Life Science CSIR NET JRF - Cell Biology questions - Part - 3

21. Discontinuous segments of DNA are joined by:
(a) telomerase (b) DNA ligase
(c) exonuclease (d) DNA polymerase

22. The concentration of calcium in a cell is 0.3%. The concentration of calcium in the surrounding fluid is 0.1%. How could the cell obtain more calcium?
(a) passive transport (b) diffusion
(c) active transport (d) osmosis

23. Phospholipid molecules in a membrane are arranged with their ____ on the exterior and their ____ on the interior.
(a) hydrophobic heads . . . hydrophilic tails
(b) hydrophilic heads . . . hydrophobic tails
(c) nonpolar heads . . . polar tails
(d) hydrophobic tails . . . hydrophilic heads

24. Sister chromatids:
(a) are created when DNA is replicated
(b) are separated during mitosis
(c) are attached at the centromere prior to division
(d) all of the above

25. Which of the following correctly matches a phase of the cell cycle
(a) S, immediately precedes cell division (b) M, duplication of DNA
(c) G1, immediately follows cell division (d) G2, cell division

26. The kinetochores:
(a) are the primary centromere structures that maintain the attachment
(b) attach to the ring of actin along the cytoplasmic surface of the plasma membrane
(c) move along spindle microtubules during anaphase, dragging
(d) are located at the center of the centromere their function is to provide attachment
site to spindle fibre

27. A biochemist measured the amount of DNA to be doubled during the cells in growing stages
(a) between prophase and anaphase
(b) between anaphase and telophase
(c) during the M phase of the cell cycle
(d) between the G1 and G2 phases

28. DNA damaged by sunlight:
(a) has undergone depurination (b) has lost its phosphate groups
(c) has formed pyrimidine dimers (d) has lost its hydrogen bonds

29. Which of the following functional processes results from the presence of protein within the plasma membrane?
(a) enzymatic activity (b) signal transduction
(c) intercellular joining (d) all of the above

30. Select the correct statement concerning membrane carbohydrate.
(a) Carbohydrates are only found associated with the membranes of prokaryotic cells.
(b) Glucose is the most abundant membrane carbohydrate.
(c) Cell membranes consist of protein and phospholipid; carbohydrate is not a membrane component.
(d) membrane carbohydrates function primarily in cell-cell recognition.

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