Question

Previous Page Next Page Page 15 of 20 3 Question 71 (4 points) Which of the following can engage in "self-destruction of the cell? 8 ribosome endoplasmic reticulum peroxisome Golgi apparatus lysosome 10 Question 72 (4 points) Which of the following is CORRECT regarding diffusion? 12 13 15 the greater the concentration gradient, the faster the diffusion rate molecular weight of a substance does not affect the rate of diffusion the rate of diffusion is independent of temperature the lower the temperature, the faster the diffusion rate 3 E R. S D G Н. к C V В. N. M

Answer 1

71. Self-destruction of cell occurs by the process of programmed cell death or apoptosis. This usually occurs when the cell is diseased, damaged or undergoing aging. Self-destruction occurs in the lysosome which has lysosomal enzymes that aid in degrading cellular organelles. Hence, lysosomes are known as suicide bags of the cell. Apoptosis lead to death of the cell via DNA fragmentation which later leads to breakdown of the organelles. The internal environment of the lysosome is acidic and thus hydrolytic enzymes functional in this environment will help degrade the organelles of the dead cells.

Peroxisomes are organelles that carry out fatty acid oxidation of very long chain fatty acids. They will also neutralize the reactive oxygen species in the body. Endoplasmic reticulum contains the RER and SER. RER is involved in synthesis of protein that are secreted or targeted to lysosome. SER is involved in synthesis and storage of lipids. RER also will carry out N-glycosylation of protein. Golgi apparatus is involved in glycosylation and packaging of protein from ER into secretory vesicles. The ribosome is the site at which translation of protein from mRNA occurs.

Right choice: Lysosome.

72. Diffusion is the movement of molecules from area of higher concentration to an area of lower concentration till the concentration in both areas is equalized. This difference in concentration between the two areas is called concentration gradient. Thus, greater the concentration gradient, higher is the diffusion rate. Molecular weight of the molecule affects the diffusion rate. Larger the molecule, slower will be the diffusion. Further, temperature also affects the diffusion rate. Higher temperatures tend to increase the diffusion rate as the kinetic energy of the molecule will rise. At lower temperature, kinetic energy of the molecules decreases, causing lesser diffusion.

Right choice: The greater the concentration gradient, faster is the diffusion rate.