All Free Biology MCQs with Answers
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19844 questions · page 671 of 1985
6701. Ribosomal RNA is synthesized in:
- A. Nucleolus
- B. Peroxisome
- C. Golgi body
- D. Nucleoplasm
Explanation: Ribosomal RNA (rRNA) is synthesized ima and stored in the nucleolus. Central fibril area of the nucleolus has large molecular weight RNA and rDNA.
Correct answer: Nucleolus6702. Digestive enzymes are present in:
- A. Ribosome
- B. Lysosomes
- C. Liposomes
- D. Mitochondria
Explanation: Digestive enzymes are present in lysosomes. Lysosomes are membrane-bound organelles that contain a variety of hydrolytic enzymes, which are enzymes that can break down large molecules into smaller molecules. These enzymes are essential for the breakdown of cellular waste products, as well as for the destruction of foreign invaders, such as bacteria.
Correct answer: Lysosomes6703. Which organelle does the tonoplast surround?
- A. Golgi complex
- B. Nucleus
- C. Endoplasmic reticulum
- D. Vacuoles
Explanation: Vacuole is single membrane bounded organelle. This single membrane is known as tonoplast. The tonoplast is the membrane that surrounds the vacuole in plant cells. It is a single membrane that is made up of phospholipids and proteins. The proteins in the tonoplast membrane are involved in a variety of functions, including: Transport of ions and molecules into and out of the vacuole: The tonoplast membrane is selectively permeable, which means that it allows some molecules to pass through it while blocking others. This selective permeability is important for maintaining the concentration of ions and molecules inside the vacuole.Storage of water: The vacuole is a large organelle that stores water. The tonoplast membrane helps to regulate the amount of water in the vacuole by controlling the movement of water in and out of the vacuole.Turgor pressure: Turgor pressure is the pressure that is exerted by the water in the vacuole against the cell wall. The tonoplast membrane helps to maintain turgor pressure by regulating the amount of water in the vacuole.
Correct answer: Vacuoles6704. In a cross section, each centriole consists of nine triplets of:
- A. Microfilaments
- B. Microvilli
- C. Microtubules
- D. Intermediate filaments
Explanation: In a cross section, each centriole appears as a ring of nine triplets of microtubules. The microtubules in the triplets are arranged in a clockwise or counterclockwise direction. The triplets are connected to each other by proteins, and they form a rigid structure that is essential for the function of the centriole.
Correct answer: Microtubules6705. Which statement is correct about mitochondria and chloroplast?
- A. Chloroplast and mitochondria cannot live independently
- B. 70S ribosome is attached with the inner membrane of mitochondria and chloroplast
- C. Chloroplast and mitochondria are single membrane structures
- D. Number of mitochondria and chloroplast are same in all cells
Explanation: 70S ribosomes are attached to the inner membrane of mitochondria and chloroplasts because they are the type of ribosomes that are found in prokaryotes. Mitochondria and chloroplasts are thought to have originated from prokaryotic cells that were engulfed by eukaryotic cells, and they have retained some of their prokaryotic characteristics, including the use of 70S ribosomes.
Correct answer: 70S ribosome is attached with the inner membrane of mitochondria and chloroplast6706. Passive processes for movement of molecules across cell surface membrane are:
- A. Facilitated diffusion and osmosis
- B. Pinocytosis and facilitated diffusion
- C. Diffusion and exocytosis
- D. Osmosis and phagocytosis
Explanation: Osmosis, diffusion and facilitated diffusion are passive processes of passage of molecules across the cell membrane but exocytosis and endocytosis are active processes of molecules across the cell.
Correct answer: Facilitated diffusion and osmosis6707. In the below given list, the glycocalyx is associated with:
- A. Ribosomes
- B. Nucleus
- C. Plasma membrane
- D. Cell wall
Explanation: The prokaryotic cell envelope consists of a three-layered structure - the outermost glycocalyx, followed by a cell wall and then the plasma membrane.
Correct answer: Cell wall6708. Among the following, which cellular organelle contains circular DNA similar to that found in bacteria?
- A. Ribosome
- B. Lysosome
- C. Chloroplast
- D. Nucleus
Explanation: Mitochondria and chloroplasts both are considered as semi autonomous organelles, as they have their own circular DNA and 70S ribosomes. Mitochondria are present in both plant and animal cells but chloroplast is present in autotrophic eukaryotes.
Correct answer: Chloroplast6709. Cell theory is not applicable to:
- A. Fungi
- B. Bacteria
- C. Algae
- D. Virus
Explanation: Cell theory is a fundamental concept in biology. It explains basis of living unit of life that is cdl. Virus is not considered a living organism.
Correct answer: Virus6710. What would be the resolving power of the objective length in a microscope, if the eyepiece is of 10X and total magnification is 40X?
- A. 4X
- B. 40X
- C. 10X
- D. 400X
Explanation: Resolving of microscope is calculated by multiplying power of an objective lense and eyepiece. 40(10)=400X
Correct answer: 400X