After conception, the main organs are established by the end of the

(a) third day.

(b) second week.

(c) eighth week.

(d) fourth month.

Nerve cells do not begin to develop until after a child is born.

Marquis is using a balance to measure the mass of a rock. After recording a reading, he removes the rock, clears the balance, and measures the rock again using the same balance. He repeats this process two more times.

The stability of atomic nuclei seems to be related to the ratio of: a] protons to electrons b] neutrons to protons c] isotopes to neutrons d] neutrinos to gamma rays

Where is the moon's gravitational pull the strongest?

Which of the following are examples of dissolved gases found in the ocean. (3 of them) calcium oxygen potassium nitrogen carbon dioxide chloride

Explain what could happen to the community if all the frogs suddenly died. Which organisms will die? Which organisms will over populate? Why?

13. Which one of the following diseases is caused by a virus? A. Tuberculosis B. Tetanus C. Hepatitis B D. Strep throat

The part of the peripheral nervous system that controls the glands and the muscles of the internal organs is called the

Most fish and birds breed at what time of the year?

The group of polar bears that live along the eastern coast of Russia makes up an organism.