33. Plant Anatomy

Splicing begins:a. as transcription occurs.b. after transcription is complete.c. as translation occurs.d. after translation is complete.

What is the role of companion cells in the movement of sugars through plants?a. They are the sites of sugar production by photosynthesis.d. They are the sites where starch is converted to sucrose.c. They secrete sucrose, which draws sugars through phloem under negative pressure.d. They accumulate sucrose, which is then transferred to adjacent sieve-tube elements.

Compared with mRNAs that have a cap and tail, predict what will be observed if a eukaryotic mRNA lacked a cap and poly(A) tail.a. The primary transcript would not be processed properly.b. Translation would occur inefficiently.c. Enzymes on the ribosome would add a cap and poly(A) tail.d. tRNAs would become more resistant to degradation.

Which of the following would not be seen in a cross section through the woody part of a root?a. sclerenchyma cellsb. parenchyma cellsc. sieve-tube elementsd. root hairs