Cell biology worksheet with answers

What is cytokinesis?

1. AThe pairing of homologous chromosomes
2. BThe copying of DNA before division
3. CThe breakdown of the nuclear envelope
4. DThe division of the cytoplasm into two daughter cells

When human muscle cells lack oxygen, pyruvate is converted into:

1. ALactate
2. BAcetyl-CoA
3. CEthanol
4. DGlucose

In chromatin, DNA is wrapped around which proteins?

1. AHistones
2. BActins
3. CTubulins
4. DCollagens

A newly made protein has an N-terminal signal sequence. Where is it directed?

1. ADirectly to the cytosol for use there
2. BInto the endoplasmic reticulum
3. CInto the nucleus
4. DInto the mitochondrial matrix

A codon consists of:

1. AA whole gene
2. BThree amino acids
3. COne nucleotide
4. DThree nucleotides on mRNA that code for an amino acid or a stop signal

In which direction do DNA and RNA polymerases add new nucleotides?

1. A3′ to 5′
2. B5′ to 3′
3. CFrom the centromere outwards
4. DIn both directions equally

Brown fat contains thermogenin (UCP1), which lets protons leak back across the inner mitochondrial membrane. What is the effect?

1. AEnergy from the proton gradient is released as heat instead of making ATP
2. BThe electron transport chain stops working because protons can no longer be pumped
3. CMore ATP is made per glucose
4. DThe cell switches to fermentation

With 23 chromosome pairs, how many different chromosome combinations can independent assortment alone produce in human gametes?

1. A2 × 23
2. B46
3. C23²
4. D2²³ (about 8 million)