The pitted end walls of sieve elements are called ____.
A. plasmodesmata
B. sieve tubes
C. companion cells
D. perforation plates
E. sieve plates
Answer: E
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In a eukaryotic cell, a gene that is initially transcribed is 1500 nucleotides in length. The mature mRNA for the product is 1200 nucleotides in length. What is the most probable reason for the discrepancy?
A) a mutation that results in a shorter product B) removal of introns C) removal of exons D) mRNA breakage E) both choices A and D
A cell moves sodium ions against its concentration gradient. This is an example of ____
a. active transport b. osmosis c. diffusion d. facilitated diffusionc e. diffusion through a channel
Approximately how many base pairs are improperly matched before being repaired by the DNA polymerase?
A. 1 in 10,000,000 B. 1 in a billion C. 1 in 100,000 D. 1 in 1,000,000 E. 1 in 10,000
Straps of connective tissue that hold bones together, support joints, and direct movement are known as ________
A) tendons B) ligaments C) bursae D) cartilages