Name the sections of the amino acid molecule marked A and B in Fig. 1.1. A ................................................................. B .................................................................
Amino acids act as monomers for proteins. Complete Fig. 1.2 by drawing a diagram to show the formation of a peptide bond between two molecules of glycine.
Plasma cells make and secrete antibodies. Fig. 1.3 is a transmission electron micrograph of a plasma cell. Use a label line and the label T on Fig. 1.3 to show where the genes for the polypeptide chains of the antibodies are found.
Calculate the true diameter of the plasma cell shown by the line P-Q. State the formula you use for your calculation. Show your working and give your answer to the nearest micrometre ($\mu$m).
The plasma cell in Fig. 1.3 is very metabolically active. Suggest why very few mitochondria can be seen in the electron micrograph in Fig. 1.3.
Sieve tube elements in plants contain very few organelles such as mitochondria. Explain how having very few organelles helps the sieve tube element function.