Select the correct answer. Pacemakers maintain the heartbeat in people who suffer from certain defects. The function of an artificial pacemaker is to send electrical impulses that will contract the heart muscles and regulate the pumping of the heart. Which condition could be corrected by a pacemaker?
A.
The individual’s sinoatrial node ceases to function.
B.
The individual’s central nervous system fails to signal the heart to contract and relax.
C.
The individual’s arteries are blocked.
D.
The valves in the individual’s heart cease to function.

Many farmers prefer cattle without horns because it is safer for their herds. the allele for no horns (n) is dominant to the allele for the presence of horns (n). a farmer mates a male with horns to a heterozygous female without horns. what is the chance that the offspring will have horns?

Hormones are chemical molecules produced by endocrine glands. one such endocrine gland is the thyroid gland, which synthesizes the thyroid hormone, which in turn affects the heart muscles. which two statements describe the probable reason for the function of the hormone? the cells in the heart have specific receptors that allow for the intake of hormones. the heart and the endocrine glands have the exact same types of cells. all cells make the same types of hormones. thyroid hormones show their effect on the heart by means of specialized cells. thyroid cells and cardiac cells have different dna.

In the desert, saguaro cacti, owls, horned lizards, and fire ants all share the same space. which of the following can be considered a population? question 9 options: all plants in the same area all cacti in the same area all species in the same area the lizards and the ants