All Free Biology MCQs with Answers
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19844 questions · page 664 of 1985
6631. Which one of the following organelles is located near the nucleus and contains a collection of flattened membrane bound cisternae?
- A. Nucleolus
- B. Mitochondrion
- C. Centriole
- D. Golgi apparatus
Explanation: Golgi apparatus is a stack of parallel, flattened, intercommunicating sacs or cisternae and many peripheral tubules and vesicles. The cisternae vary in number from 3 to 7 in most animal cells and from 10 to 20 in plant cells. They are usually equally spaced in the pile, separated from each other by thin layers of intercisternal cytoplasm. The latter may contain a layer of parallel fibres, called intercisternal elements, that support the cisternae. The cisternae are free of ribosomes and have swollen ends. They look like the smooth endoplasmic reticulum.
Correct answer: Golgi apparatus6632. Membranous bag with hydrolytic enzymes which is used for controlling intracellular digestion of macromolecules is:
- A. Endoplasmic reticulum
- B. Nucleosome
- C. Lysosome
- D. Phagosome
Explanation: A lysosome is a tiny sac bounded by a single unit membrane of lipoprotein. It contains a dense, finely granular fluid. The latter consists of glycoprotein hydrolytic (digestive) enzymes called acid hydrolases. These include proteases, lipases, nucleases, glycosidases, sulphatases, acid phosphatases, etc.
Correct answer: Lysosome6633. Golgi apparatus is absent in:
- A. Higher plants
- B. Yeast
- C. Bacteria and bluegreen algae
- D. None
Explanation: Golgi apparatus is absent in bacteria and blue green algae. Golgi bodies are absent in prokaryotic cells and present in eukaryotic cells except in male gametes of bryophytes and pteridophytes, mammalian RBCs, sieve tubes of plants and in cells of fungi.
Correct answer: Bacteria and bluegreen algae6634. Cell recognition and adhesion occur due to biochemicals of cell membranes named:
- A. Proteins
- B. Lipids
- C. Proteins and lipids
- D. Glycoproteins and glycolipids
Explanation: Cell recognition and adhesion occur due to biochemicals of cell membranes named glycoproteins and glycolipids. These are formed due to small carbohydrate molecules present on lipids and extrinsic proteins.
Correct answer: Glycoproteins and glycolipids6635. In salivary glands, chromosomes/polytene chromosomes pairing is:
- A. Absent
- B. Occasional
- C. Formed between non homologous chromosomes
- D. Formed between homologous chromosomes
Explanation: In salivary gland chromosomes/polytene chromosomes pairing is formed between homologous chromosomes. A characteristic feature of these chromosomes is that somatic pairing occurs in them and hence their number appears half of normal somatic cells.
Correct answer: Formed between homologous chromosomes6636. Which of the following is correct about cell theory in view of the current extent of our knowledge regarding cell structure?
- A. Modified cell theory means that all living beings are composed of cells capable of reproducing.
- B. Cell theory does not hold good because all living beings (e.g. viruses) do not have cellular organisation.
- C. Cell theory means that all living objects consists of cells whether or not they are capable of reproducing.
Explanation: This statement is partly correct regarding viruses as an exception to cell theory due to their acellular nature. However, Paramecium, Rhizopus, and Vaucheria are all multicellular organisms and are not exceptions to cell theory. They consist of cells and adhere to the principles of cell theory.
Correct answer: Cell theory does not hold good because all living beings (e.g. viruses) do not have cellular organisation.6637. Names of Schleiden and Schwann are associated with:
- A. Protoplasm as the physical basis of life
- B. Cell theory
- C. Theory of cell lineage
- D. Nucleus functions as control centre of cell.
Explanation: Factual Recall. Names of Schleiden and Schwann became associated with cell theory in 1839. The concept that "All living organisms are composed of cell" is known as cell theory.
Correct answer: Cell theory6638. The binding of specific proteins on regulatory DNA sequences can be studied by means of:
- A. Ultra centrifugation
- B. Electron microscope
- C. Light microscope
- D. X-rays crystallography
Explanation: X-rays crystallography is a technique which is used to study the binding of proteins on regulatory DNA sequences. In this technique, X-rays pass through a crystal of a substance and form a diffraction pattern. With the help of this technique, the arrangement of atoms in the molecular structure of enzymes, proteins, DNA, etc. can be studied. Wilkins, Watson and Crick used this technique to determine the molecular configuration of double helix of DNA.
Correct answer: X-rays crystallography6639. All types of plastids possess essentially the same structure because they:
- A. Perform the same function
- B. Store food materials like starch, fat and protein
- C. Occur in aerial parts
- D. Can transform from one form to another
Explanation: All the plastids have a common origin and one type of plastid can change into another. Plastids are of 2 main types, i.e leucoplasts and chromoplasts. The leucoplasts are colorless and occur in the cells not exposed to sunlight. The chromoplasts are colored and occur in the cells exposed to sunlight.
Correct answer: Can transform from one form to another6640. Experiments on Acetabularia by Hammerling proved the role of:
- A. Cytoplasm in controlling differentiation
- B. Nucleus in heredity
- C. Chromosomes in heredity
- D. Nucleo-cytoplasmic ratio.
Explanation: Factual Recall. Acetabularia used in Hammerling's nucleocytoplasmic experiment is unicellular uninucleate green algae. Hammerling's experiment on Acetabularia involved exchanging rhizoid and stalk. Presence of hereditary information in the nucleous was proved by the work of Hammerling on single celled alga Acetabularia
Correct answer: Nucleus in heredity