Which noncoding rna coats the inactive x-chromosome in regions of heterochromatin?

How many trophic levels are there in the following food chain? phytoplankton - shrimp - perch - pike - osprey

The breakdown of food is accomplished by enzymes. a. physical b. chemical c. mechanical d. none of the above

2. which of the following statements does not accurately describe stem cells? a. embryonic stem cells make up the inner cell mass of a blastocyst. b. with more research, stem cells may be used to repair or replace damaged cells. c. the use of stem cells is without any objections since it can be used in therapies to humans. d. adult stem cells are multipotent and can differentiate into many types of cells.