NEET MCQ
1.Which of the following statements about DNA polymerase is incorrect?
A) It can only add nucleotides to the 3' end of a growing DNA strand. B) It can proofread and correct errors during DNA replication. C) It requires a primer to begin DNA synthesis. D) It can initiate DNA synthesis de novo without any pre-existing nucleic acid template.
Answer: D) It can initiate DNA synthesis de novo without any pre-existing nucleic acid template.
Explanation: DNA polymerase is an enzyme that adds nucleotides to a growing DNA strand during DNA replication. It requires a pre-existing nucleic acid template, such as a single-stranded DNA or RNA molecule, to begin DNA synthesis. It can only add nucleotides to the 3' end of a growing DNA strand because it uses the 3'-OH group of the previous nucleotide as a primer for the next nucleotide. DNA polymerase can proofread and correct errors during DNA replication, which helps to maintain the accuracy of DNA replication. However, it cannot initiate DNA synthesis de novo without any pre-existing nucleic acid template.
2.Which of the following is not a function of the Golgi apparatus?
A) Sorting and modifying proteins and lipids for transport to different parts of the cell or for secretion. B) Synthesizing and assembling ribosomes. C) Glycosylating and modifying proteins and lipids with carbohydrates. D) Transporting proteins and lipids in vesicles to other organelles or to the cell membrane.
Answer: B) Synthesizing and assembling ribosomes.
Explanation: The Golgi apparatus is an organelle found in eukaryotic cells that is involved in sorting, modifying, and packaging proteins and lipids for transport to different parts of the cell or for secretion. It plays an important role in post-translational modifications of proteins, such as glycosylation and phosphorylation, that are necessary for their proper folding and function. The Golgi apparatus also transports proteins and lipids in vesicles to other organelles or to the cell membrane.
However, the synthesis and assembly of ribosomes occur in the nucleolus, which is a sub-organelle of the nucleus, not in the Golgi apparatus. The nucleolus is responsible for the production and assembly of ribosomal RNA and ribosomal proteins to form ribosomes, which are then transported to the cytoplasm where they play a critical role in protein synthesis. Therefore, option B is not a function of the Golgi apparatus.
3.Which of the following statements about the Krebs cycle is incorrect?
A) It occurs in the mitochondrial matrix.
B) It generates NADH and FADH2 that are used in the electron transport chain.
C) It involves the oxidation of pyruvate to acetyl-CoA.
D) It generates a net yield of 2 ATP molecules.
Answer: D) It generates a net yield of 2 ATP molecules.
Explanation: The Krebs cycle, also known as the citric acid cycle, is a series of chemical reactions that occur in the mitochondrial matrix of eukaryotic cells. It involves the oxidation of acetyl-CoA derived from pyruvate, fatty acids, and amino acids, and generates NADH and FADH2 that are used in the electron transport chain to produce ATP. However, the Krebs cycle itself only produces a net yield of 1 ATP molecule per turn, not 2 ATP molecules. Therefore, option D is incorrect.
4.Which of the following statements about RNA polymerase is incorrect?
A) It is an enzyme that catalyzes the synthesis of RNA.
B) It requires a template DNA strand to synthesize RNA.
C) It can only add nucleotides to the 3' end of a growing RNA strand.
D) It can initiate RNA synthesis de novo without any pre-existing nucleic acid template.
Answer: D) It can initiate RNA synthesis de novo without any pre-existing nucleic acid template.
Explanation: RNA polymerase is an enzyme that catalyzes the synthesis of RNA from a DNA template. It requires a template DNA strand to guide the selection and incorporation of the correct nucleotides into the growing RNA strand. RNA polymerase can only add nucleotides to the 3' end of a growing RNA strand, similar to DNA polymerase. However, it cannot initiate RNA synthesis de novo without any pre-existing nucleic acid template. Therefore, option D is incorrect.
5.Which of the following is not a type of cell junction found in animal cells?
A) Tight junctions
B) Desmosomes
C) Plasmodesmata
D) Gap junctions
Answer: C) Plasmodesmata.
Explanation: Plasmodesmata are cell junctions found in plant cells that connect adjacent cells through cytoplasmic channels. Animal cells do not have plasmodesmata, but they have other types of cell junctions, including tight junctions, desmosomes, and gap junctions. Tight junctions and desmosomes are anchoring junctions that help to attach cells to each other and provide structural support, while gap junctions are communication junctions that allow for the exchange of small molecules between cells.
6.Which of the following is not a function of the endoplasmic reticulum (ER)?
A) Synthesizing and modifying proteins and lipids.
B) Transporting proteins and lipids in vesicles to other parts of the cell or for secretion.
C) Regulating gene expression and protein synthesis.
D) Detoxifying harmful substances.
Answer: C) Regulating gene expression and protein synthesis.
Explanation: The endoplasmic reticulum (ER) is an organelle found in eukaryotic cells that is involved in the synthesis, modification, and transport of proteins and lipids. It has two distinct regions, the rough ER, which is studded with ribosomes and is involved in protein synthesis and processing, and the smooth ER, which is involved in lipid synthesis and metabolism, calcium storage, and detoxification of harmful substances. The ER does not directly regulate gene expression and protein synthesis
7.Which of the following is not a property of stem cells?
A) They have the ability to self-renew.
B) They can differentiate into multiple cell types.
C) They are found only in the embryo and fetus.
D) They have the potential to be used in regenerative medicine.
Answer: C) They are found only in the embryo and fetus.
Explanation: Stem cells are undifferentiated cells that have the ability to self-renew and differentiate into multiple cell types. They can be found in various tissues of the body, including the bone marrow, blood, and skin. While embryonic stem cells are derived from the inner cell mass of the blastocyst, there are also adult stem cells that are present in various tissues throughout the body. Therefore, option C is incorrect.
8.Which of the following is not a type of muscle tissue found in the human body?
A) Smooth muscle
B) Skeletal muscle
C) Cardiac muscle
D) Nervous muscle
Answer: D) Nervous muscle.
Explanation: Nervous tissue is a specialized tissue found in the nervous system, which includes the brain, spinal cord, and nerves. Muscle tissue, on the other hand, is specialized for contraction and movement. There are three types of muscle tissue found in the human body: skeletal muscle, which is attached to bones and is responsible for voluntary movement; smooth muscle, which is found in the walls of internal organs and is responsible for involuntary movement; and cardiac muscle, which is found in the heart and is responsible for pumping blood.
9.Which of the following is not a function of the respiratory system?
A) Bringing oxygen into the body.
B) Removing carbon dioxide from the body.
C) Regulating blood pH.
D) Regulating blood glucose levels.
Answer: D) Regulating blood glucose levels.
Explanation: The respiratory system is responsible for exchanging gases between the body and the environment. It brings oxygen into the body and removes carbon dioxide from the body, and also plays a role in regulating blood pH through the bicarbonate buffer system. However, it does not regulate blood glucose levels, which is primarily the function of the endocrine system.
10. Which of the following is not a type of immune response in vertebrates?
A) Innate immunity
B) Adaptive immunity
C) Passive immunity
D) Transient immunity
Answer: D) Transient immunity.
Explanation: The immune system in vertebrates has two main types of immune responses: innate immunity and adaptive immunity. Innate immunity is the first line of defense against pathogens and is non-specific, meaning it provides a general defense against a wide range of pathogens. Adaptive immunity, on the other hand, is specific to a particular pathogen and involves the production of antibodies and the activation of immune cells. Passive immunity is the transfer of pre-formed antibodies from one individual to another, while transient immunity is not a recognized type of immunity
Answer: A) B cells
Explanation: B cells are a type of lymphocyte that are responsible for producing antibodies, which are proteins that bind to specific antigens on the surface of pathogens and mark them for destruction by the immune system. T cells, natural killer cells, and macrophages are also important components of the immune system, but they do not produce antibodies.
12.Which of the following is an example of passive immunity?
A) Vaccination
B) Antibiotic treatment
C) Transfer of maternal antibodies to a newborn
D) Production of memory cells after an infection
Answer: C) Transfer of maternal antibodies to a newborn
Explanation: Passive immunity is the transfer of pre-formed antibodies from one individual to another. This can occur naturally, as in the transfer of maternal antibodies to a newborn through the placenta or breast milk, or artificially, as in the administration of pre-formed antibodies to an individual who has been exposed to a pathogen. Vaccination, antibiotic treatment, and the production of memory cells after an infection all involve the activation of the individual's own immune system
13.Which of the following is a characteristic of autoimmune diseases?
A) They are caused by infectious agents.
B) They are characterised by a weakened immune system.
C) They occur when the immune system attacks the body's own tissues.
D) They are treated with antibiotics.
Answer: C) They occur when the immune system attacks the body's own tissues.
Explanation: Autoimmune diseases are a group of disorders in which the immune system attacks the body's own tissues, mistaking them for foreign invaders. Examples of autoimmune diseases include rheumatoid arthritis, lupus, and multiple sclerosis. These diseases are not caused by infectious agents, and are not characterized by a weakened immune system. They are typically treated with immunosuppressive drugs rather than antibiotics.
14.Which of the following is an example of a primary immune deficiency disorder?
A) HIV/AIDS
B) DiGeorge syndrome
C) Chronic granulomatous disease
D) Severe combined immunodeficiency (SCID)
Answer: D) Severe combined immunodeficiency (SCID)
Explanation: Primary immune deficiency disorders are inherited disorders that result in a weakened or absent immune system. Examples of primary immune deficiency disorders include SCID, DiGeorge syndrome, and X-linked agammaglobulinemia. HIV/AIDS is an example of an acquired immune deficiency syndrome, while chronic granulomatous disease is a disorder of the phagocytic cells rather than the lymphocytes.
15.Which of the following is not a function of the complement system?
A) Enhancing phagocytosis of pathogens by immune cells.
B) Stimulating inflammation in response to infection or injury.
C) Directly killing pathogens by forming pores in their membranes.
D) Producing antibodies against specific antigens.
Answer: D) Producing antibodies against specific antigens.
Explanation: The complement system is a group of proteins that work together to enhance the immune response. It can enhance phagocytosis of pathogens by immune cells, stimulate inflammation in response to infection or injury, and directly kill pathogens by forming pores in their membranes. However, it does not produce antibodies against specific antigens, which is the function of B cells.
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