The channels in cell membranes that help substances to move in and out 20 poll of cells during active transport are made of
A. protein.
B. chlorophyll.
C. cytoplasm
D. carbohydrates
NEED ASAP

The observations of hooke and van leeuwenhoek documenting the existence of microscopic cells formed the basis of what important theory? a. the cell theory stating that all living things are composed of cellsb. the theory of spontaneous generation, which held that life forms could arise spontaneouslyc. the theory of chemotherapy, or use of antimicrobials to destroy pathogenic organismsd. the germ theory of disease and causative agents

Mutations associated with albinism affect proteins involved in synthesis

What is any method of measuring the age of an object or event in years, such as using atomic half-life?