Nokea
A hybridoma:
- A. Secretes both polyclonal and monoclonal antibodies
- B. Is generated from the fusion of two antigen-activated B cells
- C. Can live in tissue culture indefinitely
- D. All of these options describe a hybridoma
Correct Answer: C
Rationale: Step-by-step rationale:
1. Hybridoma is a cell line formed by the fusion of a B cell (producing a specific antibody) and a myeloma cell.
2. Choice C is correct because hybridomas can be immortalized and cultured indefinitely.
3. Choice A is incorrect because hybridomas produce monoclonal antibodies, not polyclonal antibodies.
4. Choice B is incorrect because hybridomas are formed from a single B cell and a myeloma cell, not two antigen-activated B cells.
5. Choice D is incorrect as only option C accurately describes a hybridoma's characteristic of indefinite tissue culture survival.
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What type of diseases does the immune system primarily defend against?
- A. Autoimmune diseases
- B. Infectious diseases
- C. Neurological disorders
- D. Cardiovascular diseases
Correct Answer: B
Rationale: The correct answer is B: Infectious diseases. The immune system's main function is to protect the body from foreign invaders such as bacteria, viruses, and parasites. It recognizes and eliminates these pathogens to prevent infections. Autoimmune diseases (A) occur when the immune system mistakenly attacks healthy cells. Neurological disorders (C) and cardiovascular diseases (D) are not primarily defended against by the immune system as they are not caused by external pathogens.
Which of the following is NOT a property of CD8+ T cells?
- A. They typically differentiate into cytotoxic T cells (Tc)
- B. They always recognize peptide antigen in association with an MHC molecule
- C. They are important in defense against intracellular pathogens
- D. They are the cell responsible for antibody-dependent cell-mediated cytotoxicity
Correct Answer: D
Rationale: The correct answer is D because CD8+ T cells are not responsible for antibody-dependent cell-mediated cytotoxicity. A is correct as CD8+ T cells differentiate into cytotoxic T cells. B is correct as CD8+ T cells recognize peptide antigens with MHC molecules. C is correct as CD8+ T cells are vital in defense against intracellular pathogens. D is incorrect as CD8+ T cells do not mediate cell cytotoxicity through antibodies.
The human immunodeficiency virus (HIV)
- A. Is a retrovirus
- B. Is an RNA virus
- C. Is a lentivirus
- D. All of the above A, B and C
Correct Answer: D
Rationale: Step 1: HIV is a retrovirus because it contains RNA as its genetic material and uses the enzyme reverse transcriptase to convert its RNA into DNA.
Step 2: HIV is an RNA virus because its genetic material is RNA.
Step 3: HIV is a lentivirus which is a subgroup of retroviruses known for causing slow-progressing diseases.
Therefore, the correct answer is D as all statements A, B, and C are true based on the characteristics of HIV.
Cancer cells go through stages of development. What accurately describes the stage of promotion (select all that apply)?
- A. Obesity is an example of a promoting factor
- B. The stage is characterized by increased growth rate and metastasis
- C. Withdrawal of promoting factors will reduce the risk of cancer development
- D. Tobacco smoke is a complete carcinogen that is capable of both initiation and promotion
Correct Answer: C
Rationale: Promotion involves enhancing the growth of initiated cells. Obesity and tobacco smoke are examples of promoting factors, and withdrawal of such factors can reduce cancer risk.
What is the mechanism of tissue damage in Type II hypersensitivity?
- A. Immune complex deposition
- B. Antibody binding to cell surface antigens, triggering complement activation or phagocytosis
- C. Mast cell degranulation
- D. T cell-mediated cytotoxicity
Correct Answer: B
Rationale: The correct answer is B: Antibody binding to cell surface antigens, triggering complement activation or phagocytosis. In Type II hypersensitivity, antibodies bind to antigens on host cells, leading to complement activation or phagocytosis by immune cells. This results in cell damage or destruction. Immune complex deposition (A) is more characteristic of Type III hypersensitivity. Mast cell degranulation (C) is seen in Type I hypersensitivity. T cell-mediated cytotoxicity (D) is associated with Type IV hypersensitivity, not Type II. Therefore, choice B is the most accurate mechanism of tissue damage in Type II hypersensitivity.