Biology A Level Revision quiz!

Which definition of the magnification of a drawing of a leaf is correct?

• the actual size of an object multiplied by the magnification of the microscope

• he difference in size between an actual object and a drawing of the object

• the increase in size of an object when observed using a microscope

• the size of the drawing of a specimen in comparison to the actual size

Which labelled features identify these cells as eukaryotic?

• W, X and Y

• W and X only

• W only

• X only

Plant cells are fixed, stained and viewed using a student microscope. The light source was natural light. What would be clearly visible at ×400 magnification?

• cristae of mitochondria

• grana of chloroplasts

• nucleoli

• ribosomes

Some secretory cells synthesise and release glycoproteins. What is the correct order of the sequence of events as they occur in the secretory cell?

1 exocytosis

2 product accumulates in secretory vesicle

3 mRNA binds to ribosomes

4 synthesis of glycoprotein

• 3, 4, 1, 2

• 3, 4, 2, 1

• 4, 3, 1, 2

• 4, 3, 2, 1

Which statement describes how the molecular structure of starch is suited to its function?

• Amylose has a branched structure and amylopectin is coiled to give a compact molecule for transport.

• In the breakdown of amylose and amylopectin, many condensation reactions release stored energy.

• In the formation of amylose and amylopectin, many hydrolysis reactions allow the release of stored energy.

• The amylose-amylopectin complex is insoluble and does not affect the water potential of the cell.

Cows and whales are mammals that produce milk to feed their babies. Newborn whales grow faster than newborn cows. The milk of both cows and whales contains saturated fatty acids with different chain lengths. The table shows the percentage of saturated fatty acids of different lengths in cow and whale milk.

Which statement about the ratio of short fatty acids (4–16 carbons) to long fatty acids (18 or more carbons) in the milk of cows and whales is correct?

• The ratio in cow milk is higher because young cows need more energy than young whales.

• The ratio in cow milk is lower because young cows need less energy than young whales.

• The ratio in whale milk is higher because young whales need less energy than young cows

• The ratio in whale milk is lower because young whales need more energy than young cows.

Bacterial cells divide by a process called binary fission. Which macromolecules must be synthesised for binary fission?

1 cell membrane proteins and RNA

2 DNA and peptidoglycan

3 enzymes and cellulose

• 1, 2 and 3

• 1 and 2 only

• 2 and 3 only

• 3 only

A student carried out experiments to investigate the effect of enzyme concentration on the rate of hydrolysis (break down) of protein in milk.

When the enzyme and milk were mixed, the protein was hydrolysed and the mixture changed from cloudy to clear. The student investigated five different enzyme concentrations and recorded the time taken to reach the end-point for each.

What is an appropriate control for this investigation?

• Carrying out a further experiment where the enzyme solution is replaced with water.

• Carrying out each experiment in a thermostatically regulated water-bath at 35 °C.

• Performing three repeat experiments for each of the five enzyme concentrations.

• Using the same volume of enzyme solution for each of the five experiments.

What determines the specificity of an enzyme?

1 the bonding between R groups of the polypeptide

2 the optimum pH of the enzyme

3 the peptide bonds between amino acids of the polypeptide

4 the shape of the substrate molecule

• 1, 2, 3 and 4

• 1 and 3 only

• 1 only

• 2, 3 and 4 only

The graph shows the effect of temperature on the rate at which the enzyme in a biological washing powder digests and removes fruit juice stains.

Which statements explain the shape of the graph at temperatures higher than X?

• Bonds are broken between the R groups of the amino acids in the polypeptide chains of the enzyme.

• There are more collisions between the enzyme and its substrate.

• The tertiary structure of the enzyme is altered.

• The shapes of the active site and the substrate are no longer complementary.