Which of the following describes fertilization? a. Cell differentiation to form a blastula
b. A sperm joining an egg to form a zygote
c. Sperm and egg production
d. Formation of germ layers in a deuterostome

According to the big bang theory, after the "bang," the universe remained dark until about  300,000 yearsone billion yearsthree minutesthree billion years  later, when neutral atoms began to form.

Which of the following describes a negative feedback loop? when the heart rate is too high, the body sends hormones that continually increase the heart rate higher. when a pregnant woman is in labor, the body sends hormones that increase the intensity of contractions, which then increases the secretion of the same hormones. when blood sugar is too low, the body sends hormones that raise blood sugar until it reaches a typical level and hormone secretion slows. when a person is jogging, the body sends hormones that continually decrease the rate of oxygen supply to the legs.

Connection compare and contrast genetic engineering to the process of natural selection. select all statements that are true.