Cell biology worksheet with answers

Which base is found in RNA instead of thymine?

1. AGuanine
2. BCytosine
3. CUracil
4. DAdenine

What is diffusion?

1. AMovement of water only across a membrane
2. BNet movement of particles from high to low concentration
3. CMovement of particles against their concentration gradient using ATP
4. DEngulfing of particles by the cell membrane

What is the main function of lysosomes?

1. AProducing ATP by respiration
2. BMaking proteins for export and packaging them into secretory vesicles
3. CBreaking down worn-out parts and engulfed material with enzymes
4. DStoring the cell's DNA

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

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

What directly drives ATP synthase to make ATP in mitochondria?

1. AProtons flowing back into the matrix down their gradient
2. BOxygen diffusing into the matrix
3. CGlucose binding to ATP synthase
4. DElectrons from NADH flowing directly through ATP synthase

What role does cholesterol play in animal cell membranes?

1. AIt forms channels for ions
2. BIt helps keep membrane fluidity stable across temperatures
3. CIt is the main carrier of glucose
4. DIt makes the membrane completely rigid at every temperature

Non-disjunction during meiosis can result in:

1. ACrossing over
2. BIdentical twins
3. CGametes with an abnormal number of chromosomes, such as in Down syndrome
4. DMitochondrial DNA mutations only, which are passed on through the egg cytoplasm

Tumour suppressor genes such as p53 normally:

1. AMake cells immortal
2. BProduce growth factors
3. CStop the cell cycle or trigger apoptosis when DNA is damaged
4. DSpeed up cell division so that damaged cells are quickly replaced