Heart rate, or the rate at which the muscles in the heart contract, is controlled by the sinoatrial node, a group of cells in the cardiac muscle of the right atrium. Heart rate decreases when you are asleep and increases when you are awake. Some
people require an artificial pacemaker to regulate their heart rate if it is too slow. Which hypothesis explains how the body might be affected by a dangerously slow heart rate?
A. The body might have trouble falling asleep of feeling rested after a full night of slee
B. Cells in the body might not receive enough oxygen, which could cause the person to faint.
C. The adrenal gland might not produce enough hormones to prepare the body for a quick reaction
D. Breathing might become shallow, which could cause the person to retain too much carbon dioxide.

In a hypothetical breed of dogs, coat color is controlled by two genes. there are six different coat colors in this breed: black, brown, cream, gray, silver, and tan. consider the following crosses.cross 1: black females from a lineage of all black dogs are crossed with brown males from a lineage of all brown dogs. f1 males and females are all black. when f1 are intercrossed, f2 males and females are black or brown.cross 2: black females from a lineage of all black dogs are crossed with tan males from a lineage where all males are tan and all females are cream. f1 males are black, f1 females are gray. when f1 are intercrossed, f2 males and females are black, brown, gray, or tan.cross 3: silver females from a lineage where all females are silver and all males are gray are crossed with brown males from a lineage of all brown dogs. f1 males and females are all gray. when f1 are intercrossed, f2 males are black, brown, gray, or tan, f2 females are cream, gray, silver, or tan.select the correct statements regarding the mode of inheritance of the coat color genes.a) both genes are x-linked.b) both genes are autosomal.c) one of the genes modifies the expression of the other gene.d) each gene has an additive effect on the intensity of coat color.e) each gene independently specifies three colors.f) one of the genes is autosomal, and the other is x-linked.

Give an example of a trait that is controlled by more than one gene.

What was darwins theory of common decent