A common characteristic feature of plant sieve tube cells and most mammalian erythrocytes is

1. absence of mitochondria

2. presence of cell wall

3. presence of haemoglobin

4. absence of nucleus

Which of the following features is common to prokaryotes and many eukaryotes?

1.  Chromatin material present

2.  Cell wall present

3.  Nuclear membrane present

4.  Membrane bound sub-cellular organelles present