Question

1. Peptide hormones and growth factors act on target cells by binding to cell surface and _______ receptors.

a. endoplasmic reticulum

b. cytosolic

c. nuclear

d. soluble extracellular

2. Secondary cell walls are stronger than primary cell walls because secondary cell walls contain

a. more pectin.

b. less lignin.

c. more chitin.

d. layers of cellulose fibrils at various orientations to one another.

3. Eukaryotic RNA polymerase I genes code for

a. mRNAs.

b. tRNAs.

c. small nuclear RNAs and small cytoplasmic RNAs.

d. ribosomal RNAs.

4. Mitochondrial genes are transcribed by

a. RNA polymerase I.

b. RNA polymerase II.

c. RNA polymerase III.

d. a separate mitochondrial RNA polymerase.