Question 3(a)
[Maximum number: 1]
Heart rate is influenced by electrical impulses from the brain.
State the name of the type of cell that conducts electrical impulses to the heart.
IGCSE Biology Extended 14.1.1—Electrical impulses travel along Topic Practice
14.1.1—Electrical impulses travel along
• State that electrical impulses travel along neurones
Question 4(b)(iv)
[Maximum number: 3]
The flow of blood through the skin can be investigated by using a flow-meter.
Fig. 4.1 shows a flow-meter above a section through the skin.
Fig. 4.1
The blood flow through the skin of some volunteers was measured with a flow-meter when their skin was exposed to different temperatures.
Capsaicin is a compound that gives people the sensation of feeling hot when it is put on the skin. Researchers applied capsaicin to the skin of the volunteers and again measured the blood flow through their skin at different temperatures.
Fig. 4.2 shows the results.
Fig. 4.2
The researchers thought that capsaicin stimulated receptors in the skin.
Explain the process by which capsaicin could reach these receptors.
Question 4(a)(i)
[Maximum number: 1]
A neurone is a type of specialised animal cell.
Neurones develop from unspecialised cells.
State the name of these unspecialised cells.
Question 6(b)
[Maximum number: 2]
Meningitis is a transmissible disease. One form of the disease is caused by the bacterium Neisseria meningitidis.
One effect of meningitis is a slowing down of nerve impulses.
State what is meant by a nerve impulse.