All Free Biology MCQs with Answers
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19844 questions · page 689 of 1985
6881. Peptidoglycan or murein is special or distinctive feature of cell wall in:
- A. Algae
- B. Fungi
- C. Bacteria
- D. Plants
Explanation: Bacterial cell wall is made up of unique macromoclecule called peptidoglycan or murein. It is the distinctive feature of prokaryotic cell. Bacteria is a prokaryotic organism.
Correct answer: Bacteria6882. The _ model of plasma membrane suggests that proteins are embedded in a lipid bilayer.
- A. Unit membrane
- B. Fluid mosaic
- C. Permeable
- D. Ultracentrifuge
Explanation: According to fluid mosaic model, the protein layers are not continuous and are not confined to the surface of the membrane but are embedded in lipid bilayer in a mosaic manner.
Correct answer: Fluid mosaic6883. Endoplasmic reticulum consists of a system of flattened membrane bounded sacs which are named as:
- A. Cristae
- B. Lamellae
- C. Cisternae
- D. Tubes
Explanation: ER consists of a network of membrane-bounded tubules or sacs are called cisternae.
Correct answer: Cisternae6884. When a glycoprotein is being synthesized for secretion from a cell, which route is it most likely to take?
- A. Golgi apparatus→ Rough endoplasmic reticulum→ Smooth endoplasmic reticulum
- B. Rough endoplasmic reticulum→ Golgi apparatus→ Smooth endoplasmic reticulum
- C. Rough endoplasmic reticulum→ Smooth endoplasmic reticulum→ Golgi apparatus
- D. Smooth endoplasmic reticulum→ Rough endoplasmic reticulum→ Golgi apparatus
Explanation: For the secretion of glyoprotein from the cell, protein is first synthesized by the ribosomes on RER. This protein then travel through RER to SER to be transferred to the Golgi apparatus through transport vesicles. On reaching the Golgi apparatus, this protein is modified into glycoprotein and then budded off from Golgi apparatus as goldi vesicles. These vesicles are then secreted out of the cell.
Correct answer: Rough endoplasmic reticulum→ Smooth endoplasmic reticulum→ Golgi apparatus6885. Granular endoplasmic reticulum is mainly concerned with:
- A. Proteolysis
- B. Peptide bond formation
- C. Glycosidic bond formation
- D. Fatty acid and cholesterol synthesis
Explanation: Granular ER is called so because it has ribosomes attached to its surface. These ribosomes are responsible for protein synthesis. Proteins contain polypeptide chains synthesized by peptide bond formation between amino acids.
Correct answer: Peptide bond formation6886. Pinocytosis and phagocytosis are accomplished by the:
- A. Nucleus
- B. Mitochondria
- C. Cell membrane
- D. Endoplasmic reticulum
Explanation: The cell membrane or plasma membrane is very selectively permeable. It allows only a few substances to pass through it through diffusion. However, it can intake solid or liquid food particles needed by the cell in the form of food vacuole by phagocytosis and pinocytosis, respectively.
Correct answer: Cell membrane6887. Which one of the following eukaryotic cell structures does not contain DNA?
- A. Nucleus
- B. Mitochondrion
- C. Endoplasmic reticulum
- D. Chloroplast
Explanation: The endoplasmic reticulum is a network of membrane-bound tubules. It does not contain DNA. The nucleus is the brain of the cell. It contains all the genetic information of the cell in the form of DNA. Mitochondria and chloroplasts are thought to have a symbiotic origin with bacteria. Detailed studies of mitochondria chloroplasts under an electron microscope show that a small circular DNA molecule is present in the mitochondrial matrix and stroma of chloroplast.
Correct answer: Endoplasmic reticulum6888. Phragmoplasts are formed by:
- A. ER
- B. Mitochondria
- C. Golgi bodies
- D. Nucleus
Explanation: Phragmoplast is a structure formed at the cell equator during cell division in plants. Later on, a new cell wall is derived from it. It is formed by the fusion of the Golgi vesicles.
Correct answer: Golgi bodies6889. Size of ribosomes in organelles of endosymbiotic origin:
- A. 50S
- B. 60S
- C. 70S
- D. 80S
Explanation: The size of ribosome in the organelles of symbiotic origin is 70S. It is similar to bacterial ribosome because these organelles are thought to have symbiotic origin with bacteria.
Correct answer: 70S6890. Which structure is present in a plant cell but not in an animal cell?
- A. Cell membrane
- B. Cell wall
- C. Cytoplasm
- D. Nucleus
Explanation: Cell wall is a non-living boundary of the cell present only in the plants, algae and fungi. It is absent in animal cells.
Correct answer: Cell wall