrix attachment.
3. These points are exactly why serum is important in many media.
4. So both statements are true, and the reason explains the assertion.
5. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

(A) Both assertion and reason are true and the reason is the correct explanation of the assertion

Strategic angle. Separate the two facts: finite origin from normal cells, continuous origin after transformation. The safest answer uses the exact sequence from the NCERT explanation and then adds the reason behind it.

1. The assertion is true because normal primary culture-derived lines have limited division capacity.
2. The reason is also true because some cells can transform and divide indefinitely.
3. However, the reason describes the origin of continuous cell lines.
4. It does not explain the finite nature of normal primary cell lines.
5. Therefore both are true, but the reason is not the correct explanation.
6. This supports the final response because it connects the definition, method and textbook example in one line of reasoning.

Why this matters. In board answers, marks usually come from the key term, the process and one correct example. Keeping these three parts together avoids a vague response.

(B) Both assertion and reason are true but the reason is not the correct explanation of the assertion