If you live on a river delta or coastline, you may not be able to eat the local shellfish because of high levels of toxins, even though you may be able to drink the water taken from the same source. Why?
A. Shellfish filter-feed and concentrate the dilute pollutants from the water, thus acting as early warning indicators of severe pollution.
B. Shellfish regularly consume poisonous red tide organisms.
C. Shellfish seasonally produce toxic substances.
D. Most harmless native clams have been replaced by bad species.
Answer: A
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The organisms formerly classified in the Kingdom Protista ________
A) all contain chloroplasts B) form a single monophyletic group C) include the last universal common ancestor (LUCA) of life D) are scattered throughout all branches of the eukaryote family tree E) have a fossil record extending back 3.4 million years
Which of the following statements about DNA replication is NOT correct?
A. Complementary base pairs are held together with hydrogen bonds. B. Unwinding of the DNA molecule occurs as hydrogen bonds break. C. Replication occurs as each base is paired with another exactly like it. D. The enzyme that catalyzes DNA replication is DNA polymerase. E. The process is known as semiconservative replication because one old strand is conserved in the new molecule.
Carbon dioxide and other greenhouse gases cause Earth's temperature to increase by
A) reducing photosynthetic rates. B) absorbing heat energy and holding it close to Earth. C) increasing the amount of radiation from Earth's surface. D) increasing plant respiration. E) allowing greater transmission of incoming solar radiation.
Immersion oil is used to prevent a specimen from drying out.
Answer the following statement true (T) or false (F)