Practise IB Biology HL B2.2 organelles through compartmentalization, ribosome location, secretion pathways and cristae, grana and stroma adaptations.
Testis cells are eukaryotic cells. Identify the structures seen under the electron microscope in testis cells that are not present in prokaryotic cells.
| a | nucleus/nuclear membrane |
| b | membrane bound organelles |
| c | mitochondria |
| d | rough ER/smooth ER/golgi apparatus |
| e | lysosomes / centrioles / |
| f | large/80S ribosomes / ribosomes attached to a membrane |
| g | linear chromosomes / histones / |
Nitrogen is part of many important substances in living organisms.
Distinguish between transcription and translation.
a. DNA is transcribed AND mRNA is translated
b. transcription produces RNA AND translation produces polypeptide/protein
c. RNA polymerase used in only in transcription and ribosomes only in translation
d. transcription in the nucleus «of eukaryotes» and translation in the cytoplasm
e. tRNA needed for translation but not transcription
f. nucleotides linked in transcription and amino acids in translation
OR
sugar-phosphate/phosphodiester bonds in transcription and peptide bonds in translation
Disallow the first mark, if a candidate gets transcription and translation the wrong way round, but allow marks after that up to [3 max]
4 max
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