Biology A level AQA Unit 6

The diagram shows a motor neurone. Which line shows the correct function of the labelled parts?

• A

• B

• C

• D

2. The diagram shows some biochemical pathways in a liver cell, some of which are reversible. Five reactions whose rate in a certain direction can be changed by the presence of a hormone are labelled 1 – 5.

Each number relates to the direction of the arrow nearest to the number. Which numbered reactions have their rate increased in the presence of insulin?

• 1

• 2

• 3

• 4

• 5

A sudden movement close to the eyes causes a person to blink. Which line summarises the events involved in this response?

• A

• B

• C

• D

The diagram shows part of a myofibril of skeletal muscle. There are 4 000 identical sarcomeres in the myofibril and each one contracts until the myosin filaments are just touching the Z lines.

By how much will the whole myofibril shorten during contraction?

• 1600 μm

• 3000 μm

• 3.2 mm

• 4.6 mm

Glucose moves from the filtrate in the nephron into the bloodstream during normal kidney function.

What part of the nephron allows this movement of glucose, and by what mechanism?

• collecting duct by active secretion

• distal convoluted tubule by facilitated diffusion

• glomerulus by ultrafiltration

• proximal convoluted tubule by selective reabsorption

Homeostasis maintains optimum concentrations of chemicals in tissue fluid and blood plasma, so that reactions can function optimally in cell cytoplasm. The diagram shows the concentrations of three different ions and the concentration of protein measured in these three constituents. Which line correctly identifies 1, 2 and 3?

• A

• B

• C

• D

What will increase the secretion of anti-diuretic hormone from the posterior pituitary gland?

• decreasing the external temperature of the body

• drinking a large volume of water

• Injecting a concentrated salt solution with low water potential into the body

• Injecting a dilute glucose solution with high water potential into the body

A glucose tolerance test can be used to investigate a person’s ability to homeostatically adjust their blood glucose concentration. The concentration of glucose in the blood plasma is measured before and after consuming 50 g glucose. The table shows plasma blood glucose concentrations before and during a glucose tolerance test that are diagnostic of different conditions. Results from glucose tolerance tests for three individuals are shown on the graph. Which line correctly diagnoses each individual's condition?

• 
• 
• 
• 

Hepatocytes carry out a number of different functions.

Which statement(s) describe functions that occur in hepatocytes?

• Combining ammonia and carbon dioxide via the ornithine cycle

• Storage of glycogen and some vitamins and minerals

• Breakdown of drugs and alcohol

A decrease in environmental temperature causes changes in the physiological functioning of the skin.

Which line of the table identifies the changes that occur?

• A

• B

• C

• D