How many mammal species exist today?

Which of the following causes genetic disorders and permanent changes in the DNA sequence? a. mitosis b. meiosis c. mutation d. none of these

Which of the following does not occur during the embryonic stage? a. the bones become fully developed. b. the tail begins to recede. c. the heart, brain, and spinal cord develop. d. the eyes and ears begin to form.

Using recombinant DNA techniques, you have replaced the trp operon's leader peptide open reading frame in Escherichia coli with the one from the phe (phenylalanine) operon.

Which two statements best describe the effects of ocean currents on weather? A. Cold currents remove thermal energy from the air above them. B. Warm currents warm the air above them. C.

A description of natural events that has been proven to be true time after time, without exception. This describes A) data. B) a theory. C) a conclusion. D) a law.

1. true false Carbon atoms form the building blocks of most living things.

Inhibiting enzymes involved in cell wall synthesis leads to which of the following? A) cell death by osmotic lysisB) a reduction in protein synthesisC) the incomplete synthesis of the bacterial cell wallD) a reduction in the amount of usable energy

In the 20th century where did the most ecologically destructive oil spill in the US

Which of the activities listed below are functions of the Lymphatic System? 1 transports lipids to the blood 2 transports lipid-soluble vitamins to the blood 3 drains excess interstitial fluid from tissue spaces and returns it to the blood 4

Under which circumstances must facilitated diffusion be used instead of simple diffusion?