All Free Biology MCQs with Answers
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19844 questions · page 699 of 1985
6981. When a red stain is added to a culture containing both living and dead cells, only the dead cells take up the stain. Which structure(s) prevent(s) the stain entering the living celis?
- A. cell membrane
- B. cell wall
- C. cytoplasm
- D. Vacuole
- E. all of these options
Explanation: The structure that controls the movement of substances into and out of the cell is the cell membrane, as it is selectively permeable.
Correct answer: cell membrane6982. Which of the following best illustrates "feedback" in development?
- A. Tissue X secretes RNA which changes the development of tissue Y.
- B. As tissue X develops, it secretes enzymes that inhibit the development of tissue Y.
- C. As tissue X develops, it secretes something that induces tissue Y to develop.
- D. As tissue X develops, it secretes something that slows down the growth of tissue Y.
Explanation: As tissue X develops it secretes something that induces tissue Y to develop indicating positive feedback mechanism.
Correct answer: As tissue X develops, it secretes something that induces tissue Y to develop.6983. In order to see various aspects of specimen a three dimensional image of the object can be produced using:
- A. Compound microscope
- B. Dark microscope
- C. Transmission electron microscope
- D. Scanning electron microscope
Explanation: Compound microscope produces a 2-D image, dark microscope illuminates sample against a dark background, Transmission electron microscope also produces 2-D images whereas only scanning electron microscope produces 3-D image so option D is correct
Correct answer: Scanning electron microscope6984. The process by which various components of cells including organelle can be isolated is called:
- A. Homogenization B
- B. Cell Fractionation
- C. Cell Fixation
- D. Gel Electrophoresis
- E. Ultracentrifuge
Explanation: Cell fractionation is a method to separate subcellular components, and isolate organelles and other subcellular components from one another.
Correct answer: Cell Fractionation6985. Cell wall structure of a cell of unknown origin was studied and was found to contain polysaccharide chain linked with short chains of amino acid. What do you think it can be?
- A. Bacteria
- B. Fungi
- C. Algae
- D. Plants
Explanation: The correct answer is Bacteria. The question describes a cell wall structure featuring polysaccharide chains linked by short chains of amino acids, indicative of peptidoglycan. This is a unique feature of bacterial cell walls, providing them with necessary structural integrity. In contrast, fungal cell walls are made of chitin, algal walls of cellulose or other substances, and plant walls of cellulose and hemicellulose, all lacking the peptidoglycan structure.
Correct answer: Bacteria6986. RNA is absent in:
- A. Plasmalemma
- B. Ribosomes
- C. Chromosomes
- D. Cytoplasmic
Explanation: RNA is not found in plasmalemma. Plasmalemma is also known as the plasma membrane. These are found inner the cell wall of a cell. These are made up of proteins, phospholipids, and carbohydrates and do not contain RNA in them.
Correct answer: Plasmalemma6987. A periplasmic space is:
- A. The space between outer membrane and peptidoglycan layer of cell wall
- B. The space between cell membrane and cell wall
- C. The space within the cell
- D. The space between phospholipld bilayer
Explanation: The periplasmic space is the area between the cell wall and the plasma membrane.
Correct answer: The space between cell membrane and cell wall6988. Which of these is the right combination of molecules which make up the secondary cell wall in plant cells?
- A. Cellulose, lignin and xylem
- B. Cellulose, hemicellulose and lignin
- C. Cellulose only
- D. Cellulose hemicellulose and pectin
Explanation: The composition of the secondary wall includes Inorganic salts, silica waxes, lignin, cutting, hemicellulose, cellulose. •Composition of primary wall and middle lamella is as followsPrimary wall:Cellulose, pectin, and hemicelluloseMiddle lamella:It is formed of sticky gel-like magnesium and calcium salts and pectin.
Correct answer: Cellulose, hemicellulose and lignin6989. A cell-wall that is composed of sugar and amino acids is called:
- A. Murein
- B. Chitin
- C. Lignin
- D. Pectin
Explanation: Peptidoglycan or murein is a polymer consisting of sugars and amino acids that forms a mesh-like peptidoglycan layer outside the plasma membrane of most bacteria, forming the cell wall. Hence the correct answer would be A.
Correct answer: Murein6990. Amoeboid movements and the movement of cyclosis are due to?
- A. Microfilaments
- B. Microtubules
- C. Intermediate filaments
- D. Cytoskeleton
Explanation: Microfilaments are versatile components and they play a major role in cytokinesis and the shape of a cell. The flexible arrangement of the filaments framework allows it to help in the cell movement (ameboid movement).
Correct answer: Microfilaments