Diseases or other disorders can be passed down through your family so you need to know your families history to know if you are at an increased risk.
I THINK the answer is d. Not 100% sure.
It really depends, think of it as 2 light bulbs in each parent. if both light bulbs in both parents are switched on that means their genes that they inherited are only able to have brown eyed babies, although if just 1 of the 4 light bulbs are not on it allows the baby to have blue eyes.
During the resting heart, that is, the number of times the heart beats per minute while the body is relaxed and at rest does not change significantly with age; But with age, there are changes in the ability of the heart to increase its rate during exercise and other moments of stress. Younger hearts usually usually speed up more faster than older ones when challenged. The maximum heart rate, the highest heart rate one can achieve as measured by a cardiac stress test declines gradually in adults as they age. The cause of this is slowing down of the heart's pacemaker cells.