Pure Biology Common questions

Pure Biology CAQ Commonly Asked Questions for each topic. Note : Certain concepts below may no longer be in the syllabus . Chapter 1: Cell Structure and Organization Q: Describe how proteins made in the cell are released to the outside of the cell. [3] ● Proteins synthesised by ribosomes on the rough endoplasmic reticulum pinch off in vesicles and are sent to the Golgi body ● Here, they are chemically modified, sorted, stored and packaged into vesicles that pinch off from the Golgi body ● The secretory vesicles move to and fuse with the cell membrane to release the proteins outside the cell Q: Suggest why muscle cells have many mitochondria [2] ● Muscle cells require a lot of energy to contract ● Mitochondria releases energy through aerobic respiration Q: Describe and explain how red blood cells are adapted for their function [4] Adaptation Function Contains haemoglobin Allows it to bind to oxygen to be transported throughout the body Circular, biconcave shape Increases surface area to volume ratio allowing faster rate of diffusion of oxygen No nucleus Allows it to store more haemoglobin Flexible Allows it to squeeze through narrow capillaries Q: Describe and explain how root hair cells are adapted for their function [2] ● Root hair cells have a long and narrow extension. This increases surface area to volume ratio for faster absorption of water and mineral salts. ● Maintains a lower water potential in the vacuole. This allows water to enter the root hair cell via osmosis.

Chapter 2: Movement of Substances Q: Define the term diffusion . Net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient Q: Define the term osmosis . Net movement of water molecules from a region of higher water potential to a region of lower water potential down a water potential gradient, through a partially permeable membrane Q: A 5.0 cm potato strip was placed in distilled water. After 20 minutes, the potato strip measured 5.5 cm. Describe and explain the process which caused the change in length of the potato strip. *Remember: C.M.M.O.O ( C ow MMOO ) 1. C ompare: The distilled water has a higher water potential than the potato cell 2. M ovement: There is net movement of water molecules from water to the potato cell 3. M embrane: past a partially permeable membrane 4. O smosis: via osmosis 5. O utcome: This caused the potato strip to increase in length by 0.5 cm

Q: The diagram shows a pla