The concentrations of ions is significantly higher in the vacuoles than in the cytoplasm. The reason for this:
1. Facilitated diffusion of the ions by the tonoplast
2. Active transport of the ions by the tonoplast
3. Presence of porins for diffusion of the ions
4. Bulk transport across the tonoplast

All of the following are true of protein denaturation except that it
1. is a shape change
2. is always irreversible
3. may be caused by a pH change
4. could result from a temperature change

Cyclins and cyclin-dependent kinases (CDKs) are:
1. Two key classes of regulatory molecules that determine a cell's progress through the cell cycle
2. The products of the proto oncogenes in a eukaryotic cell
3. Two very important promoters that are involved in oncogenes
4. Mediators of apoptosis

Consider the following statements:
I. In animals, meiosis always results in the formation of gametes, while in other organisms it can give rise to spores.
II. Meiosis is essential for sexual reproduction and therefore occurs in all eukaryotes (including single-celled organisms) that reproduce sexually.
III. Meiosis does not occur in archaea or bacteria, which reproduce via asexual processes such as binary fission.
The correct statements are:
1. I, II, and III
2. II and III
3. I and III
4. I and II

Which of the following is an essential amino acid?
1. Phenylalanine

2. Aspartic acid

3. Glutamic acid

4. Serine

Which of the following statements is NOT true of mitosis?
1. A single nucleus gives rise to two identical daughter nuclei.
2. The daughter nuclei are genetically identical to the parent nucleus.
3. The centromeres divide at the onset of anaphase.
4. Homologous chromosomes synapse in prophase.

In oocytes, the diplotene can last for months or years, since at this stage:
1. DNA proof reading and excision repair is performed
2. The proteins for metabolism are re-formed
3. The chromosomes condense and engage in RNA synthesis
4. The cell is temporarily withdrawn from the cell cycle

Most abundant organic compound on earth is
1. Cellulose

2. Protein

3. Lipids

4. Steroids

Assuming they all had the same number of carbon atoms, which of the following has the most C-H bonds?
1. an unsaturated fat
2. a polyunsaturated fat
3. a polysaccharide
4. a saturated fat

An alpha helix is a:
1. primary structure of a protein
2. secondary structure of a protein
3. tertiary structure of a protein
4. quaternary structure of a protein