Microscopes are often used to examine specimens which are too small to see in detail using only the human eye. Which of the following procedures should be followed prior to placing a specimen slide on the stage of the microscope?
A.
Turn the objective lens to the lowest magnification setting.
B.
Focus the microscope on the light source.
C.
Spit on the eyepiece to make sure that it is clean.
D.
Close the diaphragm so no light can enter.

Acommon kind of mechanical weathering is called

Which of these is true of the cytoplasm of an unfertilized egg? a. it is an unevenly distributed mixture of mrna, proteins, organelles, and other substances. b. it does not contain substances that are important in directing development. c. these substances are supplied by the sperm. d. it does not contain substances that are important in directing development. e. development is directed solely by the surrounding cells. f. it is a homogeneous mixture of mrna, proteins, organelles, and other substances. g. it does not contain substances that are important in directing development. h. these substances are produced by the dna of the fertilized zygote.

Make a claim about the factors that cause inherited genetic variations within populations. also make a claim about the effects of mutations.