Two organisms are shown in the diagram below. The arrows in the diagram indicate structures that help these organisms
A. detect changes in their environments.
B. move through their environments,
C. obtain nutrients from their environments,
D. exchange gases with their environments,

The concept of keystone species is controversial among ecologists because most organisms are highly interdependent. if each of the trophic levels is dependant on all others how can we say one is most important

The first amino acid of a new polypeptide chain is

7. describe two strategies that parents can use to cope with stress. 8. describe the three types of childcare available to families. 9. what can parents do to be more involved in their children's education at home and at school? 10. which factors should a parent consider when choosing a childcare option?