The layer of stem cells that constantly divide to renew the epidermis is the

Which movement of substances through a cell membrane against a concentration gradient requires energy?

True or false 1. All volcanic eruptions are explosive 2. Volcanoes change the Earths surface constantly 3. Magma forms in the mantle 4. Volcanos are randomly located across the earth surface 5. Many volcanoes exist under the oceans 6.

What is a scientific hypothesis? A. A collection of data that generates a scientific observation B. A final decision that describes a scientific model C. A rigorous procedure that produces scientific data D.

Many plants such as orchids are grown by a technique called tissue culture. small pieces of plant tissue from a leaf, stem, or root of a mature plant are placed in a medium that contains the proper nutrients.

Which macromolecules is the cause of hemophiia

Which is a type of muscle that powers the cardiovascular system? A. Skeletal muscle B. Cardiac muscle C. Cartilage muscle D. Smooth muscle

To investigate how the sex of an offspring is determined

Tightly curled hair is caused by a dominant autosomal gene in humans. This trait is rare among northern Europeans.

The rapid depolarization phase of the action potentials of myocardial contractile cells is due primarily to which ion (s) ?

Echinoderm reproduction typically is a. sexual reproduction by budding. b. sexual reproduction with internal fertilization. c. by regeneraton. d. sexual reproduction with external fertilization.