1 Both types of secondary structure occur within the molecules.
2 Large numbers of hydrogen bonds stabilise the molecules.
3 Repeated amino acid sequences determine the tertiary structure.
A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only
Why is the ans D? Why is 1 wrong
2. Which changes in a group of mammalian cells, dividing by mitosis, would be necessary for the
formation of a tumour?
1 Mitosis is no longer inhibited by cell to cell contact.
2 Cells acquire the ability to migrate and set up new colonies.
3 Cells become able to divide indefinitely.
A 1 and 2 B 1 and 3 C 1 only D 2 and 3
Can anyone explain the meaning of 1&2 to me?