Cell biology worksheet with answers

In which phase of the cell cycle is DNA replicated?

1. AM phase
2. BS phase
3. CG1 phase
4. DG2 phase

How many chromosomes are in a normal human body (somatic) cell?

1. A46
2. B23
3. C48
4. D44

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

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

How do large proteins such as transcription factors enter the nucleus?

1. AThey are made inside the nucleus by nuclear ribosomes, so they never enter
2. BBy exocytosis from the endoplasmic reticulum
3. CBy diffusing freely through the nuclear membrane lipids
4. DThrough nuclear pore complexes, guided by a nuclear localisation signal

What directly drives ATP synthase to make ATP in mitochondria?

1. AElectrons from NADH flowing directly through ATP synthase
2. BGlucose binding to ATP synthase
3. CProtons flowing back into the matrix down their gradient
4. DOxygen diffusing into the matrix

Glycolysis takes place in the:

1. AMitochondrial matrix
2. BNucleus
3. CCytoplasm
4. DInner mitochondrial membrane

A mutant Ras protein cannot hydrolyse GTP. What is the effect on cell signalling?

1. ARas moves into the nucleus and blocks transcription
2. BRas stays inactive and growth signals stop
3. CRas is broken down faster
4. DRas stays active and sends constant growth signals

Cholera toxin modifies the alpha subunit of Gs so it cannot hydrolyse GTP. Why does this cause severe watery diarrhoea?

1. AcAMP falls, so gut cells stop absorbing water and sodium from the lumen
2. BThe toxin destroys the villi
3. CcAMP stays high in gut cells, driving chloride and water secretion
4. DThe toxin blocks aquaporins in the colon