Practise IB Biology HL 2.2.3 through the exact HL evidence on membrane compartments, organelle conditions, reaction efficiency and separation of incompatible processes.
The structure of membranes allows them to carry out many functions in cells.
Discuss the use of membranes for compartmentalization in eukaryotic cells.
a. (membranes divide the cell into) organelles;
b. nucleus/chloroplast/mitochondrion is double membraned/has inner and outer membrane;
c. enzymes/substrates can be concentrated (in the small volume);
d. different/incompatible functions/processes in different organelles (so harm prevented);
e. hydrolytic/digestive enzymes held inside lysosomes/phagocytic vacuoles;
f. pH/conditions can be for optimized for (each) function/process;
g. small spaces/volumes for proton gradient/concentration gradient (to develop quickly);
h. (post- transcriptional) modification of mRNA in nucleus (before it reaches the ribosome);
i. vesicles for transport/transfers;
j. nuclear membrane/envelope protects DNA/chromosomes (from the cytoplasm);
Marking guidance:
Do not award marks
describing the functions of the plasma membrane.
4
max