(Q).
Q: Groundwater does what to the rock beneath the ground surface? Read this paragraph and choose the correct option from the provided answers: Groundwater erodes rock beneath the ground surface. Limestone is a carbonate and is most easily eroded. Choices: - accelerates it - creates it - boosts it - erodes it A:
(A).
erodes it

(Q).
Q: What kind of structure do purines have? Read this paragraph and choose the correct option from the provided answers: Figure 3.31 A nucleotide is made up of three components: a nitrogenous base, a pentose sugar, and one or more phosphate groups. Carbon residues in the pentose are numbered 1 through 5 (the prime distinguishes these residues from those in the base, which are numbered without using a prime notation). The base is attached to the 1 position of the ribose, and the phosphate is attached to the 5 position. When a polynucleotide is formed, the 5 phosphate of the incoming nucleotide attaches to the 3 hydroxyl group at the end of the growing chain. Two types of pentose are found in nucleotides, deoxyribose (found in DNA) and ribose (found in RNA). Deoxyribose is similar in structure to ribose, but it has an H instead of an OH at the 2 position. Bases can be divided into two categories: purines and pyrimidines. Purines have a double ring structure, and pyrimidines have a single ring. Choices: - triple ring structure - single ring structure - helical stucture - double ring structure A:
(A).
double ring structure

(Q).
Q: Prokaryotic cells can only regulate gene expression by controlling the amount of what? Read this paragraph and choose the correct option from the provided answers: Evolution of Gene Regulation Prokaryotic cells can only regulate gene expression by controlling the amount of transcription. As eukaryotic cells evolved, the complexity of the control of gene expression increased. For example, with the evolution of eukaryotic cells came compartmentalization of important cellular components and cellular processes. A nuclear region that contains the DNA was formed. Transcription and translation were physically separated into two different cellular compartments. It therefore became possible to control gene expression by regulating transcription in the nucleus, and also by controlling the RNA levels and protein translation present outside the nucleus. Some cellular processes arose from the need of the organism to defend itself. Cellular processes such as gene silencing developed to protect the cell from viral or parasitic infections. If the cell could quickly shut off gene expression for a short period of time, it would be able to survive an infection when other organisms could not. Therefore, the organism evolved a new process that helped it survive, and it was able to pass this new development to offspring. Choices: - folding - translation - RNA processing - transcription A:
(A).
transcription