TASK DEFINITION: In this task, you are given a paragraph, and your task is to construct a question from the given passage. Construct question in such a way that (i) it is well explained in the paragraph, (ii) the words may/may not be present in the paragraph, (iii) it should start with what/how/describe. Avoid creating a question that (i) is just relevant to one or two sentences, and (ii) not relevant to passage. 
PROBLEM: Carbon dioxide from the air passes through small pores (holes) in the leaves. These pores are called stomata. Water is absorbed by the roots. It passes through vessels in the stem on its way to the leaves. Sunlight is absorbed by a green chemical in the leaves. 

SOLUTION: What happens during photosynthesis?

PROBLEM: Energy is created by burning either diesel or petrol in a combustion chamber. The energy is transferred from the pistons moving up and down at high speeds. This piston motion is converted to a rotary motion through the crankshaft and axle. The axle turns the wheels. The car moves forward. 

SOLUTION: Describe how a car works

PROBLEM: Two large veins bring blood to the heart. The blood enters the right atrium. The blood flows through the tricuspid valve. The blood travels into the right ventricle. The blood goes through the pulmonary arteries to the lungs. Blood picks up oxygen in the lungs. Oxygenated blood enters the left atrium. Blood goes to the left ventricle. Blood leaves the heart via the aorta to the rest of the body. The deoxygenated blood returns to the heart. 

SOLUTION:
How does the heart work?