Photosynthesis: what is in a leaf?

Rubidium-87 has a half-life of 48.1 billion years. After how many years is there 25 percent parent isotope and 75 percent daughter isotope contained in the object?

What is the future of Alzheimer's disease?

Why do microbiologists need to isolate bacterial colonies from a specimen?

How do intrusive rocks form? Lava cools slowly outside a volcano. Magma cools slowly inside a volcano. Molten material is cooled quickly by water. Magma is ejected into the air and cools slowly.

A researcher observing an ecosystem describes the amount of sunlight, precipitation, and type of soil present. Which factors is the researcher most likely describing? A. Biotic factors in a forest B. Biotic factors in a tundra C.

What is the most likely cause of plate movement? A) radiation from the sun B) cold air currents on earths surface C) heat convection within the earth D) movement of ice sheets

The closer together a magnet's magnetic field lines are, a. the weaker the magnetic field. b. the stronger the magnetic field. c. the closer they are to the magnet's center. d. the closer they are to disappearing.

What are two things that carbohydrates and lipids have in common? A. Both contain C, H, O and N and are formed by dehydration snythesis. B. Both contain C, H, O and serve as a source of energy. C.

Stellar equilibrium is a balance between what two things? A. Outward and inward gravity. B. Outward pressure from light and inward pressure from heat. C. Outward pressure from hydrogen and inward helium. D. Outward pressure and inward gravity

Which genotype represents a homozygous dominant allele? HH Hh hh