Cell biology worksheet with answers

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

1. AGlucose
2. BLactate
3. CAcetyl-CoA
4. DEthanol

Which base pairs with adenine in DNA?

1. AUracil
2. BThymine
3. CCytosine
4. DGuanine

Which structure helps organise microtubules in animal cells and contains a pair of centrioles?

1. ANucleolus
2. BVacuole
3. CRibosome
4. DCentrosome

Why does DNA replication need primase?

1. APrimase unwinds the DNA double helix
2. BPrimase joins the Okazaki fragments together once their RNA primers have been removed
3. CDNA polymerase can only extend an existing strand, so a short RNA primer is needed
4. DPrimase proofreads the new DNA

Why does inserting a single nucleotide into a coding sequence usually have a large effect?

1. AIt always changes one amino acid only
2. BIt changes the sugar in the DNA backbone
3. CIt shifts the reading frame of all following codons
4. DIt stops the gene from being transcribed into messenger RNA

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

1. AIn both directions equally
2. B5′ to 3′
3. CFrom the centromere outwards
4. D3′ to 5′

In the most common cystic fibrosis mutation (ΔF508), the CFTR protein is made but is missing from the cell membrane. Why?

1. AThe protein is secreted out of the cell instead of being inserted
2. BThe gene is not transcribed at all
3. CThe mRNA cannot leave the nucleus
4. DThe misfolded protein is held in the ER and degraded

In Griffith's 1928 experiment, mice injected with heat-killed smooth (S) pneumococci plus live rough (R) bacteria died. What did this show?

1. AR bacteria are virulent on their own
2. BMice make S bacteria from R bacteria
3. CHeat does not kill S bacteria
4. DA substance from the dead S cells transformed R cells into a virulent form