Which compound was abundant in Precambrian Earth's oceans, before complex life evolved on Earth?

A.

dissolved oxygen

B.

dissolved carbon dioxide

C.

dissolved methane

D.

dissolved ammonia

Some of the drugs used to treat hiv patients are competitive inhibitors of the hiv reverse transcriptase enzyme.

Two species of clams inhabit the same marine habitat along the Atlantic coast. One releases gametes into the water in early spring, and the second species releases gametes into the water in late summer.

Because they cannot vomit and are not prone to aspiration pneumonia, which of the following animals should not routinely be fasted prior to surgery? DogsCatsPrimates

What removes the oxygen from the air? A. Photosynthesis B. Respiration C. Sunlight D. Water

Which of these steps is NOT part of the process of scientific inquiry? A) asking questions B) taking measurements C) stating beliefs D) performing tests

The genes on a chromosome were represented as abcdefgh. after chromosomal breakage the order was found to be abcefgh. which type of change has occurred in chromosomal structure

The failure of homologous chromosomes to separate during meiosis is called a. skin disorders b. translocation. c. nondisjunction. d. Down syndrome.

As the wavelength increases, the frequency (A) decreases and energy decreases. (B) increases and energy increases. (C) decreases and energy increases. (D) increases and energy decreases.

The most obvious source of gene flow into any population is A) Emigration B) Immigration

Polypeptides and proteins must fold properly to be functional. Hydrogen bonds between the oxygen and nitrogen atoms of the peptide bonds are crucial to which level of protein structure?1. primary structure2. tertiary structure3. secondary structure4.