Cell biology worksheet with answers

What is the main role of the nucleolus?

1. AMaking ribosomal RNA and assembling ribosome subunits
2. BCopying the whole genome
3. CStoring ATP for the nucleus
4. DBreaking down damaged proteins that are tagged with ubiquitin

How do enzymes speed up chemical reactions?

1. AThey lower the activation energy
2. BThey change the reaction's final equilibrium
3. CThey are used up in the reaction
4. DThey raise the temperature of the cell

Which part of the cytoskeleton forms the mitotic spindle?

1. ACollagen fibres
2. BMicrotubules
3. CActin filaments
4. DIntermediate filaments

The rough endoplasmic reticulum is "rough" because it:

1. AContains DNA
2. BHas a cell wall
3. CStores calcium only
4. DIs studded with ribosomes

A point mutation changes a codon for an amino acid into a stop codon. What type of mutation is this?

1. ANonsense mutation
2. BMissense mutation
3. CFrameshift mutation
4. DSilent mutation

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

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

Sickle cell disease is caused by a single base substitution that changes glutamate to valine in beta-globin. What type of mutation is this?

1. AFrameshift mutation
2. BMissense mutation
3. CNonsense mutation
4. DSilent mutation

The endosymbiotic theory is supported by the fact that mitochondria:

1. AHave their own circular DNA and 70S-like ribosomes
2. BAre made in the nucleus
3. CHave no membranes
4. DContain chlorophyll